Gulf Coast Joint Venture: Laguna Madre 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: , U.S. Geological Survey. Page iii: (top) pintails, C. Jeske, U.S. Geological Survey; (bottom), , G.D. Chambers, Ducks Unlimited, Inc. Page iv: U.S. Geological Survey. Page 8: American wigeon, G. Chambers, Ducks Unlimited, Inc. Page 10: scaup, B. Hinz, U.S. and Wildlife Service. Page 11: mottled duck pair, R. Paille, U.S. Fish and Wildlife Service. Page 12: lesser snow geese, T. Hess, Department of Wildlife and Fisheries. Page 14: flooded agriculture field, U.S. Geological Survey. Page 15: beneficial use of dredge material, T. Hess, Louisiana Department of Wildlife and Fisheries. Page 18: 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: pair, S. Nielsen, Ducks Unlimited, Inc. Page 25: blue-winged teal males, W.L. Hohman, U.S. Geological Survey. Gulf Coast Joint Venture: Laguna Madre 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 () Initiative, the Texas Mid-Coast Initiative, the River Coastal Initiative (southeast Louisiana), the Coastal Mississippi Wetlands Initiative, and the Mobile Bay Initiative.

Suggested citation: Esslinger, C.G., and B.C. Wilson. 2002. North American Waterfowl Manage- ment Plan, Gulf Coast Joint Venture: Laguna Madre 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 Laguna Madre Initiative Area...... 8 Seagrass Beds...... 9 Seagrass Status and Threats ...... 9 Seasonal Freshwater Wetlands...... 11 Status and Trends ...... 11 The Laguna Madre Initiative Implementation Plan...... 13 Conservation Strategies ...... 13 Maintenance of ...... 13 Restoration of Habitat...... 14 Enhancement of Agricultural Habitat ...... 14 Creation of Habitat...... 14 Habitat Objectives...... 15 Seagrass Beds...... 15 Seasonal Wetlands...... 15 Specific Activities ...... 20 Other Programs ...... 20 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 Mentioned in This Plan...... inside back cover For More Information ...... inside back cover Acknowledgments...... inside back cover

GCJV iii Figures Number Page 1 Location of the Gulf Coast Joint Venture region ...... 1 2 Location of the Laguna Madre Initiative area...... 3 3 An example of how midwinter population objectives were obtained in the Laguna Madre Initiative area ...... 5 4 Semimonthly duck population objectives for the Laguna Madre Initiative area...... 6 5 Semimonthly expected numbers of geese for the Laguna Madre Initiative area...... 7 6 Semimonthly duck population objectives for the agricultural/rangeland portion of the Laguna Madre Initiative area...... 16 7 Semimonthly expected numbers of geese for the agricultural/rangeland portion of the Laguna Madre Initiative area...... 17 8 Energetic demands of all waterfowl objectives (-use-days) in inland seasonal wetlands of the agricultural/rangeland portion of the Laguna Madre Initiative area ...... 17 Tables Number Page 1 Midwinter population objectives for initiative areas of the Gulf Coast Joint Venture...... 4 2 Flooding objectives (in acres) for new agricultural/rangeland enhancement within the Laguna Madre Initiative area...... 18 3 Recommended characteristics of restored or created freshwater wetlands adjacent to the Laguna Madre of Texas for optimum wildlife benefits...... 19

