Status of the Connecticut Warbler in British Columbia

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STATUS OF THE CONNECTICUT WARBLER IN BRITISH COLUMBIA

by J. M. Cooper K. A. Enns M. G. Shepard

Wildlife Working Report No. WR-83

February 1997

xi British Columbia, Canada’s most westerly province, has a bounty of biological diversity. British Columbia’s snowclad peaks, rain-drenched forests, arid grasslands, all sizes of rivers, lakes, and wetlands, and a long and rugged coast provide habitats for more species of living organisms than are found anywhere else in Canada. However, this very diversity means that there is much to be discovered about these organisms — their distribution, abundance, habitat requirements, and interrelationships with their environment. Increasing our knowledge of this biodiversity will help us with the complex task of sustainably managing our land and waters. In 1992, the Provincial Government initiated a co-operative biodiversity research program with funding from the Corporate Resource Inventory Initia- tive, the British Columbia Ministries of Forests (Research Branch), Environment, Lands, and Parks (Wildlife and Habitat Protection Branches), and Tourism and Culture (Royal B.C. Museum); and the Forest Resource Develop- ment Agreement (FRDA II). In 1996, funding from Forest Renewal BC (FRBC) was received for a biodiversity research extension proposal. One goal of the original research program, and more recently the FRBC extension project, is to extend information to scientists, resource managers, and the public through biodiversity publications. These publications are intended to increase awareness and understanding of biodiversity, promote the concepts and importance of conserving biodiversity, and communicate provincial government initiatives related to biodiversity. We hope that they will be used as tools for the conservation of British Columbia’s rich, living legacy.

For more information contact:

B.C. Ministry of Environment, Lands and Parks, Wildlife Branch, 780 Blanshard St., Victoria, BC V8V 1X4 or B.C. Ministry of Forests, Research Branch, 31 Bastion Square, Victoria, BC V8W 3E7 or Royal B.C. Museum, P.O. Box 9815, Stn Prov Govt, Victoria, B.C. V8W 9W2

xii STATUS OF THE CONNECTICUT WARBLER IN BRITISH COLUMBIA

J. M. Cooper K. A. Enns M. G. Shepard

Ministry of Environment, Lands and Parks Wildlife Branch Victoria, B.C.

Wildlife Working Report WR-83

February 1997

i “Wildlife Working Reports frequently contain preliminary data, so conclusions based on these may be subject to change. Working Reports receive little review. They may be cited in publications, but their manuscript status should be noted. Copies may be ob- tained, depending upon supply, from the Ministry of Environment, Lands and Parks, Wildlife Branch, 780 Blanshard Street, Victoria, BC V8V 1X4.”

Canadian Cataloquing in Publication Data

Cooper, John M. (John Morton) , 1956- Status of the Connecticut Warbler in British Columbia

(Wildlife working report ; no. WR-83)

Includes bibliographical references ISBN 0-7726-2999-4

1. Connecticut Warbler - British Columbia. I. Enns, K. A. (Katherine A.) II. Shepard, Michael G., 1951- III. BC Environment. Wildlife Branch. IV. Title. V. Series

QL696.P2438C666 1996 598.8'72 C96-960277-4

ii FOREWORD

In cases where a Wildlife Working Report or Bulletin is also a species status report, it may contain a status recommended by the author for the species. This recommended status is the opinion of the author and may not necessarily reflect that of the Wildlife Branch.

Official status designation will be made by the Wildlife Branch in consultation with experts, and the data contained in the status report will be considered during the evaluation process.

iii iv ABSTRACT

The Connecticut Warbler (Oporornis agilis) is an uncommon, forest-interior, neotropical migrant that is locally distributed in the Boreal Plains and Taiga Plains ecoprovinces of northeastern British Columbia. Its distribution is linked with the distribution of mature and old-growth deciduous (mainly aspen) forests with shrubby understories. Very few data exist on populations, habitat use, or breeding ecology. Existing data suggest that it will not occur in logged areas until forests regenerate to the late pole stage (30-40 years after harvesting).

The Connecticut Warbler is severely threatened in the northeast by plans to harvest mature and older aspen stands for pulpwood. Although it can be fairly common in suitable habitat, most of its habitat is target- ted for harvesting. Because of the short rotations forecast for second passes, none of the harvested stands will be allowed to return to older age-classes preferred by this warbler.

Because of its restricted distribution, small populations, and serious threats to habitat, the Connecticut Warbler should be retained on the B.C. Wildlife Branch Red List. It should also be given a high priority by wildlife managers because of the severe short- and medium-term threat to its habitat.

v vi ACKNOWLEDGEMENTS

This project was managed and funded by the Ministry of Environment, Lands and Parks, and production of the final report was made possible by the financial support of the Wildlife Branch, B.C. Ministry of Environment and Forest Renewal British Columbia (FRBC). Myke Chutter and Syd Cannings provided comprehensive and constructive reviews of earlier drafts of this manuscript. Ted Lea provided an extensive review of the section on habitat in an earlier draft. Jim Schieck sent us his unpublished manuscript on warbler habitat use in Alberta which provided useful context. Rhonda Millikin gave us her thoughts on the relative status of, and our provincial management responsibilities for, the Connecticut Warbler. Art Lance generously provided us with reports and unpublished information from his study near Dawson Creek. Wayne Campbell provided comments on status and access to some literature. Laura Darling gave us useful information from her study in the northeast. Mike Vislai, Richard Kabzems, Dave Parminter, Frank McAllister, Brian Churchill, Andrew Harcombe, John Parminter, Bob Ferguson, Ken Bolan, Everett Peterson, Merle Peterson, Nicola Parfitt, and Colin Woods all provided considerable help with the habitat section. We thank them all for their generous help and Myke, especially, for his encouragement. English and copy editing were done by Ted Wagstaff, and the final figures and page layout were done by Gail Harcombe.

vii viii TABLE OF CONTENTS

1.0 INTRODUCTION ...... 1 2.0 DISTRIBUTION ...... 1 2.1 Global ...... 1 2.2 British Columbia ...... 1 3.0 POPULATION SIZE AND TRENDS ...... 2 3.1 Population Size ...... 2 3.2 Population Trends ...... 4 4.0 GENERAL BIOLOGY ...... 4 4.1 Reproductive Capability ...... 4 4.2 Species Movement...... 5 4.3 Behaviour/Adaptability ...... 5 4.3.1 Tolerance to human disturbance ...... 5 4.3.2 Food...... 5 4.3.3 Response to sudden environmental change ...... 5 4.3.4 Causes of mortality ...... 6 4.3.5 Protection of areas of concentration...... 6 5.0 HABITAT ...... 6 5.1 Description of Habitats ...... 6 5.2 Nest Site Specialization ...... 7 5.3 Distribution of Habitat ...... 7 5.3.1 Biogeoclimatic Zones (BGZ)...... 8 5.3.2 Ecoregions...... 8 5.3.3 Broad Habitat Classes (BHC) ...... 8 5.4 Present Habitat Availability ...... 8 5.5 Trends in Quantity and Quality of Critical Habitat by Time ...... 8 5.6 Rate of Habitat Change ...... 8 5.7 Legal Status of Habitat ...... 10 5.7.1 Timber Supply Areas (TSA) ...... 10 5.7.2 Protected areas ...... 10 5.8 Can Critical Habitat be Protected by Means Other Than Acquisition? ...... 11 6.0 LEGAL PROTECTION ...... 12 7.0 LIMITING FACTORS ...... 12 7.1 Breeding Habitat ...... 12 7.2 Silviculture ...... 12 7.3 Forest Succession ...... 13 7.4 Brown-headed Cowbird Parasitism ...... 13 7.5 Predation ...... 14 7.6 Grazing ...... 14 7.7 Agriculture ...... 14 7.8 Urban Development ...... 14 7.9 Fire Suppression ...... 14 7.10 Air Pollution ...... 14 7.11 Seismic Lines and Roads ...... 15 7.12 Winter Habitat...... 15

ix 8.0 SPECIAL SIGNIFICANCE OF THE SPECIES ...... 15 8.1 Status ...... 15 8.2 Degree of Public Interest ...... 15 8.3 Related Species...... 15 9.0 RECOMMENDATIONS AND MANAGEMENT OPTIONS ...... 16 10.0 RESEARCH NEEDS ...... 17 11.0 EVALUATION ...... 17 12.0 LITERATURE CITED ...... 18

LIST OF TABLES

Table 1. Broad Habitat Classes (BHCs) used by the Connecticut Warbler ...... 9 Table 2. Comparison of six rare songbirds restricted to northeastern British Columbia ...... 18

