Texas Mid-Coast Initiative Area

Gulf Coast Joint Venture: Texas Mid-Coast 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: Northern pintails, Ducks Unlimited, Inc. Page iii: (top) pintails, C. Jeske, U.S. Geological Survey; (bottom), gadwall, R.J. Long, Ducks Unlimited, Inc. Page iv: U.S. Geological Survey. Page 8: mallard pair, B. Wilson, Gulf Coast Joint Venture. Page 10: scaup pair, B. Hinz, U.S. Fish and Wildlife Service. Page 11: mottled duck pair, R. Paille, U.S. Fish and Wildlife Service. Page 12: lesser snow geese, T. Hess, Louisiana Department of Wildlife and Fisheries. Page 13: hydrologic structure, B. Wilson, Gulf Coast Joint Venture; breakwater structures, T. Hess, Louisiana Department of Wildlife and Fisheries; earthen terraces, T. Hess, Louisiana Department of Wildlife and Fisheries. Page 14: erosion control vegetation, T. Hess, Louisiana Department of Wildlife and Fisheries; oil-drilling access canal plug, B. Wilson, Gulf Coast Joint Venture; marsh burning, B. Wilson, Gulf Coast Joint Venture. Page 15: flooded agriculture field, U.S. Geological Survey; beneficial use of dredge material, T. Hess, Louisiana Department of Wildlife and Fisheries; American wigeon pair, 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 25: blue-winged teal males, W.L. Hohman, U.S. Geological Survey. Gulf Coast Joint Venture: Texas Mid-Coast 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., and C.G. Esslinger. 2002. North American Waterfowl Manage- ment Plan, Gulf Coast Joint Venture: Texas Mid-Coast Initiative. North Amer- ican Waterfowl Management Plan, Albuquerque, 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 Texas Mid-Coast Initiative Area...... 8 Coastal Marsh ...... 8 Types of Coastal Marsh...... 8 Status and Trends ...... 9 Wetland Loss Factors and Threats ...... 10 Agricultural Land...... 10 Status and Trends ...... 11 Seagrass Beds...... 11 Seagrass Status and Threats ...... 12 The Texas Mid-Coast Initiative Implementation Plan ...... 13 Conservation Strategies ...... 13 Maintenance of Habitat...... 13 Restoration of Habitat...... 14 Enhancement of Agricultural Habitat ...... 15 Creation of Habitat...... 15 Habitat Objectives...... 15 Coastal Marsh ...... 16 Seagrass Beds...... 16 Agricultural Habitats...... 16 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 Appendix: Scientific Names of Plants and Animals Mentioned in This Plan ...... Inside back cover Acknowledgments...... Inside back cover For More Information ...... Inside back cover

GCJV iii Figures

Number Page

1 Location of the Gulf Coast Joint Venture region ...... 1 2 Texas Mid-Coast Initiative area...... 3 3 An example of how midwinter population objectives were obtained for a specific species in the Texas Mid-Coast Initiative area...... 5 4 Semimonthly duck population objectives for the Texas Mid-Coast Initiative area ...... 6 5 Semimonthly expected numbers of geese for the Texas Mid-Coast Initiative area ...... 7 6 Planted rice acreage for the Texas Mid-Coast Initiative area ...... 11 7 Semimonthly duck population objectives for the agricultural portion of the Texas Mid-Coast Initiative area...... 17 8 Semimonthly expected numbers of geese for the agricultural portion of the Texas Mid-Coast Initiative area...... 17 9 Energetic demands of all waterfowl objectives (mallard-use-days) in flooded habitats of the agricultural portion of the Texas Mid-Coast Initiative area ...... 18

Tables

Number Page

1 Midwinter population objectives for initiative areas of the Gulf Coast Joint Venture ...... 4 2 Prespoilage foraging values (mallard-use-days per acre) of the major habitat types of Texas Mid-Coast agricultural lands...... 18 3 a) Total agricultural flooding acreage need for the Texas Mid-Coast Initiative area ...... 20 b) Flooding objectives for new agricultural enhancement acreage within the Texas Mid-Coast Initiative area...... 20

iv NAWMP Introduction

North American Waterfowl particular physiographic region such Management Plan as the Gulf Coast. These partners come Faced with continuing wetland de- together under the NAWMP to pool struction and rapidly declining water- resources and accomplish collectively fowl 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 popu- is therefore one of the most important lations and their habitats. Updated waterfowl areas in North America, in 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 implementation 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 be designed to maximize the overlap critical to the overall success of the of benefits between the species groups. NAWMP because the area provides This joint venture will strive to balance extensive wetlands that are vitally its focus on waterfowl and wetlands important to traditional wintering with the need to expand coordination waterfowl concentrations. The primary and cooperation with existing conser- goal of the GCJV is to provide habitat vation initiatives that promote com- for waterfowl in winter and ensure that mon purposes, strategies, or habitats of they survive and return to the breed- interest. ing grounds in good condition, but not The GCJV is divided geographically exceeding levels commensurate with into six initiative areas, each with a breeding habitat capacity as is the case different mix of habitats, management with midcontinent lesser snow and opportunities, and species priorities. Ross’ geese. A secondary goal is to This document deals with planning ef- provide ample breeding and postbreed- forts for the Texas Mid-Coast Initiative ing habitat for resident waterfowl. area (Fig. 2). The goal of the Texas Actions that will achieve and maintain Mid-Coast Initiative is to provide healthy wetland ecosystems that are wintering and migration habitat for essential to waterfowl will be pursued. significant numbers of dabbling ducks, Wetland conservation actions that will redheads, lesser snow geese, and provide benefits to species of fish and greater white-fronted geese, as well as wildlife, in addition to waterfowl, will year-round habitat for mottled ducks also be supported. (Table 1). The emergence of the U.S. Shore- bird Conservation Plan, Partners In Flight physiographic plans, and the Waterbird Conservation Plan, which address conservation of other North American migratory birds, present opportunities to broaden and strengthen joint venture partnerships for wetland conservation. As definitive population data and habitat needs are developed for the migratory birds represented in these emerging strategies, areas of mutual concern in wetland ecosystems can be identified. These wetland areas of overlapping interest in the GCJV will be candidate priority sites for the integrated design and delivery of habitat conservation efforts. Although Gulf of Mexico wetland conservation projects cannot be designed to provide maximum benefits for all concerned species, they can Figure 2. Texas Mid-Coast Initiative area.