iv NAWMP Introduction

North American Waterfowl migratory and their in a Management Plan particular physiographic region such Faced with continuing de- as the Gulf Coast. These partners come struction and rapidly declining water- together under the NAWMP to pool fowl populations, the Canadian and resources and accomplish collectively U.S. governments signed the North what is often difficult or impossible to American Waterfowl Management do individually. Plan (NAWMP) in 1986, undertaking Gulf Coast Joint Venture an intense effort to protect and restore The Gulf Coast is the terminus of the ’s waterfowl popula- Central and Mississippi Flyways and tions and their habitats. Updated in is therefore one of the most important 1994 and 1998 with Mexico as a waterfowl areas in North America, signatory, the NAWMP recognizes providing both wintering and migra- that the recovery and perpetuation of tion habitat for significant numbers of waterfowl populations observed in the the continental duck and goose popula- 1970’s, which is the baseline refer- tions that use both flyways. The coastal ence for duck population objectives of Louisiana, , and under the plan, depends on restoring Mississippi regularly hold half of the wetlands and associated ecosystems wintering duck population of the Mis- throughout the continent. The purpose sissippi Flyway. Coastal wetlands of of the NAWMP is to achieve water- Texas are the primary wintering site fowl conservation while maintaining for ducks using the Central Flyway, or enhancing associated ecological val- wintering more than half of the Cen- ues in harmony with human needs. The tral Flyway waterfowl population. The benefits of such habitat conservation greatest contribution of the Gulf Coast were recognized to be applicable to Joint Venture (GCJV) region (Fig. 1) a wide array of other species as well. in fulfilling the goals of the NAWMP Six priority waterfowl habitat ranges, is as a wintering ground for waterfowl. 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 Figure 1. Location of the Gulf Coast Joint Venture region.

GCJV 1 The GCJV area also provides year- fish, and 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. 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 wetlands conservation ed in the Gulf of Mexico are dependent accomplishments, the GCJV is contrib- on the area’s and wetlands uting to the conservation of biological that are an integral part of coastal diversity. While providing habitat for ecosystems. The American 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, , 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 geese opportunities, and species priorities. and Ross’ geese. A secondary goal is to This document deals with planning provide ample breeding and postbreed- efforts for the Laguna Madre Initia- ing habitat for resident waterfowl. tive area of (Fig. 2). The Actions that will achieve and maintain goal of the Laguna Madre Initiative healthy wetland ecosystems that are is to provide wintering and migration essential to waterfowl will be pursued. habitat for significant numbers of red- Wetland conservation actions that will head ducks, greater and lesser scaup, provide benefits to species of fish and Northern pintails, and other dabbling wildlife, in addition to waterfowl, will ducks, as well as year-round habitat for also be supported. mottled ducks (Table 1). The emergence of the U.S. Shore- Conservation Plan, Partners In Flight physiographic plans, and the Nueces Waterbird Conservation Plan, which Kleberg address conservation of other North American migratory birds, presents op- portunities to broaden and strengthen joint venture partnerships for wetland Gulf of Mexico Brooks Kenedy conservation. As definitive population Texas data and habitat needs are developed Louisiana for the migratory birds represented in these emerging strategies, areas of Laguna mutual concern in wetland ecosystems Madre Starr can be identified. These wetland areas of overlapping interest in the GCJV Willacy Hidalgo will be candidate priority sites for the integrated design and delivery of habitat conservation efforts. Although Cameron wetland conservation projects cannot be designed to provide maximum ben- efits for all concerned species, they can Figure 2. Location of the Laguna Madre 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