LIST OF FIGURES

Figure 1. Breeding and wintering distribution of the Connecticut Warbler ...... 2 Figure 2. Locality records for the Connecticut Warbler in British Columbia...... 3 Figure 3. Timber Supply Areas in northeastern British Columbia ...... 11

x 1.0 INTRODUCTION 2.0 DISTRIBUTION

The Connecticut Warbler (Oporornis agilis) is a 2.1 Global long-distance, forest-interior, neotropical migrant that is restricted in British Columbia to the north- The Connecticut Warbler breeds in a narrow band eastern corner of the province. Populations are across Canada from northeastern British Columbia thought to be small and local. Because of its re- east to western Quebec and, in the USA., in stricted distribution and low populations, the northern Minnesota, Wisconsin, and Michigan Connecticut Warbler is listed on the B.C. Wildlife (Godfrey 1986; Figure 1). Most of its breeding Branch Red List as a candidate for threatened or range is in Canada. It winters from northern Ven- endangered status (B.C. Wildlife Branch 1993). ezuela to central Brazil, mainly in the Amazon River basin (American Ornithologists’ Union Recent studies have indicated a widespread de- 1983). cline in populations of neotropical migrant songbirds (those that breed in temperate regions 2.2 British Columbia and winter in tropical regions), and that these declines have accelerated for some species in recent The Connecticut Warbler occurs mainly in the years (Robbins et al. 1989; Askins et al. 1990; Peace Lowland and Kiskatinaw Plateau Finch 1991; Hagan and Johnston 1992). Causes of ecosections of the Boreal Plains Ecoprovince these declines are diverse, but are widely thought (Godfrey 1986; Enns and Siddle 1992; Figure 2). to occur on breeding, wintering, or migrating Small numbers have been reported from near Fort areas, or a combination of the three (Terborgh Nelson (Erskine and Davidson 1976; Siddle 1992) 1989; Sherry and Holmes 1993). in the Fort Nelson Lowland Ecosection of the Taiga Plains Ecoprovince. Connecticut Warblers This report contains a synthesis of available infor- reach the northwestern extremes of their range in mation on Connecticut Warblers including an central Alberta and northeastern British Columbia. overview of the species’ biology, habitat requirements, limiting factors, distribution, status, and Connecticut Warblers are probably more wide- prognosis for the future. Information was gathered spread in northeastern British Columbia than from published and unpublished literature, per- currently documented. Recent surveys have found sonal records, and personal communication with populations from areas where there were no previ- biologists. It also contains recommendations for ous reports, e.g., northeast of Chetwynd (L. management techniques and additional research Darling, pers. comm.), and south of Dawson that are needed to maintain populations in British Creek (Lance and Phinney 1994). Columbia in the future.

This report is one of six status reports on six 3.0 POPULATION SIZE AND northeastern songbirds commissioned by the B.C. TRENDS Wildlife Branch during 1994, and is part of an ongoing program to more effectively manage spe- 3.1 Population Size cies at risk for long term viability. The other five species are Bay-breasted Warbler (Dendroica There are few data on population sizes in British castanea), Black-throated Green Warbler (Dendro- Columbia, but a few studies provide conflicting ica virens), Cape May Warbler (Dendroica results. Although Siddle (1992), and Enns and tigrina), Canada Warbler (Wilsonia canadensis), Siddle (1992), reported Connecticut Warblers and Philadelphia Vireo (Vireo philadelphicus). to be the third and second, respectively, least

1 frequently recorded warbler species in the north- We feel that Lance and Phinney’s (1993, 1994) east, Lance and Phinney (1994) considered it to studies suggest that Connecticut Warblers are be “common” in aspen forest south of Dawson more widely distributed and more numerous (but Creek, and the second most frequently recorded still of local occurrence) than previously thought “northeastern” warbler, after the Ovenbird. Maxi- in the Boreal Plains. Data from the Fort Nelson mum counts of four pairs each were found in two Lowland are few, but we believe that Connecticut of their study plots (32 and 72 ha, respectively). Warblers occur there more frequently than is cur- Northeast of Chetwynd, it was also found to be rently known. Flack (1976) also suspects that, fairly common in suitable habitat (L. Darling, throughout its range, the Connecticut Warbler is pers. comm.). more locally common and widely distributed than generally thought.

Breeding Range

Winter Range

Figure 1. Breeding and wintering distribution of the Connecticut Warbler.

2 Figure 2. Locality records for the Connecticut Warbler in British Columbia.

3 The Connecticut Warbler has been found to be occur regularly between years in specific sites sparsely and locally distributed in central Alberta (Siddle 1992). during recent atlas surveys (Semenchuk 1992); our data indicate that it may be more abundant in An evaluation of Lance and Phinney’s (1994) data British Columbia, but still locally distributed, than indicate that this warbler will be eliminated in the in northern Alberta. We believe that in British short term (30-40 years) from clearcut blocks of Columbia, Connecticut Warblers have relatively aspen forest. Because mature aspen forests are be- small populations, but can be fairly common in ing rapidly harvested in the northeast and local areas with good habitat. harvesting rotations will be shortened, it is inevi- table that British Columbia populations will 3.2 Population Trends decline in the future (see HABITAT).

There are no data on population trends in British 4.0 GENERAL BIOLOGY Columbia, although some authors believe that all northeastern warblers are in decline (e.g., Siddle 1992). There are insufficient data to analyze 4.1 Reproductive Capability breeding bird survey trends in British Columbia (Erskine et al. 1992). In a comprehensive analysis There are no data on the breeding ecology of of northeastern North American breeding bird sur- Connecticut Warblers in British Columbia and, veys, Sauer and Droege (1992) found no like the Canada Warbler, many details of breeding significant population trends for the Connecticut are completely lacking from anywhere in its Warbler in the long-term (1966-1988), but found range. The following information is taken from a significant increase in the short term (1978- studies in eastern North America. 1988). Connecticut Warblers usually lay a clutch of 4 or It is important to consider that widespread popu- 5 eggs, sometimes 3 eggs (Bent 1953; Harrison lation declines are difficult to detect because a 1978; Ehrlich et al. 1988). Egg-laying likely oc- given species might contract its range, occupy curs mainly in mid-to-late June in northeastern fewer habitats, decline in abundance, or a combi- British Columbia, as it does in Alberta (Salt nation of the three, and there may be significant 1973). The incubation period is unknown, but is errors in counting methods (Wilcove and Terborgh probably 12-13 days, as in the closely related and 1984). However, because neotropical migrants are similarly-sized Kentucky Warbler (Oporornis thought to be suffering widespread population de- formosus; Bent 1953). clines (Morton and Greenberg 1989; Terborgh 1989; Finch 1991), because there is an overall Nestlings are likely present from late June paucity of records for Connecticut Warblers in through mid-July. The nestling period is unknown, British Columbia, and because Connecticut Warb- but is also probably similar to the Kentucky lers require mid-to-late seral stands (which are Warbler, whose nestlings leave the nest after 8-10 being rapidly harvested, see HABITAT), it is days, but cannot fly until about a week later (Bent probable that populations are stable or declining, 1953; Harrison 1978). A single brood is probably and improbable that populations are increasing. raised each year in British Columbia, a widespread pattern in warblers (Morse 1989). The impression we hold from our own field Double-brooding is rare in warblers, even in spe- studies is that Connecticut Warblers occur in cies nesting in the southern USA. (Nolan 1978). all suitable habitats at reasonable densities, but There are no data for Connecticut Warblers on we cannot estimate the degree of saturation. A hatching success, survival of nestlings, or fledg- contrary view is that Connecticut Warblers do not ing success. Numbers of young produced are

4 limited by clutch size (3-5 eggs) and numbers of Alberta, beginning in the last few days of May, broods produced (1 brood). with most probably arriving in early June. Early arrivals in Alberta also appear in the last few days Under normal circumstances, recruitment will re- of May (Salt 1973; Salt and Salt 1976). place mortality. The growth potential of populations under managed conditions is limited After nesting is completed, adults probably begin to an unknown degree by events occurring else- to migrate south in mid-to-late July and juveniles where in its range. In general, the annual follow in mid-August, earlier than the mid-August reproductive potential of most neotropical mi- to early September fall movement in central Al- grant warblers is relatively low compared to berta (Salt 1973; Salt and Salt 1976). many other small, short-distance, migrant or resi- dent songbirds (Morse 1989). The maximum life 4.3 Behaviour/Adaptability span reported for this warbler is 4-5 years (Klimkiewicz et al. 1983). 4.3.1 Tolerance to human disturbance Age/sex ratios of populations in British Columbia Connecticut Warblers are not unduly sensitive to are unknown. However, most warbler populations human disturbance except for activities that affect are thought to have a surplus of males (Stewart habitat integrity (logging, agricultural clearing) or and Aldrich 1952; Ficken and Ficken 1962; Proc- prey base (pesticide spraying). Their sensitivity to tor-Gray and Holmes 1981). Connecticut Warblers heavy grazing and selective logging in breeding can breed as one-year-olds, but some individual areas is unknown (see LIMITING FACTORS). yearlings likely do not breed, as in some other Large-scale spraying of insecticides in deciduous warblers (Morse 1973). forest habitat would inevitably reduce their insect prey base (see Freedman et al. 1981). Application The Connecticut Warbler is thought to be mo- of herbicides to eliminate deciduous forest and nogamous (Ehrlich et al. 1988). Upon arriving on understories would reduce available habitat (see the breeding grounds, males select nesting territo- HABITAT). ries and defend them from other conspecific males. There are no data on breeding territory size, but territories of warblers are typically small 4.3.2 Food (e.g., 0.4-1.0 ha; Morse 1976). In west-central Al- berta, density of territorial males in 30-year-old The Connecticut Warbler is a mainly ground- aspen forest was 4.4/100 ha (Westworth and dwelling, insectivorous bird that eats a variety of Telfer 1993). small insects, spiders, snails, eggs of spiders and insects, berries, and seeds (Bent 1953). It feeds 4.2 Species Movement mainly by gleaning prey from the ground, along fallen logs, and from foliage of low shrubs and Connecticut Warblers winter further south than herbs (Bent 1953; Griscom and Sprunt 1957; most other North American warblers and so have Curson et al. 1994). In British Columbia, most a longer distance to travel during migration. They foraging is done within the shrub layer or along arrive in Canada later, and leave earlier, than most the ground (Enns and Siddle 1992). other warblers except for Mourning, Canada and Blackpoll warblers (Cowan 1939; Salt 1973; 4.3.3 Response to sudden Keast 1980; Francis and Cooke 1986). Males environmental change probably arrive slightly earlier than females, a general pattern in many bird species. Spring mi- There are no data to suggest that populations grants enter the province through northern expand and contract in response to sudden

