VERTEBRATE RESPONSE TO A TIDAL
MARSH RESTORATION IN
HUMBOLDT BAY, CALIFORNIA
by
Sandra L. Jacobson
A Thesis
Presented to
The Faculty of Humboldt State University
In Partial Fulfillment
of the Requirements for the Degree
Master of Science
December, 1986 VERTEBRATE RESPONSE TO A TIDAL
MARSH RESTORATION IN
HUMBOLDT BAY, CALIFORNIA
by
Sandra L. Jacobson
Approved by the Master's Thesis Committee
Paul F. Springer
Stanley W. Harris
Director, Natural Resources Graduate Program Date
86/W-59/05/22 Natural Resources Graduate Program Number
Approved by the Dean of Graduate Studies
Alba M. Gillespie
ABSTRACT
A 5.5-ha abandoned log pond (originally salt marsh) at the end of Park Street, Eureka, California was chosen as the off-site mitigation area for the destruction of 6.8 ha of wildlife habitat during the construction of the Woodley Island marina. Passive saltmarsh restoration was attempted by breaching a dike separating the log pond from Freshwater Slough (an estuary of Humboldt Bay) in December 1980, thus allowing the periodic tidal intrusion of salt water into 3.8 ha of the area. This study measured the response of amphibians, reptiles, birds, and mammals to the change in vegetation and other habitat conditions brought about by the reestablishment of tidal action.
Previously, in August 1979 an interior dike had been constructed within a portion of the mitigation area to enhance an existing 0.7-ha freshwater marsh, and the effect of this change on the vertebrate life also was appraised.
Frogs disappeared and snakes declined in numbers within the tidal portion of the mitigation area after the dike was breached.
Savannah Sparrows (Passerculus sandwichensis) were the most common birds
in the grassland of the dried log pond before breaching, and declined after breaching. Several species of shorebirds and the Snowy Egret
(Egretta thula) increased their use of the tidal portion of the mitigation area after breaching. Small mammals such as California Vole
(Microtus californicus), Vagrant Shrew (Sorex vagrans), and Western
Harvest Mouse (Reithrodontomys megalotis) were common before breaching,
iii iv but declined in numbers in the first month after breaching. Use of the area by the most common large mammal, the Domestic Dog (Canis familiaris), increased after breaching because people used the flooded marsh to train retrievers.
Within the freshwater marsh five species of birds showed significant increases in numbers during subsequent corresponding seasons, whereas one species showed a significant decrease in numbers.
The success of the restoration after breaching was not fully known at the end of 1.5 years of study, but the trend was towards a renewed, vigorous salt marsh. In addition, the interior dike construction enhanced the freshwater marsh. In the interim the tidal and freshwater marshes provided valuable foraging areas for many species of wetland birds, and the freshwater marsh also served as a nesting area for certain bird species. ACKNOWLEDGEMENTS
I wish to acknowledge the great deal of help provided to me throughout this project.
Financial support was provided by the U. S. Fish and Wildlife
Service through a contract with the Humboldt State University
Foundation, which, in turn, administered the study through the Wildlife
Research Field Station.
Special thanks go to Dr. Paul Springer, whose advice and expert professional help went a long way toward making the project a success.
I especially acknowledge his editorial help; without it I would have missed an important step in my education.
My other committee members, Drs. Stan Harris and John Sawyer, also contributed their time and expertise for my benefit. I appreciate not only the professional help but also the moral support.
Dr. Dave Craigie helped me with the statistical analyses and interpretations. Pat Collins introduced me to the SPSS analysis and helped me to learn the seemingly thousands of details needed to successfully work with a computer.
Dana Base, John Sterling and John Kelly helped with the field
work on those days I was unable to work. Jan Kastler expertly typed the
thesis, and Laura Montagna prepared the figures.
The final person instrumental to the success of the project
contributed neither professional expertise nor field time. He did contribute love, encouragement, moral support, and gas for the many vi trips I took from my summer job sites to the study sites. He is my husband, Chris, and without his contributions I would have had a much more difficult, if not impossible, task in finishing the project. So to
Chris I address my deepest appreciation and thanks. TABLE OF CONTENTS
Page
ABSTRACT iii
ACKNOWLEDGEMENTS
LIST OF TABLES xi
LIST OF FIGURES xii
INTRODUCTION 1
STUDY AREAS 6
METHODS 13
Amphibians and Reptiles 13
Birds 13
Mammals 19
RESULTS 23
Amphibians and Reptiles 23
Birds 25
Saltmarsh Breeding Bird Counts 27
Saltmarsh Year-round Bird Counts 30
Snowy Egret 30
Black-shouldered Kite 32
Shorebirds 32
Vaux's Swift and Swallows 41
Marsh Wren 43
Emberizids 48
vii viii
TABLE OF CONTENTS (continued) Page
Western Meadowlark 53
American Goldfinch 55
Freshwater Marsh Breeding and Year-round Bird Counts . . 55
Mammals 61
Salt Marsh 61
Freshwater Marsh 64
DISCUSSION 66
Salt Marsh 66
Amphibians and Reptiles 66
Birds 66
Snowy Egret 67
Black-shouldered Kite 68
Shorebirds 68
Vaux's Swift and Swallows 69
Marsh Wren 70
Emberizids 70
Western Meadowlark 72
American Goldfinch 73
Mammals 73
Freshwater Marsh 75
Amphibians and Reptiles 75
Birds 75
Mammals 77
CONCLUSIONS 78
MANAGEMENT RECOMMENDATIONS 80
REFERENCES CITED 82 ix
TABLE OF CONTENTS (continued) Page
APPENDIXES
A. Common and Scientific Names of Amphibians and Reptiles Mentioned in the Text or Tables 88
B. Common and Scientific Names of Birds Mentioned in the Text, Tables or Appendixes 89
C. Common and Scientific Names of Mammals Mentioned in the Text or Tables 94
D. Common and Scientific Names of Plants Mentioned in the Text 95
E. Mean Number (and Standard Error) of Birds per Visit in Salt Marsh at the Mitigation Area, Eureka, California by Season 97
F. Mean Number (and Standard Error) of Birds per Visit in Salt Marsh at the Control Area, Eureka, California by Season 106
G. Mean Number (and Standard Error) of Birds per Visit in Freshwater Marsh at the Mitigation Area, Eureka, California by Season 112
H. Approximate Territorial Boundaries of Birds during the Breeding Bird Counts in 1979 at the Mitigation Area, Eureka, California 120
I. Approximate Territorial Boundaries of Birds during the Breeding Bird Counts in 1980 at the Mitigation Area, Eureka, California 121
J. Approximate Territorial Boundaries of Birds during the Breeding Bird Counts in 1981 at the Mitigation Area, Eureka, California 122
K. Approximate Territorial Boundaries of Birds during the Breeding Bird Counts in 1982 at the Mitigation Area, Eureka, California 123
L. Approximate Territorial Boundaries of Birds during the Breeding Bird Counts in 1980 at the Control Area, Eureka, California 124
M. Approximate Territorial Boundaries of Birds during the Breeding Bird Counts in 1981 at the Control Area, Eureka, California 125 x
TABLE OF CONTENTS (continued) Page
APPENDIXES (continued)
N. Approximate Territorial Boundaries of Birds during the Breeding Bird Counts in 1982 at the Control Area, Eureka, California 126 LIST OF TABLES
Table Page
1 Breeding Bird Count Dates at the Mitigation and Control Areas, Eureka, California 15
2 Number and Frequency of Occurrence of Amphibians and Reptiles Observed at the Mitigation Area, Eureka, California before and after Dike Breaching, 1979-1982 24
3 Species of Birds with Significant Differences in Numbers between at Least 2 Years at a Given Season in Salt Marsh at the Mitigation and/or Control Areas, Eureka, California, 1979-1982 . . . . 26
4 Numbers of Breeding Bird Territories during Breeding Bird Counts in Salt Marsh at the Mitigation and Control Areas, Eureka, California, 1979-1982 28
5 Species of Birds with Significant Differences in Numbers between at Least 2 Years at a Given Season in Freshwater Marsh at the Mitigation Area, Eureka, California, 1979-1982 57
6 Species of Birds with Significant Differences (P<0.05) in Numbers in Fall in Freshwater Marsh at the Mitigation Area, Eureka, California, 1980-1981. . 60
7 Number of Small Mammals Caught and the Calculated Density (No. animals/ha), Eureka, California, 1979-1981 62
8 Number and Frequency of Occurrence of Large Mammal Sign Observed at the Mitigation Area before and after Dike Breaching, Eureka, California, 1979-1982 63
9 Number and Frequency of Occurrence of Large Mammal Sign Observed in Salt Marsh at the Control Area before and after Dike Breaching, Eureka, California, 1980-1982 65
xi
LIST OF FIGURES
Figure Page
1 Location of Woodley Island Marina Site, Park Street Mitigation Area, and Bay Street Control Area on Humboldt Bay, Eureka, California 3
2 Habitat Types in 1979-80 before Dike Breaching and Bird Count Route in 1979 before Dike Construction at the Park Street Mitigation Area, Eureka, California 7
3 Habitat Types in 1981 after Dike Breaching and Bird Count Route in 1979-1982 after Dike Construction at the Park Street Mitigation Area, Eureka, California 9
4 Habitat Types and Bird Count Route at Bay Street Control Area, Eureka, California, 1980-1982 11
5 Small Mammal Trapping Grid Locations at the Mitigation Area, Eureka, California, in 1979, 1980 and 1981 20
6 Small Mammal Trapping Grid Locations at the Control Area, Eureka, California, in 1980 and 1981 21
7 Mean Number of Snowy Egrets in Salt Marsh at the Mitigation and Control Areas, Eureka, California, June 1979 to June 1982 31
8 Mean Number of Black-shouldered Kites in Salt Marsh at the Mitigation and Control Areas, Eureka, California, June 1979 to June 1982 . 33
9 Mean Number of Shorebirds in Salt Marsh at the Mitigation and Control Areas, Eureka, California, June 1979 to June 1982 34
10 Mean Number of Killdeer in Salt Marsh at the Mitigation and Control Areas, Eureka, California, June 1979 to June 1982 36
11 Mean Number of Greater Yellowlegs in Salt Marsh at the Mitigation and Control Areas, Eureka, California, June 1979 to June 1982 37
xii xiii
Figure Page
12 Mean Number of Least Sandpipers in Salt Marsh at the Mitigation and Control Areas, Eureka, California, June 1979 to June 1982 38
13 Mean Number of Common Snipe in Salt Marsh at the Mitigation and Control Areas, Eureka, California, June 1979 to June 1982 39
14 Mean Number of Vaux's Swifts in Salt Marsh at the Mitigation and Control Areas, Eureka, California, June 1979 to June 1982 42
15 Mean Number of Northern Rough-winged Swallows in Salt Marsh at the Mitigation and Control Areas, Eureka, California, June 1979 to June 1982 44
16 Mean Number of Cliff Swallows in Salt Marsh at the Mitigation and Control Areas, Eureka, California, June 1979 to June 1982 45
17 Mean Number of Barn Swallows in Salt Marsh at the Mitigation and Control Areas, Eureka, California, June 1979 to June 1982 46
18 Mean Number of Marsh Wrens in Salt Marsh at the Mitigation and Control Areas, Eureka, California, June 1979 to June 1982 47
19 Mean Number of Savannah Sparrows in Salt Marsh at the Mitigation and Control Areas, Eureka, California, June 1979 to June 1982 49
20 Mean Number of Song Sparrows in Salt Marsh at the Mitigation and Control Areas, Eureka, California, June 1979 to June 1982 52
21 Mean Number of Western Meadowlarks in Salt Marsh at the Mitigation and Control Areas, Eureka, California, June 1979 to June 1982 54
22 Mean Number of American Goldfinches in Salt Marsh at the Mitigation and Control Areas, Eureka, California, June 1979 to June 1982 56 INTRODUCTION
Along with many other bays, Humboldt Bay in northern coastal
California has had a drastic reduction in the acreage of surrounding salt marsh in the last hundred years caused by diking, filling, and industrial development (Monroe et al. 1973, Shapiro et al. 1980). In recent years, however, preservation and restoration of salt marshes for their wildlife and human values have been emphasized (Monroe et al.
1973, Daiber 1977). Unfortunately, saltmarsh restoration, especially with emphasis on fish and wildlife resources, is a relatively new concept (LaRoe 1979), and techniques are not yet well developed.
Recently, however, guidelines for restoration based on experience to date have been set forth (Harvey et al. 1983, Josselyn and Buchholz
1984, Zedler 1984).
In order to offset the loss of or damage to wildlife resources from proposed water-resource development programs, the Fish and Wildlife
Coordination Act of 1934 as amended (U.S. Code 1982) requires the preparation of proposed measures for "mitigating or compensating" for such damage, but does not define the terms. The President's Council on
Environmental Quality (1983) defined the term "mitigation" in the
National Environmental Policy Act (U.S. Code 1976) regulations to include among other measures the "compensating for the impact by replacing or providing substitute resources or environments." The U. S.
Fish and Wildlife Service (USFWS) (1981) has adopted this definition and has recommended various mitigation means and measures including
1 2
compensating for impacts by conducting habitat construction activities
to fully restore or rehabilitate previously altered habitat. In this
context the USFWS has defined compensation as "full replacement of
project-induced losses to fish and wildlife resources." The California
Coastal Act of 1976 (California Public Resources Code 1976) requires
mitigation in certain cases of coastal land use development, especially
where the degradation of wetlands is concerned. Claycomb (1983)
contains further discussion of pertinent legislation.
The construction of the Woodley Island marina in Humboldt Bay
(Figure 1) by the Humboldt Harbor, Recreation and Conservation District
in 1979-81 destroyed 1.2 ha of salt marsh, 2.4 ha of mudflat, and 3.2 ha
of riparian and upland habitat. As part of the permit from the
California Coastal Commission, in which "mitigation" of this loss was
required, the District purchased, in 1979, a 7.9-ha property at the end
of Park Street, Eureka, California. It encompassed a 5.5-ha abandoned
log pond, formerly a tidal salt marsh, and was to be restored to its
original condition by breaching a portion of the surrounding dike. In
addition, an interior dike was to be constructed to enhance an existing
freshwater marsh. From June 1979 to July 1982 this study was conducted
to determine the success of the restoration program. In order to
provide a standard against which the degree of success could be
measured, a nearby undiked salt marsh at the end of Bay Street was
selected as a control area.
Prior to initiation of this project, no saltmarsh restoration
projects had been attempted in Humboldt Bay. In August 1980, dike
breaching along the lower part of Elk River, an estuary of mid Humboldt
Bay, commenced. Preliminary findings indicated that restoration of the 3 Area on Humboldt Bay, Eureka, California. Area on Humboldt Bay, Eureka, Figure 1. Location of Woodley Island Marina Site, Park Street Mitigation Area, and Bay Street Control Island Marina Site, Park Street Mitigation Area, Figure 1. Location of Woodley 4 saltmarsh vegetation and its associated bird and mammal life was
proceeding at a relatively slow rate because the high elevation of the area did not permit complete tidal flooding (Stopher et al. 1981, Base
1982b, Caltrans 1982).
Another saltmarsh restoration project was undertaken at the
Bracut marsh in North Humboldt (Arcata) Bay in 1981 through excavating fill, breaching the surrounding dike, and planting marsh vegetation
(Josselyn and Buchholz 1982). Although no study of the project has been
conducted, general observation indicates that restoration is proceeding
slowly (Paul Springer, Wildlife Department, Humboldt State University,
Arcata, CA 95521). In September 1983 a third saltmarsh restoration
project was initiated by installation of a tide gate on a degraded marsh
along Elk River, 0.4 km northwest of the previous project there.
Results to date show little change in the vegetation (Gail Newton, P. 0.
Box 234, Arcata, CA 95521) because the tide gate was not opened until
November 1984.
Similarly, the results of saltmarsh restoration in other areas
along the Pacific Coast are not always directly comparable because the ecological factors at the marshes are quite different (Macdonald 1977).
In San Francisco Bay and south the halophyte growing at the lowest elevation is California Cordgrass (Spartina foliosa) (Macdonald 1977), and, particularly in southern California where precipitation is low, soil moisture is provided primarily by seawater (Zedler 1982). In
Humboldt Bay, precipitation is heavy and Pickleweed (Salicornia
virginica) is the halophyte found at the lowest elevation. North of
Humboldt Bay, increasingly heavier precipitation permits tidal marsh 5 vegetation to become established at lower elevations in relation to mean sea level (Eilers 1975, Jefferson 1975).
In a study in the Salmon River estuary of Oregon, Mitchell
(1981) found that salt marsh was being restored successfully during the
2 years following breaching of a dike; however, the restored marsh would not be the same functionally and compositionally as the marsh prior to diking because too many changes had occurred that changed the potential of the site. She did not address the restoration as it affected the fauna of the site.
The primary objective of this study was to determine the success of saltmarsh restoration at the mitigation area at Park Street based on
(1) utilization of the area by amphibians, reptiles, birds and mammals before and after breaching of the dike, and (2) comparison with conditions at a nearby control salt marsh at Bay Street. A secondary objective was to determine the changes caused by construction of an interior dike within the mitigation area to enhance an existing freshwater marsh. STUDY AREAS
A detailed description of both the restoration site at Park
Street and the control marsh at the foot of Bay Street is provided by
Claycomb (1983). Following is a summary. Plant names primarily follow
Munz and Keck (1973) or Mason (1957).
The abandoned log pond portion of the Park Street property
(Figure 2), hereafter referred to as the mitigation area, is located
along Freshwater Slough at the north side at the end of Park Street
(40°47'N, 124°07'W, Arcata South Quadrangle, USGS). Three distinct
habitats were present on the mitigation area prior to dike breaching:
grassland and remnant salt marsh, freshwater marsh, and dike. The central area (3.8 ha) became tidal when the north dike was breached on
18 December 1980. Grassland (3.2 ha) within the central area consisted of Hairgrass (Deschampsia caespitosa) and escaped cultivated species
including Beard Grass (Polypogon monspeliensis), Italian Ryegrass
(Lolium multiflorum), and Velvet Grass (Holcus lanatus). Also occurring
were nongrass species including Bird's-foot Trefoil (Lotus
formosissimus), Brass-buttons (Cotula coronopifolia), Saltbush (Atriplex
patula), Curly Dock (Rumex crispus), and Salt Rush (Juncus lesueurii).