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 Texas 124,193 650,395 147,053 100,214 108,667 128,747 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 Gadwall American wigeon Green-winged teal Blue-winged teal Northern shoveler Mottled duck 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 Mid winter Duck Population NAWMP Continental Northern Pintail Objectives Breeding Population Goal 7 million To obtain objectives for midwin- Proportion of Midwinter Survey ter duck populations in the GCJV Northern pintails in Central Flyway Initiative areas, we started with the 22.81% NAWMP continental breeding popu- Central Flyway Spring Flight lation goals which total 62 million and 1.597 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 1.77 million midwinter survey data proportions, the Proportion of Central Flyway numbers of those 62 million breed- Midwinter Survey Northern pintails in ing ducks that should return on spring Laguna Madre 9.77% flights from the Mississippi and Cen- Laguna Madre Midwinter tral Flyway wintering areas; we ad- Goal justed those numbers for 10% January- 173 thousand to-May mortality to obtain midwinter goals for the Mississippi and Central Figure 3. An example of how midwinter population objectives were obtained for a specific species, in this case Northern pintails, in the Laguna Madre Initiative Flyways. Finally, using 1970’s mid- area. winter survey data proportions from the Mississippi and Central Flyways, we calculated how much of each of the two flyway goals should be derived breeding habitat. Greater white-fronted from each GCJV Initiative area. Figure geese, as well as Canada geese in some 3 provides an example of how this GCJV regions, are also experiencing general process was applied at the spe- winter population increases. Therefore, cies level in the Laguna Madre Initia- regional goose objectives are ex- tive area. Exceptions to this methodol- pressed two ways. Recent population ogy include derivation of blue-winged data are used to estimate a quantity of teal and redhead objectives and the geese “expected” to occur and compete expected number of mottled ducks (see to some extent for finite resources, Derivation of GCJV Waterfowl Objec- whereas actual objectives indicate tives and Migration Patterns section, p. the desired regional goose popula- 23). tion. Both are based on indices from midwinter (December) surveys. “Ex- Mid winter Goose Population pected” numbers are derived by aver- Objectives aging recent December surveys (1995- Midcontinent lesser snow and Ross’ 97), and actual objectives are derived geese, many of which spend win- from the 1982-88 average (Table 1). ters in the GCJV, are exceeding their Canadian breeding habitat capacity to Mig r ation Chronolog y the detriment of their long-term health Midwinter populations do not ade- and the health of a myriad of other quately represent the peak, or even the birds that share this arctic/subarctic typical numbers of some waterfowl

GCJV 5 species common to the GCJV region. GCJV Initiative Areas section, p. 26). 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 ob- ate. Migrations differ regionally, even jectives 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).

2

Greater & lesser scaup Ring-necked duck Redhead

(millions) Canvasback

1 Mottled duck

Ducks Northern shoveler

Blue-winged teal Green-winged teal American wigeon 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 for the Texas Laguna Madre Initiative area.

6 NAWMP 70 60 Greater white- fronted goose Lesser snow 50 goose

40

(thousands) 30

Geese 20

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 5. Semimonthly expected numbers of geese for the Texas Laguna Madre Initiative area.

GCJV 7 The Laguna Madre Initiative Area

The Laguna Madre Initiative area is through the land bridge and provides composed of five counties along the a continuous water connection be- extreme lower coastal plain of Texas tween the upper and lower parts of the from the western shores of Nueces laguna and increases water exchange and Corpus Christi Bays to the mouth with the Gulf of Mexico. The Lower of the Rio Grande River and three Laguna Madre extends south from the adjacent inland counties. The initia- land bridge to the Brazos Santiago tive area’s estuarine environment is Pass opening to the Gulf of Mexico a hypersaline lagoon system consist- near Port Isabel, Texas, and includes ing of the Laguna Madre of Texas, the South Bay ecosystem. It is fed by Baffin Bay, Alazan Bay, and South major drainage ways including the Bay. Coastal prairie and sand plains Arroyo Colorado, the Raymondville dominate the inland areas. The entire Drain, and the North Floodway. The Laguna Madre Initiative area covers arid nature of the watershed limits the approximately 11.7 million acres and frequency of freshwater inflow events has approximately 125 miles of coast- to this system. The Port Mansfield line which are largely undeveloped. Channel, near Port Mansfield, Texas, The west boundary of the initiative cuts through Padre Island providing a area extends approximately 275 river narrow opening to the Gulf of Mexico. miles from the Gulf of Mexico to the The Laguna Madre of Texas is northwest corner of Starr County on part of the Laguna Madre of North the Rio Grande. See the June 1990 La- America, a system of long, narrow, guna Madre Initiative Plan for descrip- hypersaline lagoons along the U.S. and tions of the area’s geology, climate, Mexico Gulf Coasts that includes the and land use. Laguna Madre of Tamaulipas (Mex- The Laguna Madre of Texas is a ico). The GCJV will seek to coordinate long (124 miles), narrow (maximum and cooperate with those involved width of 7 miles), shallow (less than with wetland conservation activities 3 feet deep) lagoon that extends the along the east coast of Mexico in order entire length of the south Texas coast from Corpus Christi Bay to the Mexico border. It is separated from the Gulf of Mexico by barrier islands and is composed of distinct upper and lower geographic sections that are divided by extensive sand flats or “the land bridge” between the mainland and Padre Island. The land bridge begins just south of Baffin Bay and extends approximately 12 miles to the south. The Upper Laguna Madre extends from the west side of Corpus Christi Bay south to the land bridge and includes the Baffin Bay complex. The Gulf Intracoastal Waterway cuts American wigeon.

