Gulf Coast Joint Venture: Mississippi River Coastal Wetlands Initiative

JO ST INT V OA EN C T F U L R U E G North American Waterfowl Management Plan 2002 Photo and Illustration Credits

Cover and page i: American wigeon, G.D. Chambers, Ducks Unlimited, Inc. Page iii: (top) pintails, ( bottom) greater scaup, C. Jeske, U.S. Geological Survey. Page iv: U.S. Geological Survey. Page 7: mallard pair, B. Wilson, Gulf Coast Joint Venture. Page 8: scaup pair, B. Hinz, U.S. Fish and Wildlife Service. Page 9: mottled duck pair, R. Paille, U.S. Fish and Wildlife Service. Page 10: lesser snow geese, T. Hess, Louisiana Department of Wildlife and Fisheries. Page 12: oil-drilling access canal plug, B. Wilson, Gulf Coast Joint Venture; breakwater structures, T. Hess, Louisiana Department of Wildlife and Fisheries. Page 13: erosion control vegetation, T. Hess, Louisiana Department of Wildlife and Fisheries; marsh burning, B. Wilson, Gulf Coast Joint Venture; hydrologic structure, B. Wilson, Gulf Coast Joint Venture; beneficial use of dredge material, T. Hess, Louisiana Department of Wildlife and Fisheries. Page 19: B. Hinz, U.S. Fish and Wildlife Service. Page 20: American wigeon pair, R. Stewart, Sr., U.S. Fish and Wildlife Service. Page 22: northern shovelers and blue-winged teal, U.S. Geological Survey. Page 23: male ring-necked duck, W.L. Hohman, U.S. Geological Survey. Page 24: male American wigeon, C. Jeske, U.S. Geological Survey. Page 25: blue-winged teal males, W.L. Hohman, U.S. Geological Survey.

Gulf Coast Joint Venture: Mississippi River Coastal Wetlands Initiative

JO ST INT V OA EN C T F U L R U E G North American Waterfowl Management Plan This is one of six reports that address initiative plans for the entire North American Waterfowl Management Plan, Gulf Coast Joint Venture: the Chenier Plain Initiative, the Laguna Madre (Texas) Initiative, the Texas Mid-Coast Initiative, the Coastal Mississippi Wetlands Initiative, the Mobile Bay Initiative, and the Mississippi River Coastal Wetlands Initiative (southeast Louisiana).

Suggested citation: Wilson, B.C., C.A. Manlove, and C.G. Esslinger. 2002. North American Water- fowl Management Plan, Gulf Coast Joint Venture: Mississippi River Coastal Wetlands Initiative. North American Waterfowl Management Plan, Albu- querque, NM. 28 pp. + appendix. Contents Page Introduction...... 1 North American Waterfowl Management Plan...... 1 Gulf Coast Joint Venture...... 1 Gulf Coast Joint Venture Objectives...... 3 Midwinter Duck Population Objectives...... 5 Midwinter Goose Population Objectives...... 5 Migration Chronology ...... 5 The Mississippi River Coastal Wetlands Initiative Area ...... 7 Coastal Marsh ...... 7 Types of Coastal Marsh...... 7 Status and Trends ...... 8 Wetland Loss Factors and Threats ...... 9 Forested Wetlands...... 10 Wetland Loss Factors andThreats ...... 10 Seagrass Beds...... 11 Seagrass Status and Threats ...... 11 The Mississippi River Coastal Wetlands Initiative Implementation Plan...... 12 Conservation Strategies ...... 12 Maintenance of Habitat...... 12 Restoration of Habitat...... 13 Creation of Habitat...... 13 Habitat Objectives...... 14 Coastal Marsh ...... 14 Forested Wetlands...... 14 Seagrass Beds...... 17 Habitat Conclusions...... 18 Specific Activities ...... 20 Other Programs ...... 21 Communication and Education...... 21 Relationship to Evaluation Plan...... 22 Derivation of GCJV Waterfowl Objectives and Migration Patterns...... 23 Midwinter Duck Population Objectives...... 23 Migration Patterns...... 24 Migration Chronology for Waterfowl Species of GCJV Initiative Areas...... 26 Literature Cited ...... 28 For More Information ...... 28 Appendix: Scientific Names of Plants and Animals Mentioned in This Plan...... Inside back cover Acknowledgments...... Inside back cover

GCJV iii Figures

Number Page

1 Location of the Gulf Coast Joint Venture region ...... 1 2 Mississippi River Coastal Wetlands Initiative area...... 3 3 An example of how midwinter population objectives were obtained in the Mississippi River Coastal Wetlands Initiative area...... 5 4 Semimonthly duck population objectives and expected numbers of geese for the Mississippi River Coastal Wetlands Initiative area ...... 6 5 Semimonthly duck population objectives and expected numbers of geese for coastal marsh for the Mississippi River Coastal Wetlands Initiative area ...... 15 6 Energetic demand (mallard-use-days) of duck objectives, and expected numbers of geese and wood ducks, in coastal marsh and forested wetlands...... 15 7 Semimonthly duck population objectives and expected numbers of wood ducks for forested wetlands of the Mississippi River Coastal Wetlands Initiative area...... 16

Tables

Number Page

1 Midwinter population objectives for initiative areas of the Gulf Coast Joint Venture...... 4 2 Foraging values, habitat needs, and habitat availability for the Mississippi River Coastal Wetlands Initiative area...... 17 3 Estimated coastal marsh and forested wetland habitat that is currently under public ownership in the Mississippi River Coastal Wetlands Initiative area...... 18 4 Estimated wood duck harvest, harvest rates, and population size(s) for the Mobile Bay, Coastal Mississippi Wetlands, and Mississippi River Coastal Wetlands (southeast Louisiana) Initiatives...... 24

iv NAWMP Introduction

North American Waterfowl particular physiographic region such Management Plan as the Gulf Coast. These partners come Faced with continuing wetland together under the NAWMP to pool destruction and rapidly declining wa- resources and accomplish collectively terfowl populations, the Canadian and what is often difficult or impossible to U.S. governments signed the North do individually. American Waterfowl Management Gulf Coast Joint Venture Plan (NAWMP) in 1986, undertaking The Gulf Coast is the terminus of the an intense effort to protect and restore Central and Mississippi Flyways and North America’s waterfowl popula- is therefore one of the most important tions and their habitats. Updated in waterfowl areas in North America, 1994 and 1998 with Mexico as a providing both wintering and migra- signatory, the NAWMP recognizes that tion habitat for significant numbers of the recovery and perpetuation of wa- the continental duck and goose popula- terfowl populations to levels observed tions that use both flyways. The coastal in the 1970’s, which is the baseline ref- marshes of Louisiana, Alabama, and erence for duck population objectives Mississippi regularly hold half of the under the plan, depends on restoring wintering duck population of the Mis- wetlands and associated ecosystems sissippi Flyway. Coastal wetlands of throughout the continent. The purpose Texas are the primary wintering site of the NAWMP is to achieve water- for ducks using the Central Flyway, fowl conservation while maintaining wintering more than half of the Cen- or enhancing associated ecological val- tral Flyway waterfowl population. The ues in harmony with human needs. The greatest contribution of the Gulf Coast benefits of such habitat conservation Joint Venture (GCJV) region (Fig. 1) were recognized to be applicable to in fulfilling the goals of the NAWMP a wide array of other species as well. is as a wintering ground for waterfowl. Six priority waterfowl habitat ranges, including the Western U.S. Gulf of Mexico Coast (hereafter Gulf Coast), were identified in the 1986 document and targeted as areas to begin imple- mentation of the NAWMP. Transforming the goals of the NAWMP into actions requires a co- operative approach to conservation. The implementing mechanisms of the NAWMP are regional partnerships called joint ventures. A joint venture is composed of individuals, corporations, small businesses, sportsmen’s groups, conservation organizations, and local, state, provincial, and federal agencies that are concerned with conserving migratory birds and their habitats in a Figure 1. Location of the Gulf Coast Joint Venture region.