About 0.6 ha of the central area was remnant salt marsh consisting of
Saltgrass (Distichlis spicata), Pickleweed, Cordgrass (Recent studies by
Spicher [1984] indicate that the species growing at Humboldt Bay is not
California Cordgrass but, instead, Spartina densiflora, which was
introduced from South America), Arrow-grass (Triglochin maritimum), and
6 7
Figure 2. Habitat Types in 1979-80 before Dike Breaching and Bird Count Route in 1979 before Dike Construction at the Park Street Mitigation Area, Eureka, California. 8
Ditch-grass (Ruppia maritime). At the beginning of the study in June
1979 a freshwater marsh formed by springs was located in the southwest corner of the central area. Typical freshwater marsh plants such as
Common Cat-tail (Typha latifolia) graded into the remainder of the central area and also grew thickly along the drainage ditch from the freshwater marsh to the north end of the central area. In August 1979 an interior dike was constructed and a tide gate installed to separate the freshwater marsh from the rest of the central area and to prevent inflow of tidal water after breaching of the north dike.
In the year after dike breaching (Figure 3) the central grassland became increasingly similar to typical Humboldt Bay salt marsh characterized by Pickleweed, Saltgrass, and Cordgrass. Plants present that were not adapted to saline conditions declined, and the areas where those species had occurred were covered with decaying vegetation for much of the remaining study period. Ponded areas occurred in the northwestern, northeastern, and southwestern corners of the original grassland where no drainage systems had yet developed
(Claycomb 1983).
The freshwater marsh (0.7 ha) at the southwest corner of the study area increased in depth from about 0.2 m to 1.2 m after construction of the interior dike. The marsh supported typical freshwater marsh plants including Common Cat-tail, Marsh Pennywort
(Hydrocotyle ranunculoides), Willow (Salix hookeriana), Water Celery
(Oenanthe sarmentosa), and Red Alder (Alnus oregana) and a brackish water plant, Salt Rush, that continued to survive (Claycomb 1983).
Dikes occupied 1.0 ha and prevented tidal flow into the small freshwater marsh on the mitigation area, and, before breaching, the 9
Figure 3. Habitat Types in 1981 after Dike Breaching and Bird Count Route in 1979-1982 after Dike Construction at the Park Street Mitigation Area, Eureka, California. 10 central restoration area. Some of the existing dikes were reinforced in
August 1979 when the dike that protects the freshwater marsh was constructed. This resulted in the loss of a well-developed patch of
California Blackberries (Rubus vitifolius) along the northern edge of the mitigation area. The newly built and reinforced dikes were fertilized and seeded with Soft Chess (Bromus mollis), Tall Fescue
(Festuca arundinacea), Red Alder, and California Blackberry soon after construction, but germination was poor (W. Woodroof, California Coastal
Commission, Eureka, CA 95501). The principal vegetation developing on the new dikes were several species of grasses including Hairgrass,
Velvet Grass, Italian Ryegrass, and Beard Grass and non-grass species such as Bird's-foot Trefoil. Vegetation on the undisturbed dikes consisted primarily of Coyote Brush (Baccharis pilularis), Wax-myrtle
(Myrica californica), and California Blackberry. A small patch of salt marsh consisting of Cordgrass and Pickleweed bordered the eastern dike along Freshwater Slough (Claycomb 1983). Although this was not strictly dike habitat, it was most practical to include this and the narrow stringers of typical saltmarsh vegetation immediately bordering the slough with the dike habitat during the bird counts.
Freshwater Slough (1.3 ha), an estuarine branch of Eureka
Slough, bordered the mitigation area on the east. Hillside (1.1 ha) made up the remainder of the 7.9-ha tract purchased by the Humboldt
Harbor, Recreation and Conservation District.
The undiked marsh at Bay Street (Figure 4), hereafter referred to as the control area, was about 1.5 km west of the mitigation site, closer to the bay (40°48'N, 124°08'W, Eureka Quadrangle, USGS), and occupied approximately 6.2 ha. It was a kidney-shaped tract bordered by 11 Figure 4. Habitat Types and Bird Count Route at Bay Street Control Area, Eureka, California, 1980-1982. Bird Count Route at Bay Street Control Area, Eureka, Figure 4. Habitat Types and 12
First Slough and Eureka Slough on the north; Third Slough on the east; uplands, additional marsh, and a low dike on the south; and a recreational vehicle park on the west. Eureka Slough is a major estuary of Humboldt Bay; the others are branch estuaries. Another small estuary, Second Slough, bisected the area.
The control area had three distinct habitats. The largest was salt marsh (5.1 ha). Pickleweed, Saltgrass, and Cordgrass were dominant
species, and Salt Rush, Saltbush, and Gum-plant (Grindelia stricta) were
secondary species. Salt marsh was used as the standard to appraise the
success of restoration at the mitigation area after breaching.
Dikes occupied 0.4 ha. The dike parallel to Eureka Slough was dominated by Coyote Brush and Hairgrass. The higher ground separating
the recreational vehicle park from the marsh also was classed as dike
because of the similarity in function and vegetation. In addition to
the previously mentioned species, it also supported Argentine Pampas-
grass (Cortaderia selloana) and Willow. The low dike west of the foot
of Bay Street was occupied predominantly by Hairgrass and bare ground.
The last habitat at the control area was tidal slough (0.7 ha).
It included the channels of Second and Third Sloughs up to the permanent
vegetation line but excluded all of Eureka Slough and First Slough.
The control area experienced no habitat changes during the
study. METHODS
Amphibians and Reptiles
No systematic sampling was performed for amphibians and reptiles. Any species observed on the regular bird count was noted, along with its location. Amphibian and reptile names follow Stebbins
(1966).
Birds
Two general techniques were used to count birds: mapping territories from late May to early July during the breeding season (Hall
1964) and mapping the location of individuals during both the breeding and non-breeding season to determine a mean population index, following the method described by Kolb (1965) for winter bird counts. The spacing between adjacent count routes within an area was established to allow detectability of all species but far enough apart to allow the count to be completed within 2 hours' time. At the mitigation area this route
(Figures 2 and 3) was generally a series of north-south transects approximately 70 m apart (45 m to 90 m). At the control area (Figure 4) a circuitous route ranging from 2 m to about 70 m between adjacent parts of the route was required to cover all portions of the site adequately.
Analysis for the summer season also included those visits made during the breeding bird counts.
13 14
For both methods, birds flying over the area but not obviously
feeding within it were not counted; however, birds such as swallows or
raptors which foraged or hunted over the area were counted. Swallows
and Vaux's Swifts (Chaetura vauxi) presented a difficult counting
problem due to their mobility. A 5-minute index (Sorensen 1977) was
attempted during summer 1979 and abandoned after a study of the data
showed obvious inaccuracies. An estimate of the average number of
individuals during a count yielded a more intuitively satisfying result.
However, error was probably higher in the late summer when more
individuals were present. Although swifts and swallows used all
habitats, they were arbitrarily recorded as occurring in the grassland
(before breaching) or salt marsh (after breaching) of the mitigation
area and the salt marsh of the control area for practical reasons.
Because too few samples were taken during the summer of 1979, this
season was excluded from analysis of results for swallows, but their
numbers are included in the graphs.
Counts were conducted from June 1979 through June 1982 at the
mitigation area and from June 1980 through June 1982 at the control area
(Table 1). Between July and November 1979 the number of individuals was
tallied but their location was not mapped, so this period is excluded in
the statistical analyses. Generally, eight counts were considered
adequate to delineate the territories of all breeding pairs. One
breeding bird count (BBC) per year was conducted at each site, for a
total of four at the mitigation area (1979-1982) and three at the
control area (1980-1982). 15
Table 1. Breeding Bird Count Dates at the Mitigation and Control Areas, Eureka, California.
Year Mitigation area Control area
1979 June 12-23 -
1980 May 29-June 7 June 11-July 7
1981 May 23-June 28 June 12-July 1
1982 June 5-27 June 5-27 16
A species was recorded in the habitat in which it was first located. All totals were converted into birds/100 ha for statistical comparisons.
Findings at the mitigation and control areas were compared statistically both before and after dike breaching. Comparisons were also made in the freshwater marsh of the mitigation area before and after dike construction. Finally, comparisons were made between the mitigation area and the control area after breaching. Birds frequenting dikes and sloughs were not included in the analysis; the effect of their inclusion would have been to reduce any apparent treatment effects because these habitats were not immediately and directly affected by the restoration process.
Techniques can be used to study differences in bird populations between areas and among habitat types subject to certain types of bias
(Dawson 1981a). Following are some of the possible sources of bias in this study and how they were dealt with.
A significant source of variability in censusing birds is weather (Robbins 1981a). The weather around Humboldt Bay is maritime in nature and not subject to extreme temperature. Counts were not conducted on days with heavy rain or strong winds.
Bird densities vary seasonally with changes in demographic parameters; apparent numbers also change seasonally with the changing conspicuousness of individuals (Dawson 1981b). Conner and Dickson
(1980) recommended counting both before and after treatment in treated and control sites to lessen seasonal variability problems. Anderson et 17 al. (1981) found significant annual variation in 4.5 years of study of an avian population and recommended "sufficient replications of seasons and years to give credence to conclusions". In this study, counting commenced on the treatment site 1.5 years before the breaching of the dike, and on the control marsh 0.5 year before breaching. Counts in both areas were continued for 1.5 years after breaching. Counts were divided into four seasons for statistical analysis. Summer was considered to extend from June 1 to August 31, fall from September 1 to
December 18, winter from December 19 to February 28 and spring from
March 1 to May 31. December 18, 1980 was the date of dike breaching and was used as the date to separate the fall and winter seasons. Two species, Least Sandpiper (Calidrus minutilla) and Western Meadowlark
(Sturnella neglecta), required slight modifications of the above dates in order to conform more closely with their seasonal activity patterns.
For most bird species that are not affected by tidal cycles, peaks of activity occur early in the morning and gradually decline towards a low level during midday (Robbins 1981b). Most counts on both areas were completed before noon PST. When both areas were visited on one day, as was usually the case, the area visited earliest was
alternated. The amount of time spent at each area was approximately equal for individual observers, ranging from 1 to 2 hours. A steady
pace was maintained through an area except for pauses to record data or
to listen for songs (Shields 1979).
An attempt was made to visit each area at both high and low tide each week, but the logistical problem of dealing with weather, time of 18 tides and the need to count in early morning made this impossible.
Nevertheless, the same number of high and low tides among all visits was achieved. The average time between counts was 5 days. Counts were not conducted during very high tides because of safety considerations. Tide level was classified according to the average tide elevation during the visit.
The assumption of homogeneity of variances was severely violated when standard parametric analysis of variance tests were used, and transformations of the data were unsuccessful. Therefore, two non- parametric tests were used to statistically analyze the data:
Kruskal Wallis analysis of variance and Mann-Whitney U-test (Daniel 1978).
Except where otherwise stated, the probability level chosen for significance testing was 0.05. If the Kruskal-Wallis test indicated significant differences were present, Dunn's multiple comparison method
(Daniel 1978) with an experiment-wise error rate of 0.15 was used to determine which groups were different. Among the 5 area/year groups studied, 10 paired comparisons were made. The comparison-wise error rate was much lower than 0.15 but could not be stated exactly. In the freshwater marsh, Kruskal-Wallis analysis of variance was used for all seasons except fall when the Mann-Whitney U-test was used because habitats were not distinguished finely enough in fall 1979 to allow that year to be included in the analysis of the freshwater marsh.
Comparisons among years and areas were not always reported when significant differences were not revealed. The SPSS computer package was used for all statistical analyses (Nie et al. 1975).
A number of sources of variability can occur among observers
(Raitt 1981). Five observers conducted counts, all of whom were 19 qualified individuals familiar with the methodology of the project. No significant difference (Mann-Whitney U-test) was noted among results obtained by observers who counted during the same time period.
Bird names follow the Amereican Ornithologists' Union (1983).
Subspecies names (American Ornithologists' Union 1957) are used only for those species in which this information is pertinent.
Mammals
Small mammals were trapped in early summer at the mitigation area in 1979, 1980, and 1981, and at the control area in 1980 and 1981.
In all cases, 6.3 cm x 5.7 cm x 30.5 cm Sherman live traps were used with bait consisting of rolled oats and peanut butter; cotton balls were provided in the traps to reduce mortality from exposure. Traps were spaced 5 m apart in three or four rectangular grids of six traps by four traps (Figures 5 and 6).
Two of the original four trapping grid areas at the mitigation area were severely modified in 1979 because of dike construction and were abandoned. In 1980 and 1981 a new grid was established between these two grids, making a total of three grids. The traps were prebaited for 3 days prior to the beginning of the regular trapping period of 3 days. In 1979 only, Schnabel's capture-recapture methodology (Overton 1971) without prebaiting was used unsuccessfully at the mitigation area. Traps were checked in morning and evening; live animals were released from 100 m to 3 km away from the sites. A declining-rate-of-capture technique (Davis and Winstead 1980) was used at the mitigation area in 1980. Crude densities were determined by dividing the total number of animals trapped by the total area trapped. 20
Figure 5. Small Mammal Trapping Grid Locations at the Mitigation Area, Eureka, California, in 1979, 1980 and 1981. 21
Figure 6. Small Mammal Trapping Grid Locations at the Control Area, Eureka, California, in 1980 and 1981. 22
No systematic sampling was conducted for larger mammals at either site. Sign or direct sightings were noted during the bird
counts. All mammal names follow Jones et al. (1982). RESULTS
Amphibians and Reptiles
Before diking and breaching, Pacific Treefrogs (Hyla regilla) were the most frequently encountered amphibian, occurring commonly in the freshwater marsh and northwest corner of the central area (Table 2).
Common (Thamnophis sirtalis) and Western Terrestrial Garter Snakes
(Thamnophis elegans) were most frequently observed in grassland at the western edge of the mitigation area along the dikes.
No frogs were heard or seen within the elevations flooded by tidal water after breaching. At dike and hillside habitats in the mitigation area these species were observed at approximately the same frequency before and after breaching (0.10 percent before breaching,
0.16 percent after breaching). Three garter snakes were observed within the grassland habitat of the mitigation area both before and after breaching. Two of these snakes were observed after breaching and were found dead, close to a dike, during the first spring after tidal flow
was restored.
Garter snakes were the only reptiles observed in the control
area. Sightings were infrequent and occurred only on the higher portions of the dikes. No amphibians were observed in the area.
It was not possible to determine if construction of the interior dike affected reptile and amphibian numbers in the freshwater marsh.
The numbers of animals were not recorded consistently during the eight
visits before construction.
23 Table 2. Number and Frequency of Occurrence of Amphibians and Reptiles Observed at the Mitigation Area, Eureka, California before and after Dike Breaching, 1979-1982.
Salt marsh Freshwater marsh Before breaching After breaching Before breaching After breaching (n=86)8 (n=128) (n=86)a(n=86) (n=128)(n=128) Species No. Freq. (%) No. Freq. (%) No. Freq. (%) No. Freq. (%)
Pacific Treefrog (Hyla reqilla) 7 (8.1) 0 (0.0) 7 (8.1) 10 (7.8)
Red-legged Frog (Rana aurora) 3 (3.4) 0 (0.0) 1 (1.2) 2 (1.6)'
Western Pond Turtle (Clemmys marmorata) 0 (0.0) 0 (0.0) 1 (1.2) 0 (0.0)
Northern Alligator Lizard (Gerrhonotus coeruleus) 0 (0.0) 0 (0.0) 1 (1.2) 0 (0.0)
Common Garter Snake (Thamnophis sirtalis) 0 (0.0) 0 (0.0) 1 (1.2) 0 (0.0)
Western Terrestrial Garter Snake (Thamnophis eleqans) 3 (3.4) 0 (0.0) 0 (0.0) 0 (0.0)
Garter Snake sp. 0 (0.0) 3 (2.3) 0 (0.0) 4 (3.1)
aNumber of surveys. 2 4 25
Birds
Prior to dike breaching, the mitigation area was characterized
by grassland species of birds, principally the Savannah Sparrow
(Passerculus sandwichensis). After breaching, this species decreased,
and egrets and shorebirds increased as the tidal portion became
progressively more marshy (Appendix E). Seventeen species or groups of
species showed a significant difference (P<0.05, Kruskal-Wallis analysis
of variance) among counts in the mitigation area and in the control marsh before (1979-1980) and after (1981-1982) breaching (Table 3).
Differences were most marked in egrets, shorebirds, wrens, and sparrows.
By winter of 1981-82 the mitigation area had developed relatively large amounts of standing water because of rainfall and an incompletely developed drainage system. Five species or groups of species showed significant increases in numbers during this period compared to the one or two previous winters (see following individual species accounts). In the control area the Marsh Wren (Cistothorus palustris) increased in numbers starting in 1981 (Appendix F). It was the only species in the control area to show a significant difference in numbers during the study.
The construction of the interior dike in the mitigation area allowed water in the freshwater marsh from precipitation and springs to become 0.75 to 1.25 m deeper than before diking.- Both Virginia Rails
(Rallus limicola) and Marsh Wrens increased in number following diking
(Appendix 0).
In the mitigation area, 65 species and 3 groups of species were recorded in the grassland and remnant salt marsh; 45 species and 1 group 26
Table 3. Species of Birds with Significant Differences in Numbers between at Least 2 Years at a Given Season at the Mitigation and/or Control Areas, Eureka, California, 1979-1982. Probabilities are based on Kruskal-Wallis H; nonsignificance is noted ns.