8 NAWMP to foster an integrated continental along the Texas coast. Seagrass beds or perspective for migratory bird conser- meadows are located along the middle vation as well as strengthen wetland to lower coast where rainfall and in- conservation efforts in both countries flows are low and evaporation is high. (see Other Programs section, p. 20). Nearly 80% of the state’s seagrass Although the Laguna Madre Ini- acreage occurs in the Laguna Madre of tiative area consists of a variety of land Texas (Texas Parks and Wildlife 1999). types and wildlife habitats, this plan Five species of seagrasses occur within focuses on the two habitats that are of the area: shoalgrass, turtlegrass, mana- primary importance to waterfowl along teegrass, star grass, and widgeongrass. the south Texas coast: historically Large numbers of wintering redheads hypersaline lagoons with associated and Northern pintails, and fewer seagrass beds and shallow freshwater numbers of and American wetlands on the adjoining mainland wigeons forage in seagrass beds along and barrier islands. In contrast to the the Texas Gulf Coast. The rhizomes of upper and middle coasts of Texas, shoalgrass are the primary food source coastal marshes are not extensive on of redheads wintering along the Gulf the lower coast. Emergent can Coast. The seeds, leaves, and stems of be found in a narrow band along tid- widgeongrass also serve as forage for ally inundated shores of the mainland a variety of duck species. Although the and barrier islands. There are consid- leafy portions and rootstock of mana- erable expanses of tidal flats of sand teegrass are not considered important and mud in the Laguna Madre Initia- dietary items of waterfowl, diving tive area. These flats generally lack ducks routinely feed on matter macrophytic vegetation but support found in association with this seagrass algal mats. They are often referred to (Stutzenbaker 1999). as “wind-tidal flats” because they are Seagrass Status and Threats periodically inundated by wind and The National Oceanic and Atmo- storm tides. spheric Administration Estuarine Eutrophication Survey estimated that Seagrass Beds the spatial coverage of seagrasses in Seagrasses, primarily shoalgrass, the Gulf of Mexico was equivalent to provide food for wintering waterfowl 12-24% of the estuarine area (NOAA and important nursery sites for several 1997). Losses of seagrasses in the species of commercially important northern Gulf of Mexico over the last finfish and shellfish. It is estimated that 50 years have been large, from 20% currently 95% of the seagrass acreage to 100% for most estuaries with only in the Gulf of Mexico is localized in a few areas experiencing increases in estuarine areas of and Texas seagrasses (Handley 1995). (USEPA 1999). Salinity, water depth, Seagrass meadows of the Laguna water clarity, and substrate are the Madre of Texas are undergoing consid- dominant mechanisms affecting sea- erable change. Quammen and Onuf grass distribution. (1993) estimated that seagrass cover In Texas, seagrass distribution, to (i.e., percent of bottom vegetated) in a large extent, parallels the precipita- tion and inflow gradients to the bays