GCJV 1 The GCJV area also provides year- fish, and amphibians also rely on the round habitat for over 90% of the con- wetlands of the Gulf Coast for part of tinental population of mottled ducks their life cycles. Numerous species and serves as a key breeding area for of shorebirds, wading birds, raptors, whistling ducks. In addition, hundreds and songbirds can be found along the of thousands of waterfowl use the Gulf Gulf Coast. Of the 650 species of birds Coast as stopover habitat while migrat- known to occur in the United States, ing to and from Mexico and Central nearly 400 species are found in the and South America. The GCJV region GCJV area. Muskrats and nutria have is the primary wintering range for sev- historically been important commercial eral species of ducks and geese and is fur species of the Gulf Coast. Many a major wintering area for every other species of fish, shellfish, and other -ma North American duck except wood rine organisms also depend on the gulf ducks, black ducks, cinnamon teal, and coastal ecosystem. Almost all of the some sea ducks (Tribe Mergini). commercial fish and shellfish harvest- Through its wetland conservation ed in the Gulf of Mexico are dependent accomplishments, the GCJV is contrib- on the area’s estuaries and wetlands uting to the conservation of biological that are an integral part of coastal diversity. While providing habitat for ecosystems. The American alligator is waterfowl, especially ducks, continues an important Gulf Coast region species to be the major focus of the GCJV, and is sought commercially and recre- a great diversity of birds, mammals, ationally for its hide and meat.

2 NAWMP Gulf Coast Joint Venture Objectives

Conserving Gulf Coast habitats is of benefits between the species groups. critical to the overall success of the This joint venture will strive to balance NAWMP because the area provides ex- its focus on waterfowl and wetlands tensive wetlands that are vitally impor- with the need to expand coordination tant to traditional wintering waterfowl and cooperation with existing conser- concentrations. The primary goal of vation initiatives that promote com- the GCJV is to provide for waterfowl mon purposes, strategies, or habitats of in winter and ensure that they survive interest. and return to the breeding grounds The GCJV is divided geographically in good condition, but not exceeding into six initiative areas, each with a levels commensurate with breeding different mix of habitats, management habitat capacity as is the case with opportunities, and species priorities. midcontinent lesser snow and Ross’ This document deals with planning ef- geese. A secondary goal is to provide forts for the Mississippi River Coastal ample breeding and postbreeding Wetlands Initiative area of southeast habitat for resident waterfowl. Actions Louisiana (Fig. 2). The goal of the that will achieve and maintain healthy Mississippi River Coastal Wetlands wetland ecosystems that are essential Initiative is to provide wintering and to waterfowl will be pursued. Wetland migration habitat for significant num- conservation actions that will provide bers of dabbling ducks, diving ducks, benefits to species of fish and wildlife, and snow geese, as well as year-round in addition to waterfowl, will also be habitat for the mottled duck (Table 1). supported. The emergence of the U.S. Shore- Texas Louisiana Mississippi bird Conservation Plan, Partners in Flight physiographic plans, and the Waterbird Conservation Plan, which address conservation of other North American migratory birds, presents op- portunities to broaden and strengthen Tangipahoa St. joint venture partnerships for wetland Tammany conservation. As definitive population Livingston Lake Ascension St. John Pontchartrain data and habitat needs are developed the St. Baptist for the migratory birds represented James Orleans Iberia Assumption St. in these emerging strategies, areas of St. Charles Martin St. Bernard mutual concern in wetland ecosystems Jefferson St. Lafourche can be identified. These wetland areas Mary Breton of overlapping interest in the GCJV Sound will be candidate priority sites for Terrebonne Plaquemines Atchafalaya the integrated design and delivery of Bay habitat conservation efforts. Although wetland conservation projects cannot Gulf of be designed to provide maximum ben- Mexico efits for all concerned species, they can Figure 2. Mississippi River Coastal Wetlands Initiative area (Note: Initiative be designed to maximize the overlap area, which is shaded in gray, does not follow parish boundaries).

GCJV 3

72,249 72,194 15,207 Total

897,203 913,231 614,639 646,067 499,727 255,890 175,381 205,898 1,611,920 1,611,920 1,570,819 1,960,531 2,471,250 1,277,689 2,528,570 1,071,831 1,390,815 1,319,406 13,707,864

0 0 0 0 451 601 782 Bay 1,711 1,711 1,236 2,286 2,544 1,156 3,025 3,294 Mobile 17,086

0 0 0 0 84 619 268 191 413 397 174

1,738 5,999 Coastal Wetlands 13,836 23,719 Mississippi

0 0 0

7,516 1,233

99,967 13,731 41,450 51,614 72,250 51,614 73,483 264,119 264,119 249,257 714,356 537,313 723,140 103,221 217,642 1,722,858 4,694,568 Mississippi River Coastal Wetlands

5 5 0

. 2,000 1,052 23,585 62,529 77,821 515,895 396,313 888,456 423,845 951,853 378,953 330,612 169,544 186,917 245,746 279,157 437,841 343,686 516,714 4,511,720 4,511,720 (Louisiana) Chenier Plain

0 402 996 957 3,331 7,457

44,632 84,039 29,147 42,988 89,961 40,707 10,235 117,555 117,555 124,193 650,395 147,053 100,214 108,667 128,747 (Texas) 1,256,847 Chenier Plain

for initiative areas of the GCJV. (See Derivation of GCJV Waterfowl Objectives and Migration Patterns section Waterfowl (See Derivation of GCJV of the GCJV. for initiative areas 11,345 11,345 Texas 72,819 93,841 23,941 33,638 92,944 47,402 97,636 63,043 12,768 1,2 775,755 224,926 293,574 127,599 161,326 609,879 737,403 102,790 770,558 852,961 Mid-Coast 1,959,109

430 4,311 4,311 1,707 6,595 6,067 7,759 6,155 13,530 46,200 35,160 10,136 30,967 25,766 13,819 44,881 40,015 Madre Laguna 173,355 100,377 392,650 454,727 1,244,816

3

3

3

3

3

4 Objectives for ducks are based on 1970’s winter distributions and breeding populations. Objectives for ducks are based on 1970’s Objectives for geese are based on 1982-88 averages of December Goose Surveys. Shaded values are “expected” numbers from 1994-97 (mottled ducks) or 1995-97 (geese) estimates. populations. Scaup objectives exclude offshore January ground counts indicate historical (1986-89) and recent (1996-98) averages of 5,273 10,267, respectively Table 1. Midwinter population objectives Table of this plan, p. 23, for information about the methods used to develop these goals.) Mallard Northern pintail Gadwall American wigeon Green-winged teal Blue-winged teal Northern shoveler Mottled duck Canvasback Redhead Ring-necked duck Greater & lesser scaup ducks Total Lesser snow geese Greater white- fronted geese Canada geese geese Total 1 2 3 4 5

4 NAWMP Midwinter Duck Population NAWMP Continental Gadwall Objectives Breeding Population Goal 2 million To obtain objectives for midwin- Proportion of Midwinter Survey ter duck populations in the GCJV Gadwalls in Mississippi Flyway Initiative areas, we started with the 77.47% NAWMP continental breeding popula- Mississippi Flyway Spring Flight tion goals, which total 62 million and 1.55 million are based on averages of 1970’s breed- January-to-May Mortality ing population surveys with adjust- 10% ments for birds in nonsurveyed areas. We then estimated, from nationwide Mississippi Flyway Midwinter Goal midwinter survey data proportions, the 1.72 million numbers of those 62 million breed- Proportion of Mississippi Flyway Midwinter Survey Gadwalls in ing ducks that should return on spring Mississippi River Coastal Wetlands flights from the Mississippi and Cen- Initiative Area 41.5% Mississippi River Coastal Wetlands tral Flyway wintering areas; we ad- Midwinter Goal justed those numbers for 10% January- 714 thousand to-May mortality to obtain midwinter Figure 3. An example of how midwinter population objectives for a specific goals for the Mississippi and Central species, in this case gadwalls, were obtained in the Mississippi River Coastal Flyways. Finally, using 1970’s mid- Wetlands Initiative area. winter survey data proportions from the Mississippi and Central Flyways, we calculated how much of each of geese, as well as Canada geese in some the two flyway goals should be de- GCJV regions, are also experiencing rived from each GCJV Initiative area. winter population increases. Therefore, Figure 3 provides an example of how regional goose objectives are ex- this general process was applied at the pressed two ways. Recent population species level in the Mississippi River data are used to estimate a quantity of Coastal Wetlands Initiative area. Ex- geese “expected” to occur and compete ceptions to this methodology include to some extent for finite resources, derivation of blue-winged teal and whereas actual objectives indicate redhead objectives and the expected the desired regional goose popula- number of mottled ducks (see Deriva- tion. Both are based on indices from tion of GCJV Waterfowl Objectives midwinter (December) surveys. “Ex- and Migration Patterns section, p. 23). pected” numbers are derived by aver- aging recent December surveys (1995- Midwinter Goose Population 97), and actual objectives are derived Objectives from the 1982-88 average (Table 1). Midcontinent lesser snow and Ross’ geese, many of which spend win- Mig r ation Chronolog y ters in the GCJV, are exceeding their Midwinter populations do not ad- Canadian breeding habitat capacity to equately represent the peak, or even the detriment of their long-term health the typical numbers of some waterfowl and the health of a myriad of other species common to the GCJV. Because birds that share their arctic/subarctic of the variety of GCJV waterfowl and breeding habitat. Greater white-fronted the interspecific variability in their