5 changes in prey availability, as do Cape May and ¥ Saskatchewan — aspen groves with a well- Bay-breasted warblers to spruce budworm out- developed shrub and ground understorey breaks (Morse 1978). In general, late spells of (Johns 1993); cold weather are known to cause mortality in early migrant warblers (Morse 1976). ¥Alberta — open, deciduous forests, with scattered jackpine at times, and along the margins 4.3.4 Causes of mortality of meadows (Salt 1973); small prairies scattered through aspen forest (Henderson in Bent Specific data are lacking for this species, but pre- 1953); small dry ridges with aspen forest dation and cowbird parasitism are the two leading above bogs (Taverner 1928); young (23-26 causes of nest mortality for neotropical migrants years), pole (30 years), mature (51-63 years), in general (Martin 1992). Predation and cowbird and old (80 years) aspen forests (Westworth parasitism are known to increase with increasing and Telfer 1993); and old-growth (>120 habitat fragmentation (Wilcove 1985; Martin years) aspen forests near Lac La Biche (J. 1992). Migrating warblers suffer mortality from Schieck, pers. comm); natural environmental effects and from human- ¥ Southern Manitoba — open tamarack/moss related factors such as collision with light-towers swamp (Seton 1884); (e.g., Crawford 1978; Ralph 1981). ¥Minnesota — spruce and tamarack swamps 4.3.5 Protection of areas of (Roberts in Bent 1953). concentration J. Schieck’s (pers. comm. 1994) study found no Like all warblers, this species is widely scattered on utilization in recent clearcuts and highest utiliza- the breeding and wintering grounds. In British Co- tion in old aspen forests (>120 years). In D.A. lumbia, small numbers are likely protected in Westworth Ltd. (1984), Connecticut Warblers various reserves/parks, but data are lacking. Siddle were most frequently associated with high (1992) lists Gundy (north of Tupper) and Cecil Lake amounts of deciduous canopy cover typical of 60- as areas of consistent occurrence, but densities of 80-year-old stands. Westworth and Telfler’s birds and status of lands are uncertain. (1993) study, with four age classes of forest, found highest utilization in mature, open, decidu- 5.0 HABITAT ous stands.

In northeastern British Columbia, Connecticut 5.1 Description of Habitats Warblers were found in:

The Connecticut Warbler is a bird of mature and ¥ The edges of old-growth and younger stage old-growth, deciduous-dominated forests with rich stands of aspens and white spruce near Swan understories, including both pure deciduous and Lake (Cowan 1939). mixedwood stands. Understorey development is critical for this warbler as it forages almost exclu- ¥Mixed balsam poplar and white spruce is- sively on, or very near, the ground. Populations in lands in the Peace River (Penner 1976). different geographic regions may occupy somewhat different forest types, but all descriptions of ¥Old-growth aspen stands with white spruce habitat in Saskatchewan, Alberta, and British sapling understorey near Tupper, Cecil Lake, Columbia include deciduous (mainly aspen) for- and Fort Nelson (Siddle 1992). est. Habitat descriptions include:

6 ¥White spruce/trembling aspen or pure aspen Connecticut Warblers were not found in recent forests on flat or gentle slopes, with clearcut slash, sapling, or early pole seral stands understories less than 3 m high (Enns and during this study, nor were they found in recent Siddle 1992). clearcuts or sapling stands in west-central Alberta (Westworth and Telfer 1993), we believe that ¥ Pole, mature, and old-growth seral stages of Connecticut Warblers will be eliminated from trembling aspen (Lance and Phinney 1993, aspen stands after clearcutting and will not 1994). recolonize clearcut blocks until the regenerating forest reaches the late pole stage (dbh >10 cm and Some common characteristics of reported Con- age >35-40 years). The data provided in these necticut Warbler breeding habitat in British studies reaffirm our view that Connecticut Warb- Columbia include (from sources listed above): lers in British Columbia occur mainly in mature to old-growth aspen stands. Pole stage forests are ¥ Flat to gently sloping sites with variable-aged, the minimum growth stage suitable. Note that but almost always large, aspen in a widely Westworth and Telfer (1993) did find this species spaced configuration. in 23-26 year-old stands, the youngest stage reported to be used, but early pole stages are ¥High, thin crowns with few lower lateral probably not “good” habitat. branches and plenty of free, mid-canopy-level space. 5.2 Nest Site Specialization

¥Noticeable gaps in cover between the dense, Nest site microhabitat seems to be relatively con- shrubby understorey and the even, high stant throughout its range, but no data are canopy of aspen. available from British Columbia. The ground cover at nest sites can be characterized as richly ¥Well-developed understorey, usually <3 m. vegetated. An overstorey of late pole or older Associated species include tall bluebell, stage aspen is required. white geranium, baneberry, rose, northern bedstraw, red-osier dogwood, willow, Nests are compact, deep cups of fine grass and bluegrass, wildrye, timothy, paintbrush, rootlets lined with finer grass and hair. Nests are junegrass, bunchberry, soopolallie, fireweed, placed on the ground among herbs and grass or at American vetch and purple peavine. the base of a sapling, in mossy hummocks, or a few inches off the ground in the base of a shrub ¥ Spruce are often interspersed sporadically (often wild rose), and are usually well-concealed throughout the stand. by overhanging vegetation (Bent 1953; Harrison 1978; Harrison 1984). Nesting and foraging habitat requirements are similar except that territorial males may perch in 5.3 Distribution of Habitat middle canopy levels when singing (Enns and Siddle 1992). Otherwise, this warbler rarely oc- The distribution of potential Connecticut Warbler curs more than 2 metres above ground. habitat can be described with three general classi- fications (Biogeoclimatic Zones, Ecoregions, and We have evaluated some data summarized during Broad Habitat Classes) that are currently used in research on bird use of aspen forests in the Peace British Columbia. Lowland (Lance and Phinney 1994). Because

7 5.3.1 Biogeoclimatic Zones (BGZ) 5.3.3 Broad Habitat Class (BHC)

The Connecticut Warbler occurs in two variants The Connecticut Warbler has been recorded using of the Boreal White and Black Spruce (BWBS) three BHCs in the Boreal Plains and Taiga Plains Biogeoclimatic Zone: the BWBSmw1 variant ecoprovinces (Lea and Harcombe 1992). Descrip- (Peace Moist Cool Boreal White and Black tions of these BHCs and general abundances of Spruce) and the BWBSmw2 variant (Fort Nelson each BHC in Ecosections (Figure 2) where the Moist Cool Southern Boreal White and Black Connecticut Warbler is known to occur are in- Spruce) (DeLong et al. 1990; Meidinger and Pojar cluded in Table 1. 1991). The BWBSmw1 is generally aligned with the Boreal Plains Ecoprovince and the BWBSmw2 is aligned mainly with the Taiga 5.4 Present Habitat Availability Plains Ecoprovince (Demarchi 1993). Connecticut Warbler habitat is distributed over The BWBS is the most widespread BGZ in much of the Peace Lowland and parts of the Fort Canada (DeLong et al. 1990) and occupies virtu- Nelson Lowland. Note that there is considerable ally all of the Boreal Plains and Taiga Plains uncertainty in the amount of suitable habitat ecoprovinces. The BWBS also occurs west of the available in British Columbia because Connecti- Rocky Mountains in northern British Columbia, cut Warblers are found almost always in pure mainly along major river valleys, but the Con- aspen stands, not in aspen-dominated mixedwoods necticut Warbler does not occur there. (Enns and Siddle 1992; Lance and Phinney 1993, 1994; L. Darling, pers. comm.). The Connecticut Warbler occurs mainly within the White spruce - Wildrye - Peavine (03) site series 5.5 Trends in Quantity and Quality of (Meidinger and Pojar 1991). This site unit has Critical Habitat by Time at least 50% trembling aspen occurring in submesic, coarse- to fine-textured soils, on a vari- Trends in habitat quality and quantity over time ety of materials with an upper-, mid-, or level for Connecticut Warblers are directly linked with slope position. harvesting of mature aspen stands, particularly in the Peace Lowland. Quantity and quality of 5.3.2 Ecoregions habitat are judged to be currently declining. In- creasing harvesting rates, silviculture, and The Connecticut Warbler has been recorded in the agricultural conversion will be the primary limit- following ecosections within its normal range in ing factors for Connecticut Warblers in the British Columbia (Figure 2): northeast (see LIMITING FACTORS).