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

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

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 Mallard Objectives Breeding Population Goal 11 million To obtain objectives for midwin- Proportion of Midwinter Survey ter duck populations in the GCJV Mallards in Central Flyway Initiative areas, we started with the 30.2% NAWMP continental breeding popu- Central Flyway Spring Flight lation goals, which total 62 million and 3.32 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 Central Flyway Midwinter Goal 3.69 million midwinter survey data proportions, the Proportion of Central Flyway numbers of those 62 million breed- Midwinter Survey Mallards in ing ducks that should return on spring Texas Mid-Coast 1.97% flights from the Mississippi and Cen- Texas Mid-Coast Midwinter tral Flyway wintering areas; we ad- Goal justed those numbers for 10% January- 73 thousand to-May mortality to obtain midwinter Figure 3. An example of how midwinter population objectives were obtained for goals for the Mississippi and Central a specific species, in this case mallards, in the Texas Mid-Coast Initiative area. Flyways. Finally, using 1970’s midwinter survey data proportions from the Mississippi and Central Flyways, we calculated how much of each of the two flyway goals should be derived from each GCJV Initiative area. geese, as well as Canada geese in some Figure 3 provides an example of how GCJV regions, are also experiencing this general process was applied at the winter population increases. Therefore, species level in the Texas Mid-Coast regional goose objectives are ex- Initiative area. Exceptions to this meth- pressed two ways. Recent population odology include derivation of blue- data are used to estimate a quantity of winged teal and redhead objectives and geese “expected” to occur and compete the expected number of mottled ducks to some extent for finite resources, (see Derivation of GCJV Waterfowl whereas actual objectives indicate the Objectives and Migration Patterns sec- desired regional goose population. tion, p. 23). Both are based on indices from mid- Midwinter Goose Population winter (December) surveys. “Expect- Objectives ed” numbers are derived by averaging Midcontinent lesser snow and Ross’ recent December surveys (1995-97), geese, many of which spend win- and actual objectives are derived from ters in the GCJV, are exceeding their the 1982-88 average (Table 1). Canadian breeding habitat capacity to Mig r ation Chronolog y the detriment of their long-term health Midwinter populations do not ad- and the health of a myriad of other equately represent the peak, or even birds that share their arctic/subarctic the typical numbers of some waterfowl breeding habitat. Greater white-fronted species common to the GCJV region.

GCJV 5 Because of the variety of GCJV wa- Combining migration patterns and terfowl and the interspecific variability midwinter duck objectives (see Deri- in their migration patterns, incorporat- vation of GCJV Waterfowl Objectives ing species-specific migration patterns and Migration Patterns section, p. 23) into population objectives is appropri- yields semimonthly population objec- ate. Migrations differ regionally, even tives by species (Fig. 4). Similarly, for the same species, so migration combining goose migration patterns patterns were determined separately with expected numbers of midwinter for each initiative area (see Migration geese yields semimonthly expected Chronology for Waterfowl Species of numbers of geese (Fig. 5). GCJV Initiative Areas section, p. 26).

Figure 4. Semimonthly duck population objectives for the Texas Mid-Coast Initiative area.

6 NAWMP Figure 5. Semimonthly expected numbers of geese for the Texas Mid-Coast Initiative area.

GCJV 7 The Texas Mid-Coast Initiative Area

The Texas Mid-Coast Initiative area salinity gradients. Moving inland from includes 16 Texas counties along the the Gulf of Mexico, salt marsh is fol- coast from Galveston Bay to Corpus lowed by brackish, intermediate, and Christi and inland. The area consists of fresh marsh. In addition to associations large bay and estuary systems that are of plant species, each coastal marsh nearly isolated from the Gulf of Mex- type has characteristic hydrological ico by barrier islands or peninsulas. patterns, soils, and fish and wildlife Extensive coastal prairies are inland resources. from the bays and estuaries. The initia- Types of Coastal Marsh tive area encompasses a total land area Salt Marsh of 13,748 square miles or 8.8 million Salt marshes are prevalent in the acres. See the June 1990 Texas Mid- Texas Mid-Coast. This marsh type is Coast Initiative Plan for descriptions immediately adjacent to the shoreline of the area’s geology, climate, and land of the Gulf of Mexico and associated use. bays. Salt marsh has the greatest tidal Although the Texas Mid-Coast area fluctuation of the four marsh types in consists of a variety of land types and the Texas Mid-Coast and has a well- wildlife habitats, this plan focuses on developed drainage system. Water the three habitat types most important salinity averages 18 parts per thou- to the waterfowl population objectives sand (ppt), and this marsh type sup- of this initiative area: coastal marsh, ports the least diverse vegetation. The agricultural lands that are dominated predominant salt-tolerant plants are by rice and pasture, and seagrasses as- smooth cordgrass, seashore saltgrass, sociated with estuarine subtidal aquatic and needlegrass rush. Salt marsh is bed wetlands. generally considered of only low value Coastal Marsh to waterfowl; however, this marsh type Marshes in the Texas Mid-Coast buffers the more valuable marsh types are less extensive than the great delta farther inland from the impacts of tide marshes of southeast Louisiana and and salinity. the “chenier” marshes of southwest Louisiana and southeast Texas that are associated with standard beach ridges. The marshes here tend to be restricted to estuarine systems as fringes of emergent grasses and other salt-tolerant herbaceous vegetation. There are four distinct coastal marsh types in the Texas Mid-Coast based on plant species composition, which is primarily influenced by species tolerance to water salinity. The four marsh type classifications are salt, brackish, intermediate, and fresh. These marsh Mallard pair. types generally occur in bands par- alleling the coast that correspond to