GCJV 5 migration patterns, incorporating spe- midwinter duck objectives (see Deri- cies-specific migration patterns into vation of GCJV Waterfowl Objectives population objectives is appropriate. and Migration Patterns section, p. 23) Migrations differ regionally, even for yields semimonthly population ob- the same species, so migration pat- jectives by species (Fig. 4). Similarly, terns were determined separately for combining goose migration patterns each initiative area (see Migration with expected numbers of midwinter Chronology for Waterfowl Species of geese yields semimonthly expected GCJV Initiative Areas section, p. 26). numbers of geese (Fig. 4). Combining migration patterns and

Greater white- fronted goose 5 Lesser snow goose Greater & lesser scaup Ring-necked duck 4 Redhead Canvasback 3 Mottled duck

(millions) Northern shoveler

Ducks Blue-winged teal 2 Green-winged teal American wigeon 1 Gadwall Northern pintail Mallard 0 Late Early Late Early Late Early Late Early Late Early Late Early Late Early Late

Aug. Sept. Sept. Oct. Oct. Nov Nov Dec. Dec. Jan. Jan. Feb. Feb. Mar Mar . . . .

Figure 4. Semimonthly duck population objectives and expected numbers of geese for the Mississippi River Coastal Wetlands Initiative area.

6 NAWMP The Mississippi River Coastal Wetlands Initiative Area

The Mississippi River Coastal Wet- the Gulf of Mexico, salt marsh is fol- lands Initiative area is bounded on the lowed by brackish, intermediate, and east by the Louisiana state line and ex- fresh marsh. In addition to associations tends westward to Vermilion Bay. It in- of plant species, each coastal marsh cludes extensive marshland dominated type has characteristic hydrological by salt and brackish marshes with patterns, soils, and fish and wildlife numerous large, open water bays and resources. barrier islands. Although the northern Types of Coastal Marsh boundary occurs at roughly the marsh- Salt Marsh swamp interface, the region extends Extensive salt marshes exist in the far enough inland to include a fringe of southern portion of the Mississippi swampland south and east of Louisiana River Coastal Wetlands Initiative area, State Highways 90, 70, and 22 and especially in association with barrier Interstate 12. Of particular significance islands; Breton Sound; and Terre- to regional waterfowl populations are bonne, Barataria, and Black Bays. Salt two major river deltas—the Missis- marsh has the greatest tidal fluctuation sippi and the Atchafalaya—dominated of the four marsh types in the area and by fresh marsh. The Mississippi River has a well-developed drainage sys- Coastal Wetlands Initiative area in- tem. Water salinity averages 18 parts cludes all or portions of 17 Louisiana per thousand (ppt), and this marsh parishes. See the June 1990 Missis- type supports the least diverse vegeta- sippi River Coastal Wetlands Initiative tion. The predominant salt-tolerant Plan for a description of the area’s plants are smooth cordgrass, seashore geology, climate, and land use. saltgrass, and needlegrass rush. Salt Although the Mississippi River marsh is generally considered of only Coastal Wetlands Initiative area con- low value to waterfowl; however this sists of a variety of land types and marsh type buffers the more valuable wildlife habitats, this plan focuses on marsh types farther inland from the the three major waterfowl habitats impacts of tide and salinity. available: coastal marshes, forested Brackish Marsh wetlands, and seagrass meadows of Except for narrow Chandeleur Sound. zones along the banks Coastal Marsh of the Mississippi River There are four distinct coastal marsh north of the delta, ex- types in the Mississippi River Coastal tensive brackish marshes Wetlands Initiative area based on occur in broad zones in- plant species composition, which is land from the salt marsh. primarily influenced by species toler- This marsh type is also ance to water salinity. The four marsh subjected to daily tidal type classifications are salt, brackish, action. Water salinity av- erages 8.2 ppt, and plant intermediate, and fresh. These marsh Mallard pair. types generally occur in bands par- diversity is greater than alleling the coast that correspond to that of salt marsh. This salinity gradients. Moving inland from marsh type is dominated

GCJV 7 by saltmeadow cordgrass, seashore by tides than more brackish marsh. saltgrass, Olney bulrush, and widgeon- Water salinity in fresh marsh averages grass. Ponds are also prevalent within only 1.0 ppt. Fresh marsh supports the brackish marshes, where an abundance greatest diversity of plants. Maiden- of submerged aquatic vegetation varies cane, spikerush, bulltongue arrowhead, tremendously among sites and years. and alligatorweed are the dominant Brackish marsh is of high value to gad- plants. Many submerged and floating- walls and greater and lesser scaup, and leafed plants are present in this marsh provides year-round habitat for mottled type. Fresh marsh provides feeding ducks. This marsh type represents the and resting sites to many species of traditional wintering grounds for lesser ducks and geese and is considered to snow geese. be the most valuable marsh type to Intermediate Marsh waterfowl. Intermediate marsh, Status and Trends which lies inland from In 1990 marsh acreage of the Missis- brackish marsh, is some- sippi River Coastal Wetlands Initiative what influenced by area was estimated to be 1,683,600 tides, and water salinity acres, and marsh composition was 33% averages 3.3 ppt. Plant fresh, 11% intermediate, 34% brack- species diversity is high. ish, and 22% salt (Louisiana Coastal This marsh type is also Wetlands Conservation and Restora- dominated by saltmead- tion Task Force [LCWCRTF] and the ow cordgrass, and other Wetlands Conservation and Restora- Scaup pair. common plants include tion Authority [WCRA] 1998). Growth common reed, bulltongue arrowhead, and deterioration of coastal wetlands and coastal waterhyssop. Submerged have been naturally occurring in the aquatics such as pondweeds and Gulf of Mexico region for thousands southern waternymph are abundant in of years. As wetlands were degraded, intermediate marsh. This marsh type their loss was balanced by natural wet- is used by many species of ducks for land building processes. Coastal wet- feeding and resting. This less saline lands of the Mississippi River Coastal zone of intermediate marsh provides Wetlands Initiative area were created habitat for mottled duck broods, and by 5,000 years of active delta building use of this marsh type by wintering and degradation in alternating regions ducks is second only to fresh marsh. throughout Louisiana. A sequence of Fresh Marsh these overlapping deltaic lobes histori- Fresh marsh in the Mississippi River cally spanned from Vermilion Bay to Coastal Wetlands Initiative area lies Chandeleur Sound. These lobes alter- between the intermediate marsh and nately served as the active delta as the either uplands or forested wetlands. river periodically changed course and Large areas of fresh marsh also occur altered distribution of fresh water and at the mouth of the Mississippi and sediments. Degrading delta lobes are Atchafalaya Rivers. Normally, the tidal characterized by an increase in ma- range is less in inland marshes, with rine influence and the deterioration of fresh marsh generally less influenced freshwater plants that may be replaced