GCJV 9 the Upper and Lower Lagunas was both direct removal and burial of the 75.2% and 70.5%, respectively. The vegetation. Of greater importance is area of vegetated bottom in the Up- the increased turbidity associated with per Laguna increased 50 square miles dredging activities. The loss of sea- between 1967 and 1988. Most of this grasses from deep areas, especially in increase was shoalgrass. At the same the Lower Laguna, has resulted from time, seagrass cover in the Lower reduced light reaching the bay bot- Laguna decreased by 54 square miles. tom near navigation channels because This decrease was confined to deeper of turbidity caused by maintenance areas, which was the result of reduced dredging. Increased turbidity results light reaching the bottom (Quammen from the resuspension of dredged and Onuf 1993). sediments from spoil banks by wind Even larger areas of the Lower La- generated waves. guna Madre have experienced changes Changes to the hydrology of the La- in the species composition of seagrass guna Madre of Texas are considered to beds. The work by Quammen be the primary cause of the expansion and Onuf (1993) indi- of seagrass cover in the Upper Laguna cated that in 1988 shoal- as well as the shift in the species com- grass covered 33% of the position of seagrass beds in the Lower bay bottom compared Laguna. The permanent water connec- to 82% in 1965. Con- tion (i.e., the Gulf Intracoastal Water- currently, bay bottom way) between these two lagoons and coverage by manatee- increased base flows from agricultural grass increased from 9% drains have resulted in modification pair. to 27%, and coverage by turtlegrass of the salinity regime, especially in increased from 1% to 7%. Almost 40% Lower Laguna Madre, and the subse- of the loss of shoalgrass in the Lower quent shift in species distribution. Laguna between 1965 and 1988 was Human-induced disturbances asso- offset by an increase over the same ciated with residential and industrial period in the Upper Laguna. However, development pressures also impact this increasing trend of shoalgrass seagrass meadows. Excess nutrients cover in the Upper Laguna started from sewage treatment discharges, to reverse in the early 1990’s (Onuf septic systems, and drainage from 1995). agricultural fields (i.e., water quality) Natural disturbances to seagrass, can stimulate growth of phytoplankton including such things as hurri- in the waters over seagrass beds. This canes, cold-front storms, floods, and phytoplankton growth decreases the droughts, are cause for seagrass loss amount of light reaching the plants. and cannot be controlled. However, The long-term persistence of a phyto- human-induced disturbances are plankton bloom known as the “brown responsible for most of the changes in tide,” believed to be related to human seagrass abundance and composition caused changes in nutrient levels in the of surviving meadows in the Laguna Laguna Madre of Texas, has resulted Madre of Texas. Dredging of new in seagrass loss in the Upper Laguna. canals can cause seagrass loss from Seagrass beds are also often damaged