8 NAWMP Brackish Marsh ppt and slow drainage. Fresh marsh Brackish marsh is transitional supports the greatest plant diversity. between salt and fresh marshes. This Maidencane, spikerush, bulltongue marsh type is also subjected to daily arrowhead, and alligatorweed are the tidal action, and its water depths nor- dominant plants. Many submerged and mally exceed that of salt marsh. Water floating-leafed plants are present in salinity averages 8.2 ppt, and plant this marsh type. Fresh marsh provides diversity is greater than that of salt feeding and resting sites to many spe- marsh. This marsh type is dominated cies of ducks and geese and is con- by saltmeadow cordgrass, seashore sidered to be the most valuable marsh saltgrass, Olney bulrush, and widgeon- type to waterfowl. grass. Brackish marsh is of high value Status and Trends to gadwalls and greater and lesser Growth and deterioration of coastal scaup, and provides year-round habitat wetlands have been naturally occur- for mottled ducks. This marsh type ring in the Gulf of Mexico region for represents the traditional wintering thousands of years. As wetlands were grounds for lesser snow geese. degraded their loss was balanced by Intermediate Marsh natural wetland building processes. Intermediate marsh, which lies in- The most extensive marsh zone within land from brackish marsh, is somewhat the Texas Mid-Coast is located from influenced by tides, and water salin- Galveston Bay to Port Lavaca. Marsh- ity averages 3.3 ppt. Water levels are es from Port Lavaca to Corpus Christi slightly higher than in brackish marsh, occupy mostly narrow margins along and plant species diversity is high. drainages that enter the bays. The bay This marsh type is also dominated by systems are complex and may involve saltmeadow cordgrass, and other com- a large outer (or primary) bay with mon plants include common reed, bull- moderate to sea-strength salinities, a tongue arrowhead, and coastal water- secondary bay with brackish to mod- hyssop. Submerged aquatics such as erate salinities, and inner (or tertiary) pondweeds and southern waternymph bays that may be brackish to fresh are abundant in intermediate marsh. water. This marsh type is used by many spe- Over half of the coastal wetlands for cies of ducks for feeding and resting. the entire conterminous United States This less saline zone of intermediate are in the Gulf of Mexico region. Total marsh provides habitat for mottled coastal wetlands for Texas account for duck broods, and use of this marsh 6% of the national total and 12% of the type by wintering ducks is second only regional total. Coastal Texas wetlands to fresh marsh. show decreasing trends over the past Fresh Marsh 5 decades. Loss of coastal wetlands Fresh marsh in the Texas Mid-Coast in Texas is estimated at 8.9 square lies between the intermediate marsh miles per year (5.696 acres) between and the rice prairies. This marsh type the mid-1950’s and the early 1990’s is normally free of tidal influence and (Moulton et al. 1997). has average water salinity of only 1.0

GCJV 9 Wetland Loss Factors and Threats tree. Reservoir construction has also Preliminary data from selected contributed to marsh loss by chang- coastal areas studied in the 1980’s ing downstream freshwater flows show a reduced rate of wetland loss and increasing saltwater encroach- compared with earlier decades (John- ment. Texas River Authorities manage ston et al. 1995). For Galveston Bay, reservoirs and irrigation in many of both wetland gains and losses have the estuary systems of the Texas Mid- been reported from the 1950’s to 1989; Coast and ultimately influence the rate however, the net trend was one of of freshwater inflows to the bays. wetland loss (White et al. 1993). The Agricultural Land general consensus is that a slow steady Immediately inland from the coastal loss of wetland habitat is occurring marshes are the agricultural lands within the Texas Mid-Coast. Palustrine of the coastal prairie, also a major emergent wetlands (including fresh waterfowl habitat of the Texas Mid- marsh) are the most threatened of all Coast Initiative. The original plant types of Texas coastal wet- community in the coastal prairie was lands. Emergent intertidal mostly tallgrass prairie with some live marsh of the mid- and oak/post oak savanna on the upland upper coasts is among the areas. This prairie landscape was inter- most threatened estuarine spersed with numerous small depres- system habitat in Texas. sional wetlands important to migratory The primary cause of birds. However, the prairie’s high loss of fresh marsh in the average annual rainfall, 270-day grow- extreme upper end of the ing season, and fertile soils resulted in Scaup pair. Texas Mid-Coast (conversion to open extensive areas being converted (e.g., water) appears to be human-induced plowed, leveled, and/or drained) for subsidence and faulting associated agricultural use. Especially valuable to with groundwater withdrawal and oil waterfowl are those agricultural lands and gas extraction. Other causes of devoted to rice production. When they loss of fresh marsh as well as the loss are flooded with a few inches of water of other coastal marsh types include during the fall and winter, harvested drainage and conversion to rangeland rice fields and fallow fields that are and cropland, and destruction of urban- part of traditional rice field rotation are ization, industrialization, saltwater in- excellent sources of waste rice, natural trusion and sea-level rise. Subsidence waterfowl foods, and invertebrates. and sea-level rise are natural processes Lands devoted to rice production have that contribute to marsh deterioration contour levees and other water control and loss but in some cases have prob- structures already in place that can ably been exacerbated by humans. The be managed during the winter with total area of fresh marsh has decreased, minimal cost and effort to make feed- in part, because of its conversion to ing and roosting habitat available to scrub-shrub habitats, resulting from waterfowl. invasion by the exotic Chinese tallow

10 NAWMP Status and Trends tree degrading the coastal prairies, is a The Texas Mid-Coast area averaged significant threat to the land’s value as 371,199 acres of planted rice during waterfowl habitat. the period 1972-79 (Fig. 6). The com- Seagrass Beds bination of a world rice surplus and Seagrass beds (meadows) provide poor economic conditions in the early food for wintering waterfowl and 1980’s dealt the Texas rice industry a important nursery sites and foraging severe blow. The area’s rice acreage habitat for several species of commer- dropped considerably (almost 22%) cially important finfish and shellfish. during 1980-89—planted rice acreage These beds exist in isolated patches averaged 290,310 acres. The decline in and narrow bands within the Texas Texas rice acreage of the 1980’s con- Mid-Coast, primarily in the subtidal tinued in the 1990’s. Planted rice acre- zone with some extending into the age for the Texas Mid-Coast in 1990- intertidal zone. In a study of the upper 98 averaged 234,667 acres. Recent Texas coast, Adair (1994) found sea- changes in federal agriculture policy grass meadows predominantly along are expected to hasten a decline in rice south shorelines and occasionally acreage. In many situations, agricul- along north shorelines. Salinity, water tural land is abandoned. The potential depth, water clarity, and substrate are for moist-soil management (managing the dominant mechanisms affecting wetland units with seasonal flooding seagrass distribution. to stimulate growth and establishment Five species of seagrasses are com- of annual seed-bearing waterfowl food mon within the Texas Mid-Coast: plants) on these lands is high. How- Mottled duck pair. shoalgrass, turtlegrass, manateegrass, ever, the ready invasion of abandoned clover or star grass, and widgeongrass. cropland by Chinese tallow trees, a fast-growing and expanding exotic

Figure 6. Planted rice acreage for the Texas Mid-Coast Initiative area (U.S. Department of Agriculture, 1999).