8 NAWMP by more salt tolerant species, or result of emergent wetlands was attributed to in open water. The gulfward remnants the conversion to open water, a much of these degrading lobes typically form less productive habitat of far less value a fringe of barrier islands. Prograding to ducks. or active deltas are characterized by Wetland Loss Factors and Threats fresh inflows of sediment-laden water, Wetland loss in the Mississippi Riv- resulting in mudflat deposition that er Coastal Wetlands Initiative area can is colonized by emergent vegetation. be divided by location into two broad This naturally cyclic process created categories: shore and bank erosion and a diversity of habitats that benefited a interior loss. Shore and bank erosion is wide variety of fish and wildlife spe- the breakdown of the shorelines of the cies. Unfortunately, this cyclic bal- Gulf Coast and interior lakes and the ance was permanently interrupted by banks of navigation channels and pe- a variety of human-induced changes, troleum access canals. This breakdown including the channelization of the ma- is caused by the actions of forces such jor distributary outlet that permanently as natural wave energy, tides, currents, directs the sediments and nutrients of boat wakes, and water surges associ- Mississippi River waters to the deep ated with the passage of large vessels water off the Continental Shelf where and storms. Erosional forces are exac- it cannot contribute to the marsh-build- erbated by relative sea-level rise and ing processes. hydrologic alterations affecting coarse Over half of the coastal wetlands for sediment distribution. The continued the entire conterminous United States effect of these forces gradually wears are in the Gulf of Mexico region. Total down the shoreline and bank soils coastal wetlands for Louisiana account and eventually blows or washes them for 12% of the national total and 24% away. The erosion can be particularly of the regional total (Field et al. 1991). rapid and can cause the direct loss of Louisiana has the highest coastal significant wetland acreage. Shoreline wetland loss rate of any state in the and bank erosion also can dramatically Nation with currently a loss rate of 25- affect wetland loss when it causes 35 square miles (16,000-22,400 acres) hydrologic connections between a year. Louisiana’s average coastal relatively isolated marsh systems and land loss rate accounts for an estimated dynamic water bodies such as navi- 80% of the national total. Coast-wide gation channels and large bays. land loss rates for Louisiana from Interior marsh loss is caused by a va- 1956 to 1978 were estimated to be riety of factors. Subsidence 39.4 square miles per year (25,200 and sea-level rise are natural acres). Although land loss rates in processes that contribute coastal Louisiana were decreasing, to marsh deterioration and losses continued, and the loss rate loss but in some cases have remained high at 34.9 square miles per probably been exacerbated year (22,340 acres) for 1978-90. The by human intervention. Mississippi River Coastal Wetlands The numerous dredged Initiative area accounted for over 80% navigation channels and Mottled duck pair. of this 1978-90 loss. Most of the loss

GCJV 9 access canals that crisscross the coastal among the most productive natural marshlands are another cause of ecosystems in the world. In their interior marsh loss because they have natural condition, forested wetlands disrupted the natural hydrology of the provide many benefits including area. The effects of the disruptions food and habitat for fish and wildlife, vary, but generally they have created flood protection, erosion control, and artificial barriers between wetlands and ground water exchange. In addition, wetland building and maintenance pro- forested wetlands help maintain and cesses, or they have removed natural improve water quality by intercept- barriers between wetlands and wetland ing surface water runoff, removing or deterioration processes. The canals retaining nutrients (e.g., nitrogen and and channels facilitate the penetration phosphorus), processing chemical and of salt water far inland into previously organic wastes, and reducing sediment fresh marshes, resulting in the death of loads downstream. However, the loss marsh plants and the eventual erosion or degradation of these wetlands can or oxidation of organic substrate. Ero- lead to serious consequences including sion of the substrate is accelerated by habitat fragmentation, species decline, the increased water-flow through the increased frequency of flooding, and marsh as a result of the canals. In addi- declines in water quality. tion, the construction of straight canals The Mississippi River Coastal in areas previously drained by natural Wetlands Initiative area encompasses channels has increased the speed by approximately 543,320 acres of wet- which the limited amount of fresh land habitats dominated by forested water provided by local rainfall drains swamps and seasonally flooded bot- seaward. Many canals have high spoil tomland hardwoods (LCWCRTF and banks that can restrict both the drain- WCRA 1998). This extensive area of age of water from the marsh, which forested wetlands provides habitat for results in excessive ponding, and the several species of wintering waterfowl. delivery of fresh water and sediments Wood ducks are the primary waterfowl Lesser snow geese. to the marsh that are essential for species in these forested wetlands, marsh nourishment and maintenance. while other ducks use these habitats to Herbivory by muskrats, nutria, and a lesser degree. occasionally geese is believed to be Wetland Loss Factors and Threats related to some interior wetland loss. From the mid-1970’s to the mid- The impact of moderate herbivory 1980’s, forested wetlands such as bot- alone is not enough to cause wetland tomland hardwood swamps and cy- loss; however, its impact is more press sloughs declined by 3.1 million pronounced in marshes experiencing acres in the Southeast. In Louisiana, additional stresses such as excessive the net loss of palustrine forested ponding or saltwater intrusion. wetlands statewide was estimated to Forested Wetlands be 628,000 acres. Most of this loss Forested wetland ecosystems occur occurred in the Mississippi Alluvial along the northern boundary of the Plain, which is primarily to the north Mississippi River Coastal Wetlands of the GCJV area and was primarily Initiative area. These wetlands are caused by agriculture (Hefner et al.

10 NAWMP 1994). In the Mississippi River Coastal Seagrass Status and Threats Wetlands Initiative area, saltwater It is estimated that the spatial cov- intrusion associated with changes in erage of seagrasses in the Gulf of hydrology and isohaline encroachment Mexico was equivalent to 12-24% is one of the primary causes of forested of the estuarine area (NOAA 1997). wetland loss. Over 40% of the existing Losses of seagrasses in the northern acreage is expected to be lost over the Gulf of Mexico over the last 50 years next 50 years as land use increases and have been large—from 20% to 100% hydrology is altered (LCWCRTF and for most estuaries (Handley 1995). WCRA 1998). Most of the loss is attributed to coastal population growth and accompanying Seagrass Beds municipal, industrial, and agricultural Seagrass beds (meadows) provide development. food for wintering waterfowl and Hurricanes, cold-front storms, and important nursery and foraging habitat salinity changes are natural causes of for several species of commercially seagrass loss and cannot usually be important finfish and shellfish. The controlled. The loss of seagrasses is most prominent of these within the also attributable to human-induced Mississippi River Coastal Wetlands effects associated with residential Initiative area exists in an isolated and industrial development pressures. band associated with the Chandeleur Seagrass meadows are susceptible to Islands barrier island chain. In a study the adverse effects of filling in two of the Chandeleur Sound, Michot ways: (1) from direct impacts of filling (1997) documented a 19,651-acre and (2) from indirect impacts of fill- seagrass meadow along the back bar- ing, which include the production of rier flat on the west side of the 45-mile suspended material in the water col- island chain, where salinity ranged umn (i.e., turbidity). Excess nutrients 20-36 ppt. from sewage treatment discharges, Five species of seagrasses occur septic systems, and drainage from within the Chandeleur Sound: shoal- agricultural fields (i.e., water quality) grass, turtlegrass, manateegrass, star can stimulate growth of phytoplankton grass, and widgeongrass. Within the in the waters over the grass beds. Mississippi River Coastal Wetlands Seagrass beds can also be damaged by Initiative area, nearly all redhead boat anchors and propellers of shallow ducks are found in association with the draft recreational boats. “Prop scars” seagrass beds of Chandeleur Sound. may contribute to additional degra- Redheads feed almost exclusively on dation of seagrass beds by accelerating shoalgrass rhizomes while wintering erosion near the broken root mats. along the Gulf Coast, and widgeon- grass also serves as forage for a variety of duck species.

GCJV 11 The Mississippi River Coastal Wetlands Initiative Implementation Plan

Habitat conservation is imperative GCJV. These strategies are mainte- for meeting waterfowl population ob- nance (i.e., loss prevention), resto- jectives of both the NAWMP and the ration, enhancement, and creation of GCJV. The critical habitat conservation wetland habitat. Though not a strategy, needs on public and private lands of routine management activities are im- the GCJV are to stop and reverse the portant and inherent components of the deterioration and loss of wetlands, restoration and maintenance strategies. especially coastal marshes, and to Conservation actions under each of improve the waterfowl value of agri- these strategies take several forms. The cultural lands. Loss of coastal marsh types of wetland conservation actions can be addressed by actions that either identified in each initiative area reflect reduce the rate of loss or that build the differences previously discussed land. In the Mississippi River Coastal that characterize each area. A descrip- Wetlands Initiative area, actions ad- tion of the strategies applicable to the dressing the loss of coastal marsh must Mississippi River Coastal Wetlands be based largely on prevention of pre- Initiative area is presented below. dictable loss, restoration of degraded Maintenance of Habitat areas, and wetland construction. Maintenance involves preserving The availability of food resources is existing functions and values of the the most likely effect of winter habitat habitat. The intent is to prevent ad- on survival and recruitment of water- ditional loss and degradation of wet- fowl populations. Availability of food lands, particularly in remaining coastal can be affected by production of foods marshes that are most vulnerable to (submerged aquatics, annual seeds, or erosion or conversion to more saline invertebrates), flooding at appropri- types through saltwater intrusion. Ex- ate times and depths for foraging, and amples of conservation actions under access to food influenced by floating this strategy include the following: exotics, human disturbance, or other (1) plugging of abandoned oil-drill- factors. In addition to fall and winter ing access canals to prevent food resources, mottled duck popu- further widening of the canal into Oil-drilling access canal plug. lations are influenced by breeding and emergent marsh; postbreeding habitat in the Mississippi (2) placing nearshore breakwater River Coastal Wetlands Initiative area. structures to reduce or reverse Availability of fresh or intermediate wave erosion on beachfronts into shallow water in brood-rearing and adjacent marsh; molting areas is critical during the (3) supporting public policy, educa- spring and summer. Therefore, the tional efforts, and sign installation habitat conservation actions outlined to promote an awareness of the in this plan intend to influence one or values of seagrass meadows and more of these habitat parameters. to avoid mechanical damage from Breakwater structures. Conservation Strategies recreational boating activities; Four broad strategies of wetland (4) planting erosion control vege- conservation are important for achiev- tation at key points protecting the ing the goals and objectives of the