10 NAWMP by recreational boating activity. Boat plants include Drummond’s rattle- propellers and anchors can destroy the bush, brownseed paspalum, knot- leaves, roots, and rhizomes of seagrass root bristlegrass, and other grasses thereby disrupting the continuity of (Moulton and Dall 1998). The work the beds. The propeller damaged areas of Spiller and French (1986) indi- (i.e., prop scars) may contribute to ad- cated that the pothole wetlands of the ditional degradation of seagrass beds Lower Rio Grande Valley (Cameron, by accelerating erosion near the broken Hidalgo, Starr, and Willacy Counties) root mats. This erosion can also result were generally from 0.1 to 15 acres in in increased sediment resuspension size and ranged in depth from 0.5 to (i.e., increased turbidity) which inhib- 2.5 feet. The shape and ratio of open its seagrass growth. water to vegetation varied with loca- Seasonal Freshwater Wetlands tion and season, but typically each Shallow isolated depressions of the pothole consisted of a circular body of mainland and barrier islands, and re- water surrounded by emergent wetland sacas (i.e., oxbow wetlands which have vegetation. formed in historic floodplain chan- The shallow basins provide the nels of the Rio Grande River) provide main source of freshwater for wild- foraging and drinking sites for numer- life throughout the inland and barrier ous species of ducks. High evaporation island areas of the Laguna Madre rates and temperatures combined with Initiative area. Dietary freshwater is an low rainfall cause many of these wet- essential component of duck wintering lands to lack surface water for variable habitat along the lower coast of Texas Mottled duck pair. periods from a few months to a few (Woodin 1994). Ducks feeding in the years. Flood control and land develop- Laguna Madre are exposed to high ment in the Lower Rio Grande Valley levels of salt ingestion. Fresh drink- (includes Cameron, Hidalgo, Starr, ing water provided by coastal ponds and Willacy Counties) have virtu- is critically important for ducks to use ally eliminated flood flows to resacas. in diluting ingested salt loads (Woodin Although some of the oxbow wetlands 1994, Adair et al. 1996). are filled by pumping or input from Status and Trends irrigation return flows, most are filled Temporary and seasonal freshwa- only by rainfall. Seasonal wetlands of ter “pothole” wetlands are located the Laguna Madre Initiative often con- along the length of the Laguna Madre tain a variety of seed producing plants on the adjacent mainland and barrier that are dependent on the duration and islands. Although ground water input timing of surface flooding. Dominant may contribute to the water supply of species of vegetation associated with some of these wetlands, most of these the temporarily and seasonally flooded shallow ponds are seasonal because of basins (water regime modifiers accord- the area’s low rainfall and high evapo- ing to Cowardin et al. 1979) include ration rates. These shallow basins are spikerushes, flatsedges, cattail, Olney often called “hurricane ponds” because bulrush, annual sumpweed, seashore they are filled following rains asso- or inland saltgrass, seashore dropseed, ciated with late summer and early fall and smartweeds; other characteristic tropical depressions. McAdams (1987)

GCJV 11 documented the existence of 4.8 the sand plains. Although livestock freshwater ponds per square kilometer often use these ponds there is not an following a hurricane in the coastal apparent conflict with wintering wa- areas of southern Nueces County, all terfowl. Some ponds have been modi- of Kleberg and Kenedy Counties, and fied with a predictable water source northern Willacy County adjacent to (i.e., well or pipeline) for livestock. On the Laguna Madre. Spiller and French the barrier islands, some freshwater (1986) reviewed the status of inland wetlands have been lost to residential pothole wetlands for the Lower Rio development, which continues to be a Grande Valley. They reported an aver- threat to remaining basins. Freshwater age loss of 30% acreage and 41% for ponds are protected within the bound- number of potholes from 1955 to 1979 aries of Padre Island National Seashore for an area of the three southernmost and barrier island properties owned by counties (i.e., Cameron, Hidalgo, and The Nature Conservancy. Willacy) covered by six USGS quad- Resacas are found in urban and rangle maps. Many of these shallow rural areas of the Lower Rio Grande basins have been eliminated by land Valley. Many of those in urban areas leveling practices and major drainage have been landscaped as community projects associated with crop produc- or residential showplaces, or they have tion and by road development. been made a part of stormwater drain- Precipitation has the greatest impact age systems. Most of the rural resacas on abundance and distribution of hurri- are left as natural wetlands, but some cane ponds. The basins are numerous; are owned or leased by irrigation dis- however, many become filled with tricts or municipal water corporations, water only after a large rain. There has and the hydrology of these wetlands is been little human-induced disturbance artificially controlled. to the ponds within the rangeland of

Lesser snow geese.