GCJV 11 Large numbers of redheads and North- suggest an additional 25,878 acres in ern pintails and lesser numbers of gad- the eight bays between Port O’Connor walls and American wigeons wintering and Corpus Christi, with 73% of this along the Texas Gulf Coast feed in total occurring in Espiritu Santo, seagrass beds. Redheads feed almost Copano, and Redfish Bays (Adair, exclusively on shoalgrass rhizomes unpublished data). This represented an while wintering along the Gulf Coast, overall increase from the 19,491 acres and widgeongrass serves as forage for documented in 1969-71, but the ear- a variety of duck species. lier study excluded many of the back Seagrass Status and Threats bay areas of this region. For the bays Spatial coverage of seagrasses in that were directly comparable, slight the Gulf of Mexico is estimated at increases were found in Espiritu Santo 12-24% of the estuarine area (NOAA and Aransas Bays, and slight decreases 1997). Handley (1995) reported large were found in San Antonio, Copano, losses of seagrasses (from 20% to and Corpus Christi Bays. 100%) over the last 50 years from Hurricanes, cold-front storms, and most estuaries in the northern Gulf of increased or decreased salinities are Mexico. Most of the loss is attributed natural causes of seagrass loss and to coastal population growth and ac- cannot be controlled. The loss of companying municipal, industrial, and seagrasses is also attributable to hu- agricultural development. The areal man-induced effects associated with extent of seagrasses in the Galveston residential and industrial develop- Bay estuary decreased from more than ment pressures. Seagrass meadows 5,000 acres in the mid-1950’s to ap- are susceptible to the adverse effects proximately 700 acres in 1989 (White of filling in two ways: (1) from direct et al. 1993). In the estuary’s West impacts of filling and (2) from indi- Bay nearly 2,200 acres of seagrasses rect impacts of filling, which include have been completely lost, primarily the production of suspended material through human activities, including in the water column (i.e., turbidity). Lesser snow geese. development, wastewater discharge, Excess nutrients from sewage treat- chemical spills, and increased turbidity ment discharges, septic systems, and from dredging and boat traffic (Pulich drainage from agricultural fields (i.e., and White 1991). In 1987, coverage water quality) can stimulate growth of of seagrass beds in the Matagorda phytoplankton in the waters over the and western portions of the Galves- grass meadows. Seagrass beds are also ton Bay complexes were estimated at often damaged by boat anchors and 2,715 acres and 2,994 acres, respec- propellers of shallow draft recreational tively (Adair 1994). This represented boats. “Prop scars” may contribute to a slight increase since 1971-72 for additional degradation of seagrass beds the Matagorda Bay complex and a by accelerating erosion near the broken 44% decrease for the Galveston Bay root mats. complex. Unpublished data from 1988

12 NAWMP The Texas Mid-Coast Initiative Implementation Plan

Habitat conservation is imperative Conservation Strategies for meeting the waterfowl population Four broad strategies of wetland objectives of both the NAWMP and the conservation are important for achiev- GCJV. The critical habitat conservation ing the goals and objectives of the needs on public and private lands of GCJV. These strategies are mainte- the GCJV are to stop and reverse the nance (i.e., loss prevention), resto- deterioration and loss of wetlands, ration, enhancement, and creation of especially coastal marshes, and to wetland habitat. Though not a strategy, improve the waterfowl value of agri- routine management activities are im- cultural lands. Loss of coastal marsh portant and inherent components of the can be addressed by actions that either restoration and maintenance strategies. reduce the rate of loss or that build Conservation actions under each of land. In the Texas Mid-Coast, actions these strategies take several forms. The addressing the loss of coastal marsh types of wetland conservation actions must be based largely on prevention identified in each initiative area reflect of predictable loss and restoration of the differences previously discussed degraded areas. The private agricul- that characterize each area. A descrip- tural lands of the Texas Mid-Coast are tion of the strategies applicable to the working landscapes, used to produce Texas Mid-Coast are presented below. economic returns; therefore, the impact Maintenance of Habitat of GCJV actions must be beneficial or Maintenance involves preserving neutral with respect to agricultural land existing functions and values of the uses. habitat. The intent is to prevent ad- The availability of food resources is ditional loss and degradation of wet- the most likely effect of winter habitat lands, particularly in remaining coastal Hydrologic structure. on survival and recruitment of water- marshes that are most vulnerable to fowl populations. Availability of food erosion, or conversion to more saline can be affected by production of foods types through saltwater intrusion. Ex- (submerged aquatics, annual seeds, or amples of conservation actions under invertebrates), flooding at appropri- this strategy include the following: ate times and depths for foraging, and (1) replacing structures and main- access to food influenced by floating taining levees critical to pro- exotics, human disturbance, access to tecting the hydrologic integrity of dietary fresh water, or other factors. vulnerable marshes; Breakwater structures. In addition to fall and winter food (2) placing nearshore breakwater resources, mottled duck populations structures to reduce or reverse are also influenced by breeding and wave erosion on beachfronts into postbreeding habitat in the Texas Mid- adjacent marsh; Coast. Availability of fresh or inter- (3) constructing earthen terraces or mediate shallow water in brood-rear- vegetative barriers (e.g., Cali- ing and molting areas is critical during fornia bulrush) within opened, the spring and summer. Therefore, the degraded marshes to reduce fetch habitat conservation actions outlined which would eventually erode Earthen terraces. are intended to influence one or more of these habitat parameters.

GCJV 13 the perimeter and result in larger Restoration of Habitat open water areas; Restoration involves conservation (4) planting erosion control vege- actions necessary to re-establish a tation at key points protecting the naturally occurring but degraded wet- hydrologic integrity of vulnerable land ecosystem. The goal is to restore marshes; or mimic the original wetland func- (5) plugging of abandoned oil drill- tions and values of the site. Examples Erosion control vegetation. ing location canals to prevent of conservation actions under this further widening of the canal into strategy include the following: emergent marsh; (1) restoring historic salinities and (6) implementing managed fire to hydrology to degraded systems maintain vegetative communities through hydrologic structures and susceptible to invasion by woody levees; exotics (carefully implemented (2) restoring water quality and subse- prescribed burns also increase quent SAV productivity by reduc- the availability of belowground ing fetch and turbidity; foods for geese in their historic (3) restoring areas suffering Chinese marsh range, potentially reducing tallow infestations to a native competition with ducks for food prairie environment that is attrac- tive to nesting mottled ducks; Oil-drilling access canal plug. in other habitats); (7) conducting floating or submersed (4) constructing earthen terraces or exotic vegetation control to main- vegetative barriers (e.g., Cali- tain natural plant communities; fornia bulrush) within opened, (8) providing technical guidance to degraded marshes to aid in restor- achieve the above maintenance ing emergent vegetation; measures; (5) backfilling oil drilling location (9) promoting public policy, edu- canals to return emergent wetland cation, and placement of signs to where it once existed naturally; and channel markers around and (6) implementing managed fire to within seagrass beds to avoid restore vegetative communities mechanical damage from recre- altered by woody exotics; ational boat activity; (7) conducting floating or submersed (10) promoting public policy, edu- exotic vegetation control to re- Marsh burning. cation, and technical assistance store natural plant communities; that encourages maintenance of (8) beneficially using dredge spoil existing depressional wetlands in from navigation projects to agricultural settings; and restore emergent wetlands and (11) acquiring vulnerable tracts associated mudflats; through fee title acquisition, con- (9) planting seagrass (various tech- servation easement, or manage- niques should be tried/developed) ment agreement for the purpose where it once existed naturally; of implementing the above main- (10) providing technical guidance to tenance measures. achieve the above restorative measures; and