12 NAWMP hydrologic integrity of vulnerable (2) restoring historic salinities and marshes; hydrology to degraded systems (5) replacing structures and main- through hydrologic structures and taining levees critical to pro- levees; tecting the hydrologic integrity of (3) restoring water quality, and vulnerable marshes; subsequently submerged aquatic (6) implementing managed fire to vegetation productivity, by reduc- maintain vegetative communities ing nutrient loading, fetch, and Erosion control vegetation. susceptible to invasion by woody turbidity; exotics (carefully implemented (4) modifying existing spoil banks prescribed burns also increase and canals to restore hydrology, the availability of belowground emergent wetlands, and asso- foods for geese in their historic ciated mudflats to their historical marsh range, potentially reducing condition (e.g., degrading levees competition with ducks for food and backfilling, plugging, and in other habitats); filling canals); (7) controlling floating or submersed (5) directing and/or trapping fallout exotic vegetation to maintain from sediment-laden water to natural plant communities; restore mudflats, and ultimately (8) implementing forest management emergent vegetation, on degraded plans that maintain the integrity areas; Marsh burning. and historical resource values of (6) conducting floating or submersed this ecosystem; exotic vegetation control to re- (9) providing technical guidance to store natural plant communities; achieve the above maintenance (7) beneficially using dredge ma- measures; and terial from navigation projects to (10) securing vulnerable tracts restore emergent wetlands and through fee title acquisition, con- associated mudflats; servation easement, or manage- (8) providing technical guidance ment agreement for implementing to achieve the above restorative the above maintenance measures. measures; and Restoration of Habitat (9) securing degraded tracts through Hydrologic structure. Restoration involves conservation fee title acquisition, conservation actions necessary to reestablish a natu- easement, or management agree- rally occurring but degraded wetland ment for the purpose of imple- ecosystem. The goal is to restore or menting the above restorative mimic the original wetland functions measures. and values of the site. Examples of Creation of Habitat conservation actions under this strat- Creation of habitat is the con- egy include the following: struction of wetlands where none (1) restoring historic salinities and previously existed in recent geological hydrology via freshwater diver- terms. Conservation actions develop Beneficial use of dredge sions; the hydrological, geochemical, and material.

GCJV 13 biological components necessary to We modeled waterfowl energetic support and maintain a wetland. Ex- demand on coastal marsh habitats amples of conservation actions under for comparison to forested wetlands. this strategy include the following: Based on food habits research and (1) beneficially using dredge spoil general knowledge of habitat use by from navigation projects to create various species, we estimated the emergent wetlands and associated proportion of each species’ energetic mudflats, and needs in coastal marsh to be 75% for (2) implementing sediment diver- mallards; 95% for gadwalls, Ameri- sions to create emergent wetlands can wigeon, blue-winged and green- and associated mudflats. winged teal, Northern shovelers, and Habitat Objectives ring-necked ducks; and 100% for The three major waterfowl habi- mottled ducks, Northern pintails, and tats available in the Mississippi River other diving ducks. We estimated that Coastal Wetlands Initiative area are 100% of the geese that occur in Mis- coastal marshes, forested wetlands, sissippi River coastal wetlands oc- and seagrass meadows. Habitat ob- cur in coastal marsh. These estimates jectives are based on the assumption result in population objectives for that food availability is the most likely Mississippi River Coastal Wetlands limiting factor for wintering ducks in Initiative coastal marsh habitats (Fig. the GCJV. Food availability is poten- 5). Energetic demand is based on the tially influenced by factors that affect dietary energy requirements of mal- food production (e.g., marsh health) lards (Petrie 1994), with other species and access (e.g., disturbance, water at having energetic needs in proportion appropriate depths, etc.). to their body weight (Kendeigh 1970). We arrived at an energy demand curve, Coastal Marsh in terms of mallard-use-days, through Food density data are not available the wintering waterfowl period (Fig. for coastal marsh habitats of the GCJV, 6). precluding quantitative modeling of habitat needs. However, given the Forested Wetlands importance of this habitat and its food Estimates are available for the resources to waterfowl, the enormous density of desirable mast and other loss of coastal marsh, and the limited waterfowl food sources in forested opportunities for restoration and cre- wetland habitats, so we can model the ation, the GCJV supports all projects waterfowl habitat requirements for that seek to restore lost or degraded that particular habitat. Based on food marshes to sustainable historic or more habits research and general knowledge natural conditions. The GCJV will be of habitat use by various species, we particularly supportive of those resto- estimated the proportion of each spe- ration and creation projects that will cies’ energetic needs in these forested provide the most long-term benefits wetland habitats to be 100% for wood to waterfowl. Additionally, the GCJV ducks; 25% for mallards; and 5% for supports all protective measures that gadwalls, American wigeon, blue- maintain current habitat values that winged and green-winged teal, North- would otherwise be predictably lost. ern shovelers, and ring-necked ducks.

14 NAWMP 5 Greater white- fronted goose Lesser snow goose Greater & lesser scaup 4 Ring-necked duck Redhead

3 Canvasback Mottled duck

(millions) Northern shoveler

Ducks 2 Blue-winged teal Green-winged teal American wigeon 1 Gadwall Northern pintail Mallard 0 Late Early Late Early Late Early Late Early Late Early Late Early Late Early Late

Aug. Sept. Sept. Oct. Oct. Nov Nov Dec. Dec. Jan. Jan. Feb. Feb. Mar Mar . . . .

Figure 5. Semimonthly duck population objectives and expected numbers of geese for coastal marsh of the Mississippi River Coastal Wetlands Initiative area.

50

40

(millions) 30

20 Coastal marsh

Mallard-use-days Forested wetlands

10

0 Late Early Late Early Late Early Late Early Late Early Late Early Late Early Late

Aug. Sept. Sept. Oct. Oct. Nov Nov Dec. Dec. Jan. Jan. Feb. Feb. Mar Mar . . . .

Figure 6. Energetic demand (mallard-use-days) of duck objectives, and expected numbers of geese and wood ducks, in coastal marsh and forested wetlands of the Mississippi River Coastal Wetlands Initiative area.

GCJV 15 We used recent estimates of waterfowl 1970). We therefore used average body harvest to determine the expected weights of each species in conjunction number of wood ducks for parishes of with semimonthly population objec- the Mississippi River Coastal Wetlands tives to arrive at an energy demand Initiative area (see Derivation of GCJV curve, in terms of mallard-use-days, Waterfowl Objectives and Migration through the wintering waterfowl pe- Patterns section, p. 23), thus resulting riod (Fig. 6). in estimates of waterfowl population Over 543,000 acres of forested wet- demand on forested wetland habitats land habitat are available as foraging within the Mississippi River Coastal habitat for migrating and wintering Wetlands Initiative area (Fig. 7). waterfowl in the Mississippi River We modeled the waterfowl energetic Coastal Wetlands Initiative area. Red demand for this portion of our popu- oak species comprise approximately lation objectives based on the dietary 30% of bottomland hardwood stands. energy supply necessary to sustain Foraging values for bottomland hard- them. Researchers estimate energetic woods have been estimated for the requirements of mallards to be 290 Lower Mississippi Valley Joint Venture kcal per day (Petrie 1994), with other area (Loesch et al. 1994). We assumed species having energetic needs in pro- the relationship between percent red portion to their body weight (Kendeigh

Wood duck 400 Ring-necked duck

300 Northern shoveler

Blue-winged teal

(thousands)

200 Green-winged teal

Ducks

American wigeon 100 Gadwall

Mallard 0 Late Early Late Early Late Early Late Early Late Early Late Early Late Early Late

Aug. Sept. Sept. Oct. Oct. Nov Nov Dec. Dec. Jan. Jan. Feb. Feb. Mar Mar . . . . Figure 7. Semimonthly duck population objectives and expected numbers of wood ducks for forested wetlands of the Mississippi River Coastal Wetlands Initiative area.