12 NAWMP The Laguna Madre Initiative Implementation Plan

Habitat conservation is imperative critical during the spring and summer. for meeting the waterfowl population Therefore, the habitat conservation objectives of both the NAWMP and actions outlined in this plan intend to the GCJV. The critical habitat con- influence one or more of these habitat servation needs on public and private parameters. lands of the GCJV are to stop and Conservation Strategies reverse the deterioration and loss of Four broad strategies of wetland wetlands, especially coastal marshes, conservation are important for achiev- and to improve the waterfowl value of ing the goals and objectives of the agricultural lands. The Laguna Madre GCJV. These strategies are mainte- is unique within the GCJV Initiative nance (i.e., loss prevention), resto- areas in that seagrass meadows are ration, enhancement, and creation of dominant among the wetland habitats wetland habitat. Though not a strategy, important to waterfowl. Actions ad- routine management activities are im- dressing the conservation of seagrass portant and inherent components of the must be based largely on maintaining restoration and maintenance strategies. existing meadows and restoring those Conservation actions under each of that have been lost or fragmented. Ad- these strategies take several forms. The ditionally, actions addressing the value types of wetland conservation actions of seagrass meadows to waterfowl will identified in each initiative area reflect involve protecting, restoring, or creat- the previously discussed differences ing adjacent freshwater wetland drink- that characterize each area. Descrip- ing sites in an appropriate spatial dis- tions of the strategies applicable to tribution. Enhancement of agricultural the Laguna Madre Initiative area are rangelands and pasture via restoration presented below. or creation of seasonal wetlands will Maintenance of Habitat also be a priority. 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 addi- on survival and recruitment of water- tional loss and degradation of seagrass fowl populations. Availability of food beds, existing coastal marshes that are can be affected by production of foods most vulnerable to degradation, and (submerged aquatics, annual seeds, existing freshwater ponds adjacent to or ), flooding at appro- the Laguna Madre. Examples of con- priate times and depths for foraging, servation actions under this strategy access to food influenced by human include the following: disturbance, access to dietary fresh- (1) promoting public policy, edu- water, or other factors. In addition to cation, and placement of sign fall and winter food resources, mottled and channel markers around and duck populations are also influenced within seagrass beds to avoid by breeding and postbreeding habitat mechanical damage from recre- in the Laguna Madre. Availability of ational boat activity; fresh or intermediate shallow water (2) promoting public policy, edu- in brood-rearing and molting areas is cation, and technical assistance

GCJV 13 that encourages maintenance of may actually be restoration of a for- existing, critically located fresh- mer depressional or oxbow wetland. water ponds; and Enhancement actions under this strat- (3) securing vulnerable tracts through egy provide capabilities, management fee title acquisition, conservation options, structures, or other actions to easement, or management agree- influence one or several functions or ment for the purpose of imple- values of the site. Examples of con- menting the above maintenance servation actions under this strategy measures. include the following: Restoration of Habitat (1) providing structures and/or water Restoration involves conservation delivery sufficient to flood agri- actions necessary to re-establish a nat- cultural and natural wetlands for urally occurring but degraded wetland early migrating ducks, winter- ecosystem. The goal is to restore or ing waterfowl, or summer brood Flooded agriculture field. mimic the original wetland functions habitat; and values of the site. Examples of (2) providing reliable water, which conservation actions under this strat- may also be used for livestock egy include the following: watering, to freshwater basins (1) restoring water quality, and adjacent to seagrass beds that are subsequent seagrass productiv- underutilized by waterfowl; ity (primarily shoalgrass) by (3) providing technical guidance to reducing nutrient loading, fetch, achieve the above enhancements; and turbidity; and (2) planting seagrass, especially (4) securing tracts through fee title shoalgrass, where it once existed acquisition, conservation ease- naturally (various techniques will ment, or management agreement be tried/developed); for the purpose of implementing (3) providing technical guidance the above enhancements. to achieve the above restorative Creation of Habitat measures; and Creation of habitat is the con- (4) securing degraded tracts through struction of wetlands where none fee title acquisition, conservation previously existed in recent geological easement, or management agree- terms. Conservation actions develop ment for the purpose of imple- the hydrological, geochemical, and menting the above restorative biological components necessary to measures. support and maintain a wetland. Ex- Enhancement of Agricultural amples of conservation actions under Habitat this strategy include the following: Enhancement of cropland, pasture, (1) developing seasonal wetlands to rangeland, and fallow fields improved provide foraging habitat for early for agriculture, and resacas are focused migrating ducks and wintering on the alteration of existing habitat waterfowl, or for summer brood to increase its carrying capacity for habitat; waterfowl. Actions under this strategy