14 NAWMP (11) acquiring degraded tracts through (5) acquiring tracts through fee title fee title acquisition, conservation acquisition, conservation ease- easement, or management agreement, or management agreement ment for the purpose of imple- for the purpose of implementing menting the above restorative the above enhancements; and Flooded agriculture field. measures. (6) providing reliable water, which Enhancement of Agricultural may also be used for livestock Habitat watering, to freshwater basins Enhancement of agricultural areas adjacent to seagrass beds that are such as croplands, pasture, and fal- underutilized by waterfowl. low fields is an attempt to restore the Creation of Habitat historic wetland functions of that broad Creation of habitat is the con- region, which was formerly dotted struction of wetlands where none with small seasonal and semiper- previously existed in recent geological manent wetlands. But the agricultural terms. Conservation actions develop prairie is so highly altered that it is not the hydrological, geochemical, and necessary and often very difficult to biological components necessary to ascertain the historic condition of each support and maintain a wetland. Ex- specific site. Consequently, actions amples of conservation actions under under this strategy may actually be this strategy include the following: restoration of a former depressional (1) beneficially using dredge spoil wetland or creation of new wetland from navigation projects to create habitat. Enhancement actions under emergent wetlands and associated this strategy provide capabilities, man- mudflats. agement options, structures, or other Habitat Objectives actions to influence one or several The three major waterfowl habi- functions or values of the site: tats available in the Texas Mid-Coast (1) providing structures and/or water Beneficial use of dredge Initiative area are coastal marshes, material. delivery sufficient to flood agri- agricultural lands lying north of the cultural wetlands for early mi- marsh zone, and seagrass beds. Habitat grating ducks, wintering water- objectives are based on the assump- fowl, or summer brood habitat; tion that food availability is the most (2) providing structures and/or water likely limiting factor for wintering delivery sufficient to flood fallow ducks in the GCJV. Food availability is fields or moist-soil wetlands for potentially influenced early migrating ducks, winter- by factors that affect ing waterfowl, or summer brood food production (e.g., habitat; marsh health, farming (3) altering vegetation and substrate practices, etc.) and ac- with mechanical implements or cess (e.g., disturbance, American wigeon pair. livestock grazing to maximize water at appropriate food availability to waterfowl; depths, proximity to di- (4) providing technical guidance to etary fresh water, etc.). achieve the above enhancements;

GCJV 15 Coastal Marsh if only 21% of the habitat is rendered Food density data are not available unavailable by excessive recreational for coastal marsh habitats of the GCJV, boating disturbance, and an additional precluding quantitative modeling of 21% is not close enough to a dietary habitat needs. However, given the freshwater source to make feeding importance of this habitat to water- energetically advantageous, then the fowl, the enormous loss and continued predicted carrying capacity would dip threats to this habitat, and the limited below the population objective. Com- opportunities for restoration and cre- bined, these factors suggest the po- ation, the GCJV supports all projects tential for current habitat conditions to that seek to restore lost or degraded limit redhead populations during some marshes to sustainable historic or more years and suggest the need to protect natural conditions. Additionally, the the existing habitat base. GCJV supports all protective measures Agricultural Habitats that maintain current habitat values Estimates of the density of desirable that would otherwise be predictably plant seeds for waterfowl in agricul- lost. tural habitats are available, and from Seagrass Beds this data, we can model the waterfowl Some food density data are available habitat requirements for that particular for seagrass beds, and researchers have habitat. Based on food habits research used existing information to model the and general knowledge of habitat use carrying capacity of Texas (Michot by various species, we estimated the 2000) and Louisiana (Michot 1997) proportion of each species’ energetic shoalgrass beds for redheads. Texas needs that we should provide for in Mid-Coast seagrass beds have been these agricultural habitats to be 75% estimated to encompass 28,872 acres, for most dabbling ducks (e.g., mallard, 22,746 acres of which is shoalgrass Northern pintail, green-winged teal, (Adair 1994 and unpublished data). blue-winged teal, Northern shoveler, Using these estimates in a published and mottled duck), 10% for dabblers model for redhead carrying capac- that specialize on submerged aquatic ity Michot (1997) suggests that the vegetation (e.g., gadwall and Ameri- Texas Mid-Coast can annually support can wigeon), and 30% for most diving 157,492 redheads through a given win- ducks (e.g., ring-necked ducks and ter. Though this compares favorably greater and lesser scaup). We assume with the region’s redhead population canvasbacks and redheads obtain no objective of 92,444 based on 1970’s food items from this habitat. We esti- averages, it is less than observed num- mated 90% of Texas Mid-Coast geese bers in 2 of the 18 years from 1970 occur in these habitats, using food to 1988. The model also assumes that sources from flooded and unflooded all portions of seagrass meadows are fields without preference. These equally and totally accessible for red- estimates result in population objec- head foraging, ignoring potential (but tives for Texas Mid-Coast agricultural untested) effects of disturbance or lack habitats (Figs. 7 and 8). of adjacent dietary fresh water in limiting redhead accessibility. For instance,

16 NAWMP Figure 7. Semimonthly duck population objectives for the agricultural portion of the Texas Mid-Coast Initiative area.

800 Canada goose Greater white-fronted goose Lesser snow goose 600

(thousands) 400

Geese 200

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 8. Semimonthly expected numbers of geese for the agricultural portion of the Texas Mid-Coast Initiative area.