Probability Breeding bird b c d Species Summers Fall Winter Spring counts
Snowy Egret (Egretta thula) 0.035 0.003 <0.001 <0.001 ns Black-shouldered Kite (Elanus caeruleus) ns <0.001 ns ns ns Killdeer (Charadrius vociferus) ns ns ns <0.001 ns Greater Yellowlegs (Trinqa melanoleuca) ns f ns <0.001 <0.001 ns Least Sandpiper (Calidris minutilla) 0.001 ns 0.001 0.025 ns Common Snipe (Gallinaqo gqallinaqo) ns ns 0.029 ns ns Shorebirds 0.002 <0.001 <0.001 <0.001 ns Vaux's Swift (Chaetura vauxi) 0.005 n932=8 ns ns ns Northern Rough-winged Swallowg (Stelgidopteryx serripennis) 0.028 ns ns ns ns Cliff Swallows (Hirundo pyrrhonota) <0.001 ns ns ns ns Barn Swallowg (Hirundo rustics) 0.045 ns ns ns ns Marsh Wren (Cistothorus palustris) <0.001 <0.001 <0.001 <0.001 <0.001 Savannah Sparrow (Passerculus sandwichensis) <0.001 0.005 <0.001 <0.001 <0.001 Song Sparrow (Melospiza melodic) <0.001 <0.001 <0.001 <0.001 0.001 Red-winged Blackbird (Aqelaius phoeniceus) ns ns ns ns 0.040 h Western Meadowlark (Sturnella neglects) ns 0.029 <0.001 ns 0.019 American Goldfinch (Carduelisallinaqo 0.037 ns ns ns <0.001 a Sample sizes: Mitigation area: 1979=8; 1980=15; 1981=24. Control area: 1980=16; 1981=24; d.f.=4. b Sample sizes: Mitigation area: 1979=4; 1980=14; 1981=23. Control Area: 1980=13; 1981=22; d.f.=4. c Sample sizes: Mitigation area: 1979-80=15; 1980-81=16; 1981-82=18. Control area: 1980-81=10; 1981-82=17; d.f.=4. d Sample sizes: Mitigation area: 1980=12; 1981=19; 1982=20. Control area: 1981=20; 1982=21; d.f.=4. e Sample sizes: Mitigation area: 1979=8; 1980=7; 1981=6; 1982=8. Control area: 1980=6; 1791=6; 14.932=8; d.f.=6. (Late summer season (July 15-August 30) significantly different. gThe three species of swallows had too few samplAgelaiusmmer 1979 to analyze; therefore, only four variables were analysed (d.f.=3). h Significantly different in late summer and fall combined (July 1- December 18). 27 of species of the total were recorded before breaching compared to 62 species and 2 groups after breaching (Appendix E). Sixty-two species were recorded in the freshwater marsh of the mitigation area (Appendix
G). Forty-four species were recorded in salt marsh in the control area
(Appendix F).
No significant difference (Mann-Whitney U-test) was detected between low and high tide censuses for any species at either the control or mitigation area within the seasons. However, shorebirds as a group and Least Sandpipers did show significant increases (P<0.05) at low tide during their period of peak abundance in late winter at the mitigation area.
Saltmarsh Breeding Bird Counts
Marsh Wrens were not significantly different in numbers of breeding birds before and in the first year after breaching at the mitigation area but were absent during the BBC in the second year after breaching (Table 4). Marsh Wrens were significantly more numerous at the control area in 1982 than in 1980. Numbers of wrens increased at the control area throughout the study period. The control area contained significantly more Marsh Wrens than the mitigation area in
1982. No significant difference in numbers was indicated between the two areas in 1980.
Savannah Sparrows were the most common breeding bird of the central grassland in the mitigation area before breaching, with three territories in 1979 and almost four in 1980 (Table 4). After breaching, their territories were significantly reduced to none in 1981 and one in
1982. Savannah Sparrows were not present as breeders at the control 28
Table 4. Numbers of Breeding Bird Territories during Breeding Bird counts in Salt Marsh at the Mitigation and Control Areas, Eureka, California, 1979-1982.
Number of territories
Mitigation area Control area 1979 1980 1981 1982 1980 1981 1982
Marsh Wren 0 1(2)a 3(1) 0 4 9 12
Savannah Sparrow 3 3(1) 0 1 0 0 0
Song Sparrow 0(1) 0(1) 0(1) 0(2) 2(6) - 6(4) 4
Western Meadowlark 0 1 0 2 0 0 0 aNumbers in parentheses indicate number of partial territories also occurring in salt marsh. 29 area; thus, they were significantly less numerous there than at the mitigation area before breaching, but their numbers in 1981 and 1982 were not significantly different between the two areas.
Song Sparrows occupied portions of the central area of the mitigation area only incidentally before and after breaching (Table 4).
Their territories centered on the dikes (Appendixes H-K). In each year of the study, at least one Song Sparrow territory partially included the central area. There was no significant difference in Song Sparrow numbers at the control area before and after breaching, but there were more territories in 1981 (six whole plus four partial territories) than in 1980 (two whole plus six partial territories) and in 1982 (four whole territories) (Table 4). Significantly greater numbers bred at the control area than at the mitigation area before breaching (1980) and after breaching (1981 only).
Red-winged Blackbirds were significantly more numerous at the mitigation area 1 year before breaching (1980) than during both years after breaching when they no longer occurred within the central area during the summer (Appendix E). They did not occur at the control area as a breeding species. Thus, they were significantly less numerous at the control area than at the mitigation area during the year before breaching (1980) but were not statistically different in numbers after breaching.
One Western Meadowlark territory was present at the mitigation area before breaching in 1980 and two were present after breaching in
1982 (Table 4). During the years in which no nesting occurred, both before (1979) and after (1981) breaching, meadowlarks were significantly different in numbers from those years in which they nested. Western 30
Meadowlarks did not occur as a breeder in the control marsh; thus, no significant difference in numbers was noted before and after breaching at that site. The control area had significantly fewer Meadowlarks than did the mitigation area during the 2 years that Meadowlarks bred in the latter area.
American Goldfinches were a significantly more numerous breeder at the mitigation area before breaching (1979 and 1980) than after breaching (1982) when they no longer bred at the site (Appendix E).
American Goldfinches did not occur as a breeding species at the control area and, thus, were significantly less numerous than at the mitigation area before breaching but not significantly different after breaching.
Saltmarsh Year-round Bird Counts
Year-round counts provided information on the mean number of birds in the salt marsh during the fall, winter, and spring, as well as during the summer but without regard to their breeding status. Larger numbers of birds were generally recorded during the summer on the year- round counts than on the breeding bird counts because non-breeding individuals and young were included in addition to breeding birds.
Snowy Egret. Snowy Egrets occurred sporadically at all seasons at the mitigation area prior to breaching but were less common at the control area except in fall 1980 (Figure 7). After breaching, this species increased in numbers at the mitigation area. In both winter
1980-81 and 1981-82, significantly more egrets were present than during the year before breaching. The spring season was similar to winter in that by 1982, (the second spring after breaching), egrets had increased to the point that they were significantly more numerous than during both Figure 7. Mean Number of Snowy Egrets in Salt Marsh at the Mitigation and Control Areas, Eureka, California, June 1979 to June 1982. Right-hand scales show actual counts; left-hand scale shows 31
density. Vertical lines indicate ± one standard error. 32 the spring before breaching and the first spring after breaching.
Significantly more egrets occurred in fall 1981 after breaching than in fall 1980 before breaching. Conversely, Snowy Egrets revealed no significant difference in numbers at the control area among the seasons through the entire study.
Significantly larger numbers of Snowy Egrets occurred in salt marsh at the mitigation area in summer and fall 1981 after breaching than at the control area. The numbers at the mitigation area by winter
1981-82 and spring 1982 were significantly larger than the numbers of egrets occurring at the control area during all years of the study, both before and after breaching.
Black-shouldered Kite. The mitigation area did not have significantly different numbers of Black-shouldered Kites (Elanus caeruleas) before and after breaching, nor were the numbers at the control area significantly different throughout the study (Figure 8).
However, the number of kites was significantly greater at the control area than at the mitigation area in fall 1980 before breaching and again in fall 1981 after breaching. No significant differences were found in other seasons.
Shorebirds. Shorebirds as a group (Scolopacids and Charadriids combined) showed dramatic changes over the study period (Figure 9).
They were uncommon at the mitigation area before breaching, but through all of the following years the area attracted increasingly larger numbers and diversity, except in summer 1982 when counts were made only through June before migrating shorebirds had returned south. This increase culminated in winter 1981-82 with the highest density on one Figure 8. Mean Number of Black-shouldered Kites in Salt Marsh at the Mitigation and Control Areas, Eureka, California, June 1979 to June 1982. Right-hand scales show actual counts; left-hand scale shows 3
density. Vertical lines indicate ± one standard error. 3 Figure 9. Mean Number of Shorebirds in Salt Marsh at the Mitigation and Control Areas, Eureka, California,
June 1979 to June 1982. Right-hand scales show actual counts; left-hand scale shows 34
density. Vertical lines indicate ± one standard error. 35 visit of 332 birds/ha. The highest mean density occurred in spring 1982 with 30.5 birds/ha/visit. Significantly larger numbers were present in winter 1980-1981 than in winter 1979-1980, and significantly larger numbers were present in winter 1981-82 than in both previous winters.
Significantly larger numbers were present in spring 1981 than in spring
1980, and significantly larger numbers were present in spring 1982 than in both previous springs. Significantly larger numbers of shorebirds were present at the mitigation area in summer 1981 than in the summers of 1979 and 1980 before breaching. No significant differences in numbers of shorebirds were noted among any years at the control area.
Numbers of shorebirds as a group were significantly higher at the mitigation area after breaching beginning in fall 1981 and continuing through winter 1981-82 and spring 1982 than during the corresponding seasons at the control area. No significant difference in numbers was apparent between the mitigation area and the control area during the period before breaching.
Tides greater than approximately 2.1 m above the mean lower low water (MLLW) completely inundate the central part of the mitigation area, making it unusable for shorebirds; however, during tides between approximately 1.1 m and 2.1 m MLLW the area was used significantly
(P<0.05) more by shorebirds from fall 1981 through late winter 1982 than during tides below 1.1 m MLLW.
Numbers of Killdeer (Figure 10), Greater Yellowlegs (Figure 11),
Least Sandpiper (Figure 12) and Common Snipe (Figure 13) in the mitigation area were significantly different within a species before and after breaching during at least one season throughout the study. Black- bellied Plover (Pluvialis squatarola), Marbled Godwit (Limosa fedoa),
Figure 10. Mean Number of Killdeer in Salt Marsh at the Mitigation and Control Areas, Eureka, California, June 1979 to June 1982. Right-hand scales show actual counts; left-hand scale shows density. 36
Vertical lines indicate ± one standard error. Figure 11. Mean Number of Greater Yellowlegs in Salt Marsh at the Mitigation and Control Areas, Eureka,
California, June 1979 to June 1982. Right-hand scales show actual counts; left-hand scale 3 shows density. Vertical lines indicate ± one standard error. 7 Figure 12. Mean Number of Least Sandpipers in Salt Marsh at the Mitigation and Control Areas, Eureka,
California, June 1979 to June 1982. Right-hand scales show actual counts; left-hand scale 38
shows density. Vertical lines indicate ± one standard error. Figure 13. Mean Number of Common Snipe in Salt Marsh at the Mitigation and Control Areas, Eureka,
California, June 1979 to June 1982. Right-hand scales show actual counts; left-hand scale 39
shows density. Vertical lines indicate ± one standard error. 40
Western Sandpiper (Calidris mauri), Dunlin (Calidris alpina), and Long- billed Dowitcher (Limnodromus scolopaceus) had numbers that were significantly different between areas and among years when the species were analyzed as a group but not when they were considered individually.
Killdeer were significantly greater in numbers in the mitigation area after breaching than before breaching only during spring 1982
(Figure 10). The pattern of significance was the same as for the collective shorebird group.
Greater Yellowlegs also showed a pattern similar to the collective shorebird group, with significantly larger numbers of individuals occurring at the mitigation area in winter 1981-82 and spring 1982 than at the mitigation site in earlier years (Figure 11).
Again, no significant differences occurred among years at the control area.
The Least Sandpiper was the most abundant species at any time during the study, with a maximum density at the mitigation area of 132.2 birds/ha on one visit during winter 1981-82, and a maximum mean density of 15.4 birds/ha/visit in spring 1982 (Figure 12). They constituted the largest percentage (44.9 percent of the mean number of individuals) of shorebirds using the mitigation area in winter 1981-82. Least
Sandpipers displayed the same pattern as other shorebirds. In late summer and fall 1981 significantly more Least Sandpipers used the mitigation area than at these seasons during other years. The numbers
at the mitigation area were significantly larger in winter 1981-82 and
spring 1982 than in winter 1980-81 and spring 1981. Least Sandpipers
did not occur on any visits to the mitigation or control area before 41 breaching; significantly larger numbers occurred at the mitigation area after breaching than at the control area.
Least Sandpipers were significantly more abundant (P<0.05) during moderately high tides than low tides at the mitigation area from late December 1981 to late April 1982.
Common Snipe occurred on both the mitigation and control sites most commonly in fall and winter (Figure 13). Numbers generally increased after breaching, but not significantly, at the mitigation area at these seasons. Numbers generally decreased at the control area over the study period, but also not significantly. In winter 1981-82, significantly larger numbers of snipe were present at the mitigation area than at the control area, but numbers in the previous winter revealed no significant difference between areas.
Vaux's Swifts and Swallows. Vaux's Swifts and swallows were common aerial insectivores in late spring and summer over all habitats at the mitigation area but usually were much less common at the control marsh. Summer was the only season in which significant differences were revealed in the numbers of these birds between areas.
Vaux's Swifts did not differ significantly in numbers among the years before and after breaching at the mitigation area, nor did they differ significantly in numbers at the control area (Figure 14). While they were not significantly more numerous at the mitigation area before breaching than at the control site, by summer 1981 they were present at the mitigation area in significantly greater numbers than during summers
1980 and 1981 at the control area. One sighting of 50 swifts at the Figure 14. Mean Number of Vaux's Swifts in Salt Marsh at the Mitigation and Control Areas, Eureka, California, June 1979 to June 1982. Right-hand scales show actual counts; left-hand scale 4
shows density. Vertical lines indicate ± one standard error. 2 43 control area in summer 1981 accounts for the large mean for that season
(Figure 14).
Northern Rough-winged Swallows (Stelgidopteryx serripennis) were not significantly different in numbers at the mitigation area after the breaching than before, nor was there a significant difference at the control area (Figure 15). Similar numbers were present at the control area and the mitigation area in 1980, but by 1981, after breaching, a significantly larger number generally occurred at the mitigation area than at the control area in the spring and summer.
Cliff Swallows (Hirundo pyrrhonota) bred under the eaves of sheds at the mitigation area in 1980 but not in the year following the breaching, and thus showed a significant decrease in numbers for that year (Figure 16). The numbers at the control area did not differ significantly among years. Significantly more swallows occurred at the mitigation area in 1980 before breaching than occurred at the control area in either summer 1980 or 1981.
Barn Swallows (Hirundo rustica) were not significantly different in numbers among the years at both the mitigation and control areas
(Figure 17). This species was significantly more numerous at the mitigation area after breaching in spring and summer 1981 and summer
1982 than at the control area the same years, but not significantly during summer 1980 before breaching.
Marsh Wren. Marsh Wrens showed marked population fluctuations over the study period; some of the most dramatic occurred at the control area and thus cannot be attributed to treatment effects (Figure 18). Figure 15. Mean Number of Northern Rough-winged Swallows in Salt Marsh at the Mitigation and Control Areas, Eureka, California, June 1979 to June 1982. Right-hand scales show actual counts; left- 4
hand scale shows density. Vertical lines indicate ± one standard error. 4 Figure 16. Mean Number of Cliff Swallows in Salt Marsh at the Mitigation and Control Areas, Eureka, California, June 1979 to June 1982. Right-hand scales show actual counts; left-hand scale 4
shows density. Vertical lines indicate ± one standard error. 5 Figure 17. Mean Number of Barn Swallows in Salt Marsh at the Mitigation and Control Areas, Eureka, California, June 1979 to June 1982. Right-hand scales show actual counts; left-hand scale 46 shows density. Vertical lines indicate ± one standard error. Figure 18. Mean Number of Marsh Wrens in Salt Marsh at the Mitigation and Control Areas, Eureka, California, June 1979 to June 1982. Right-hand scales show actual counts; left-hand scale 4
shows density. Vertical lines indicate ± one standard error. 7 48
No significant difference in numbers of Marsh Wrens occurred during the summer, fall and winter seasons among the years at the mitigation area. Although an increase in numbers occurred the first spring after breaching (1981) compared to spring 1980, by spring 1982 the numbers of Marsh Wrens were significantly lower than in spring 1981, and also lower, but not significantly so, than in spring 1980 (before breaching).
Winter was the only season in which significant differences in numbers of Marsh Wrens were not noted at the control area. In 1981, wrens occurred in significantly larger numbers in summer, and fall than in the corresponding seasons in 1980. Marsh Wrens were larger in numbers in the winter of 1981-82 after breaching, but this was not significantly larger than in the previous winter. By spring 1982 the numbers were again significantly larger than in spring 1981.
The large fluctuations in the population size of Marsh Wrens on the control area make it difficult to compare the changes due to treatment effects. In all seasons, significant differences occurred between the areas. Marsh Wrens were significantly more abundant at the control area than the mitigation area beginning in winter 1980-81 and continuing through the seasons to spring 1982.
Emberizids. Savannah Sparrows were the most abundant breeder in the mitigation area before breaching but declined in numbers over the course of the study (Figure 19). These changes were significant in all seasons.
The reactions of Savannah Sparrows to the changing habitat of the mitigation area were clearly apparent in the spring. Significantly Figure 19. Mean Number of Savannah Sparrows in Salt Marsh at the Mitigation and Control Areas, Eureka, California, June 1979 to June 1982. Right-hand scales show actual counts; left-hand scale 4 shows density. Vertical lines indicate ± one standard error. 9 50 more sparrows were present in spring 1980 before breaching than in both springs after breaching. No significant difference in the numbers of sparrows in spring was evident between the two post-breaching years at both the mitigation and control areas. The number of Savannah Sparrows at the mitigation area in spring 1980 before breaching was significantly higher than at the control area in the springs of both post-breaching years, but numbers in both years after breaching at the mitigation area were not significantly different from the corresponding years at the control area.
In summer 1981 after breaching, Savannah Sparrows at the mitigation area showed a significant reduction from pre-breaching numbers. Numbers of Savannah Sparrows at the control area did not differ significantly during this same period. The mitigation area in summer 1979 and 1980 before breaching had significantly more Savannah
Sparrows than the control area before breaching in 1980 and after breaching in 1981.
Savannah Sparrows occurred at both areas during the fall period; in 1980 and 1981, numbers were higher than at other seasons.
No significant differences in the numbers at this season occurred at the mitigation area or the control area in the years before and after breaching. This species was significantly more numerous at the mitigation area in fall 1980 before breaching than at the control area during the same time.