Boreal Plains Ecoprovince: Peace Lowland, 5.6 Rate of Habitat Change Kiskatinaw Plateau, and Clear Hills ecosections. The changes that are expected to take place in Connecticut Warbler habitat are directly linked Taiga Plains Ecoprovince: Fort Nelson Low- with forestry effects, especially rates of harvest land Ecosection. (B.C. Ministry of Forests 1994). Aspen mixedwood harvesting is at approximately 40 000 It is unlikely to occur in any other ecosections in to 1 00 000 m3 annually, which is the current in- these ecoprovinces. dustry capacity. Because the average aspen stand contains about 250 m3/ha, an estimated 1800-4000

8 Table 1. Broad Habitat Classes (BHCs) used by the Connecticut Warbler and general distribution of the BHCs in ecosections where the Connecticut Warbler occurs (adapted from Lea and Harcombe 1992; Enns and Siddle 1992). Distributions are cross-referenced with Bonnor (1985).

Broad Habitat Class and distribution in ecosections1 Description

BA Boreal White Spruce-Trembling Aspen Typically a dense, broad-leaved, mixed or coniferous mixed forest, with shrub and herb dominated Distribution of BA in ecosections: understories, which includes plant communities that PEL: widespread succeed through trembling aspen seral forests to a KIP: widespread white spruce climax. Includes all of the pure aspen CLH: localized to widespread areas around Ft. St. John and Dawson Creek. FNL: widespread to localized

PR Boreal White Spruce-Balsam Poplar Typically a deciduous, mixed or coniferous forest Riparian with dense shrub understories, found on or in asso- ciation with fluvial sites, which include plant Distribution of PR in ecosections: communities that succeed through deciduous forests PEL: widespread to localized to a white (or hybrid) spruce climax. KIP: widespread to localized CLH: widespread to localized FNL: widespread to localized

AC Trembling Aspen Copse Not a recognized class in the Boreal and Taiga Plains (Lea and Harcombe 1992); but is common Distribution of AC in ecosections: throughout. Typically a dense deciduous forest, with PEL: widespread a shrub-dominated understorey, which includes plant KIP: widespread communities that succeed through shrub thickets to CLH: localized an edaphic climax of trembling aspen, found in as- FNL: widespread to localized sociation with shrub/grasslands.

1 PEL-Peace Lowland KIP-Kiskatinaw Plateau CLH-Clear Hills FNL-Fort Nelson Lowland

ha are being harvested annually (B.C. Ministry of distribution will be primarily <50 years of age Forests 1994). in 50 years. In 100 years, less than 12 000 ha of deciduous forest is forecast to be >80 years. Fur- There are a number of constraints to the quality ther, forest managers are uncertain about how to of 223 000 ha of aspen reported (see 5.7.1) for the treat these older stands: should they be left for Dawson Creek Timber Supply Area (TSA). About habitat, or logged and the intrinsic silvics of 112 000 ha, or a large proportion of the aspen allowed to take its course? In addition, the harvestable area in the TSA, is currently cover- conservation of habitat for the Connecticut Warb- ed by deciduous forest greater than 80 years (in- ler is not currently part of the aspen forest harvest cludes primarily aspen and about 10% planning process. cottonwood). It is projected that age class

9 At present there are no plans to allow older age minor component (41-60 years) and 40 000 ha classes of aspen into the harvesting rotation, other of cottonwood-deciduous >101 years (Massie than those stands which have a poor operability. et al. 1994). This poor operability translates into poor access (i.e., steeper slopes), and other factors that may Pulpwood Agreements 10 and 13, both with Loui- not be suitable for Connecticut Warblers. In other siana-Pacific Panel Products Ltd., cover roughly words, we do not know how much, if any, “good” 75% of the Dawson Creek TSA and probably all habitat will remain in the long term. of the habitat suitable for Connecticut Warblers on Crown Land. In comparison, the private At the present time, all aspen harvesting is sup- landbase in the Dawson Creek TSA is about posed to be taking place on private lands, with no 800 000 ha of aspen-dominated forest. Protection harvest occurring on Crown Lands (D. Parminter, of habitat on private lands is currently at the dis- pers. comm. 1994). However, most mature aspen cretion of the owners. that is accessible is targeted for harvest at some point (B.C. Ministry of Forests 1994). Rates of 5.7.2 Protected areas change of mature aspen on flat, rolling topography, to clearcuts should be classed as rapid A few areas with habitat suitable for Connecticut because of easy access. Demand for British Co- Warblers are currently protected in British Colum- lumbia hardwoods is expected to increase in the bia (B.C. Ministry of Forests 1993). near term also because 100 truckloads/day coming from Alberta will be shifted to a new mill in Provincial Parks Grande Prairie, Alberta in 1996, and profitability Several Class A parks that are within the known is high (Massie et al. 1994). range and habitat type of the Connecticut Warbler include: 5.7 Legal Status of Habitat ¥ Beatton, northwest of Fort St. John (312 ha) The legal status of lands with potential habitat for in a trembling aspen upland. the Connecticut Warbler is discussed below. ¥Taylor Landing, 16 km northeast of Fort St. John (2102 ha) in riparian mixedwood, and 5.7.1 Timber Supply Areas (TSA) trembling aspen upland. ¥Kiskatinaw River, 34 km northeast of Dawson Estimates of potentially suitable aspen-dominated Creek (1148 ha) in riparian cottonwood and habitat in northeastern Timber Supply Areas (Fig- mixedwood forest. ure 3) are given below: ¥ East Pine, 24 km east of Chetwynd (14 ha) in mixed deciduous riparian. ¥ Fort St. John TSA: 190 000 ha of aspen- deciduous seral stages in age classes 21-60 years. Older age classes (>60 years) include Ecological Reserves an additional 30 000 ha (B.C. Ministry of For- Ecological Reserves that may have small amounts ests 1994). of suitable habitat include:

¥ Dawson Creek TSA: 223 000 ha of young to ¥No. 8, Clayhurst, on the Peace River near the mature (21-100 years) deciduous forest (B.C. Alberta border (316 ha), in dry aspen park- Ministry of Forests 1994). land. ¥ No. 62, Fort Nelson River, 20 km northeast of ¥ Fort Nelson TSA: 28 000 ha of aspen- Fort Nelson (121 ha) in cottonwood riparian deciduous forest types where spruce is a forest.

10 Proposed Protected Areas 5.8 Can Critical Habitat be Protected There are several areas that have been proposed by Means Other Than as protected areas (proposed status uncertain) Acquisition? that may include small amounts of good habitat, including: Critical habitat for Connecticut Warblers can cer- tainly be protected on Crown Lands at present, • Belcourt River, a large area in the southeast- while there is no aspen harvest allowed. Habitat ern border of the Boreal Plains south of protection by way of Wildlife Habitat Areas (for Dawson Creek (37 441 ha) in a pine-aspen other species), Protected Area Strategy initiatives and mixedwood riparian forest. (i.e., additional parks and reserves), and harvest- •Prophet River, an old-growth riparian ecosys- ing methodologies (i.e., Forest Ecosystem tem including mixed cottonwood and white Networks and Riparian Management Areas) are spruce. viable methods of protecting small amounts of • Conroy Creek an old-growth riparian ecosys- habitat. tem including mixedwood riparian.

Figure 3. Timber Supply Areas in northeastern British Columbia.

11 The Biodiversity Field Guide of the Forest Prac- Saskatchewan (Johns 1993), however, determined tices Code states that, for wildlife listed on the that the presence of Connecticut Warblers was: Red List, habitat capability/suitability maps must be completed for the area of an operational plan 1. positively related to aspen grove area (i.e., and the habitat needs of those species must be ad- the larger the grove the more likely it would dressed. This presumably means that a certain contain Connecticut Warblers), and amount of suitable habitat must be retained during forest or range development. Implementation of 2. negatively related to isolation of the grove the Forest Practices Code may be critical for the (the further away from other groves the survival of this species in British Columbia (see less likely that it would contain Connecticut LIMITING FACTORS). Warblers.