GCJV 17 We modeled the habitat require- idle fields in rice rotations have been ments for Texas Mid-Coast agricultural estimated at 149 kg per acre (Davis habitats based on the dietary energy et al. 1960). Rice specialists estimate supply necessary to sustain them. the yield of second-crop rice, which is Researchers estimate energetic require- occasionally left unharvested, is 30% ments of mallards to be 290 kcal per of normal yields, or 600 kg per acre. day (Petrie 1994), with other species A minimum seed density threshold having energetic needs in propor- has been estimated at 20 kg per acre, tion to their body weight (Kendeigh below which we assume waterfowl 1970). We therefore used average body foraging becomes too energetically weights of each species in conjunction costly to benefit them (Reinecke et al. with semimonthly population objec- 1989). Flooded waste rice and moist- tives and expected numbers of geese in soil seeds decompose at a rate of flooded habitats to arrive at an energy approximately 5% per month (Neely demand curve, in terms of mallard-use- 1956). True metabolizable energy days, through the wintering waterfowl for rice and seeds of moist-soil plants period (Fig. 9). have been estimated at 2.81 and 3.0 Seed density estimates for rice fields kcal per g, respectively (Petrie 1994). harvested in southwest Louisiana are These estimates result in the prespoil- 64.6 kg per acre of rice and 14.3 kg age foraging values for the three major per acre of other waterfowl food seeds habitat types of the Texas Mid-Coast (Harmon et al. 1960). In southwest agricultural lands seen in Table 2. Louisiana, moist-soil seed densities of The acreage estimate of Texas Mid-Coast planted rice for 1997 was 194,200. A first crop is usually harvested in late July and early August, 35 with some harvests occurring slightly later where no second crop is intended. 30

(millions) 20 Table 2. Prespoilage foraging values (mallard-use-days/acre) of the major habitat types of Texas Mid-Coast agricultural lands. 15

use-days Harvested rice 576 10 Moist-soil 1,332

Mallard Unharvested second crop rice 5,618

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 9. Energetic demands of all waterfowl objectives (mallard-use-days) in flooded habitats of the agricultural portion of the Texas Mid-Coast Initiative area.

18 NAWMP Some rice fields are cultivated for a period of greatest habitat need (Fig. second harvest, which usually occurs 9) and is sometimes accompanied by late October through early November. some coastal marsh habitats becoming Using these assumptions of ener- too deep for optimal dabbling duck getic demand, seed availability, caloric foraging. Rice fields cultivated for a value of seed, and farming practices, second crop (both harvested and not) we modeled habitat needs in the agri- and moist-soil and/or idle fields are cultural belt of the Texas Mid-Coast the targeted habitats modeled for late based on two target flooding periods. flooding. The early flooding period (late August The relative availability, and thus through October) would serve the the management potential, for each habitat needs of early migrants (Figs. habitat type was assessed based on the 7 and 8) and some shorebird species. following assumptions. Texas Mid- This period is typically characterized Coast rice is usually grown on 2- or by relatively dry conditions, with less 3-year rotations, with approximately incentive for landowners to provide 50% cultivated for a second crop. Rice managed habitat for duck hunting specialists estimate 80% of the rotation season. Also, due to decomposition of fields out of current rice production flooded seeds and sprouting and dep- are left idle, with potential for moist- redation of unflooded seeds, rice fields soil management. These assumptions, not cultivated for a second harvest combined with recent rice acreages, have their highest potential as duck yield rough acreage estimates for habitat during this period. Therefore, moist-soil (233,040), once-harvested single-cut rice and moist-soil and/or idle fields are the targeted habitats modeled for early flooding. The late flooding period (November through March) is typically characterized by more available water on the agricultural landscape, due to both rainfall and the incentive to flood provided by hunting seasons. How- ever, this period coincides with the

GCJV 19 rice (97,100), and second-cropped rice the driest of years. Until we are able to (97,100) in the Texas Mid-Coast. Ad- estimate the amount of flooded habitat ditionally, we estimate 5% of second that has occurred in the recent past crops are left unharvested for various during dry years, we suggest that 50% reasons. We used these potential habi- of this need represents flooding objec- tat proportions as ratios in our ener- tives for new agricultural enhancement getics model to determine acreages of (Table 3b). flooded agricultural habitats necessary Specific Activities to sustain our waterfowl population The wetland habitat objectives of objectives (Table 3a). the GCJV will be addressed through We emphasize that the acreages in various projects that focus on coastal Table 3a include both intentional man- marsh and agricultural lands. A pack- aged flooding for waterfowl as well age of actions designed to meet some as flooding that otherwise occurs as a of the Texas Mid-Coast Initiative/ result of precipitation, crawfish cul- GCJV objectives as well as contribute ture, or farming practices. Because our to the fulfillment of the NAWMP goals objective is to consistently provide wa- will be developed. The wetland habitat terfowl foraging habitat, these should objectives of the GCJV will be ad- be viewed as minimum amounts of dressed through various projects that managed and unmanaged habitat focus on coastal marsh and agricultural (combined) that should be available in lands. Coastal marsh projects will involve protecting critical shorelines and banks, improving or restoring more natural hydrological conditions (to stabilize water and salinity levels, and Table 3a. Total agricultural flooding acreage need for the Texas Mid-Coast Initiative area.

Early1 Late2 Harvested rice 9,839 - Harvested second rice - 59,750 Unharvested second rice - 3,145 Moist-soil 23,614 135,653 Table 3b. Flooding objectives for new agricultural enhancement acreage within the Texas Mid-Coast Initiative area.

Early1 Late2 Harvested rice 4,920 - Harvested second rice - 29,875 Unharvested second rice - 1,573 Moist-soil 11,807 67,827 1 Late August through October flooding to target early migrant waterfowl and some shorebirds 2 November through March flooding for wintering waterfowl.

American wigeon pair.

20 NAWMP reduce tidal scour), trapping sediments Other Programs (to accelerate natural wetland build- We recognize and support other ing), and creating marsh with dredged conservation efforts that contribute material. Many of these projects will to the goals of this plan. Coastal be designed to address localized prob- marsh projects implemented under the lems while others will be designed to Coastal Wetlands Planning, Protec- provide benefits to coastal wetlands far tion and Restoration Act contribute beyond the construction footprint. The significantly to the maintenance and focus of these projects will be reducing restoration objectives of this plan interior wetland loss, rebuilding wet- through the National Coastal Wetlands lands in open water areas, and main- Conservation Grant Program in Texas. taining the geologic framework of the Similarly, shallow flooding provisions coast by addressing shoreline and bank of some Natural Resources Conserva- erosion. Projects on agricultural lands tion Service programs contribute to will be designed to provide landowners agricultural enhancement objectives, with financial and technical assistance as does voluntary field flooding by rice to hold winter water on harvested farmers. crop lands, set aside lands, and natural Communication and wetlands and will be compatible with Education sustainable agriculture. Additionally, Public awareness of the importance partners will initiate the activities of the Gulf Coast to waterfowl and described in this document as other other renewable resources is key to the opportunities become available. An success of the GCJV. Communication evolving package of actions designed efforts will be developed to educate to meet some of the Texas Mid-Coast decision makers, resource managers, Initiative/GCJV objectives as well landowners, conservation organiz- as contribute to the fulfillment of the ations, and the general public about NAWMP goals has been developed wetlands conservation in the Texas and will be continually updated. Mid-Coast Initiative area.