Savannah Sparrows were commonly recorded at the mitigation area in winter, both before and after breaching, and also occurred at the control area during this season. Savannah Sparrows at the mitigation area were recorded in winter in their highest numbers after breaching in 51
1981-82 when they were significantly more numerous than in the first winter after breaching (1980-81). Fewer sparrows occurred during the first winter after breaching than the winter before breaching, but this difference was not significant. No significant difference in the numbers of this species occurred among winters at the control area.
Significantly more Savannah Sparrows occurred at the mitigation area in winter 1981-82 after breaching than during either winters 1980-1981 or
1981-1982 at the control area.
At the mitigation area, Song Sparrows used the dikes and freshwater marsh more commonly than the salt marsh. At the control area the sparrows used both the dikes and the Cordgrass salt marsh.
Significantly lower numbers of Song Sparrows were present at all seasons before and after breaching in the mitigation area than in the control area (Figure 20).
In the summer, Song Sparrows at the mitigation area were not significantly different in numbers between before- and after- breaching years. Song Sparrow numbers at the control area were also not significantly different over the years during the summer. Significantly more Song Sparrows were present at the control area in both summers 1980 and 1981 than in all three summers at the mitigation area.
In fall, Song Sparrows at the mitigation area showed no significant difference in numbers over the years. Similarly, no significant differences were apparent in fall among years at the control area. Significantly more Song Sparrows were present at the control area
in fall 1981 after breaching than at the mitigation area in fall 1980
before breaching. No significant differences were noted in a comparison Figure 20. Mean Number of Song Sparrows in Salt Marsh at the Mitigation and Control Areas, Eureka,
California, June 1979 to June 1982. Right-hand scales show actual counts; left-hand scale 52 shows density. Vertical lines indicate ± one standard error. 53 of the two areas in fall 1980. The control area had significantly more sparrows than the mitigation area in fall 1981 after breaching.
Patterns in winter and spring seasons were exactly the same pattern as in summer: numbers in the mitigation and control areas did not differ significantly in both winter and spring among years, but in both winters and springs after breaching the numbers at the control area were significantly larger than those during all years in the mitigation area.
Western Meadowlark. Western Meadowlarks occurred at the mitigation area as both breeders and winter visitors. In late summer and fall seasons combined, significantly larger numbers of Meadowlarks occurred at the mitigation area before breaching than in both years after breaching (Figure 21). No significant difference in numbers at these seasons was apparent at the control area over the years of the study. Significantly more meadowlarks occurred at the mitigation area in late summer and fall before breaching than at the control area after breaching.
No significant difference in the number of Western Meadowlarks occurred in winter at the mitigation area before and after breaching.
However, a significantly larger number of meadowlarks were found at the mitigation area in 1979-80 before breaching than at the control area during the winter of 1980-81 and 1981-82 after breaching. Numbers were larger, but not significantly so, at the mitigatic area than the control area during the winters after breaching. Figure 21. Mean Number of Western Meadowlarks in Salt Marsh at the Mitigation and Control Areas, Eureka,
California, June 1979 to June 1982. Right-hand scales show actual counts; left-hand scale 54
shows density. Vertical lines indicate ± one standard error. 55
American Goldfinch. American Goldfinches used the mitigation and control areas most commonly during the warmer seasons and did not occur at either area in winter (Figure 22). They were significantly more numerous at the mitigation area during the summer before breaching than during the summers after breaching. No significant changes occurred in the control area over the years although the numbers averaged higher in summer and fall 1981 than 1980. Goldfinches were significantly more numerous at the mitigation area before breaching in summer 1979 but not in 1980 than at the control area in 1980. The numbers in 1981 after breaching were not significantly different between the two areas, but numbers averaged higher at the control area.
Freshwater Marsh Breeding and Year-round Bird Counts
Six species of birds in the freshwater marsh had significant changes in numbers over the years of the study. Of these only the Marsh
Wren had significant differences in all seasons (Table 5). Because of the shrubbery and young Willows and Red Alders in the freshwater marsh, some species commonly seen there were not typical of such marshes.
These included the Ruby-crowned Kinglet (Regulus calendula), Yellow- rumped Warbler (Dendroica coronata), and Fox Sparrow (Passerella iliaca) which showed significant differences in numbers over the study period.
The Green-backed Heron (Butorides striatus), Black-crowned Night-Heron
(Nycticorax nycticorax), and Black Phoebe (Sayornis nigricans) did not show significant differences in numbers during the study.
The effect of the construction of the interior dike separating
the freshwater from the salt marsh in August 1979 on birds using the Figure 22. Mean Number of American Goldfinches in Salt Marsh at the Mitigation and Control Areas, Eureka, California, June 1979 to June 1982. Right-hand scales show actual counts; left-hand scale 56
shows density. Vertical lines indicate ± one standard error. 57
Table 5. Species of Birds with Significant Differences in Numbers between at Least 2 Years at a Given Season in Freshwater Marsh at the Mitigation Area, Eureka, California, 1979-1982. Probabilities are based on Kruskal-Wallis H; nonsignificance is noted ns.
Probability
Breeding bird countd Summera Winterb Springc (June)
Virginia Rail ns <0.001 0.029 0.032
Marsh Wren <0.001 <0.001 0.001 0.001
Ruby-crowned Kinglet ns 0.018 ns ns
Yellow-rumped Warbler ns 0.047 ns ns
Fox Sparrow ns 0.044 ns ns
Song Sparrow ns 0.005 ns ns a Sample sizes: 1979:8; 1980:15; 1981:24; 1982:8; d.f.=3. b Sample sizes: 1979-80:11; 1980-81:16; 1981-82:18; d.f.=2. c Sample sizes: 1980:4; 1981:19; 1982:20; d.f.=2. d Sample sizes: 1979:8; 1980:7; 1981:6; 1982:8; d.f.=3. 58 freshwater marsh could be determined only for the BBC's because habitats were not distinguished between late June and late fall 1979. Thus, no significant difference in numbers could be determined for other seasons.
During the BBC in 1980 after diking and before breaching,
Virginia Rails were significantly more numerous than during both subsequent years, but they were not significantly more numerous than in
1979 before both diking and breaching (Table 5). A different pattern emerged during the winter season. Numbers of Virginia Rails increased over the three winters of the study, but were not significantly different between winter 1979-80 and 1980-81. By winter 1981-82,
Virginia Rails had increased significantly over both previous years.
Numbers in spring showed no significant difference between before (1980) and after (1981) breaching, but were significantly greater in 1982 than in 1981.
During the BBC's, numbers of Marsh Wrens were not significantly different between each year before breaching (1979 and 1980), or between each year after breaching (1981 and 1982) (Table 5). However, in both
BBC's after breaching, significantly higher numbers were present than during the first BBC of the study in 1979 before diking. Marsh Wrens increased in numbers during the study in a pattern similar to that in the control area. When the remainder of the summer season was included in the analysis, the pattern of significance was identical to the BBC analysis except that in summer 1981, significantly more wrens were present than in 1980. A drop in the trend of increasing numbers in summer 1982 was probably because the study period terminated at the end of June before the second or third broods were fledged. 59
Significantly more (P=0.002) Marsh Wrens were recorded during
fall 1981 than during the same period in 1980 (Table 6). The trend
towards greater numbers of wrens continued into the winter period when
the increase from 1979-80 to 1980-81 was significant, as was the
increase from 1980-81 to 1981-82 (Table 5). The pattern in spring was
similar to the pattern in winter: numbers were significantly higher in
1981 than 1980, and also significantly higher in 1982 than 1981.
Ruby-crowned Kinglets were significantly more numerous (P=0.036)
in fall 1981 than fall 1980 (Table 6). While more kinglets were
recorded in winter 1980-81 than 1981-82, no significant difference was
detected. Significantly higher numbers were present in winter 1980-81
than the winter prior to breaching (1979-80) (Table 5).
Yellow-rumped Warblers are abundant winter visitors in the area.
This species was not significantly different in numbers in seasons
before and after breaching years, but they were significantly more
numerous in winter 1980-81 than winter 1981-82 (Table 5).
Fox Sparrows, another common winter visitor, were not
significantly different in numbers between the winter before breaching
(1979-80) and the first winter after breaching (1980-81), but by winter
1981-82, they were significantly more numerous than in both previous
winters (Table 5).
As in Marsh Wrens, a gradual increase was evident in numbers of
Song Sparrows in corresponding seasons over the study period. No sig-
nificant difference occurred in numbers before and after diking. Song
Sparrows were significantly more numerous (P=0.005) in fall 1981 than in
fall 1980 before breaching (Table 6). Significantly more birds were
present in winter 1981-82 than in both previous winters; however, a 60
Table 6. Species of Birds with Significant Differences (P<0.05) in Numbers in Fall in Freshwater Marsh at the Mitigation Area, Eureka, California, 1980-1981. Probabilities are based on Mann-Whitney U.
Species Probabilitya
Marsh Wren 0.002 Ruby-crowned Kinglet 0.036 Song Sparrow 0.005 a Sample sizes: 1980:14, 1981:23. 61 nonsignificant increase occurred between winter 1979-80 before breaching and the first winter after breaching (1980-81) (Table 5).
Mammals
Salt Marsh
In descending order of relative abundance the three species of small mammals trapped in both areas were California Vole (Microtus californicus), Vagrant Shrew (Sorex vagrans), and Western Harvest Mouse
(Reithrodontomys megalotis) (Table 7). Except for the mitigation area in 1980 the trapping results yielded data which could not be converted to densities by the declining rate of capture technique, primarily due to low trapping success. In 1980, declining rate of capture results yielded an estimated 33.8 California Voles/ha and 25.7 Vagrant
Shrews/ha. Comparison of results between 1980 and 1981 showed that a marked decline had occurred at the mitigation area after breaching; the number of animals trapped dropped from 0.29 per trap-night (60 individuals) to 0.02 per trap-night (3 individuals). Qualitative observations also support a marked decline in the small mammal population; fewer rodent trails, droppings, and grass clippings were observed after the breaching. During the same period, small mammal populations increased slightly at the control area, and California Vole replaced Vagrant Shrew as the most numerous species.
Tracks of large mammals were usually seen at the mitigation area in small numbers (Table 8). The most abundant track observed was of the
Domestic Dog (Canis familiaris); indeed, dogs were so common after breaching as to make it impossible to distinguish new from old tracks.
Domestic Cats (Felis domesticus) were seen in much lower numbers. Table 7. Number of Small Mammals Caught and the Calculated Density (no. animal/ha), Eureka, California, 1979-1981.
No. of animals (animals/ha) Total per Vagrant W. Harvest California 100 Site Date Trap-nightsa Shrew Mouse Vole Total trap-nights
Mitigation June 22-28, 1979 563 13 (8.7) 2 (1.3) 12 (8.0) 27 (18.0) 4.8 area June 8-10, 1980 209 26 (23.1) 6 (5.3) 28 (24.9) 60 (53.3) 28.7
June 23-25, 1981 190 1 (0.9) - (0.0) 2 (1.8) 3 (2.7) 1.6
Control June 19-21, 1980 262 16 (10.7) 4 (2.7) 10 (6.7) 30 (20.0) 11.4 area June 30-July 2, 214 8 (5.3) 9 (6.0) 16 (10.7) 33 (22.0) 15.4 1981
aNo prebaiting was conducted in 1979. In 1980 and 1981, trapping was preceded by 3 days (216 trap-nights at the mitigation area, 288 trap-nights at the control area) of open traps, which are not included in the figures. 6 2 Table 8. Number and Frequency of Occurrence of Large Mammal Sign Observed at the Mitigation Area before and after Dike Breaching, Eureka, California, 1979-1982.
Salt marsh Freshwater marsh Before breaching After breaching Before breaching After breaching (n=86)a (n=128) (n=86) (n=128) Species No. Freq. (%) No. Freq. (%) No. Freq. (%) No. Freq. (%)
Domestic Dog (Canis familiaris) 5 (5.8) 19 (14.8) 5 (5.8) 2 (1.6)
Gray Fox (Urocyon cinereoargenteus 0 (0.0) 0 (0.0) 0 (0.0) 1 (0.8)
Raccoon (Procyon lotor) 1 (1.2) 3 (2.3) 0 (0.0) 0 (0.0)
Striped Skunk (Mephitis mephitis) 1 (1.2) 0 (0.0) 0 (0.0) 0 (0.0)
Domestic Cat (Felis domesticus) 1 (1.2) 1 (0.8) 3 (3.5) 2 (2.3)
Mule (Black-tailed) Deer (Odocoileus hemionus) 3 (3.5) 0 (0.0) 0 (0.0) 0 (0.0)
Domestic Cow (Bos taurus) 1 (1.2) 0 (0.0) 0 (0.0) 0 (0.0)
aNumber of surveys. 6 3 64
Raccoon (Procyon lotor) tracks and droppings were observed infrequently.
Mule (Black-tailed) Deer (Odocoileus hemionus) observations dropped to zero after breaching.
The control area (Table 9) had visiting dogs, probably due to the proximity of the recreational vehicle park. Tracks at the control area were seen most frequently after breaching. Raccoon tracks were occasionally observed on the northwest side of the control area.
Freshwater Marsh
The signs of only three species of mammals were observed in the freshwater marsh (Table 8). The Domestic Dog and Domestic Cat were the species recorded most frequently. The single observation of the Gray
Fox (Urocyon cinereoargenteus) during the study was in the freshwater marsh.
As with amphibians and reptiles, mammals were inconsistently recorded prior to construction of the interior dike; thus, no effect of dike construction could be determined.
65
Table 9. Number and Frequency of Occurrence of Large Mammal Sign Observed in Salt Marsh at the Control Area before and after Dike Breaching, Eureka, California, 1980-1982.
Before breaching After breaching (n=39)a (n=112)
No. Freq. (Z) No. Freq. (Z)
Domestic Dog 1 (2.6) II (9.8)
Raccoon I (2.6) 5 (4.5)
aNumber of surveys. DISCUSSION
Salt Marsh
Amphibians and Reptiles
An expected result of the reintroduction of salt water to the mitigation area was the decline in freshwater-adapted species. This was clearly seen in the absence of observations of Pacific Treefrogs and
Red-legged Frogs (Rana aurora) after breaching allowed flooding by tide water. Macdonald (1977) reported that Pacific Treefrogs were found occasionally in salt marshes of his Goleta, California study area following heavy rains but were otherwise rare.
Macdonald (1977) also listed garter snakes, Southern Alligator
Lizards (Gerrhonotus multicarinatus), and other snakes and lizards as occurring in the more elevated portions of salt marshes. At the control area the two observations of garter snakes were on the dikes, not in the regularly inundated portions of the salt marsh. Observations of dead garter snakes in the flooded area of the mitigation area after breaching implies that they were not able to reach high ground before succumbing, although they could have been left there by predators as well.
Birds
The distribution of saltmarsh birds is affected by changes in vegetation, tidal flooding, and salinity (Daiber 1977). The saltmarsh environment is more harsh than that of adjacent uplands, and fewer species are adapted to it (Daiber 1977). For birds, some of the
66 67 problems of living in a salt marsh can be lessened by using it only during certain favorable parts of the day or season. No endemic taxa of birds occur in Humboldt Bay salt marshes (Yocom and Harris 1975).
Snowy Egret. Snowy Egrets began using the mitigation area almost immediately after breaching but showed their most dramatic increases after a full year of tidal influence at the mitigation area.
By winter 1982 much of the grassland and remnant salt marsh had become an area of shallow standing water because of the higher-than-normal seasonal rainfall and an incompletely developed drainage system that restricted outflow of water at low tide. This produced attractive feeding areas for egrets. The control site did not have comparable standing water although the few areas of standing water present were used by the egrets frequenting the salt marsh. I believe that the high densities of egrets using the tidal marsh in winter 1982 represent a transitional stage in the restoration of the marsh. If the control area is a typical model by which to gauge the success of the restoration, development of a drainage system and the subsequent loss of both standing water and its high density of egrets will indicate that restoration of the mitigation area is progressing.
Cogswell (1981) noted that, contrary to the present study, Snowy
Egrets were more common on the Hayward restoration site in summer than in other seasons. In his study, Snowy Egrets were more common during low tide than during high or intermediate tides; however in my study no preference was indicated. The Hayward site may have been too deep at high tide to be acceptable to Snowy Egrets. The Park Street mitigation 68 area was dissimilar to the Hayward area in several important ways including being shallower, being located closer to the bay, and having lower use of the area prior to breaching.
Black-shouldered Kite. Black-shouldered Kites are not commonly considered to be saltmarsh-inhabiting birds (Peterson 1961, Yocom and
Harris 1975), but Brown and Amadon (1968) reported that in California the species occurs in marshes. In northwestern California they are most often observed in agricultural areas (Yocom and Harris 1975) where they feed primarily on voles (Koplin et al. 1980). While the number of kites was larger at the control area than at the mitigation area, this appeared to be due to the occurrence of one pair whose nest was within
0.5 km of the former area. The breaching of the dike had an adverse effect on the small mammal population, and while this did not significantly affect the total number of kites using the mitigation area, it negatively affected their frequency of use. Black-shouldered
Kites will probably increase at the mitigation area if the small rodent population increases to the levels in the control area; however, their stenophagus diet will limit their use of the mitigation area until that time.
Shorebirds. Humboldt Bay is one of the most important shorebird winter concentration areas in California (Monroe et al. 1973); therefore this group of species will be an important indicator of the success of the mitigation. As of the winter of 1981-82 the changes at the mitigation area have been highly favorable in providing a foraging site for shorebirds, particularly Killdeer, Greater Yellowlegs, and Least
Sandpipers. Shorebirds use bay mud flats during low tide (Gerstenberg 69
1972, Burger et al. 1977) and then move to adjacent upland sites when
the tide rises and during periods of heavy rains (Monroe et al. 1973,
Hoff 1979). Thus, after breaching, the mitigation area provided
attractive alternate habitat for shorebirds when they were forced off
the bay at high tide.
The indirect benefits of nutrient exchange in a salt marsh
(Clark 1978) may be more important over time than the area's current
value as a site in which shorebirds can forage for invertebrate food.
In addition, the use of the mitigation area by shorebirds will probably
decrease as restoration proceeds and the marsh becomes more densely
vegetated.
Common Snipe occasionally use salt marshes as winter habitat in
Humboldt Bay (White and Harris 1966), and flocks were observed at times
at the control site. The soggy nature of the mitigation area in winter
1980-81, and in fall and winter 1981-82, with a large number of small
puddles interspersed with vegetation, provided ideal snipe habitat.