6.0 LEGAL PROTECTION These results suggest that as suitable habitat be- comes increasingly fragmented in unit size and The Connecticut Warbler, its nests and its eggs, distance between units, then fewer Connecticut are protected from direct persecution in Canada Warblers will occur because they are relatively and the USA. under the Migratory Birds Conven- sensitive to area effects (Thompson et al. 1993b). tion Act of 1994 and, in British Columbia, by the There are no data available for British Columbia British Columbia Wildlife Act of 1982. See com- but, in Saskatchewan, Connecticut Warblers were ments above regarding the Forest Practices Code not found in groves less than 3.5 ha. Lance and of British Columbia Act. Phinney (1994) do not have data on minimum areas, but did record Connecticut Warblers in 7.0 LIMITING FACTORS study plots as small as 4 ha. In general, forest fragmentation and loss of forest The factors that are likely to limit populations of habitat has been widely blamed for declines in the Connecticut Warbler in British Columbia are warbler breeding populations, and changes in predominantly forest harvesting and silviculture in overall bird community structure (e.g., Tit- the Boreal Plains Ecoprovince. However, addi- terington et al. 1979; Whitcomb et al. 1981; tional factors are likely to have some impact on Askins et al. 1987; Terborgh 1989; Freemark and populations and all of these are discussed below. Collins 1992; Maurer and Heywood 1993); and there is no reason to believe that Connecticut 7.1 Breeding Habitat Warblers will respond differently to change in habitat than many other neotropical migrants. Connecticut Warblers are dependent on mature or older, open aspen forests. Aspen forests on flat or 7.2 Silviculture rolling areas and along river valleys are prime habitats and are, with few exceptions, targeted for Alternatives to clearcut logging are not likely to harvesting. Harvesting of mature aspen stands will be adopted by foresters trying to promote a new remove the clearcut blocks as suitable habitat for aspen crop. Methods such as natural selection log- at least 30-40 years, until second-growth stands ging are not of benefit in trembling aspen stands reach the late pole stage. because of clonal suppression. Forms of selective logging have been used to suppress deciduous There are few data available on the direct effect trees in areas desired for conversion to coniferous of habitat loss, habitat fragmentation, or forest crops, which is of equal concern (Peterson and succession on Connecticut Warblers. One study in Peterson 1992).

12 The forest management imperative is unquestion- (1992) found Connecticut Warblers only in mature ably away from long rotations of trembling aspen. or old-growth forest. The suitability of small pole In a synopsis of interviews with silviculturalists in stages is uncertain, but is likely poor. Our analy- regions with boreal mixedwood, conducted in sis of the available data suggests that aspen 1988, Peterson et al. (1989) found the following forests will regenerate into “useable” habitat (late concerns expressed that run counter to habitat re- pole stage) after about 30-40 years. However, one quirements by the Connecticut Warbler: major question needs to be answered before we can assume that late pole stage forests will pro- ¥ Softwood and hardwood harvesting on the vide “suitable” habitat — is reproductive success same lands (e.g., two-pass system) is to be similar in late pole and mature and older stage expected. forests? If reproductive success is lower in late pole stage forest than in mature or older forest, ¥ Shorter rotations will be the norm; pure de- then forest succession will not replace any lost ciduous stands will be harvested at 35-45 habitat for even a short period of time (assuming years. that forests will be harvested again after 35-45 years). If it is equal or higher, which is unlikely, ¥Decay in aspen is viewed as a problem in then forest succession will replace lost habitat older stands, therefore shorter rotations may more quickly. The effect of various forestry prac- also be viewed as a prophylactic for tices on breeding productivity of neotropical Hypoxylon spp. and other decay organisms migrants is largely unknown, and much remains associated with older age classes. to be determined for Connecticut Warblers.

¥Vegetation management is still prevalent in 7.4 Brown-headed Cowbird boreal hardwood stands, at least in younger Parasitism seral stages. Effects of herbicide are usually lost within a decade of treatment (Santillo et The impact of nest parasitism by Brown-headed al. 1989, Bell 1991). The long-term effects of Cowbirds is thought to be severe on neotropical mechanical site preparation on species com- migrant songbirds, especially in fragmented for- position and organic material in older stands, ests (Brittingham and Temple 1983; Askins et al. and thus the quality of the understorey, is 1990; Robinson et al. 1993). Cowbird parasitism poorly known (Enns 1994). and predation are the two leading causes of nest mortality (Martin 1992; Sherry and Holmes As fragmentation of aspen forest land base ad- 1993). Although the Connecticut Warbler has not vances, crown character is expected to change. been reported as a host-species for cowbirds Unless longer rotations are allowed to occur, (Friedmann and Kiff 1985), we believe this crown development typical of suitable Connecti- may be because of a combination of the general cut Warbler habitat will not be achieved, nor will paucity of nest records for this elusive warbler, adequate understories. and its forest-interior preference. The closely related Mourning (Oporornis philadelphia) and 7.3 Forest Succession MacGillivray’s (O. tolmiei) warblers are common cowbird hosts, but are both “edge” species, rather Connecticut Warblers do not use recently clearcut than forest-interior species. There is little reason or sapling stage forests in British Columbia, but to believe that Connecticut Warblers will not be do occur in late pole, mature, and old stage for- routinely parasitized as well, if cowbirds are ests, an evaluation of data in Lance and Phinney present. So, if we accept that Connecticut (1993, 1994). Enns and Siddle (1992), and Siddle Warblers are not regularly parasitized because

13 they are a forest-interior species, then the rate of 7.8 Urban Development parasitism can only increase with increasing fragmentation of northeastern forests. Urban development has not advanced as rapidly in the range of Connecticut Warbler as in other 7.5 Predation areas of British Columbia, but human settlements provide habitat for predators such as jays, mag- Fragmentation through clearcutting, road building, pies, crows, domestic cats, and squirrels. agricultural clearing, etc., also increases edge habitat favoured by predatory species such as 7.9 Fire Suppression jays, crows, magpies, squirrels and weasels. Be- cause the probability of predation on forest Fire has a vital role in the regeneration of aspen songbird nests increases with increasing forest forests. Fires are rarely severe in older mesic fragmentation (Wilcove 1985; Yahner and Scott stands on rolling topography, especially in the ab- 1988; Askins et al. 1990), it is likely that Con- sence of heavy debris fuels in the understorey necticut Warblers will face increasing predation (Brown and Simmerman 1986). Cool ground fires intensity as forests are cleared. in these stands may act to rejuvenate shrub and herbaceous subcanopies that appear to be required 7.6 Grazing by Connecticut Warblers. Fire suppression has a secondary effects which is the eventual domi- Connecticut Warblers inhabit forests with a mod- nance of spruce understories; suppression in this erately rich ground cover of saplings, shrubs, and case acts as a very patient agent of stand conver- herbs. High-intensity grazing by cattle may de- sion that is detrimental to Connecticut Warblers. stroy much of the structural integrity of the lower shrub layer in local sites and seriously degrade Prescribed fire may also be used to remove what habitat. Grazing, thinning, or control of shrub lay- foresters may perceive as “decadent old aspen ers is a potential cause of population decline for stands,” which are very good habitats for Con- ground-dwelling species dependent on rich necticut Warblers. Impacts of fire in aspen are understories (see Askins and Philbrick 1987; Bock reviewed by Peterson and Peterson (1992). et al. 1993). However, at least two of ten locations for Connecticut Warbler in the northeast Ungulate forage enhancement using prescribed were noticeably grazed by cattle (Enns and Siddle fire may occur in some habitat types frequented 1992), which suggests tolerance of at least mini- by Connecticut Warblers. This will have an un- mal grazing. Note also that Brown-headed known impact on habitat suitability over the Cowbirds are attracted to cattle. long-term but short-term effects will be negative because of the destruction of vegetation 7.7 Agriculture understories.

Many of the pure aspen stands of large stem size 7.10 Air Pollution occur on private lands adjacent to agricultural fields in the Dawson Creek TSA. Harvesting is Mapping of pulpwood, oil and gas-related emis- currently taking place on private lands, and an un- sions in the northeast (Parfitt 1994) indicates an known proportion of these lands are being overlap with Connecticut Warbler habitat in the converted to agriculture. Lands cleared for agri- Fort Nelson, Dawson Creek, and Fort St. John culture are likely permanently lost as habitat for areas. Emissions from sour gas processing, explo- this warbler. Brown-headed Cowbirds are also ration well venting, and the kraft pulping process, attracted to clearings. (eg., SO2, NOx, H2S, TRS and particulate matter)