GCJV 21 Relationship to Evaluation Plan

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

Northern shovelers and blue-winged teal.

22 NAWMP Derivation of GCJV Waterfowl Objectives and Migration Patterns

Midwinter Duck Population flyway goal and obtained a midwinter Objectives population objective of about 516,000 Although the coordinated midwin- for mallards in the Louisiana Chenier ter survey is an inaccurate count of Plain. This method yields midwinter total wintering birds, and not cor- objectives for most species of ducks rected for visibility bias, it provides that commonly occur in the GCJV area a reasonable approximation of the (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 aver- population objectives for each species age winter population estimates from to arrive at the number of birds each the Special Redhead Cruise Survey for initiative area should supply to the the same time period (1970-79). Us- breeding population. We assume 10% ing direct estimates from aerial winter mortality between midwinter (January) and breeding (May) periods to arrive at midwinter objectives (Table 1). Using mallards as an example, during 1970-79, 42.9% of all continental mallards counted during the midwinter survey were in the Mississippi Flyway (see also Fig. 3). The NAWMP continental breeding population 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 Flyway. Because 9.8% of all Mississippi Flyway mallards were counted in the Louisiana Chenier Plain, we applied the percentage to the Male ring-necked duck.

GCJV 23 surveys is appropriate for determining Migration Patterns objectives for redheads but not other Louisiana migration patterns for ducks, because (1) wintering redheads ducks were determined by using pe- occur almost exclusively in known riodic coastwide aerial surveys along locations of offshore seagrass habi- established transects that generally tat with good visibility, (2) visibility were flown one to two times per month bias has been estimated and found September through March, 1970-98 negligible for portions of this special (Louisiana Department of Wildlife survey, and (3) redhead habitats are not and Fisheries coastal transect survey, consistently surveyed during the mid- unpublished data). Chandeleur Sound, winter survey, precluding the method- the primary redhead area in Louisiana, ology applied for most species. is not covered by these coastal tran- To estimate the number of mottled sects, so for Louisiana redheads we ducks expected to occur during win- instead used 1987-92 periodic redhead ter, we used mark-recapture analyses surveys from that region (Thomas of direct recoveries from bandings in C. Michot, U.S. Geological Survey, Louisiana and Texas during 1994-97. unpublished data). Each survey was Preseason population estimates were assigned to a half-month period. For derived from the assumption that the each species, each survey of a given ratio of the total population to the total year was expressed as a proportion of harvest (U.S. Fish and Wildlife Service that year’s peak. These proportions estimate) equals the ratio of the banded were averaged across all years to yield population to the banded harvest the average proportion of the annual (direct recoveries/band reporting rate peak for each half-month period. All estimate; band reporting rates are as- proportions were then expressed rela- sumed to be 33% for 1994-95 and 59% tive to the midwinter (January) propor- for 1996-97). Preseason population tion (see Migration Chronology for estimates were then averaged, and an Waterfowl Species of GCJV Initiative estimated fall/winter mortality rate of Areas section, p. 26). 30% was assumed to be evenly distrib- uted September through March. The resulting midwinter estimate was then apportioned to initiative areas by the midwinter survey (Table 1).

24 NAWMP For Texas, aerial surveys of fed- March values. Because Texas surveys eral refuges and select other proper- were never conducted in late August, ties provide the basis for determining we assumed late August blue-winged migration patterns (U.S. Fish and teal values were 15% of early Sep- Wildlife Service’s Coastal Waterfowl tember values. Because geese are not Survey Data, unpublished data). These periodically surveyed in Louisiana, we monthly Texas surveys were conducted applied migrational information from September through March of 1984-97, the Texas Chenier Plain to all eastward and data from all sites that were con- initiative areas. For the Coastal Missis- sistently surveyed within a given year sippi Wetlands and Mobile Bay Initia- were used. Analyses were conducted as tive Areas, we applied duck migra- above, except each survey represented tional information from the Mississippi an entire month (see Migration Chro- River Coastal Wetlands Initiative area nology for Waterfowl Species of GCJV (southeast Louisiana). Initiative Areas section, p. 26). Multiplying these semimonthly proportions by the midwinter population objectives yields semimonthly population objectives by species and initiative area (Figs. 4 and 5). Because Louisiana surveys were never conducted in late March, we assumed late March values for all species were 50% of early

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

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, (Tommy Redhead Surveys of Chandeleur Sound, LA USGS-NWRC, 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 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

Adair, S.E. 1994. Distribution and status Michot, T.C. 2000. Comparison of win- of submerged vegetation in estuaries of tering redhead populations in four Gulf of the upper Texas coast. Wetlands 14(2): Mexico seagrass beds. Pages 243-260 in 110-121. F.A. Comin, J.A. Herrera, and J. Ramirez, Davis, J.P., C.H. Thomas, and L.L. Glasgow. editors. Limnology and Aquatic Birds: 1960. Foods available to waterfowl in Monitoring, Modelling, and Manage- fallow rice fields of southwest Louisiana, ment. Universidad Autónoma de Yucatán 1960-1961. Proceedings of the Annual Mérida (Mexico). Conference of the Southeastern Asso- Moulton, D.W., T.E. Dahl, and D.M. Dall. ciation of Game and Fish Commissioners 1997. Texas coastal wetlands; Status 15:60-66. and trends, mid-1950s to early 1990s. Handley, L.R. 1995. Seagrass distribution U.S. Department of the Interior, Fish and in the northern Gulf of Mexico. Pages Wildlife Service, Albuquerque, NM. 32 273-275 in E.T. LaRoe, G.S. Farris, C.E. pp. Puckett, P.D. Doran, and M.J. Mac, edi- National Oceanic and Atmospheric Adminis- tors. Our living resources: a report to the tration. 1997. NOAA’s estuarine eutrophi- nation on the distribution, abundance, and cation survey, volume 4: Gulf of Mexico health of U.S. plants, animals, and eco- region. U.S. Department of Commerce, systems. U.S. Department of the Interior, National Oceanic and Atmospheric Ad- National Biological Service, Washington, ministration, Office of Ocean Resources DC. Conservation and Assessment (ORCA). Harmon, B.G., C.H. Thomas, and L. 77 pp. Glasgow. 1960. Waterfowl foods in Neely, W.W. 1956. How long do duck foods Louisiana rice fields. Transactions of the last underwater? Transactions of the North American Wildlife and Natural North American Wildlife and Natural Resources Conference 25:153-161. Resources Conference 21:191-198. Johnston, J.B., M.C. Watzin, J.A. Barras, Petrie, M.J. 1994. True metabolizable energy and L.R. Handley. 1995. Gulf of Mexico of waterfowl foods. M.S. thesis, Univer- coastal wetlands: case studies of loss sity of Missouri, Columbia. 138 pp. trends. Pages 269-272 in E.T. LaRoe, Pulich, W.M., Jr., and W.A. White. 1991. G.S. Farris, C.E. Puckett, P.D. Doran, and Decline of submerged vegetation in the M.J. Mac, editors. Our living resources: Galveston Bay system: chronology and a report to the nation on the distribution, relationship to physical processes. Journal abundance, and health of U.S. plants, of Coastal Restoration 4:1125-1138. animals, and ecosystems. U.S. Depart- Reinecke, K.J., R.M. Kaminski, D.J. ment of the Interior, National Biological Moorhead, J.D. Hodges, and J.R. Nassar. Service, Washington, DC. 1989. Mississippi Alluvial Valley. Pages Kendeigh, S.C. 1970. Energy requirements 203-247 in L.M. Smith, R.L. Pederson, for existence in relation to size of bird. and R.M. Kaminski, editors. Habitat Condor 72:60-65. management for migrating and wintering Michot, T.C. 1997. Carrying capacity of waterfowl in North America. Texas Tech seagrass beds predicted for redheads win- University Press, Lubbock. 560 pp. tering in Chandeleur Sound, Louisiana, U.S. Department of Agriculture. 1999. Na- USA. Pages 93-102 in J.D. Goss-Custard, tional Agriculture Statistics Service. (http: R. Rufino, and A. Luis, editors. Effect of //www.usda.gov/nass) habitat loss and change on waterbirds. White, W.A., T.A. Tremblay, E.G. Wermund, Proceedings of the 10th International Jr., and L.R. Handley. 1993. Trends and Waterfowl Ecology Symposium, Univer- status of wetland and aquatic habitats in sity of Aveiro, Portugal, 18-21 September the Galveston Bay system, Texas. The 1995. Institute of Terrestrial Ecology Galveston Bay National Estuary Program, Symposium No. 30, Wetlands Interna- publication GBNEP-31. 225 pp. tional Pub. No. 42.