Such habitat will probably not be present in as large a proportion as
the drainage system develops. Consequently, the presence of snipe
should continue, but in declining numbers, as the area progresses to
denser Pickleweed and Cordgrass.
Vaux's Swift and Swallows. Vaux's Swifts and swallows can be
expected to use areas which provide both aerial insects and suitable
nesting sites within commuting distance. Lane (1969) found Diptera and
Homoptera to be the two major insect orders in a San Francisco Bay salt
marsh; both orders, especially the former, contain flying members.
Davis and Gray (1966) found a larger number of species of insects in 70 tidal wetlands having a greater variety of habitats. The mitigation site may have more species or biomass of insects due to more favorable and varied adjacent habitat than the control area, but this was not investigated in this study. If true, the numbers of aerial insectivores would be expected to be correspondingly higher, A shortage of suitable nest sites may have been a factor in the fewer numbers of these species at the control area; both Cliff Swallows and Barn Swallows were known to nest at or close to the mitigation site. It would be necessary to have data on the insect populations of the study areas to make further hypotheses concerning the future use by swifts and swallows.
Marsh Wren. The extreme fluctuations of count data which make analysis of Marsh Wren populations difficult may be partly a function of plot size. Engstrom (1981) stated that results from study plots less than 10 ha can be misleading due to variable results. Both areas in this study are less than 10 ha. Kale (1965) found very little change in
Marsh Wren density over 4 years in a Georgia salt marsh of 882 ha.
The control marsh had higher Marsh Wren densities overall than the mitigation area before and after breaching, except in the freshwater marsh. The densities of wrens at the mitigation area may be expected to rise, however, with the development of dense stands of Cordgrass. Wrens were most often associated with dense emergent vegetation; at the mitigation site this was Common Cat-tail in the freshwater marsh or in the ditch within the salt marsh leading from the freshwater marsh.
Emberizids. Unlike the resident subspecies of Savannah Sparrow in the salt marshes of southern California (P. s. beldingi), the subspecies that breeds in the Humboldt Bay area (P. s. brooksi) (A.O.U. 71
1957) is not specialized for salt marshes (Small 1974). The results of
the breeding bird censuses conducted during this study suggest that the
Humboldt Bay sparrows breed more in pasture-like fields than in salt
marsh. However, Savannah Sparrows were common visitors to the control
area when the Cordgrass florets ripened. Savannah Sparrows used the
salt marsh in the mitigation area in relatively large numbers during
winter 1982, but most often inhabited Hairgrass growing at higher
elevations. During some higher tides these were seen clinging to
isolated bunches of Cordgrass. If the mitigation site continues to be
restored to a true salt marsh, this species can be expected to remain
uncommon and an unlikely breeder, but they will probably use the
Cordgrass for foraging in the fall and winter. Marshall (1948) and
Johnston (1956) considered Savannah Sparrows to be a species using the
drier, upper marsh areas in San Francisco Bay, whereas Song Sparrows
were the common sparrow in the lower California Cordgrass marsh.
In contrast to the San Francisco saltmarsh subspecies of Song
Sparrow (M. m. pusillula, samuelis, and maxillaris), the subspecies in
the Humboldt Bay area (M. m. cleonensis) (A.O.U. 1957) is not
specialized for salt marshes (Marshall 1948). The Song Sparrows at the
control marsh used the dike habitat dominated by Coyote Brush. Marshall
(1948) found that Song Sparrows in San Francisco Bay avoided the Coyote
Brush, and he concluded that a lack of high perches was a limiting
factor. At the Bay Street control marsh Coyote Brush and boat sheds
often were used as song perches. Few elevated'song perches occurred at
the mitigation site except for dikes and the Common Cat-tails in the
ditch leading from the freshwater marsh. Sparrows there centered their
activities in the brush on the dikes and ventured into the salt marsh 72 only occasionally to forage. The significantly lower number of Song
Sparrows in all habitats in the mitigation area between summer 1979 and
1980 probably can be attributed to a reduction in vegetation on the dikes caused by construction in August 1979. The birds rarely foraged in the mud of the slough, whereas this was a common habitat of the birds at the control marsh and in Marshall's (1948) study.
Marshall (1948) also found that Song Sparrows were absent from salt marshes where California Cordgrass was less than 46 cm high. He believed closeness of stems limited foraging ability and cover availability. Hairgrass was widespread and very dense at the mitigation area before breaching, but was not nearly as sturdy as Cordgrass.
Establishment of Cordgrass with its more rigid structure and consequent protective cover during high tides is probably necessary before Song
Sparrows will begin to use the mitigation area as a breeding area. If they do begin to breed in the salt marsh of the mitigation area, the tidal marsh could probably be considered to be "restored" because Song
Sparrows, as well as Marsh Wrens, were the most typical and common breeders in the salt marsh in the control area.
Western Meadowlark. The mitigation area before breaching provided more suitable habitat for Western Meadowlarks than either the control area or the mitigation area after breaching, although numbers in winter 1981-82 at the mitigation area did show a modest increase.
Shanholtzer (1974) reported that some passerines use saltmarsh grasses as roosting sites. One visit to the control marsh in early evening revealed a flock of meadowlarks roosting in low Saltgrass and
Pickleweed. Macdonald (1977) listed the meadowlark as a sporadic 73 forager in salt marshes. Meadowlarks used the Saltgrass and Pickleweed flats for foraging at the control area. This species will probably increase when the standing water at the mitigation area declines and should continue to use the area in small numbers.
American Goldfinch. American Goldfinches nested in shrubs and trees at the edge of the freshwater marsh at the mitigation area and foraged frequently in the grasses in the salt marsh and along the dikes.
During the first summer after breaching at the mitigation area, vegetational productivity was reduced as dry land plants were dying and saltmarsh plants still had not become well established. American
Goldfinches frequently foraged in the control area when the florets of
Cordgrass were ripe but were not seen there at other times. It is not surprising that at the mitigation area the American Goldfinch was most common before breaching when grasses were still productive, and least common the first summer after breaching when productivity of species other than those adapted to tidal influx was low. The intermediate numbers of American Goldfinches at the control marsh suggest that they will increase in numbers as their forage grasses increase at the mitigation area.
Mammals
Unlike San Francisco Bay, Humboldt Bay salt marshes contain no endemic species of mammals (Ingles 1965). Macdonald (1977) listed the more abundant mammals in Pacific North American salt marshes. The results of my trapping in the control area generally agree with
MacDonald's results. However, he listed the Deer Mouse (Peromyscus maniculatus) and Ornate Shrew (Sorex ornatus) as abundant in salt marsh, 74 but neither of these were trapped or observed in this study. The
Vagrant Shrew replaces the Ornate Shrew in this area. Of the three carnivores listed by MacDonald, the Long-tailed Weasel (Mustela frenata) was not recorded. More intensive trapping may have revealed the Deer
Mouse and Long-tailed Weasel, because they are both present in Humboldt
County (Ingles 1965).
Small mammals use saltmarsh vegetation for a variety of needs including shelter and escape cover (Shanholtzer 1974). As the flooding and salinity killed Hairgrass or prevented it from growing in the mitigation area, cover became decreasingly available, and the small mammal population apparently declined accordingly. About 75 to 100 individuals were seen drowning during the first high tide after breaching, but if the habitat was suitable, enough individuals should have survived or invaded to maintain the population (Johnston 1957,
Fisler 1961). Fisler (1961) found that voles used higher elevations more than lower elevations, presumably because of the decreased probability of inundation of all cover at the higher tides. Hairgrass is a more fragile species than is Cordgrass; thus, it would provide less cover for voles during high tides when they must crawl up the remaining emergent stems. As the Hairgrass died in the year after breaching at the mitigation area, cover became increasingly scarce. As the mitigation area develops healthy and dense stands of Cordgrass,
California Voles and other small mammals should increase in numbers again, at least in the areas of higher elevation.
Unleashed dogs were very common residents of the area surrounding the mitigation as well as the control area. After breaching of the dike, dogs were brought to the mitigation area for retriever 75 training, causing an increase in the number of tracks seen. While the numbers of observations also increased at the control area, I believe this was more probably a chance occurrence than evidence of a change in habitat quality. Tracks of Raccoons were seen more frequently after breaching at the mitigation area than before breaching, but this could have been because the mud made observation easier. They were seen uncommonly at the control area where apparently one individual provided most of the observations. Chapman (1977) and Macdonald (1977) reported that rabbits sometimes occur in salt marshes; I once saw droppings of a
Brush Rabbit (Sylvilagus bachmani) on a dike at the control area.
Freshwater Marsh
Amphibians and Reptiles
The number of amphibians and reptiles recorded in or adjacent to the freshwater marsh was similar before and after breaching (Table 2).
The frequencies of occurrence of both frog species before and after breaching were very similar. Although more garter snakes were observed after breaching than before breaching, the numbers were still very low and the difference probably does not represent a significant change.
Northern Alligator Lizards (Gerrhonotus coeruleus) and Western Pond
Turtles (Clemmys marmorata) were each seen only once.
Birds
The freshwater marsh was too small to determine statistical significance of population changes satisfactorily, but it is still valuable to note the general trends of populations apparent in the freshwater marsh. The breaching of the dike and the subsequent changes 76 toward redevelopment of the salt marsh did not adversely affect the freshwater marsh as wildlife habitat. The same species were present both prior to and after breaching. One indirect effect of the dike breaching, however, was to force birds that used the salt marsh during average tidal fluctuations to seek refuge in the freshwater marsh during extreme high tides. The freshwater marsh served this function ideally.
Several times I saw American Bitterns (Botaurus lentiginosus), Marsh
Wrens, and Savannah Sparrows retreat from the salt marsh into the thicker vegetation of the freshwater marsh during rising extreme high tides or upon my approach. As denser saltmarsh vegetation develops over time, the freshwater marsh should become decreasingly important as cover for such species.
A more significant change in the freshwater marsh undoubtedly was caused by the construction of the dike separating it from the salt marsh. This raised the level of the water in the pond and increased the growth of Common Cat-tail which favored Marsh Wrens. Unfortunately, counts during the period before dike construction were not recorded by habitat except during the BBC, so quantitative information for comparison with post-diking use was not available except for breeding birds. However, after diking, most species in the freshwater marsh increased in numbers. Vegetation height and density also increased after diking, especially Red Alder and Common Cat-tail. The increasing structural diversity was apparently suitable to support more individuals of those birds typical of shrubs or small trees, such as Ruby-crowned
Ringlet, Yellow-rumped Warbler, and some sparrows.
The Virginia Rail was the only bird that decreased in the fresh- water marsh after diking. This decrease was noted only in the BBC's 77 from 1980 onward, and the species actually showed an increase based on the entire summer seasons. It also increased in most other seasons as the study progressed. The decline during the BBC's is perhaps explainable by the limited number of territorial birds in a very small area, whereby a change of only one or two individuals could significantly affect the count results.
The significant increases of Marsh Wrens over all years of the study suggest that the increases of this species in the control area salt marsh and the freshwater marsh could be part of a local population increase or a rebound from a previous low. Base (1981, 1982a) also documented an increase in Marsh Wrens during the BBC period in 1980 and
1981 at his Elk River saltmarsh restoration site in mid Humboldt Bay.
Mammals
Sign of few species was observed in the freshwater marsh because of its very small size and because the dense Common Cat-tail made detection difficult. The greater growth of cat-tail and the higher water level after construction of the dike at the marsh increased this problem and probably accounted for the decrease (from 8 to 5 observations) in observation of tracks and other sign. CONCLUSIONS
Results of the faunal studies indicate that the tidal portion of the mitigation area began to acquire more of the characteristics of a salt marsh. Certain animals including amphibians, reptiles, and small
mammals decreased with the dike breaching, but I expect that small
mammals will increase as the tidal marsh vegetation becomes more dense.
Among the birds, some species, such as shorebirds and egrets, initially
increased in response to the occurrence of standing water, whereas
others, such as the Savannah Sparrow, decreased as the dry grassland
present before breaching was replaced by marsh vegetation subject to
daily flooding. As the drainage system becomes better established, I
anticipate that the present standing water will be drained at low tide,
thereby reducing use by wading birds. Accordingly, the tidal portion of
the mitigation area will assume more of the characteristics of the
present control marsh, which has stands of Cordgrass, Saltgrass, and
Pickleweed, instead of the Hairgrass and small patches of remnant salt
marsh that characterized the mitigation area before breaching.
Based on the evidence collected to date, passive saltmarsh
restoration by dike breaching will probably be successful in situations
similar to those at the Park Street mitigation area. However, 5-10
years will be needed to determine whether the project will be a total
success.
The development at the Woodley Island marina provided new
habitat for certain species of birds that require deep water or that are
78 79
adaptable to man's presence. Included in this group are Brown Pelicans
(Pelecanus occidentalis), several species of gulls, cormorants, and
anatids. All of these species were unlikely to have used the salt marsh
present before the marina development to any great extent because they
did not use the remaining salt marsh at Woodley Island. Some of these species roosted on the mudflats present before marina development.
Shorebirds probably suffered most from the loss of the mudflat when the marina was developed. This loss was apparently partially mitigated in kind during this transition stage of restoration, but as saltmarsh vegetation at the mitigation area continues to develop, the loss of mudflat will become more acute. The tidal portion of the mitigation area will probably adequately replace the lost salt marsh and its associated animal life, whereas- the enhancement of the freshwater marsh provides benefits for certain birdss. However, the loss of the mudflat
will not be replaced in quality of habitat by the deeper water of the boat docks and the perching sites of the docks and street lights. MANAGEMENT RECOMMENDATIONS
During winter and spring of 1982 large numbers of birds from several taxa used the areas of standing water within the tidal portion of the mitigation area. This area was also used by various groups of people, including persons merely traversing the area, hunters, and people training dogs. Some form of control of these individuals may be desirable to maximize wildlife use of the area. Efforts to control vehicular traffic by construction of ditches limiting access to the site have had moderate success. Because many of the people currently visiting the mitigation area are interested in uses other than wildlife, an educational program of plaques or signs on the importance of the marsh ecosystem may be helpful in lessening their impact by developing greater respect in their use of the area.
Standing water at low tide has great value as a foraging site for egrets and certain species of shorebirds but limits the export of detrital matter. If it is desired to speed up restoration of the mitigation area to a natural salt marsh, it may be necessary to improve the present, poorly defined drainage system. A small amount of mosquito breeding was observed in the mitigation area, but unless this becomes a more serious problem, the cost of control would probably not be worthwhile, especially because it could lower the present value of the marsh which is obviously attractive to many species of birds.
Criteria should be developed to judge when, or if, the mitigation area has actually become a completely restored salt marsh. A
80 81 time limit should also be set whereby more active means of restoration, such as planting or ditching, should be begun if the criteria for a restored salt marsh have not been met.
Construction of a weir at the breach site may be useful in facilitating water level manipulation.
An effort should be made to arrange for help, either paid or volunteer, to continue at least the breeding bird counts over several more years. Only over a succession of years can the annual variability be more precisely ascertained so that the results can be seen more clearly. In addition, this would provide regular surveillance on the functioning of the system and the degree of restoration. Management which may not be needed now may be required in the future if maximum productivity is to be achieved.
The freshwater marsh is a valuable part of the mitigation area.
A large number of species and individuals use it even though it is very small. This habitat will continue to be valuable as it is now or as succession allows the moderate increase in density of woody plants providing for additional strata and interspersion of habitats. However, the marsh should not be allowed to become so choked with vegetation that it ceases to function as a marsh and becomes increasingly similar to upland habitat. To that end, periodic high flooding, burning, or cutting may be necessary to retain its optimal usefulness. REFERENCES CITED
American Ornithologists' Union. 1957. Check-list of North American birds. Fifth edition. Port City Press, Baltimore. 691 pp.
American Ornithologists' Union. 1983. Check-list of North American birds. Sixth edition. Allen Press, Lawrence, Kansas. 877 pp.
Anderson, B. W., R. D. Ohmart and J. Rice. 1981. Seasonal changes in avian densities and diversities. Pp. 262-264 in C. J. Ralph and J. M. Scott (Eds.), Estimating numbers of terrestrial birds. Cooper Ornithological Society, Studies in Avian Biology No. 6. 630 pp.
Base, D. L. 1981. No. 208. Diked coastal brackish marsh. Pp. 101-102 in W. T. VanVelzen (Ed.), Forty-fourth breeding bird census. Amer. Birds 35:46-112.
Base, D. L. 1982a. No. 198. Restored coastal brackish marsh. P. 103 in W. T. and A. C. VanVelzen (Eds.), Forty-fifth breeding bird census. Amer. Birds 36:49-106.
Base, D. L. 1982b. Composition, status, and changes of birds and other wildlife on a tidal marsh restoration site at Humboldt Bay. M.S. Thesis. Humboldt State University, Arcata, Calif. 64 pp.
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APPENDIX A. Common and Scientific Names of Amphibians and Reptiles Mentioned in the Text or Tables.
Common name Scientific name
Pacific Treefrog Hyla regilla
Red-legged Frog Rana aurora
Western Pond Turtle Clemmys marmorata
Southern Alligator Lizard Gerrhonotus multicarinatus
Northern Alligator Lizard Gerrhonotus coeruleus
Common Garter Snake Thamnophis sirtalis
Western Terrestrial Garter Snake Thamnophis elegans 89
APPENDIX B. Common and Scientific Names of Birds Mentioned in the Text, Tables or Appendixes.
Common name Scientific name
Brown Pelican Pelecanus occidentalis
American Bittern Botaurus lentiginosus
Great Blue Heron Ardea herodias
Great Egret Casmerodias albus
Snowy Egret Egretta thula
Green-backed Heron Butorides striatus
Black-crowned Night-Heron Nycticorax nycticorax
Green-winged Teal Anas crecca
Mallard Anas platyrynchos
Turkey Vulture Cathartes aura
Black-shouldered Kite Elanus caeruleus
Northern Harrier Circus cyaneus
Sharp-shinned Hawk Accipiter striatus
Cooper's Hawk Accipiter cooperii
Red-shouldered Hawk Buteo lineatus
Red-tailed Hawk Buteo jamaicensis
American Kestrel Falco sparverius
Merlin Falco columbarius
Peregrine Falcon Falco peregrinus
California Quail Callipepla californica
Virginia Rail Rallus limicola
Sora Porzana carolina
American Coot Fulica americana 90
APPENDIX B. Common and Scientific Names of Birds Mentioned in the Text, Tables or Appendixes. (Continued)
Common name Scientific name
Black-bellied Plover Pluvialis squatarola
Killdeer Charadrius vociferus
Greater Yellowlegs Tringa melanoleuca
Solitary Sandpiper Tringa solitaria
Willet Catoptrophorus semipalmatus
Spotted Sandpiper Actitis macularia
Marbled Godwit Limosa fedoa
Western Sandpiper Calidris mauri
Least Sandpiper Calidris minutilla
Sharp-tailed Sandpiper Calidris acuminata
Dunlin Calidris alpina
Long-billed Dowitcher Limnodromus scolopaceus
Common Snipe Gallinago gallinago
Red-necked Phalarope Phalaropus lobatus
Red Phalarope Phalaropus fulicaria
Gull Larus sp.