16 NAWMP oaks and waterfowl foraging values in population objective of 13,731 that bottomland hardwood stands would be is based on 1970’s averages, it is less similar to the Mississippi River Coast- than observed numbers in 1 of those al Wetlands Initiative area, and thus we 10 years (i.e., from 1970-79). The modeled waterfowl habitat needs for model also assumes that all portions forested wetlands of the Mississippi of seagrass meadows are equally and River Coastal Wetlands Initiative area totally accessible for redhead forag- (Table 2). ing, ignoring potential (but untested) Seagrass Beds effects of disturbance or other fac- Some food density data are avail- tors in limiting redhead accessibility. able for seagrass beds, and research- Observed numbers exceed 80% of the ers have used existing information to modeled carrying capacity in at least model the carrying capacity of Lou- 4 years from 1970 to 1998. The winter isiana shoalgrass beds for redheads following Hurricane Georges, which (Michot 1997). Chandeleur Sound in 1998 destroyed or buried many of seagrass beds have been estimated to the seagrasses in Chandeleur Sound, encompass 19,651 acres, 1,331 acres saw observed redhead numbers fall to of which is shoalgrass (Michot 1997). only 2,125, demonstrating the potential Michot’s (1997) published model for for food resource limitation to affect redhead carrying capacity suggests that redheads. Combined, these factors Chandeleur Sound can annually sup- suggest the potential for current habitat port 22,827 redheads through a given conditions to limit redhead populations winter. Though this number compares during some years, and the need to favorably with the region’s redhead protect the existing habitat base.

Table 2. Foraging values, habitat needs, and habitat availability for the Mississippi River Coastal Wetlands Initiative area.

Foraging value per acre Habitat need Current2 2050 projected Public ownership3 (MUDs1) (MUDs) Acres MUDs Acres MUDs Acres MUDs

Coastal marsh * 405,320,0544 1,683,600 *6 1,381,690 * 377,628 * Forested wetland 62 30,201,2635 543,320 33,685,8406 311,430 19,308,660 29,774 1,845,988 Seagrass bed 936 1,096,8526 19,651 1,823,4536 * * Total 436,618,1691 2,246,571 *6 * * 407,402 *

* Unknown. 1 Mallard-use-days. 2 1989 or 1990 acreage estimates. 3 Refer to Table 3. 4 Sum of all energetic demands for coastal marsh habitats (Fig. 6). 5 Sum of all energetic demands for forested wetland habitats (Fig. 6). 6 Back-calculated from Michot (1997) model.

GCJV 17 Table 3. Estimated coastal marsh and forested wetland habitat Habitat Conclusions that is currently under public ownership in the Mississippi Forested wetlands of the Mississippi River Coastal Wetlands Initiative area1. River Coastal Wetlands Initiative area provide habitat for less than 8% of Coastal Forested marsh wetlands all ducks, including wood ducks, that Land tract2 Ownership3 (acres) (acres) occur in the region. The current acre- age of forested wetlands is apparently Atchafalaya Delta WMA LDWF 6,000 2,100. sufficient to meet waterfowl foraging Bayou Sauvage NWR USFWS 22,000 0. Bayou Segnette SP LOSP 0 400. needs at objective population levels, Big Branch NWR USFWS 9,000 0. although only about 6% of this acre- Biloxi WMA LDWF 39,583 0. age is in public ownership (Table 3). Cypremort Point SP LOSP 43 0. Delta NWR USFWS 48,800 0. Of paramount concern, however, is the Elm Hall WMA LDWF 0 2,839. 50-year projected loss of forested wet- Fairview Riverside SP LOSP 0 40. lands (regardless of ownership status) Fontainbleau SP LOSP 1,000 200. to levels below that which meets forag- Grand Isle SP LOSP 20 0. Jean Lafitte-Barataria NP NPS 5,266 2,363. ing needs. This projected loss high- Joyce WMA LDWF 0 15,609. lights the need to support large-scale Lake Boeuf WMA LDWF 0 670 hydrologic modifications to restore the Manchac WMA LDWF 8,325 0. isohaline imbalance that is threatening Mandalay NWR USFWS 4,100 0. Marsh Island SWR LDWF 76,000 0. these habitats and their ability to meet Pass a Loutre WMA LDWF 50,000 0. regional waterfowl needs. Pearl River WMA LDWF 18,560 5,453.4 Point au Chien WMA LDWF 35,000 0. St. Bernard SP LDWF 0 100. St. Tammany SWR LDWF 1,310 0. Salvador/Timken WMA LDWF 30,000 0. Terrebonne Barrier Is. SWR LDWF 1,000 0. Wisner WMA LDWF 21,621 0.

Total 377,628 29,774.

1 Data from 1999 U.S. Shorebird Conservation Plan/GCJV Questionnaire, unless otherwise specified. Data for all Louisiana Office of State Parks sites provided by the Louisiana Office of State Parks. Data for National Park Service site provided by Tommy Michot (U.S. Geological Survey’s National Wetlands Research Center). Data for Elm Hall and Lake Boeuf Wildlife Management Areas provided by Louisiana Department of Wildlife and Fisheries. Data for Mandalay National Wildlife Refuge provided by Steve Reagan (U.S. Fish and Wildlife Service). 2 WMA = Wildlife Management Area, NWR = National Wildlife Refuge, SP = State Park, NP = National Park, SWR = State Wildlife Refuge. 3 LDWF = Louisiana Department of Wildlife and Fisheries, USFWS = U.S. Fish and Wildlife Service, LOSP = Louisiana Office of State Parks, NPS = National Park Service. 4 Includes only that portion (approx. 1/3) inside the GCJV boundary.

18 NAWMP Coastal marsh of the Mississippi Seagrass beds of Chandeleur Sound River Coastal Wetlands Initiative area appear to be capable of sustaining red- provides habitat for over 90% of all head population objectives, but there is waterfowl that occur in the region. potential for redheads to be food lim- We lack food density data for these ited in that system in some years. Over habitats, precluding a quantitative as- 90% of continental redhead popula- sessment of the carrying capacity of tions winter in only four areas, one of available coastal marsh habitats. None- which is Chandeleur Sound (Michot theless, whatever the current capacity 2000). The limited geographical distri- to support waterfowl, it will surely de- bution of redheads, coupled with their crease as 50-year projections estimate heavy reliance on a single prey plant that only about 80% of the acreage species (shoalgrass), dictates a very that exists now will persist, even given conservative approach to the conserva- current restoration efforts. Until we are tion of habitats they rely upon. There able to quantify these food resources, are few options for actively conserving a conservative approach to waterfowl seagrass beds of Chandeleur Sound, management requires that we main- but available maintenance actions tain conservation of marshes as a high should be undertaken. priority within the Mississippi River Coastal Wetlands Initiative area.

GCJV 19 Specific Activities designed to provide benefits to coastal The wetland habitat objectives of wetlands far beyond the construction the Mississippi River Coastal Wetlands footprint. The focus of projects will be Initiative will be addressed through reducing interior wetland loss, rebuild- various projects that focus on coastal ing wetlands in open water areas, and marsh, forested wetlands, and seagrass maintaining the geologic framework of meadows. Coastal wetland projects the coast by addressing shoreline and will involve protecting critical shore- bank erosion. Additionally, partners lines and banks, improving or restoring will initiate activities described herein more natural hydrological conditions as other opportunities become avail- (to stabilize water and salinity levels able. An evolving package of actions and to reduce tidal scour), trapping designed to meet some of the Missis- sediments (to accelerate natural wet- sippi River Coastal Wetlands Initiative/ land building), and creating marsh GCJV objectives as well as contribute with dredged material. Many of these to the fulfillment of the NAWMP goals projects will be designed to address lo- has been developed and will be con- calized problems, while others will be tinually updated.