14 have relatively severe effects on trembling aspen Columbia populations, we believe it is obvious and cottonwood, in comparison to other species that effects of habitat loss on the wintering (Malhotra and Blauel 1980). Trembling aspen grounds are substantially less significant than the near Alberta sour gas processing plants show in- loss of breeding habitat in the Peace and Fort creased mortality in high-impact zones, a higher Nelson lowlands, and the Kiskatinaw Plateau. incidence of Armillaria root-rot and Hypoxylon canker, as well as depression of annual volume 8.0 SPECIAL SIGNIFICANCE OF increments (Maynard et al. 1994.). A somewhat THE SPECIES unpredictable, but voluminous increase in sour gas exploration (and SO2 venting) is expected in the northeast. The threshold for maintaining 8.1 Status healthy stands of deciduous Connecticut Warbler habitat is unknown. The Connecticut Warbler is widely considered to be an uncommon and poorly known warbler 7.11 Seismic Lines and Roads throughout its range (Bent 1953; Godfrey 1986; Ehrlich et al. 1988; Curson et al. 1994). In British Gas and oil exploration in the Dawson Creek area Columbia, Munro and Cowan (1947) referred to it is not as prevalent as near Fort Nelson, but the as “known only from a few specimens in the impact of seismic line gridlock in aspen ecosys- Peace River”. Its status has changed little since tems is likely to affect habitat quantity and quality then except that it is known to be more widely over the long-term through removal of habitat, distributed (Erskine and Davidson 1976; Enns and and create edge habitat favoured by cowbirds and Siddle 1992; Lance and Phinney 1994), and may predators. be fairly common in local areas (Lance and Phinney 1994). 7.12 Winter Habitat In British Columbia, the Connecticut Warbler should be considered as a rare to locally fairly Connecticut Warblers winter in the jungles of the common breeder in deciduous forests of the Amazon River basin, and this habitat is relatively northeast. secure compared to the winter habitats of most other neotropical migrants. Loss of montane and tropical forest habitat (about 2% annually) is a 8.2 Degree of Public Interest widespread problem for neotropical migrants in Latin America and is undoubtedly of long-term Connecticut Warblers are highly valued by significance for Connecticut Warblers, but the ef- birdwatchers because of their rarity and the diffi- fect is buffered by the vastness of the Amazon culty of finding them in the dense undergrowth River basin (Ehrlich et al. 1988; Terborgh 1989; that they frequent. This species is a definite Finch 1991; Hartshorn 1992), and by the ability “highlight” bird on any trip to the northeast. Oth- of Connecticut Warblers to occupy moderately erwise, this species probably goes unnoticed by disturbed winter habitat (Petit et al. 1993). How- the general public. ever, if the rate of habitat loss is accelerated in the Amazon River basin, then the effects on Con- 8.3 Related Species necticut Warbler populations will also accelerate. In addition, low-density populations, particularly Two other Oporornis warblers also occur in Brit- those at the edge of a species' range are thought ish Columbia. The Mourning Warbler is restricted to be the first to decline when overall numbers in British Columbia to the northeast, but is much decline (Wilcove and Terborgh 1984). For British more common than the Connecticut Warbler

15 (Enns and Siddle 1992). The MacGillivray’s War- versity in those isolated patches and may reduce bler is widely distributed over most of the the impact of clearcutting (MacClintock et al. province (Godfrey 1986). 1977). Johns (1993) suggested that small patches of aspen (i.e., <3.5 ha), even if too small to sup- 9.0 RECOMMENDATIONS AND port breeding pairs, may provide foraging habitat MANAGEMENT OPTIONS and corridors for pairs moving to larger, or more isolated, reserves. In British Columbia, retention of mature to old- growth deciduous (aspen/cottonwood) stands is If we assume that the goal of managing for critical for maintaining populations of Connecti- biodiversity is to maintain natural populations and cut Warblers. Connecticut Warblers are in serious patterns across broad landscapes, then a number jeopardy of near-extirpation if current aspen har- of general guidelines apply (from Hutto et al. vesting plans are carried out. The first priority for 1993): management is to establish reserves of mature aspen in areas with core populations. Provisions 1. Manage for desired landscape patterns with a within the Forestry Practices Code (Riparian clear picture of land-use trends and conditions Management Areas, Forest Ecosystem Networks, over a broad landscape, not by harvest-by- Wildlife Habitat Areas) may be sufficient to sat- harvest decisions. isfy the habitat requirements for sustainable populations, but only if Connecticut Warbler 2. Allow natural processes to occur - fire, insect habitat requirements are used as a primary deter- outbreak, blowdowns, etc., because the adap- minant in selecting those reserves. tive histories of most species in natural ecosystems are linked to natural periodic dis- Because populations are local, and pairs may be turbances. fairly common in those areas, then Oldgrowth Management Areas and Riparian Management 3. Use knowledge of local ecology and be wary Areas centred on Connecticut Warbler populations of extrapolating results from other regions. would help to maintain habitat for this species. The creation of Wildlife Habitat Areas (WHA) in 4. Manage for multiple species except when areas of concentration are recommended because single species become species of special of the forecast of almost complete loss of poten- concern (e.g., Red and Blue List). The tial habitat (old aspen) and the unknown value to Connecticut Warbler may require species- Connecticut Warblers of the remainder. The specific management. WHAs should be relatively large (minimum 500 m diameter) so as to include at least several 5. Monitor populations of forest birds to keep breeding pairs and to discourage parasitism by current on effects of silvicultural practices. Brown-headed Cowbirds. Combinations of the above-mentioned reserves are the best method of Other general principles provided by Robbins conserving habitat if we assume that logging will et al. (1993) are appropriate for management continue to occur. of Connecticut Warblers and other neotropical migrants: Habitat corridors that connect isolated patches of forest with continuous forest are proving to be an 1. Maximize size of forest reserves and mini- important factor in retaining bird community di- mize edge and isolation.

16 2. Promote microhabitat diversity by providing 11.0 EVALUATION uneven-aged forests and precluding grazing by domestic stock which destroys the ground In British Columbia, the Connecticut Warbler has layer. localized populations in the northeast that are mainly associated with rich understories in stands 3. Preserve as much old-growth forest as possible. of mature or older aspen. In suitable habitat, recent studies have found it to be a fairly common 4. Promote public awareness of the plight of warbler. However, its habitat is under severe pres- neotropical migrants. Project Wild would be sure from timber harvesting, and there are no an appropriate vehicle for some education alternative habitats available. The effects of habi- programs. tat fragmentation (including increased cowbird parasitism and predation) are projected to be rela- 10.0 RESEARCH tively severe compared to most other species. REQUIREMENTS Very little habitat is protected in existing reserves. There are few data on habitat use and no data on Additional research is required to improve our reproductive success related to the impacts of for- ability to manage habitat for Connecticut Warblers estry practices. in British Columbia: Thompson et al. (1993a) ranked Connecticut 1. Examination of Landsat Imagery to determine Warblers as the twelfth out of 110 midwestern locations of all potential breeding habitat. North American, neotropical migrants for management priority, mainly because of relatively 2. Studies of habitat utilization for nesting and small, scattered populations and sensitivity to foraging, and comparative reproductive suc- breeding habitat fragmentation. However, Reed cess related to stand age structure and patch (1992) ranked it as a species with a low overall size. probability of extinction. Our outlook for this species in British Columbia is more comparable to 3. Field studies to locate and map distribution of Thompson et al. (1993a). core populations. This warbler is seriously imperilled by aspen for- 4. A further review of the harvesting plans for est harvesting and may face local and regional aspen forests in the northeast to refine esti- extirpation in the medium term, given current har- mates of mature aspen forest loss. vesting trends. The Connecticut Warbler is more seriously imperilled than other songbird species of 5. Studies of cowbird parasitism and predation concern in the northeast (Table 2). Protection of in fragmented stands. sizeable areas of suitable habitat must occur in the near to mid term to ensure that stable, repre- 6. Studies of the effect of grazing on habitat sentative populations remain in British Columbia. quality. For the above reasons, the Connecticut Warbler 7. Migration surveys to determine importance of should be considered as Threatened, and should habitats other than on breeding grounds. remain on the Red List.

8. Banding of breeding birds to study site fidelity.

17 Table 2. Comparison of six rare songbirds restricted to northeastern British Columbia. Species are ranked in order of conservation priority.

Recommended Population Size Species Status Primary Habitat Major Threats and Distribution

Connecticut Warbler Red Old-growth aspen forest Logging Small and local Agriculture Silviculture Fragmentation Black-throated Green Warbler Red Old-growth riparian Logging Small and local mixedwoods Fragmentation Cape May Warbler Red Old-growth spruce Logging Very small and forest scattered Bay-breasted Warbler Red Old-growth spruce forest Logging Very small and scattered Canada Warbler Blue Mature/old-growth aspen Logging Small and local forest Silviculture Fragmentation Philadelphia Vireo Blue Habitat generalist Fragmentation Small and local

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19 Friedmann, H., and L.F. Kiff. 1985. The parasitic about ecological plasticity and wintering pat- cowbirds and their hosts. West. Found. Vert. terns? Pages 457-476 in A. Keast and E.S. Zool. 2:225-302. Morton, eds. Migrant birds in the neotropics: ecology, behavior, distribution and conserva- Godfrey, W.E. 1986. The birds of Canada. Natl. tion. Smithsonian Inst. Press, Washington, Mus. Can, Ottawa, ON. 595pp. DC.