Mourning Dove Zenaida macroura
Short-eared Owl Asio flammeus
Vaux's Swift Chaetura vauxi
Anna's Hummingbird Calypte anna
Allen's Hummingbird Selasphorus Basin
Belted Kingfisher Ceryle alcyon
Downy Woodpecker Picoides pubescens 91
APPENDIX B. Common and Scientific Names of Birds Mentioned in the Text, Tables or Appendixes. (Continued)
Common name Scientific name
Northern Flicker Colaptes auratus
Western Wood-Pewee Contopus sordidulus
Western Flycatcher Empidonax difficilis
Black Phoebe Sayornis nigricans
Ash-throated Flycatcher Myiarchus cinerascens
Western Kingbird Tyrannus verticalis
Purple Martin Progne subis
Tree Swallow Tachycineta bicolor
Violet-green Swallow Tachycineta thalassina
Northern Rough-winged Swallow Stelgidopteryx serripennis
Cliff Swallow Hirundo pyrrhonota
Barn Swallow Hirundo rustica
American Crow Corvus brachyrynchos
Common Raven Corvus corax
Chestnut-backed Chickadee Parus rufescens
Winter Wren Tryglodytes tryglodytes
Marsh Wren Cistothorus palustris
Ruby-crowned Kinglet Regulus calendula
Swainson's Thrush Catharus ustulatus
Hermit Thrush Catherus guttatus
American Robin Turdus migratorius
Varied Thrush Ixoreus naevius
Wrentit Chamaea fasciata 92
APPENDIX B. Common and Scientific Names of Birds Mentioned in the Text, Tables or Appendixes. (Continued)
Common name Scientific name
Water Pipit Anthus spinoletta
Cedar Waxwing Bombycilla cedrorum
European Starling Sturnus vulgaris
Hutton's Vireo Vireo huttoni
Warbling Vireo Vireo gilvus
Orange-crowned Warbler Vermivora celata
Yellow Warbler Dendroica petechia
Yellow-rumped Warbler Dendroica coronata
Black-throated Gray Warbler Dendroica nigrescens
Common Yellowthroat Geothlypis trichas
Wilson's Warbler Wilsonia pusilla
Black-headed Grosbeak Pheucticus melanocephalus
Rufous-sided Towhee Pipilo erythrophthalmus
Savannah Sparrow Passerculus sandwichensis beldingi Passerculus sandwichensis brooksi
Grasshopper Sparrow Ammodramus savannarum
Fox Sparrow Passerella iliaca
Song Sparrow Melospiza melodia cleonensis Melospiza melodia maxillaris Melospiza melodia samuelis Melospiza melodia pusillula
Lincoln's Sparrow Melospiza lincolnii
Swamp Sparrow Melospiza georgiana
White-crowned Sparrow Zonotrichia leucophrys
Dark-eyed Junco Junco hyemalis 93
APPENDIX B. Common and Scientific Names of Birds Mentioned in the Text, Tables or Appendixes. (Continued)
Common name Scientific name
Red-winged Blackbird Agelaius phoeniceus
Western Meadowlark Sturnella neglecta
Brewer's Blackbird Euphagus cyanocephalus
Brown-headed Cowbird Molothrus ater
Purple Finch Carpodacus purpureus
House Finch' Carpodacus mexicanus
Pine Siskin Carduelis pinus
Lesser Goldfinch Carduelis psaltria
American Goldfinch Carduelis tristis
House Sparrow Passer domesticus 94
APPENDIX C. Common and Scientific Names of Mammals Mentioned in the Text or Tables.
Common name Scientific name
Vagrant Shrew Sorex vagrans
Ornate Shrew Sorex ornatus
Brush Rabbit Sylvilagus bachmani
Western Harvest Mouse Reithrodontomys megalotis
Deer Mouse Peromyscus maniculatus
California Vole Microtus californicus
Domestic Dog Canis familiaris
Gray Fox Urocyon cinereoargenteus
Raccoon Procyon lotor
Long-tailed Weasel Mustela frenata
Striped Skunk Mephitis mephitis
Domestic Cat Felis domesticus
Mule (Black-tailed) Deer Odocoileus hemionus
Domestic Cow Bos taurus 95
APPENDIX D. Common and Scientific Names of Plants Mentioned in the Text.
Common name Scientific name
Curly Dock Rumex cris.us
Saltbush (Fat-hen) Atriplex patula
Pickleweed Salicornia virginica
California Blackberry Rubus vitifolius
Bird's-foot Trefoil Lotus formosissimus
Red Alder Alnus oregona
Wax-myrtle Myrica californica
Willow Salix hookeriana
Marsh Pennywort Hydrocotyle ranunculoides
Water Celery Oenanthe sarmentosa
Gum-plant Grindelia stricta
Coyote Brush Baccharis pilularis
Brass-buttons Cotula coronopifolia
Ditch-Grass Ruppia maritima
Arrow-grass Triglochin maritimum
Common Cat-tail Typha latifolia
Salt Rush Juncus lesueurii
Soft Chess Bromus mollis
Tall Fescue Festuca arundinacea
Saltgrass Distichlis spicata
Argentine Pampas Grass Cortaderia selloana
Italian Ryegrass Lolium multiflorum
Hairgrass Deschampsia caespitosa 96
APPENDIX D. Common and Scientific Names of Plants Mentioned in the Text. (Continued)
Common name Scientific name
Velvet Grass Holcus lanatus
Beard Grass Polypogon monspeliensis
California Cordgrass Spartina foliosa
Cordgrass Spartina densillora APPENDIX E. Mean Number (and Standard Error) of Birds per Visit in Grassland and Salt Marsh at the Mitigation Area, Eureka, California, by Season.
Before breaching After breaching
1979 1980 1981 1982 Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Species n=8 n=4 n=15 n=12 n=15 n=14 n=16 n=19 n=24 n=23 n=18 n=20 n=8
American Bittern 0.0 0.0 0.0 0.0 0.0 0.07 0.0 0.32 0.08 0.13 0.11 0.05 0.0 0.0 0.0 0.0 0.0 0.0 (0.07) 0.0 (0.01) (0.06) (0.07) (0.08) (0.05) 0.0
Great Blue Heron 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.29 0.17 0.06 0.05 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.14) (0.08) (0.06) (0.05) 0.0
Great Egret 0.0 0.0 0.13 0.17 0.0 0.21 0.06 0.47 0.33 0.44 0.50 0.55 0.0 0.0 0.0 (0.09) (0.11) 0.0 (0.16) (0.06) (0.25) (0.13) (0.14) (0.15) (0.17) 0.0
Snowy Egret 0.0 0.25 0.13 1.42 0.27 0.21 0.69 4.58 3.00 3.87 16.06 7.95 0.34 0.0 (0.25) (0.09) (1.09) (0.27) (0.16) (0.69) (2.06) (1.14) (1.23) (2.60) (1.86) (0.26)
Black-crowned 0.0 0.0 0.0 0.0 0.0 0.07 0.0 0.0 0.17 0.0 0.0 0.0 0.0 Night-Heron 0.0 0.0 0.0 0.0 0.0 (0.07) 0.0 0.0 (0.10) 0.0 0.0 0.0 0.0
Green-winged Teal 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.09 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.09) 0.0 0.0 0.0
Mallard 0.0 0.0 0.0 0.0 0.20 0.0 0.25 0.16 0.04 0.70 0.0 0.35 0.0 0.0 0.0 0.0 0.0 (0.20) 0.0 (0.25) (0.12) (0.04) (0.70) 0.0 (0.15) 0.0
Turkey Vulture 0.88 0.0 0.0 0.50 0.33 0.07 0.0 0.32 0.33 0.26 0.0 0.25 0.12 (0.23) 0.0 0.0 (0.42) (0.16) (0.07) 0.0 (0.26) (0.12) (0.16) 0.0 (0.18) (0.12) 97 APPENDIX E. Mean Number (and Standard Error) of Birds per Visit in Grassland and Salt Marsh at the Mitigation Area, Eureka, California, by Season. (Continued)
Before breaching After breaching
1979 1980 1981 1982 Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Species n=8 n=4 n=15 n=12 n=15 n=14 n=16 n=19 n=24 n=23 n=18 n=20 n=8
Black-shouldered 0.38 1.25 0.20 0.58 0.13 0.14 0.38 0.0 0.08 0.04 0.28 0.0 0.0 Kite (0.26) (0.75) (0.14) (0.23) (0.09) (0.14) (0.16) 0.0 (0.06) (0.04) (0.14) 0.0 0.0
Northern Harrier 0.0 1.00 0.80 0.42 0.27 0.57 0.62 0.05 0.08 0.22 0.56 0.40 0.0 0.0 (0.71) (0.18) (0.15) (0.12) (0.20) (0.20) (0.05) (0.06) (0.09) (0.14) (0.13) 0.0
Sharp-shinned 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.05 0.0 Hawk 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.05) 0.0
Cooper's Hawk 0.0 0.25 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.25) 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Red-tailed Hawk 0.0 0.50 0.07 0.0 0.0 0.0 0.0 0.0 0.0 0.04 0.0 0.0 0.0 0.0 (0.50) (0.07) 0.0 0.0 0.0 0.0 0.0 0.0 (0.04) 0.0 0.0 0.0
American Kestrel 0.12 0.75 0.07 0.33 0.0 0.07 0.25 0.10 0.0 0.04 0.0 0.0 0.0 (0.12) (0.48) (0.07) (0.14) 0.0 (0.08) (0.11) (0.07) 0.0 (0.04) 0.0 0.0 0.0
Merlin 0.0 0.0 0.0 0.0 0.0 0.07 0.0 0.0 0.0 0.0 0.17 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.07) 0.0 0.0 0.0 0.0 (0.09) 0.0 0.0
Peregrine Falcon 0.0 0.25 0.07 0.0 0.07 0.0 0.0 0.0 0.0 0.0 0.06 0.0 0.0 0.0 (0.25) (0.07) 0.0 (0.07) 0.0 0.0 0.0 0.0 0.0 (0.06) 0.0 0.0 98
APPENDIX E. Mean Number (and Standard Error) of Birds per Visit in Grassland and Salt Marsh at the Mitigation Area, Eureka, California, by Season. (Continued)
Before breaching After breaching
1979 1980 1981 1982 Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Species n=8 n=4 n=15 n=12 n=15 n=14 n=16 n=19 n=24 n=23 n=18 n=20 n=8
Black-shouldered 0.38 1.25 0.20 0.58 0.13 0.14 0.38 0.0 0.08 0.04 0.28 0.0 0.0 Kite (0.26) (0.75) (0.14) (0.23) (0.09) (0.14) (0.16) 0.0 (0.06) (0.04) (0.14) 0.0 0.0
Northern Harrier 0.0 1.00 0.80 0.42 0.27 0.57 0.62 0.05 0.08 0.22 0.56 0.40 0.0 0.0 (0.71) (0.18) (0.15) (0.12) (0.20) (0.20) (0.05) (0.06) (0.09) (0.14) (0.13) 0.0
Sharp-shinned 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.05 0.0 Hawk 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.05) 0.0
Cooper's Hawk 0.0 0.25 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.25) 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Red-tailed Hawk 0.0 0.50 0.07 0.0 0.0 0.0 0.0 0.0 0.0 0.04 0.0 0.0 0.0 0.0 (0.50) (0.07) 0.0 0.0 0.0 0.0 0.0 0.0 (0.04) 0.0 0.0 0.0
American Kestrel 0.12 0.75 0.07 0.33 0.0 0.07 0.25 0.10 0.0 0.04 0.0 0.0 0.0 (0.12) (0.48) (0.07) (0.14) 0.0 (0.08) (0.11) (0.07) 0.0 (0.04) 0.0 0.0 0.0
Merlin 0.0 0.0 0.0 0.0 0.0 0.07 0.0 0.0 0.0 0.0 0.17 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.07) 0.0 0.0 0.0 0.0 (0.09) 0.0 0.0
Peregrine Falcon 0.0 0.25 0.07 0.0 0.07 0.0 0.0 0.0 0.0 0.0 0.06 0.0 0.0 0.0 (0.25) (0.07) 0.0 (0.07) 0.0 0.0 0.0 0.0 0.0 (0.06) 0.0 0.0 98
APPENDIX E. Mean Number (and Standard Error) of Birds per Visit in Grassland and Salt Marsh at the Mitigation Area, Eureka, California, by Season. (Continued)
Before breaching After breaching
1979 1980 1981 1982 Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Species n=8 n=4 n=15 n=12 n=15 n=14 n=16 n=19 n=24 n=23 n=18 n=20 n=8
Virginia Rail 0.0 0.0 0.0 0.0 0.07 0.0 0.0 0.0 0.08 • 009 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.07) 0.0 0.0 0.0 (0.06) (0.06) 0.0 0.0 0.0
American Coot 0.0 0.0 0.0 0.0 0.0 0.0 0.69 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.37) 0.0 0.0 0.0 0.0 0.0 0.0
Black-bellied 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.05 0.0 0.0 0.0 0.05 0.0 Plover 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.05) 0.0 0.0 0.0 (0.05) 0.0
Killdeer 0.0 0.0 0.33 0.67 0.13 0.0 0.19 0.37 0.46 0.26 1.56 1.65 1.38 0.0 0.0 (0.33) (0.36) (0.13) 0.0 (0.14) (0.16) (0.19) (0.16) (0.53) (0.17) (0.38)
Greater 0.0 1.25 0.0 0.0 0.0 0.0 0.12 1.05 0.04 0.22 14.17 18.70 0.0 Yellowlegs 0.0 (0.63) 0.0 0.0 0.0 0.0 (0.08) (0.51) (0.04) (0.18) (2.94) (4.25) 0.0
Solitary 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.05 0.0 Sandpiper 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.05) 0.0
Willet 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.10 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.07) 0.0
Spotted 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.10 0.12 Sandpiper 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.07) (0.12) 99 APPENDIX E. Mean Number (and Standard Error) of Birds per Visit in Grassland and Salt Marsh at the Mitigation Area, Eureka, California, by Season. (Continued)
Before breaching After breaching
1979 1980 1981 1982 Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Species n=8 n=4 n=15 n=12 n=15 n=14 n=16 n=19 n=24 n=23 n=18 n=20 n=8
Marbled Godwit 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.44 0.05 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.14) (0.05) 0.0
Western 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.68 0.0 0.35 0.50 0.15 0.0 Sandpiper 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (1.16) 0.0 (0.35) (0.50) (0.15) 0.0
Least Sandpiper 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.84 4.38 2.95 22.61 58.35 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (1.84) (2.16) (1.03) (5.58) (28.10) 0.0
Sharp-tailed 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.04 0.0 0.0 0.0 Sandpiper 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.04) 0.0 0.0 0.0
Dunlin 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.37 0.0 0.0 0.56 1.75 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.37) 0.0 0.0 (0.56) (1.22) 0.0
Peep Sandpipersa 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.12 0.22 0.0 5.00 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.12) (0.22) 0.0 (5.00) 0.0
Long-billed 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.04 0.0 0.0 0.0 Dowitcher 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.04) 0.0 0.0 0.0
Dowitcher spp. 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.11 28.70 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.11) (20.54) 0.0 100 APPENDIX E. Mean Number (and Standard Error) of Birds per Visit in Grassland and Salt Marsh at the Mitigation Area, Eureka, California, by Season. (Continued)
Before breaching After breaching
1979 . 1980 1981 1982 Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Species n=8 n=4 n=15 n=12 n=15 n=14 n=16 n=19 n=24 n=23 n=18 n=20 n=8
Common Snipe 0.0 0.25 0.20 0.0 0.0 2.21 3.38 0.74 0.0 2.44 1.72 1.20 0.0 0.0 (0.25) (0.11) 0.0 0.0 (1.46) (1.92) (0.38) 0.0 (0.88) (0.58) (0.60) 0.0
Red-necked 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.04 0.0 0.20 0.0 Phalarope 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.04) 0.0 (0.14) 0.0
Red Phalarope 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.04 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.04) 0.0 0.0 0.0
Total Shorebirds 0.0 1.50 0.53 0.67 0.13 2.21 3.69 6.10 5.00 6.56 41.67 116.00 1.50 0.0 (0.64) (0.34) (0.36) (0.13) (1.46) (1.91) (3.26) (2.16) (1.63) (6.86) (47.23) (0.46)