American wigeon pair.

20 NAWMP Other Programs Communication and We recognize and support other Education conservation efforts that contribute to Public awareness of the importance goals of this plan. Coastal marsh proj- of the Gulf Coast to waterfowl and ects implemented under the Coastal other renewable resources is key to the Wetlands Planning, Protection and success of the GCJV. Communication Restoration Act contribute significantly efforts will be developed to educate to the maintenance and restoration decision makers, resource managers, objectives of this plan through the landowners, conservation organiz- Louisiana planning effort known as ations, and the general public about “Coast 2050.” Similarly, larger scale wetland conservation in the Missis- projects implemented through the sippi River Coastal Wetlands Initiative Water Resources Development Act by area. the U.S. Army Corps of Engineers will also contribute to goals set forth in this plan.

GCJV 21 Relationship to Evaluation Plan

Objectives and strategies outlined in the most critical of these assumptions this document represent a compilation will be addressed in the GCJV Eval- of the best available information re- uation Plan, which is being developed garding the habitat needs of waterfowl simultaneously with this plan. The in this region. However, information GCJV Evaluation Plan will provide a gaps require numerous assumptions mechanism for feedback to, and refine- about both the basic framework for ment of, Initiative Area Implement- planning habitat conservation (i.e., ation Plans. These plans will therefore food limitation) and specific variables be updated periodically, as evaluation used in energetic modeling of habitat feeds the planning and implementation needs (e.g., relative importance of processes. habitat types by species). Testing of

Northern shovelers and blue-winged teal.

22 NAWMP Derivation of GCJV Waterfowl Objectives and Migration Patterns

Midwinter Duck Population that percentage to the flyway goal and Objectives obtained a midwinter population ob- Although the coordinated midwin- jective of about 516,000 for mallards ter survey is an inaccurate count of in the Louisiana Chenier Plain. This total wintering birds, and not cor- method yields midwinter objectives for rected for visibility bias, it provides most species of ducks that commonly a reasonable approximation of the occur in the GCJV area (Table 1). relative distribution of birds across Exceptions to this method include broad regional and temporal scales. derivations for blue-winged teal and Therefore, we used averages from the redhead objectives, and estimation of 1970-79 midwinter surveys for each the expected number of mottled ducks. species to determine the proportion of For blue-winged teal, the continental surveyed ducks that occurs in each of breeding population was first reduced the initiative areas. (For greater and by 79% to account for the proportion lesser scaup, offshore counts were estimated to winter outside the range excluded due to inconsistent survey of the U.S. midwinter survey, mainly coverage, resulting in “inland-only” in Mexico and Central and South scaup objectives.) We then applied America. those species-specific proportions to Population objectives for redheads the NAWMP continental breeding were determined directly from average population objectives for each species to arrive at the number of birds each initiative area should supply to the breeding population. We assume 10% mortality between midwinter (January) and breeding (May) periods to arrive at midwinter objectives (Table 1). Using mallards as an example, dur- ing 1970-79, 42.9% of all continental mallards counted during the midwinter survey were in the Mississippi Flyway (see Fig. 3 for a similar example). The NAWMP continental breeding popu- lation objective for mallards is 11 million, so we estimate the portion of the continental breeding population objective from the Mississippi Flyway to be 42.9% of that, or 4.72 million. Expanding this number to account for 10% mortality between January and May yields a midwinter objective of 5.24 million in the Mississippi Fly- way. Because 9.8% of all Mississippi Flyway mallards were counted in the Male ring-necked duck. Louisiana Chenier Plain, we applied

GCJV 23 winter population estimates from the estimate. Band reporting rates are as- Special Redhead Cruise Survey for sumed to be 33% for 1994-95 and 59% the same time period (1970-79). Us- for 1996-97). Preseason population ing direct estimates from aerial winter estimates were then averaged, and an surveys is appropriate for determining estimated fall/winter mortality rate of objectives for redheads but not other 30% was assumed to be evenly distrib- ducks, because (1) uted September through March. The wintering redheads oc- resulting midwinter estimate was then cur almost exclusively apportioned to initiative areas by the in known locations of midwinter survey (Table 1). offshore seagrass habitat Though not actually an objective, with good visibility, (2) recent wood duck numbers are used in visibility bias has been some initiative areas to augment ener- estimated and found getic models depicting habitat needs negligible for portions of in forested wetlands. These recent this special survey, and population size approximations are (3) redhead habitats are derived from a combination of harvest Male American wigeon. not consistently surveyed and harvest rate estimates. The Har- during the midwinter vest Surveys Section of the U.S. Fish survey, precluding the methodology and Wildlife Service (Laurel, MD) applied for most species. provided wood duck harvest data by To estimate the number of mottled county for 1990-99. Wood duck har- ducks expected to occur during win- vest rates are approximated to be 10%. ter, we used mark-recapture analyses This is based on both band recovery of direct recoveries from bandings in rates and estimates of band reporting Louisiana and Texas during 1994-97. rate (Table 4). Preseason population estimates were Migration Patterns derived from the assumption that the Louisiana migration patterns for ratio of the total population to the total ducks were determined by using pe- harvest (U.S. Fish and Wildlife Service riodic coastwide aerial surveys along estimate) equals the ratio of the banded established transects that generally population to the banded harvest were flown one to two times per month (direct recoveries/band reporting rate September through March, 1970-98 (Louisiana Department of Wildlife and Fisheries coastal transect survey, Table 4. Estimated wood duck harvest, harvest rates, and population size(s) for unpublished data). Chandeleur Sound, the Mobile Bay, Coastal Mississippi Wetlands, and Mississippi River Coastal Wetlands (southeast Louisiana) Initiatives. the primary redhead area in Louisiana, is not covered by these coastal tran- Number Expected sects, so for Louisiana redheads we harvested Harvest peak Initiative Area (10-yr average) rate population Mobile Bay 1,3001 10% 13,000 Coastal Mississippi Wetlands 5301 10% 5,300 Mississippi River Coastal Wetlands 21,9001 10% 219,000 (southeast Louisiana) 1 Due to low sample size, we used the upper range of harvest estimates from 1990-99.

24 NAWMP instead used 1987-92 periodic redhead (1994) to estimate the relative propor- surveys from that region (Thomas tion of the annual peak in each semi- C. Michot, U.S. Geological Survey, monthly period. unpublished data). Each survey was Multiplying these semimonthly pro- assigned to a half-month period. For portions by the midwinter population each species, each survey of a given objectives yields semimonthly popula- year was expressed as a proportion of tion objectives by species and initia- that year’s peak. These proportions tive area (Fig. 4). Because Louisiana were averaged across all years to yield surveys were never conducted in late the average proportion of the annual March, we assumed late March val- peak for each half-month period. All ues for all species were 50% of early proportions were then expressed rela- March values. Because Texas surveys tive to the midwinter (January) propor- were never conducted in late August, tion (see Migration Chronology for we assumed late August blue-winged Waterfowl Species of GCJV Initiative teal values were 15% of early Sep- Areas section, p. 26). tember values. Because geese are not For Texas, aerial surveys of fed- periodically surveyed in Louisiana, we eral refuges and select other proper- applied migrational information from ties provide the basis for determining the Texas Chenier Plain to all eastward migration patterns (U.S. Fish and initiative areas. For the Coastal Missis- Wildlife Service’s Coastal Waterfowl sippi Wetlands and Mobile Bay Ini- Survey Data, unpublished data). These tiative areas, we applied duck migra- monthly Texas surveys were conducted tional information from the Mississippi September through March of 1984-97, River Coastal Wetlands Initiative area and data from all sites that were con- (southeast Louisiana). sistently surveyed within a given year were used. Analyses were conducted as above, except each survey represented an entire month (see Migration Chro- nology for Waterfowl Species of GCJV Initiative Areas section, p. 26). For wood ducks, we used fall and spring migration data depicted for the Gulf Coast in Bellrose and Holm

Blue-winged teal males.