Griscom, L., and A. Sprunt, Jr. 1957. The war- Klimkiewicz, M.K., R.B. Clapp, and A.G. blers of America. Devin-Adair Co., New Futcher. 1983. Longevity records of North York, NY. 356pp. American birds: Remizidae through Parulinae. J. Field Ornith. 54:287-294. Hagan, J.M., III and D.W. Johnston. 1992. Ecol- ogy and conservation of neotropical migrant Lance, A.N., and M. Phinney. 1993. Bird diversity landbirds. Smithsonian Inst. Press, Washing- and abundance following aspen clearcutting in ton, D.C. 609pp. the boreal white and black spruce biogeoclimatic zone. Forest Renewal Pro- Harrison, C. 1978. A field guide to the nests, gram, FRDA Project B28, Hardwood and eggs, and nestlings of North American birds. Vegetation Manage. Rep. to B.C. Minist. For., Collins, New York, NY. 416pp. Industrial For. Serv., Prince George, BC. 40pp. Harrison, H. 1984. Wood warblers world. Simon and Schuster, New York, NY. 335pp. Lance, A.N., and M. Phinney. 1994. Bird diversity and abundance following aspen clearcutting in Hartshorn, G.S. 1992. Forest loss and future op- the boreal white and black spruce tions in Central America. Pages 13-19 in J.M. biogeoclimatic zone. Rep. for 1993, Unpubl. Hagan III and D.W. Johnston, eds. Ecology FRDA rep. prepared for B.C. Minist. For., and conservation of neotropical migrant Victoria, BC. 40pp. landbirds. Smithsonian Inst. Press, Washing- ton, DC. Lea, E.C., and A.P. Harcombe. 1992. Wildlife habitats of British Columbia. B.C. Minist. Hutto, R.L., S.J. Hejl, C.R. Preston, and D.M. Environ., Lands and Parks, Wildl. Branch. Finch. 1993. Effects of silvicultural treat- Victoria, BC. 5pp. ments on forest birds in the Rocky Mountains: implications and management rec- MacClintock, L., R.F. Whitcomb, and B.L. ommendations. Pages 386-391 in D.M. Finch Whitcomb. 1977. Evidence for the value of and P.W. Stangel, eds. Status and manage- corridors and minimization of isolation in ment of neotropical migratory birds. Gen. preservation of biotic biodiversity. Am. Birds Tech. Rep., RM-229. U.S. Dep. Agric. For. 31:6-13. Serv., Fort Collins, CO. Malhotra, S.S., and R.A. Blauel. 1980. Diagnosis Johns, B.W. 1993. The influence of grove size on of air pollutants and natural stress systems on bird species richness in aspen parklands. forest vegetation in western Canada. Northern Wilson Bull. 105:256-264. For. Res. Centre Inf. Rep. NOR-X-228. 78pp.

Keast, A. 1980. Migratory Parulidae: what can Martin, T.E. 1992. Breeding productivity consid- species co-occurrence in the north reveal erations: what are appropriate habitat features

20 for management? Pages 455-473 in J.M. Munro, J.A., and I.McT. Cowan. 1947. A review Hagan, III and D.W. Johnston, eds. Ecology of the bird fauna of British Columbia. Spec. and conservation of neotropical migrant Publ. No. 2. B.C. Prov. Mus., Victoria, BC. landbirds. Smithsonian Inst. Press, Washing- 285pp. ton, DC. Nolan, V. 1978. The ecology and behavior of the Maurer, B.A., and S.G. Heywood. 1993. Geo- Prairie Warbler (Dendroica discolor). graphic range fragmentation and abundance of Ornithol. Monogr. 26:1-595. neotropical migratory birds. Conserv. Biol. 7:501-509. Parfitt, N. 1994. 1:2 000 000 mapping of sources of S from natural gas, oil, and pulpwood in Massie, M.R.C., E.B. Peterson, N.M. Peterson B.C. Can. For. Serv., Victoria, BC. and K.A. Enns. 1994. An assessment of the strategic importance of the hardwood resource Penner, D.F. 1976. Peace River Sites C and E en- in British Columbia. FRDA Rep. 221. Can. - vironmental impact studies: wildlife B.C. Partnership Agreement on For. Resour. resources. Unpubl. rep. prepared by Thurber Dev.: FRDA II. Victoria, BC. 206pp. Consultants Ltd for B.C. Hydro, Vancouver, BC. 307pp. Maynard, D.G., J.J. Stadt, K.I. Mallett and W.J.A. Volney. 1994. Sulphur impacts on forest Peterson, E.B., A. Kabzems, R.D. Kabzems and health in west-central Alberta. Nat. Resour. N.M. Peterson. 1989. Boreal mixedwood for- Can., Can. For. Serv. Northwest Reg., North. est management challenges: a synopsis of For. Cent. Edmonton, AB. NOR-X-334. 54pp. opinions from 1988 interviews. For. Can. North. For. Res. Centre. Edmonton, AB. Meidinger, D., and J. Pojar. 1991. Ecosystems of ENFOR Proj. P-353. 39pp. British Columbia. Spec. Rep. Ser., No. 6. B.C. Minist. For., Victoria, BC. 330pp. Peterson, E.B., and N.M. Peterson. 1992. Ecol- ogy, management, and use of aspen and Morse, D.H. 1973. The foraging of small balsam poplar in the prairie provinces, populations of Yellow Warblers and American Canada. Spec. Rep. 1. Northern For. Can.. Redstarts. Ecology 54:346-355. Northwest Reg. Northern For. Centre. 252pp.

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21 Ralph, C.J. 1981. Age ratios and their possible Sauer, J.R., and S. Droege. 1992. Geographic use in determining autumn routes of passerine patterns in population trends of neotropical migrants. Wilson Bull. 93:164-188. migrants in North America. Pages 26-42 in J.M. Hagan III and D.W. Johnston, eds. Ecol- Reed, J.M. 1992. A system for ranking conserva- ogy and conservation of neotropical migrant tion priorities for neotropical migrant birds landbirds. Smithsonian Inst. Press, Washing- based on relative susceptibility to extinction. ton, DC. Pages 524-536 in J.M. Hagan, III and D.W. Johnston, eds. Ecology and conservation of Semenchuk, G.P. 1992. The atlas of breeding neotropical migrant landbirds. Smithsonian birds of Alberta. Fed. Alberta Nat., Edmon- Inst. Press, Washington, DC. ton, AB. 391pp.

Robbins, C.S., J.R. Sauer, R. Greenberg, and S. Seton, E.T. 1884. Nest and habits of the Connecti- Droege. 1989. Population declines in North cut Warbler (Oporornis agilis). Auk American birds that migrate to the neotropics. 1:192-193. Proc. Natl. Acad. Sci. USA 86:7658-7662. Sherry, T.W., and R.T. Holmes. 1993. Are populations of neotropical migrants limited in Robbins, C.S., J.R. Sauer, and B.G. Peterjohn. summer or winter? Implications for manage- 1993. Population trends and management op- ment. Pages 47-57 in D.M. Finch and P.W. portunities for neotropical migrants. Pages Stangel, eds. Status and management of 17-23 in D.M. Finch and P.W. Stangel, eds. neotropical migrants. U.S. Dep. Agric. For. Status and management of neotropical migra- Serv. Gen. Tech. Rep., RM-229. Fort Collins, tory birds. Gen. Tech. Rep., RM-229. U.S. CO. Dep. Agric. For. Serv., Fort Collins, CO. Siddle, C. 1992. The declining populations of Robinson, S.K., J.A. Grzybowski, S.I. Rothstein, warblers in northeastern British Columbia. M.C. Brittingham, L.J. Petit, and F.R. Pages 143-151 in S. Rautio, ed. Community Thompson. 1993. Management implications action for endangered species: a public sym- of cowbird parasitism on neotropical migrant posium on B.C.’s threatened and endangered songbirds. Pages 93-102 in D.M. Finch and species and their habitat, Vancouver, B.C., P.W. Stangel, eds. Status and management of September 28-29, 1991. Fed. B.C. Nat. and neotropical migratory birds. U.S. Dep. Agric. Northwest Wildl. Preserv. Soc., Vancouver, For. Serv. Gen. Tech. Rep., RM-229, Fort BC. Collins, CO. Simberloff, D., J.A. Farr, J. Cox, and D.W. Salt, W.R. 1973. Alberta vireos and wood war- Mehlman. 1992. Movement corridors: conser- blers. Publ. No. 3, Prov. Mus. and Archives of vation bargains or poor investments? Conserv. Alberta, Edmonton, AB. 141pp. Biol. 6:493-504.

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22 Terborgh, J.W. 1989. Where have all the birds of boreal aspen stands. Can. Wildl. Serv. Ed- gone? Princeton Univ. Press, Princeton, NJ. monton, AB. ENFOR Project P-203. 148pp. 207pp. Westworth, D.A., and E.S. Telfer. 1993. Summer Thompson, F.R., S.J. Lewis, J. Green, and D. and winter bird populations associated with Ewert. 1993a. Status of neotropical migrant five age-classes of aspen forest in Alberta. landbirds in the midwest: identifying species Can. J. For. Res. 23:1830-1836. of management concern. Pages 145-158 in D.M. Finch and P.W. Stangel, eds. Status and Whitcomb, R.F., C.S. Robbins, J.F. Lynch, B.L. management of neotropical migratory birds. Whitcomb, M.K. Klimkiewicz, and D. Gen. Tech. Rep., RM-229. U.S. Dep. Agric. Bystrak. 1981. Effects of forest fragmentation For. Serv., Fort Collins, CO. on avifauna of the eastern deciduous forest. Pages 125-205 in R.L. Burgess and D.M. Thompson, F.R., J.R. Probst, and M.G. Raphael. Sharpe, eds. Forest island dynamics in 1993b. Silviculture options for neotropical man-dominated landscapes. Springer-Verlag, migratory birds. Pages 353-362 in D.M. Finch New York, NY. and P.W. Stangel, eds. Status and management of neotropical migratory birds. Gen. Wilcove, D.S. 1985. Nest predation in forest Tech. Rep., RM-229. U.S. Dep. Agric. For. tracts and the decline of migratory songbirds. Serv., Fort Collins, CO. J. Ecology 66:1211-1214.