Mourning Dove 0.12 0.0 0.0 0.0 0.07 0.0 0.0 0.0 0.58 0.0 0.0 0.15 0.75 (0.12) 0.0 0.0 0.0 (0.07) 0.0 0.0 0.0 (0.19) 0.0 0.0 (0.08) (0.53)
Short-eared Owl 0.0 0.0 0.20 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.11) 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Vaux's Swift 0.33b 0.0 0.0 1.42 1.33 1.14 0.0 0.79 1.67 1.30 0.0 0.05 0.75 (0.33) 0.0 0.0 (0.10) (0.53) (1.07) 0.0 (0.31) (0.47) (1.30) 0.0 (0.05) (0.31)
Belted 0.0 0.0 0.07 0.0 0.0 0.0 0.06 0.0 0.0 0.09 0.0 0.0 0.0 Kingfisher 0.0 0.0 (0.07) 0.0 0.0 0.0 (0.06) 0.0 0.0 (0.06) 0.0 0.0 0.0 101 APPENDIX E. Mean Number (and Standard Error) of Birds per Visit in Grassland and Salt Marsh at the Mitigation Area, Eureka, California, by Season. (Continued)
Before breaching After breaching
1979 1980 1981 1982 Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Species n=8 n=4 n=15 n=12 n=15 n=14 n=16 n=19 n=24 n=23 n=18 n=20 n=8
Northern Flicker 0.12 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.12) 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Black Phoebe 0.0 0.75 0.53 0.0 0.07 0.21 0.12 0.0 0.08 0.35 0.50 0.0 0.38 0.0 (0.48) (0.19) 0.0 (0.07) (0.11) (0.08) 0.0 (0.06) (0.16) (0.17) 0.0 (0.26)
Western Kingbird 0.0 0.0 0.0 0.08 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.08) 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Purple Martin 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.04 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.04) 0.0 0.0 0.0 0.0
Tree Swallow 0.12 0.0 0.0 0.42 0.13 0.0 0.0 2.16 0.12 0.0 0.11 0.50 0.12 (0.12) 0.0 0.0 (0.23) (0.09) 0.0 0.0 (0.89) (0.07) 0.0 (0.11) (0.26) (0.12)
Violet-green 0.0e0.0c 0.0 0.0 1.33 0.64d 0.0 0.0 1.79 0.79 0.52 0.0 7.00 1.12 Swallow 0.0 0.0 0.0 (0.81) (0.17) 0.0 0.0 (0.79) (0.34) (0.522) 0.0 (3.76) (0.35)
Northern Rough- 0.29e 0.0 0.0 0.42 0.21d 0.0 0.0 0.79 0.96 0.0 0.0 0.25 0.88 winged Swallow (0.18) 0.0 0.0 (0.23) (0.11) 0.0 0.0 (0.34) (0.26) 0.0 0.0 (0.16) (0.40)
Cliff Swallow 0.50f 0.0 0.0 2.75 5.07d 0.21 0.0 2.21 1.88 0.0 0.0 0.80 3.25 (0.50) 0.0 0.0 (1.18) (1.06) (0.21) 0.0 (1.01) (0.65) 0.0 0.0 (0.25) (0.59) 102 APPENDIX E. Mean Number (and Standard Error) of Birds per Visit in Grassland and Salt Marsh at the Mitigation Area, Eureka, California, by Season. (Continued)
Before breaching After breaching
1979 1980 1981 1982 Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Species n=8 n=4 n=15 n=12 n=15 n=14 n=16 n=19 n=24 n=23 n=18 n=20 n=8
Barn Swallow 0.67b 0.0 0.0 6.00 9.21d 6.29 0.0 4.53 13.76g 3.44 0.0 4.85 8.00 (0.67) 0.0 0.0 (1.53) (1.04) (3.08) 0.0 (0.81) (2.20) (1.78) 0.0 (0.98) (2.10)
American Crow 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.16 0.0 0.0 0.0 0.35 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.16) 0.0 0.0 0.0 (0.26) 0.0
Common Raven 0.0 1.25 0.0 0.0 0.0 0.0 0.06 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.95) 0.0 0.0 0.0 0.0 (0.06) 0.0 0.0 0.0 0.0 0.0 0.0
Marsh Wren 0.25 1.50 1.80 1.17 2.07 2.64 1.88 2.05 3.29 3.17 2.22 0.45 0.0 (0.16) (0.64) (0.30) (0.27) (0.49) (0.52) (0.43) (0.30) (0.43) (0.51) (0.30) (0.18) 0.0
American Robin 0.0 0.25 0.13 0.0 0.0 0.0 0.0 0.05 0.0 0.0 0.0 0.0 0.0 0.0 (0.25) (0.13) 0.0 0.0 0.0 0.0 (0.05) 0.0 0.0 0.0 0.0 0.0
Water Pipit 0.0 0.75 1.87 0.0 0.0 0.0 0.12 0.0 0.0 0.13 0.11 0.0 0.0 0.0 (0.48) (0.03) 0.0 0.0 0.0 (0.08) 0.0 0.0 (0.10) (0.11) 0.0 0.0
European 0.0 6.25 3.00 0.25 0.0 0.0 0.0 0.0 0.0 0.0 27.83 10.05 0.0 Starling 0.0 (2.90) (1.47) (0.18) 0.0 0.0 0.0 0.0 0.0 0.0 (9.30) (4.77) 0.0
Yellow-rumped 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.04 2.83 0.0 0.0 Warbler 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.04) (1.27) 0.0 0.0 10 3 APPENDIX E. Mean Number (and Standard Error) of Birds per Visit in Grassland and Salt Marsh at the Mitigation Area, Eureka, California, by Season. (Continued)
breachin Before After breaching
1979 1980 1981 1982 Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Species n=8 n=4 n=15 n=12 n=15 n=14 n=16 n=19 n=24 n=23 n=18 n=20 n=8
Savannah 7.50 3.25 2.80 4.67 4.53 13.36 1.88 0.74 0.88 6.91 4.00 1.35 0.0 Sparrow (1.32) (0.75) (0.59) (0.69) (1.10) (4.24) (0.58) (0.25) (0.38) (1.02) (0.49 ) (0.38) 0.0
Grasshopper 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.17 0.0 0.0 0.0 0.0 Sparrow 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.08) 0.0 0.0 0.0 0.0
Song Sparrow 0.25 1.50 0.33 0.08 0.07 1.00 0.31 0.10 0.29 0.30 0.67 0.35 0.0 (0.16) (0.87) (0.21) (0.08) (0.07) (0.33) (0.15) (0.07) (0.13) (0.12) (0.23) (0.13) 0.0
Lincoln's 0.0 1.50 0.07 0.0 0.0 0.29 0.06 0.0 0.0 0.13 0.11 0.05 0.0 Sparrow 0.0 (1.50) (0.07) 0.0 0.0 (0.16) (0.06) 0.0 0.0 (0.10) (0.08) (0.05) 0.0
Red-winged 0.25 0.0 0.0 0.42 0.80 0.0 0.0 0.0 0.0 2.17 0.06 0.20 0.0 Blackbird (0.16) 0.0 0.0 (0.29) (0.36) 0.0 0.0 0.0 0.0 (2.17) (0.06) (0.16) 0.0
Western 0.0 3.00 10.40 1.67 0.60 2.79 1.69 0.63 0.0 0.13 2.89 1.70 0.50 Meadowlark 0.0 (1.78) (3.47) (0.95) (0.27) (1.05) (0.60) (0.33) 0.0 (0.13) (0.85) (0.84) (0.19)
Brewer's 1.50 0.0 0.73 1.58 1.00 0.0 0.0 0.32 0.0 0.0 0.11 0.0 0.0 Blackbird (0.68) 0.0 (0.73) (0.69) (0.40) 0.0 0.0 (0.19) 0.0 0.0 (0.11) 0.0 0.0
Brown-headed 0.0 0.0 0.0 0.0 0.07 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Cowbird 0.0 0.0 0.0 0.0 (0.07) 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1 04
APPENDIX E. Mean Number (and Standard Error) of Birds per Visit in Grassland and Salt Marsh at the Mitigation Area, Eureka, California, by Season. (Continued)
Before breaching After breaching
1979 1980 1981 1982 Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Species n=8 n=4 n=15 n=12 n=15 n=14 n=16 n=19 n=24 n=23 n=18 n=20 n=8
House Finch 0.0 1.00 0.0 0.25 0.13 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.71) 0.0 (0.25) (0.13) 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Lesser 0.0 0.0 0.0 0.0 0.0 0.07 0.0 0.0 0.12 0.0 0.0 0.0 0.0 Goldfinch 0.0 0.0 0.0 0.0 0.0 (0.07) 0.0 0.0 (0.09) 0.0 0.0 0.0 0.0
American 4.12 0.0 0.0 0.83 1.20 0.79 0.0 0.0 0.58 0.09 0.0 0.0 0.0 Goldfinch (1.30) 0.0 0.0 (0.40) (0.37) (0.41) 0.0 0.0 (0.28) (0.09) 0.0 0.0 0.0
House Sparrow 0.0 0.0 0.0 0.08 0.20 0.0 0.0 0.0 0.25 0.0 0.0 0.0 0.25 0.0 0.0 0.0 (0.08) 0.11 0.0 0.0 0.0 (0.12) 0.0 0.0 0.0 (0.25) aPeeps include Western Sandpiper, Least Sandpiper and Dunlin. b n=3. c n=6. dn=14. e n=7. f n=2. gn=21. 10 5 APPENDIX F. Mean Number (and Standard Error) of Birds per Visit in Salt Marsh at the Control Area, Eureka, California, by Season.
1980 1981 1982 Summer Fall Winter Spring Summer Fall Winter Spring Summer Species n=16 n=13 n=10 n=20 n=24 n=22 n=17 n=21 n=8
Great Blue 0.0 0.08 0.0 0.0 0.0 0.18 0.0 0.05 0.0 Heron 0.0 (0.08) 0.0 0.0 0.0 (0.08) 0.0 (0.05) 0.0
Great Egret 0.0 0.08 0.0 0.0 0.17 0.50 0.24 0.0 0.0 0.0 (0.08) 0.0 0.0 (0.10) (0.18) (0.11) 0.0 0.0
Snowy Egret 0.0 0.46 0.0 0.05 0.0 0.18 0.0 0.05 0.0 0.0 (0.31) 0.0 (0.05) 0.0 (0.10) 0.0 (0.05) 0.0
Black-crowned 0.12 0.0 0.0 0.0 0.04 0.0 0.0 0.0 0.0 Night-Heron (0.08) 0.0 0.0 0.0 (0.04) 0.0 0.0 0.0 0.0
Mallard 0.0 0.0 0.0 0.10 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.10) 0.0 0.0 0.0 0.0 0.0
Turkey Vulture 0.0 0.08 0.0 0.05 0.08 0.04 0.0 0.05 0.0 0.0 (0.08) 0.0 (0.05) (0.06) (0.04) 0.0 (0.05) 0.0
Black-shouldered 0.19 1.31 0.80 0.50 0.29 0.82 0.76 0.10 0.25 Kite (0.10) (0.24) (0.25) (0.17) (0.13) (0.17) (0.22) (0.07) (0.16)
Northern 0.12 0.46 0.10 1.00 0.08 0.14 0.29 0.05 0.0 Harrier (0.08) (0.24) (0.10) (0.07) (0.06) (0.08) (0.11) (0.05) 0.0
Sharp-shinned 0.0 0.0 0.0 0.05 0.0 0.0 0.0 0.0 0.0 106 Hawk 0.0 0.0 0.0 (0.05) 0.0 0.0 0.0 0.0 0.0
APPENDIX F. Mean Number (and Standard Error) of Birds per Visit in Salt Marsh at the Control Area, Eureka, California, by Season. (continued)
1980 1981 1982 Summer Fall Winter Spring Summer Fall Winter Spring Summer Species n=16 n=13 n=10 n=20 n=24 n=22 n=17 n=21 n=8
American 0.0 0.08 0.40 0.05 0.0 0.18 0.12 0.05 0.0 Kestrel 0.0 (0.08) (0.163) (0.05) 0.0 (0.08) (0.08) (0.05) 0.0
Merlin 0.0 0.08 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.08) 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Virginia Rail 0.0 0.0 0.0 0.0 0.0 0.0 0.12 0.0 0.0 ' 0. 0.0 0.0 0.0 0.0 0.0 (0.08) 0.0 0.0
American Coot 0.0 0.0 0.0 0.0 0.0 0.04 0.06 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.04) (0.06) 0.0 0.0
Common Snipe 0.06 0.69 0.80 0.0 0.0 0.04 0.0 0.0 0.0 (0.06) (0.47) (0.70) 0.0 0.0 (0.04) 0.0 0.0 0.0
Shorebirds 0.26 2.95 3.40 0.0 0.0 0.19 0.0 0.0 0.0 (0.26) (2.02) (2.97) 0.0 0.0 (0.19) 0.0 0.0 0.0
Mourning Dove 0.0 0.0 0.0 0.10 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.10) 0.0 0.0 0.0 0.0 0.0
Vaux's Swift 0.0 0.0 0.0 0.30 2.33 0.0 0.0 0.0 0.12 0.0 0.0 0.0 (0.22) (2.08) 0.0 0.0 0.0 (0.12)
Belted 0.0 0.15 0.30 0.05 0.04 0.36 0.0 0.0 0.0 10
Kingfisher 0.0 (0.10) (0.15) (0.05) (0.04) (0.12) 0.0 0.0 0.0 7
APPENDIX F. Mean Number (and Standard Error) of Birds per Visit in Salt Marsh at the Control Area, Eureka, California, by Season. (continued)
1980 1981 1982 Summer Fall Winter Spring Summer Fall Winter Spring Summer Species n=16 n=13 n=10 n=20 n=24 n=22 n=17 n=21 n=8
Northern 0.0 0.08 0.10 0.0 0.0 0.0 0.0 0.0 0.0 Flicker 0.0 (0.08) (0.10) 0.0 0.0 0.0 0.0 0.0 0.0
Black Phoebe 0.19 0.08 0.0 0.0 0.17 0.18 0.0 0.05 0.0 (0.14) (0.08) 0.0 0.0 (0.10) (0.08) 0.0 (0.05) 0.0
Ash-throated 0.0 0.08 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Flycatcher 0.0 (0.08) 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Western 0.0 0.0 0.0 0.05 0.0 0.0 0.0 0.0 0.0 Kingbird 0.0 0.0 0.0 (0.05) 0.0 0.0 0.0 0.0 0.0
Purple Martin 0.0 0.0 0.0 0.0 0.04 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.04) 0.0 0.0 0.0 0.0
Violet-green 0.38 0.0 0.0 0.80 0.67 0.0 0.0 0.76 0.0 Swallow (0.22) 0.0 0.0 (0.65) (0.19) 0.0 0.0 (0.33) 0.0
Northern Rough- 0.06 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 winged Swallow (0.06) 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Cliff Swallow 0.71a 0.0 0.0 0.15 0.33 0.0 0.0 0.05 0.0 (0.24) 0.0 0.0 (0.11) (0.13) 0.0 0.0 (0.05) 0.0 108 Barn Swallow 6.30b 0.54 0.0 2.20 7.18c 0.62d 0.0 2.57 2.50 (2.44) (0.31) 0.0 (0.54) (1.02) (0.32) 0.0 (0.64) (0.68) APPENDIX F. Mean Number (and Standard Error) of Birds per Visit in Salt Marsh at the Control Area, Eureka, California, by Season. (continued)
1980 1981 1982 Summer Fall Winter Spring Summer Fall Winter Spring Summer Species n=16 n=13 n=10 n=20 c=24 n=22 n=17 n=21 n=8
American Crow 0.0 0.31 0.0 0.35 0.29 0.04 0.12 0.71 0.0 0.0 (0.31) 0.0 (0.15) (0.15) (0.04) (0.12) (0.20) 0.0
Common Raven 0.0 0.0 0.0 0.50 0.0 0.0 0.60 0.0 0.0 0.0 0.0 0.0 (0.05) 0.0 0.0 (0.06) 0.0 0.0
Marsh Wren 2.56 4.46 5.70 6.75 12.33 8.73 9.53 14.43 15.50 (0.38) (0.46) (0.79) (0.44) (1.00) (0.48) (0.75) (0.73) (1.07)
Ruby-crowned 0.0 0.0 0.0 0.0 0.0 0.0 0.12 0.0 0.0 Ringlet 0.0 0.0 0.0 0.0 0.0 0.0 (0.12) 0.0 0.0
American Robin 0.0 0.0 0.0 0.15 0.0 0.0 0.24 0.10 0.0 0.0 0.0 0.0 (0.11) 0.0 0.0 (0.14) (0.07) 0.0
European 0.12 139.85 70.10 3.05 0.0 39.86 19.71 0.62 0.12 Starling (0.12) (82.56) (47.24) (2.06) 0.0 (32.04) (12.70) (0.40) (0.12)
Yellow-rumped 0.0 0.0 0.0 0.0 0.0 0.04 0.12 0.0 0.0 Warbler 0.0 0.0 0.0 0.0 0.0 (0.04) (0.12) 0.0 0.0
Savannah 1.19 5.54 1.30 0.7 0 1.04 9.18 1.24 1.24 0.0 Sparrow (1.06) (1.18) (0.34) (0.25) (0.35) (1.15) (0.26) (0.30) 0.0
Song Sparrow 3.88 2.69 4.10 4.10 3.46 4.82 5.76 5.38 1.00 (0.68) (0.56) (1.07) (0.64) (0.43) (0.49) (0.62) (0.67) (0.37) 10 9 APPENDIX F. Mean Number (and Standard Error) of Birds per Visit in Salt Marsh at the Control Area, Eureka, California, by Season. (continued)
1980 1981 1982 Summer Fall Winter Spring Summer Fall Winter Spring Summer Species n=16 n=13 n=10 n=20 n=24 n=22 n=17 n=21 n=8
Lincoln's 0.0 0.0 0.0 0.05 0.0 0.09 0.24 0.19 0.0 Sparrow 0.0 0.0 0.0 (0.05) 0.0 (0.06) (0.11) (0.11) 0.0
Red-winged 0.0 0.0 2.60 0.65 0.0 1.18 0.88 0.24 0.0 Blackbird 0.0 0.0 (1.36) (0.46) 0.0 (0.92) (0.57) (0.19) 0.0
Western 0.0 0.38 0.0 1.05 0.0 1.54 1.06 0.33 0.0 Meadowlark 0.0 (0.38) 0.0 (0.49) 0.0 (0.92) (0.51) (0.20) 0.0
Brewer's 0.0 0.54 2.30 1.00 1.33 6.23 5.65 0.05 0.25 Blackbird 0.0 (0.54) (1.98) (0.65) (0.71) (6.13) (5.40) (0.05) (0.25)
Brown-headed 0.81 0.0 0.0 0.10 0.17 0.0 0.0 0.05 0.25 Cowbird (0.38) 0.0 0.0 (0.10) (0.08) 0.0 0.0 (0.05) (0.25)
House Finch 4.69 0.46 0.0 0.0 2.75 0.0 0.0 0.0 0.0 (1.86) (0.46) 0.0 0.0 (1.77) 0.0 0.0 0.0 0.0
Pine Siskin 0.0 0.0 0.0 0.0 0.0 0.18 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.18) 0.0 0.0 0.0 11 0 APPENDIX F. Mean Number (and Standard Error) of Birds per Visit in Salt Marsh at the Control Area, Eureka, California, by Season. (continued)
1980 1981 1982 Summer Fall Winter Spring Summer Fall Winter Spring Summer Species n=16 n=13 n=10 n=20 n=24 n=22 n=17 n=21 n=8
American 1.81 1.38 0.0 0.0 6.00 5.68 0.0 0.0 0.0 Goldfinch (1.16) (1.14) 0.0 0.0 (2.20) (3.06) 0.0 0.0 0.0
House Sparrow 0.12 0.0 0.0 0.0 0.25 0.0 0.0 0.0 0.12 (0.12) 0.0 0.0 0.0 (0.11) 0.0 0.0 0.0 (0.12) an=14 bn=10 cn=22 dn=21 . 111
APPENDIX G. Mean (and Standard Error) of Birds per Visit in Freshwater Marsh at the Mitigation Area, Eureka, California, by Season.