GCJV 25 2 s d n a l t e W

l a t s a o C

r e v i R

i p p i s s i s s i M ) a n a i s i u o L (

n i . a l 1 P

r e i n e h C t s a o C - d i M

s a x e T ) s a x e T (

e r d a M

a n u g

a

L

l l a w d a G l a e t d e g n i w - n e e r G l a e t d e g n i w - e u l B d r a l l a M l i a t n i p n r e h t r o N n o e g i w n a c i r e m A Migration Chronology for Waterfowl Species of Areas Migration Chronology GCJV Initiative Waterfowl for

26 NAWMP

1970-1998 Louisiana Department of Wildlife and Fisheries coastal waterfowl transect survey. 1984-1997 U. S. Fish and Wildlife Service coastal waterfowl surveys of refuges and selected properties. Michot, USGS-NWRC, (Tommy Redhead Surveys of Chandeleur Sound, LA unpublished data).

Data sources: . r a M . b e F . n a J . c e D . v o N . t c O . t p e S . r a M . b e F . n a J . c e D . v o N . t c O . t p e S . r a M . b e F . n a J . c e D . v o N . t c O . t p

e

S

e s o o g d e t n o r f p u a c s

- e t i h w r e t a e r G k c a b s a v n a C r e s s e l & r e t a e r G d a e h d e R k c u d d e k c e n - g n i R e s o o g w o n s r e s s e L Average proportion of the annual peak, relative to January (midwinter) survey. Data are not available for Coastal Mississippi Wetlands and Mobile Bay Initiative areas. Coastal Mississippi Wetlands Data are not available for of the annual peak, relative to January (midwinter) survey. proportion Average Southeast Louisiana. 1 2

GCJV 27 Literature Cited

Bellrose, F.C., and D.J. Holm. 1994. Louisiana Coastal Wetlands Conservation Ecology and management of the Wood and Restoration Task Force and the Duck. Stackpole Books, Mechanisburg, Wetlands Conservation and Restoration PA. Authority. 1998. Coast 2050: toward Field, D.W., A.J. Reyer, P.V. Genovese, a sustainable coastal Louisiana. Loui- and B.D. Shearer. 1991. Coastal siana Department of Natural Resources, wetlands of the United States, an ac- Baton Rouge, LA. 161pp. counting of a valuable natural resourc- Michot, T.C. 1997. Carrying capacity of es. National Oceanic and Atmospheric seagrass beds predicted for redheads Administration Special Report. 59 pp. wintering in Chandeleur Sound, Lou- Handley, L.R. 1995. Seagrass distribution isiana, USA. Pages 93-102 in J. Goss in the northern Gulf of Mexico. Pages Custard, R. Rufino, and A. Luis, edi- 273-275 in E.T. LaRoe, G.S. Farris, tors. Effect of habitat loss and change C.E. Pucket, P.D. Doran, and M.J. Mac, on waterbirds. Institute of Terrestrial editors. Our living resources: a report to Ecology Symposium No. 30, Wetlands the nation on the distribution, abun- International Pub. No. 42. dance, and health of U.S. plants, ani- Michot, T.C. 2000. Comparison of win- mals, and ecosystems. U.S. Department tering redhead populations in four Gulf of the Interior, National Biological of Mexico seagrass beds. Pages 243- Service, Washington, DC. 260 in F.A. Comin, J.A. Herrera, and Hefner, J.M., B.O.Wilen, T.E. Dahl, and J. Ramirez, editors. Limnology and W.E. Frayer. 1994. Southeast wetlands: Aquatic Birds: Monitoring, Modelling, status and trends, mid-1970’s to mid- and Management. Universidad Autóno- 1980’s. U.S. Department of the Interior, ma de Yucatán, Mérida (Mexico). U.S. Fish and Wildlife Service, Atlanta, National Oceanic and Atmospheric Ad- GA. ministration (NOAA). 1997. NOAA’s Kendeigh, S.C. 1970. Energy requirements estuarine eutrophication survey, volume for existence in relation to size of bird. 4: Gulf of Mexico region. Office of Condor 72:60-65. Ocean Resources Conservation and As- Loesch, C.R., K.J. Reinecke, and C.K. sessment, Silver Spring, MD. 77 pp. Baxter. 1994. Lower Mississippi Valley Petrie, M.J. 1994. True metabolizable Joint Venture Evaluation Plan. North energy of waterfowl foods. M.S. thesis, American Waterfowl Management University of Missouri, Columbia. 138 Plan, Vicksburg, MS. 34 pp. pp.

For More Information

North American Waterfowl Management the Commitment. 1994. U.S. De- Plan. 1986. U.S. Department of the In- partment of the Interior, Environment terior and Environment Canada. 19 pp. Canada, and Secretaria de Desarrollo Mississippi River Coastal Wetlands Initia- Social Mexico. 30 pp. + appendixes. tive Gulf Coast Joint Venture North Expanding the Vision 1998 Update North American Waterfowl Management Plan. American Waterfowl Management Plan. 1990. Mississippi River Coastal Wet- 1998. U.S. Department of the Interior, lands Initiative Team. 39 pp. Environment Canada, and Secretaria de 1994 Update to the North American Wa- Medio Ambiente, Recursos Naturales y terfowl Management Plan: Expanding Pesca. 32 pp.

28 NAWMP Appendix Acknowledgments

Scientific Names of Plants and This planning document benefited from the input of numerous Animals Mentioned in This Plan individuals. I. Plants alphabetical by common name. Common Name Scientific Name The Waterfowl Working Group of the Gulf Coast Joint Ven- Alligatorweed Alternanthera philoxeroides ture’s Monitoring, Evaluation, and Research Team—A.D. Bulltongue arrowhead Sagittaria lancifolia Afton, W.P. Johnson, M.T. Merendino, T.C. Michot, T.E. Moor- man, and M.J. Petrie—provided initial direction, review of the Coastal waterhyssop Bacopa monnieri biological foundation, and identification of critical underlying Common reed Phragmites australis assumptions for the plan. Maidencane Panicum hemitomon Manateegrass Syringodium filiforme The Gulf Coast Joint Venture Management Board provided Needlegrass rush Juncus roemerianus input during plan development and commented on completed Olney bulrush Schoenoplectus americanus drafts, as well as provided the impetus and encouragement to Pondweed Potamogeton sp. initiate and complete this effort. Red oak Quercus spp. Saltmeadow cordgrass Spartina patens Former Mississippi River Coastal Wetland Initiative Area Seashore saltgrass or Distichlis spicata Chairperson R. Paille was instrumental in organizing team inland saltgrass members for discussing this plan. U.S. Fish and Wildlife Ser- Shoalgrass Halodule wrightii vice Region 4 Migratory Bird Coordinator F. Bowers, current Smooth cordgrass Spartina alterniflora Initiative Area Chairperson K. Roy, and other initiative team Southern waternymph Najas guadalupensis members reviewed and commented on an earlier draft. Spikerush Eleocharis sp. Star grass Cynodon plectostachyus K.E. Gamble, D.A. Haukos, T.C. Michot, R.N. Helm, J.E. Turtlegrass Thalassia testudinum Neaville, D. Orr, and B.D. Sullivan gathered and provided Widgeongrass Ruppia maritima unpublished waterfowl survey data for use in this document.

II. Waterfowl alphabetical by common name. Common Name Scientific Name The publishing staff at the U.S. Geological Survey’s National American black duck Anas rubripes Wetlands Research Center provided significant advice to im- American wigeon Anas americana prove the readability and attractiveness of this document. C.A. Black-bellied whistling duck Dendrocygna autumnalis Manlove and J. Holden provided early drafts of Fig. 1. Blue-winged teal Anas discors Financial or substantial in-kind support for the preparation and Canada goose Branta canadensis publication of this plan was provided by Ducks Unlimited; the Canvasback Aythya valisineria North American Waterfowl and Wetlands Office and Region Fulvous whistling duck Dendrocygna bicolor 2 of the U.S. Fish and Wildlife Service; the Texas Parks and Gadwall Anas strepera Wildlife Department; the U.S. Geological Survey’s National Greater scaup Aythya marila Wetlands Research Center; and the Gulf Coast Joint Venture Greater white-fronted goose Anser albifrons Management Board. Green-winged teal Anas crecca Lesser scaup Aythya affinis Lesser snow goose Chen caerulescens Mallard Anas platyrhynchos Northern pintail Anas acuta Northern shoveler Anas clypeata Redhead Aythya americana Ring-necked duck Aythya collaris Ross’ goose Chen rossii Wood duck Aix sponsa

III. Other animals alphabetical by common name. Common Name Scientific Name Alligator Alligator mississippiensis Muskrat Ondatra zibethicus Nutria Myocastor coypus