28 NAWMP Appendix Acknowledgments This planning document benefited from the input of numerous individuals. Scientific Names of Plants and Animals Mentioned in This Plan The Waterfowl Working Group of the Gulf Coast Joint Venture’s Monitoring, Evaluation, and Research Team—A.D. I. Plants alphabetical by common name. Afton, W.P. Johnson, M.T. Merendino, T.C. Michot, T.E. Moor- Common Name Scientific Name man, and M.J. Petrie—provided initial direction, review of the Alligatorweed Alternanthera philoxeroides biological foundation, and identification of critical underlying Baccharis Baccharis sp. Bulltongue arrowhead Sagittaria lancifolia assumptions for the plan. California bulrush Schoenoplectus californicus Texas Mid-Coast Initiative Chairperson R. Bisbee was instru- Chinese tallow Sapium sebiferum mental in organizing team members for discussing this plan Coastal waterhyssop Bacopa monnieri and/or reviewing drafts. Initiative team members participated Common reed Phragmites australis Live oak Quercus virginiana in discussions and reviewed drafts. Maidencane Panicum hemitomon The Gulf Coast Joint Venture Management Board provided Manateegrass Syringodium filiforme input during plan development and commented on completed Needlegrass rush Juncus roemerianus drafts, as well as provided the impetus and encouragement to Olney bulrush Schoenoplectus americanus initiate and complete this effort. Pondweed Potamogeton sp. Post oak Quercus stellata K.E. Gamble, D.A. Haukos, T.C. Michot, J.E. Neaville, and Rice Oryza sp. B.D. Sullivan gathered and provided unpublished waterfowl Saltmeadow cordgrass Spartina patens survey data for use in this document. Seashore saltgrass or inland saltgrass Distichlis spicata Regional agriculture specialist J.W. Stansel provided neces- Shoalgrass Halodule wrightii sary information about common farming practices in the Texas Smooth cordgrass Spartina alterniflora Mid-Coast. Southern waternymph Najas guadalupensis Spikerush Eleocharis sp. The publishing staff at the U.S. Geological Survey’s National Star grass Halophila englemannii Wetlands Research Center provided significant advice to im- Turtlegrass Thalassia testudinum prove the readability and attractiveness of this document. C.A. Widgeongrass Ruppia maritima Manlove and J. Holden provided early drafts of Figs. 1 and 2. II. Waterfowl alphabetical by common name. Common Name Scientific Name Financial or substantial in-kind support for the preparation and publication of this plan was provided by Ducks Unlimited, American black duck Anas rubripes American wigeon Anas americana Inc.; the Division of Bird Habitat Conservation and Region Black-bellied whistling duck Dendrocygna autumnalis 2 of the U.S. Fish and Wildlife Service; the Texas Parks and Blue-winged teal Anas discors Wildlife Department; the Gulf Coast Joint Venture Manage- Canada goose Branta canadensis ment Board; the U.S. Geological Survey’s National Wetlands Canvasback Aythya valisineria Research Center; and the Gulf Coast Joint Venture Manage- Cinnamon teal Anas cyanoptera ment Board. Fulvous whistling duck Dendrocygna bicolor Gadwall Anas strepera Greater scaup Aythya marila Greater white-fronted goose Anser albifrons Green-winged teal Anas crecca For More Information Lesser scaup Aythya affinis North American Waterfowl Management Plan. 1986. U.S. Lesser snow goose Chen caerulescens Department of the Interior and Environment Canada. 19 Mallard Anas platyrhynchos pp. Mottled duck Anas fulvigula Texas Mid-Coast Initiative Gulf Coast Joint Venture North Northern pintail Anas acuta Northern shoveler Anas clypeata American Waterfowl Management Plan. 1990. Texas Redhead Aythya americana Mid-Coast Initiative Team. 57 pp. Ring-necked duck Aythya collaris 1994 Update to the North American Waterfowl Management Ross’ goose Chen rossii Plan: Expanding the Commitment. 1994. U.S. Depart- Wood duck Aix sponsa ment of the Interior, Environment Canada, and Secretaria III. Other animals alphabetical by common name. de Desarrollo Social Mexico. 30 pp. + appendixes. Common Name Scientific Name Expanding the Vision 1998 Update North American Wa- American alligator Alligator mississippiensis terfowl Management Plan. 1998. U.S. Department of the Muskrat Ondatra zibethicus Interior, Environment Canada, and Secretaria de Medio Nutria Myocastor coypus Ambiente, Recursos Naturales y Pesca. 32 pp.