1979 1980 1981 1982
SummSumera m Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Species n=11 n=4 n=15 n=14 n=16 n=19 n=24 n=23 n=18 n=20 n=8
American Bittern 0.0 0.0 0.0 0.0 0.0 0.12 0.16 0.04 0.09 0.28 0.10 0.0 0.0 0.0 0.0 0.0 0.0 (0.08) (0.09) (0.04) (0.06) (0.11) (0.07) 0.0
Great Egret 0.0 0.0 0.0 0.07 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.07) 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Green-backed 0.0 0.0 0.0 0.0 0.0 0.0 0.05 0.0 0.0 0.0 0.0 0.0 Heron 0.0 0.0 0.0 0.0 0.0 0.0 (0.05) 0.0 0.0 0.0 0.0 0.0
Black-crowned 0.0 0.0 0.50 0.73 0.0 0.0 1.10 0.67 0.0 0.0 0.10 0.62 Night-Heron 0.0 0.0 (0.50) (0.15) 0.0 0.0 (0.36) (0.23) 0.0 0.0 (0.07) (0.38)
Mallard 0.0 0.0 0.0 0.27 0.0 0.0 0.21 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.12) 0.0 0.0 (0.14) 0.0 0.0 0.0 0.0 0.0
Black-shouldered 0.0 0.0 0.25 0.0 0.0 0.06 0.0 0.0 0.13 0.11 0.0 0.0 Kite 0.0 0.0 (0.25) 0.0 0.0 (0.06) 0.0 0.0 (0.07) (0.08) 0.0 0.0
Northern Harrier 0.0 0.0 0.0 0.0 0.07 0.06 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.07) (0.06) 0.0 0.0 0.0 0.0 0.0 0.0
Sharp-shinned Hawk 0.0 0.09 0.0 0.0 0.0 0.06 0.05 0.0 0.09 0.0 0.0 0.0 0.0 (0.091) 0.0 0.0 0.0 (0.06) (0.05) 0.0 (0.06) 0.0 0.0 0.0
Red-shouldered Hawk 0.0 0.0 0.0 0.0 0.0 0.12 0.0 0.0 0.0 0.0 0.0 0.0 1
0.0 0.0 0.0 0.0 0.0 (0.08) 0.0 0.0 0.0 0.0 0.0 0.0 12
APPENDIX G. Mean (and Standard Error) of Birds per Visit in Freshwater Marsh at the Mitigation Area, Eureka, California, by Season. (Continued)
1979 1980 1981 1982
Summers Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Species n=8 n=11 n=4 n=15 n=14 n=16 n=19 n=24 n=23 n=18 n=20 n=8
American Kestrel 0.0 0.09 0.0 0.0 0.14 0.0 0.05 0.0 0.0 0.0 0.0 0.0 0.0 (0.09) 0.0 0.0 (0.10) 0.0 (0.05) 0.0 0.0 0.0 0.0 0.0
California Quail 0.75 0.0 0.0 0.13 0.0 0.0 0.10 0.04 0.0 0.0 0.0 0.0 (0.41) 0.0 0.0 (0.13) 0.0 0.0 (0.10) (0.04) 0.0 0.0 0.0 0.0
Virginia Rail 0.75 0.0 0.75 1.20 1.36 0.19 0.58 1.33 1.65 1.33 1.45 0.38 (0.25) 0.0 (0.75) (0.26) (0.34) (0.10) (0.19) (0.24) (0.20) (0.21) (0.22) (0.18)
Sora 0.0 0.0 0.0 0.27 0.0 0.19 0.10 0.0 0.04 0.0 0.0 0.0 0.0 0.0 0.0 (0.12) 0.0 (0.14) (0.07) 0.0 (0.04) 0.0 0.0 0.0
American Coot 0.0 0.0 0.0 0.0 0.0 0.06 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.06) 0.0 0.0 0.0 0.0 0.0 0.0
Common Snipe 0.0 0.27 0.0 0.0 0.07 0.44 0.05 0.0 0.0 0.0 0.10 0.0 0.0 (0.20) 0.0 0.0 (0.07) (0.20) (0.05) 0.0 0.0 0.0 (0.10) 0.0
Mourning Dove 0.0 0.0 0.0 0.0 0.0 0.0 0.10 0.04 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.10) (0.04) 0.0 0.0 0.0 0.0
Anna's 0.0 0.0 0.0 0.07 0.07 0.0 0.0 0.25 0.26 0.0 0.15 0.0 Hummingbird 0.0 0.0 0.0 (0.07) (0.07) 0.0 0.0 (0.09) (0.11) 0.0 (0.08) 0.0 113 APPENDIX G. Mean (and Standard Error) of Birds per Visit in Freshwater Marsh at the Mitigation Area, Eureka, California, by Seaaon. (Continued)
1979 1980 1981 1982
Summera Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Species n=8 n=11 n=4 n=15 n=14 n=16 n=19 n=24 n=23 n=18 n=20 n=8
Allen's 0.0 0.0 0.0 0.0 0.0 0.0 0.05 0.33 0.13 0.0 0.0 0.12 Hummingbird 0.0 0.0 0.0 0.0 0.0 0.0 (0.05) (0.12) (0.10) 0.0 0.0 (0.12)
Downy Woodpecker 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.08 0.13 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.08) (0.10) 0.0 0.0 0.0
Northern Flicker 0.12 0.0 0.0 0.0 0.0 0.25 0.16 0.04 0.0 0.17 0.0 0.0 (0.125) 0.0 0.0 0.0 0.0 (0.25) (0.16) (0.04) 0.0 (0.12) 0.0 0.0
Western Wood-Pewee 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.04 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.04) 0.0 0.0 0.0
Western Flycatcher 0.12 0.0 0.25 0.07 0.0 0.0 0.0 0.17 0.0 0.0 0.0 0.0 (0.12) 0.0 (0.25) (0.07) 0.0 0.0 0.0 (0.10) 0.0 0.0 0.0 0.0
Black Phoebe 0.25 0.54 0.0 0.13 0.29 0.44 0.21 0.17 0.44 0.17 0.0 0.0 (0.16) (0.16) 0.0 (0.09) (0.12) (0.16) (0.10) (0.13) (0.11) (0.09) 0.0 0.0
Barn Swallowb 0.0 0.0 0.0 0.47 0.36 0.0 0.0 0.71 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.47) (0.36) 0.0 0.0 (0.33) 0.0 0.0 0.0 0.0
American Crow 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.04 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.04) 0.0 0.0'0.0 0.0 0.0 114
APPENDIX G. Mean (and Standard Error) of Birds per Visit in Freshwater Marsh at the Mitigation Area, Eureka, California, by Season. (Continued)
1979 1980 1981 1982
Summeran=8 Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Species n=11 n=4 n=15 n=14 n=16 n=19 n=24 n=23 n=18 n=20 n=8
Chestnut-backed 0.12 0.27 0.0 0.0 0.0 0.0 0.37 0.0 1.26 0.0 0.05 0.0 Chickadee (0.12) (0.27) 0.0 0.0 0.0 0.0 (0.18) 0.0 (0.765) 0.0 (0.05) 0.0
Winter Wren 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.04 0.06 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.04) (0.06) 0.0 0.0
Marsh Wren 1.75 1.82 1.75 3.47 3.36 3.50 4.32 8.92 5.52 5.39 5.40 5.00 (0.25) (0.32) (0.63) (0.36) (0.51) (0.47) (0.32) (0.91) (0.39) (0.39) (0.30) (0.46)
Ruby-crowned 0.0 0.36 0.0 0.0 0.64 1.50 0.42 0.0 1.70 1.06 0.35 0.0 Kinglet 0.0 (0.20) 0.0 0.0 (0.22) (0.27) (0.16) 0.0 (0.30) (0.30) (0.18) 0.0
Swainson's Thrush 0.50 0.0 0.0 0.60 0.0 0.0 0.0 0.04 0.0 0.0 0.05 0.50 (0.19) 0.0 0.0 (0.21) 0.0 0.0 0.0 (0.04) 0.0 0.0 (0.05) (0.27)
Hermit Thrush 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.11 0,0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.08) 0.0 0.0
American Robin 0.0 0.0 0.0 0.40 0.07 0.12 0.0 0.08 0.04 1.11 0.05 0.12 0.0 0.0 0.0 (0.34) (0.07) (0.08) 0.0 (0.06) (0.043 (0.58) (0.05) (0.12)
Varied Thrush 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.05 0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.05) 0.0 11 5 APPENDIX G. Mean (and Standard Error) of Birds per Visit in Freshwater Marsh at the Mitigation Area, Eureka, California, by Season. (Continued)
1979 1980 1981 1982
Summmera Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Species n=11 n=4 n=15 n=14 n=16 n=19 n=24 n=23 n=18 n=20 n=8
Wrentit 0.0 0.0 0.0 0.0 0.14 0.12 0.0 0.0 0.26 0.17 0.10 0.0 0.0 0.0 0.0 0.0 (0.10) (0.12) 0.0 0.0 (0.13) (0.12) (0.10) 0.0
Cedar Waxwing 0.0 0.0 0.0 0.53 0.0 0.0 0.0 0.71 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.47) 0.0 0.0 0.0 (0.46) 0.0 0.0 0.0 0.0
European Starling 0.0 0.0 5.00 0.0 0.0 0.0 0.0 0.0 0.04 0.11 0.0 0.0 0.0 0.0 (5.00) 0.0 0.0 0.0 0.0 0.0 (0.04) (0.11) 0.0 0.0
Hutton's Vireo 0.0 0.0 0.0 0.07 0.07 0.0 0.05 0.0 0.22 0.06 0.0 0.0 0.0 0.0 0.0 (0.07) (0.07) 0.0 (0.05) 0.0 (0.11) (0.06) 0.0 0.0
Warbling Vireo 0.12 0.0 0.0 0.0 0.0 0.0 0.0 0.12 0.04 0.0 0.0 0.0 (0.12) 0.0 0.0 0.0 0.0 0.0 0.0 (0.07) (0.04) 0.0 0.0 0.0
Orange-crowned 0.12 0.0 0.0 0.20 0.0 0.0 0.32 0.21 0.0 0.0 0.40 0.0 Warbler (0.12) 0.0 0.0 (0.14) 0.0 0.0 (0.13) (0.12) 0.0 0.0 (0.15) 0.0
Yellow Warbler 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.13 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.10) 0.0 0.0 0.0
Yellow-rumped 0.0 3.09 0.0 0.0 5.43 3.50 0.63 0.0 1.04 0.78 0.70 0.0 Warbler 0.0 (1.77) 0.0 0.0 (2.40) (1.01) (0.34) 0.0 (0.42) (0.28) (0.32) 0.0 116
APPENDIX G. Mean (and Standard Error) of Birds per Visit in Freshwater Marsh at the Mitigation Area, Eureka, California, by Season. (Continued)
1979 1980 1981 1982
Summera Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Species n=8 n=11 n=4 n=15 n=14 n=16 n=19 n=24 n=23 n=18 n=20 n=8
Black-throated 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.09 0.0 0.0 0.0 Gray Warbler 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.09) 0.0 0.0 0.0
Common Yellowthroat 0.62 0.0 0.25 0.20 0.21 0.0 0.21 0.0 0.48 0.0 0.70 0.62 (0.32) 0.0 (0.25) (0.14) (0.16) 0.0 (0.10) 0.0 (0.16) 0.0 (0.24) (0.18)
Wilson's Warbler 0.0 0.0 0.25 0.27 0.43 0.0 0.05 0.67 0.22 0.0 0.05 0.0 0.0 0.0 (0.25) (0.21) (0.43) 0.0 (0.05) (0.29) (0.11) 0.0 (0.05) 0.0
Black-headed 0.38 0.0 0.25 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Grosbeak (0.18) 0.0 (0.25) 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Rufous-sided Towhee 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.04 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.04) 0.0 0.0 0.0
Savannah Sparrow 0.0 0.0 0.0 0.33 0.79 0.0 0.0 0.46 0.87 0.0 0.05 0.0 0.0 0.0 0.0 (0.19) (0.35) 0.0 0.0 (0.26) (0.28) 0.0 (0.05) 0.0
Fox Sparrow 0.0 0.0 0.0 0.0 0.21 0.0 0.10 0.0 0.17 0.61 0.20 0.0 0.0 0.0 0.0 0.0 (0.16) 0.0 (0.07) 0.0 (0.10) (0.20) (0.09) 0.0
Song Sparrow 1.88 1.09 1.75 2.60 1.93 1.50 2.00 2.75 3.87 2.44 2.20 2.12 (0.35) (0.28) (1.11) (0.50) (0.42) (0.26) (0.28) (0.19) (0.45) (0.29) (0.26) (0.30) 117 APPENDIX G. Mean (and Standard Error) of Birds per Visit in Freshwater Marsh at the Mitigation Area, Eureka, California, by Season. (Continued)
1979 1980 1981 1982
Summera Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Species n=8 n=11 n=4 n=15 n=14 n=16 n=19 n=24 n=23 n=18 n=20 n=8
Lincoln's Sparrow 0.0 0.09 0.0 0.0 0.64 0.44 0.0 0.0 0.65 0.17 0.20 0.0 0.0 (0.09) 0.0 0.0 (0.37) (0.22) 0.0 0.0 (0.26) (0.09) (0.12) 0.0
Swamp Sparrow 0.0 0.0 0.0 0.0 0.07 0.0 0.0 0.0 0.0 0.06 0.0 0.0 0.0 0.0 0.0 0.0 (0.07) 0.0 0.0 0.0 0.0 (0.06) 0.0 0.0
White-crowned 0.0 0.0 0.0 0.0 0.21 0.0 0.16 0.0 0.13 0.0 0.05 0.0 Sparrow 0.0 0.0 0.0 0.0 (0.21) 0.0 (0.12) 0.0 (0.13) 0.0 (0.05) 0.0
Dark-eyed Junco 0.0 0.27 0.0 0.0 0.0 0.0 0.05 0.0 0.65 0.22 0.15 0.0 0.0 (0.27) 0.0 0.0 0.0 0.0 (0.05) 0.0 (0.46) (0.13) (0.15) 0.0
Red-winged 1.75 0.09 0.50 2.33 0.07 0.0 1.05 1.12 2.56 0.39 1.70 1.75 Blackbird (0.84) (0.09) (0.29) (1.00) (0.07) 0.0 (0.28) (0.34) (2.17) (0.16) (0.45) (0.45)
Western Meadowlark 0.0 0.0 0.0 0.0 0.0 0.0 0.16 0.0 0.0 0.11 0.20 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.12) 0.0 0.0 (0.11) (0.20) 0.0
Brewer's Blackbird 0.25 0.0 0.0 0.07 0.0 0.0 0.05 0.0 0.0 0.0 10.00 0.0 (0.25) 0.0 0.0 (0.07) 0.0 0.0 (0.05) 0.0 0.0 0.0 (10.00) 0.0
Brown-headed 0.62 0.0 0.25 0.53 0.0 0.0 0.21 0.29 0.04 0.0 0.0 0.0 Cowbird (0.32) 0.0 (0.25) (0.19) 0.0 0.0 (0.12) (0.18) (0.04) 0.0 0.0 0.0 1 18
APPENDIX G. Mean (and Standard Error) of Birds per Visit in Freshwater Marsh at the Mitigation Area, Eureka, California, by Season. (Continued)
1979 1980 1981 1982
Summera Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Species n=8 n=11 n=4 n=15 n=14 n=16 n=19 n=24 n=23 n=18 n=20 n=8
Purple Finch 0.0 0.0 0.0 0.20 0.07 0.0 0.16 0.0 0.0 0.0 0.05 0.0 0.0 0.0 0.0 (0.20) (0.07) 0.0 (0.12) 0.0 0.0 0.0 (0.05) 0.0
House Finch 0.0 0.0 0.0 0.20 0.0 0.0 0.0 0.0 0.04 0.0 0.20 0.0 0.0 0.0 0.0 (0.20) 0.0 0.0 0.0 0.0 (0.04) 0.0 (0.20) 0.0
Pine Siskin 0.0 0.0 0.0 0.33 0.21 0.0 0.10 0.04 0.30 0.0 0.0 0.0 0.0 0.0 0.0 (0.23) (0.21) 0.0 (0.10) (0.04) (0.21) 0.0 0.0 0.0
American Goldfinch 0.12 0.0 0.75 2.87 3.43 0.0 0.05 3.71 3.87 0.0 0.30 0.12 (0.12) 0.0 (0.75) (1.10) (0.89) 0.0 (0.05) (1.01) (1.65) 0,0 0.0 0.0
House Sparrow 0.0 0.0 0.0 0.33 0.0 0.0 0.0 0.04 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (0.33) 0.0 0.0 0.0 (0.04) 0.0 0.0 0.0 0.0 aFreshwater marsh habitat was not differentiated in fall 1979 counts. bBarn Swallow was the only swallow to be seen perched in this habitat, although other species were seen foraging over it. Refer to salt marsh habitat for averages. 11 9 120
Appendix H. Approximate Territorial Boundaries of Birds during the Breeding Bird Counts in 1979 at the Mitigation Area, Eureka, California. 121
Appendix I. Approximate Territorial Boundaries of Birds During the Breeding Bird Counts in 1980 at the Mitigation Area, Eureka, California. 122
Appendix J. Approximate Territorial Boundaries of Birds during the Breeding Bird Counts in 1981 at the Mitigation Area, Eureka, California. 123
Appendix K. Approximate Territorial Boundaries of Birds during the Breeding Bird Counts in 1982 at the Mitigation Area, Eureka, California. Appendix L. Approximate Territorial Boundaries of Birds during the Breeding Bird Counts in 1980 at the Control Area, Eureka, California. 124
Appendix M. Approximate Territorial Boundaries of Birds during the Breeding Bird Counts in 1981 at the Control Area, Eureka, California. 1 25 Appendix N. Approximate Territorial Boundaries of Birds during the Breeding Bird Counts in 1982 at the Control Area, Eureka, California 126