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23 Wildlife Working Reports may be cited, but the preliminary nature of the data they contain should be noted. Working Reports 1-15 (and others) are presently out of print, but photocopies may be available through the Wildlife Branch, Ministry of Environment, Lands and Parks.

WR-26 Quesnel Highlands wolf control project. D. Hebert. January 1987. 10pp. WR-27 Muskwa Wolf Management Project of northeastern B.C. 1986-87 annual report. J.P. Elliott. April 1987. 20pp. WR-28 Vancouver Island wolf control project. Year 1 progress report. D. Janz. July 1987. 11pp. WR-29 Habitat survey of the Mackenzie Heritage Trail corridor. V. Hignett. June 1987. 21pp + 5 maps. WR-30 A proposal to manage coyote and cougar populations of the Junction Wildlife Management Area. D. Hebert. September 1987. 11pp. WR-31 Wildlife habitat suitability of the Mackenzie Heritage Trail corridor. V. Hignett. May 1988. 16pp + 6 maps. WR-32 Research priorities for furbearers in British Columbia. D. Blood. June 1988. 49pp. WR-33 Electrically triggered drop net to capture wild sheep. J.W. Hirsch. January 1988. 18pp. WR-34 A lynx management strategy for British Columbia. D.F. Hatler. July 1988. 121pp. WR-35 Causes of bighorn sheep mortality and dieoffs - literature review. H.M. Schwantje. April 1988. 54pp. WR-36 Explanatory legend for vegetation maps of the Kamloops Lake bio-physical study area. E.C. Lea. December 1988. 78pp. WR-37 Bio-physical habitat units and interpretations for moose use of the upper Cariboo River Wildlife Management Area. E.C. Lea, T. Vold, J. Young, M. Beets, D. Blower, J. Youds, A. Roberts. December 1988. 24pp. WR-38 Grizzly bear habitat of the Flathead River area: expanded legend. E.C. Lea, B.L. Fuhr, and L.E.H. Lacelle. December 1988. 24pp. WR-39 Managing habitat through guidelines: How far can you go? M. Fenger and V. Stevens, eds. February 1989. 48pp. WR-40 Wolf-prey dynamics. Proceedings of a symposium sponsored by B.C. Ministry of Environment, Wildlife Branch, Faculty of Forestry, University of British Columbia and the Northwest Wildlife Preservation Society. February 1989. 188pp. WR-41 Caribou research and management in B.C.: proceedings of a workshop. R.Page, ed. November 1988. 275pp. (Also printed as WHR-27) WR-42 Trapping in British Columbia - a survey. R. Reid. January 1989. 55pp. WR-43 Biophysical habitat units of the Lower Halfway study area: expanded legend. E.C. Lea and L.E.H. Lacelle. December 1989. 33pp. WR-44 Long range habitat planning: proceedings. M. Fenger and V. Stevens, eds. March 1990. 49pp. WR-45 Biophysical habitat units of the Mosley Creek study area: expanded legend and interpretations. E.C. Lea and R.C. Kowall. March 1990. 33pp.

WR-46 Habitat Management Section. Annual General Meeting. Yellowpoint Lodge - 1989 April 25-27. Wildlife and Recreational Fisheries Branches, Ministry of Environment. July 1990. 107pp. WR-47 Working plan — Khutzeymateen Valley grizzly bear study. A.N. Hamilton and J.A. Nagy. September 1990. 35pp. (Also printed as WHR-28). WR-48 Khutzeymateen Valley grizzly bear study. Annual progress report - year 1 (1989/90), annual working plan - year 2 (1990/91). J.A. Nagy and A.G. MacHutchon. January 1991. 44pp. (Also printed as WHR-29). WR-49 Fort Nelson and area average winter maximum snowpack mapping. R. Chilton. July 1990. 12pp. WR-50 Marten habitat suitability research project - working plan. E.C. Lofroth and V. Banci. January 1991. 31pp. WR-51 Khutzeymateen Valley grizzly bear study. Annual progress report - year 2 (1990/91), annual working plan - year 3 (1991/92). A.G. MacHutchon and S. Himmer. March 1992. 36pp. (Also printed as WHR-30) WR-52 Abundance, Distribution and Conservation of Birds in the Vicinity of Boundary Bay, B.C. R.W. Butler, ed. 1992. 132pp. (Also printes as Technical Report Series No. 155, Pacific and Yukon Region, Can. Wildlife Service). WR-53 Status of the Clouded Salamander in British Columbia. T.M. Davis and P.T. Gregory. March 1993. 19pp. WR-54 Status of the Northern Pacific Rattlesnake in British Columbia. M.B. Charland, K.J. Nelson, P.T. Gregory. March 1993. 23 pp. WR-55 Status of the Shrew-mole in British Columbia. L. Kremsater, L. Andrusiak, F.L. Bunnell. March 1993. 26 pp. WR-56 Status of the Nuttall’s Cottontail in British Columbia. D.W. Carter, A. Harestad, F.L. Bunnell. March 1993. 33 pp. WR-57 Status of the Sharp-tailed Snake in British Columbia. D.J. Spalding. March 1993. 15pp. WR-58 Guidelines for Technical Publications of the Wildlife Program. E. Stanlake. March 1993. 57pp. WR-59 Status of Keen's Long-eared Myotis in British Columbia. M. Firman, M. Getty, and R.M.B. Barclay. March 1993. 29pp. Continued from inside back cover:

WR-60 Biophysical Habitat Units for the Tatlayoko Lake Study Area: expanded legend and interpretations. E.C. Lea and R.C. Kowall. March 1993. 22pp. WR-61 Status of the Pallid Bat in British Columbia. K. Chapman, K. Mc Guinness, R.M. Brigham. February 1994. 32pp. WR-62 Status of the Bald Eagle in British Columbia. D.A. Blood and G. G. Anweiler. February 1994. 92pp WR-63 A Survey of the Bat Fauna of the Dry Interior of British Columbia. S.L. Holroyd, R.M.R. Barclay, L.M. Merk, and R.M. Brigham. March 1994. 80pp. WR-64 Distribution and Abundance of Four Species of Small Mammals At Risk in a Fragmented Landscape. G.A. Zuleta and C. Galindo-Leal. March 1994. 80pp. WR-65 Problem Analysis of Integrated Resource Management of Riparian Areas in British Columbia. S.L. Rautio, P. Bunnell. March 1994. 26pp. (Also RRP3003-HQ Minist. of For. Res. Br.) WR-66 A Bibliography of Selected Literature on Wildlife Trees with Annotations and Abstracts. Wildlife Tree Committee. December 1994. 90pp. WR-67 Status of the Vaux's Swift in British Columbia. K. Summers and M. Gebauer. March 1995. 24pp. WR-68 Status of the White-throated Swift in British Columbia. K. Summers. March 1995. 24pp. WR-69 Status of the Williamson's Sapsucker in British Columbia. J.M. Cooper. March 1995. 24pp. WR-70 Status of the Sharp-tailed Grouse in British Columbia. R. Ritcey. March 1995. 52pp. WR-71 Status of the Western Harvest Mouse in British Columbia. D.W. Nagorsen. March 1995. 32pp. WR-72 Status of the Badger in British Columbia. A.H. Rahme, A.S. Harestad and F.L. Bunnell. March 1995. 64pp. WR-73 Status of the Fringed Myotis in British Columbia. S.A. Rasheed, P.F.J. Garcia, and S.L. Holroyd. October 1995. 28pp. WR-74 Status of the Western Small-footed Myotis in British Columbia. P.F.J. Garcia, S.A. Rasheed, and S.L. Holroyd. October 1995. 24pp. WR-75 Status of the Spotted Bat in British Columbia. P.F.J. Garcia, S.A. Rasheed, and S.L. Holroyd. October 1995. 24pp. WR-76 The Distribution, Abundance, and Habitat Requirements of Selected Passerine Birds of the Boreal and Taiga Plains of British Columbia. K.A. Enns and C. Siddle. March 1996. 54pp. WR-77 Status of the Brewer's Sparrow (breweri subspecies) in British Columbia. M.J. Sarell and K.P. McGuinness. March 1996. 22pp. WR-78 Status of the Green Heron in British Columbia. D.F. Fraser and L.R. Ramsay. March 1996. 28pp. WR-79 Status of the Bay-breasted Warbler in British Columbia. J.M. Cooper, K.A. Enns, and M.G. Shepard. February 1997. 36pp. WR-80 Status of the Black-throated Warbler in British Columbia. J.M. Cooper, K.A. Enns, and M.G. Shepard. February 1997. 36pp. WR-81 Status of the Canada Warbler in British Columbia. J.M. Cooper, K.A. Enns, and M.G. Shepard. February 1997. 36pp. WR-82 Status of the Cape May Warbler in British Columbia. J.M. Cooper, K.A. Enns, and M.G. Shepard. February 1997. 34pp. WR-83 Status of the Connecticut Warbler in British Columbia. J.M. Cooper, K.A. Enns, and M.G. Shepard. February 1997. 32pp.