14 NAWMP (2) developing freshwater wetlands (but untested) effects of disturbance adjacent to underutilized seagrass or lack of adjacent dietary fresh water beds; and in limiting redhead accessibility. For (3) beneficially using dredge spoil instance, if only 22% of the habitat from navigation projects to create is rendered unavailable by excessive emergent wetlands and associated recreational boating disturbance, and mudflats. an additional 22% is not close enough Habitat Objectives to a dietary freshwater source to make Beneficial use of dredge The two major waterfowl habitats feeding energetically advantageous, material. available in the Laguna Madre Initia- then the predicted carrying capacity tive area are hypersaline lagoons with would dip below the population objec- associated seagrass beds and fresh- tive. Combined, these factors suggest water wetlands. Habitat objectives the potential for current habitat condi- are based on the assumption that food tions to limit redhead populations dur- availability is the most likely limit- ing some years and suggest the need to ing factor for wintering ducks in the protect the existing habitat base. GCJV. Food availability is potentially Seasonal Wetlands influenced by factors that affect food Estimates are available for the den- production (e.g., marsh health, farming sity of desirable plant seeds for water- practices, etc.) and access (e.g., dis- fowl in seasonal wetlands, so we can turbance, water at appropriate depths, model the waterfowl habitat require- proximity to dietary fresh water, etc.). ments for that particular habitat. Based on the food habits research and general Seagrass Beds Some food density data are available knowledge of habitat use by various for seagrass beds, and researchers have species, we estimated the proportion used existing information to model the of each species’ energetic needs that carrying capacity of shoalgrass beds we should provide for in these inland for redheads in Texas (Michot 2000) habitats (i.e., mainland and barrier is- and Louisiana (Michot 1997). Laguna land wetlands) to be 80% for , Madre seagrass beds have been esti- blue-winged and green-winged teal, mated to encompass 1,808,210 acres Northern shovelers, and mottled ducks, of which 101,161 acres are shoalgrass and 10% for gadwalls, American (Onuf 1995). Using these estimates in wigeons, and Northern pintails. While a published model for redhead carrying inland ponds are important drink- capacity, Michot (1997) suggests that ing sites for diving ducks, we assume Laguna Madre seagrass beds can annu- these species meet all their energetic ally support 700,414 redheads through needs elsewhere. We estimate 90% of a given winter. Though this compares Laguna Madre geese occur in these favorably with the region’s redhead inland areas, and that one-fourth of population objective of 392,650 based inland geese feed in seasonal wetlands. on 1970’s averages, the model assumes These estimates result in population that all portions of seagrass meadows objectives for seasonal/temporary wet- are equally and totally accessible for land habitats within the agricultural/ redhead foraging, ignoring potential rangeland portion of the Laguna

GCJV 15 Madre (Figs. 6 and 7). We modeled the Mississippi Alluvial Valley (Reinecke habitat requirements for this portion et al. 1989). We assume that moist-soil of our population objectives based on seeds in shallow freshwater wetlands the dietary energy supply necessary to of the Laguna Madre Initiative area sustain them. Researchers estimate en- occur at densities similar to idle rice ergetic requirements of mallards to be fields. A minimum seed density thresh- 290 kcal/day (Petrie 1994), with other old has been estimated at 20 kg/acre, species having energetic needs in pro- below which we assume waterfowl portion to their body weight (Kendeigh foraging becomes too energetically 1970). We therefore used average body costly to benefit them (Reinecke et weights of each species in conjunction al. 1989). Flooded, moist-soil seeds with semimonthly population objec- decompose at a rate of approximately tives and expected numbers of geese 5% per month (Neely 1956). in these habitats to arrive at an energy True metabolizable energy for demand curve, in terms of mallard-use- seeds of moist-soil plants have been days, through the wintering waterfowl estimated at 3.0 kcal/g (Petrie 1994). period (Fig. 8). Seed densities in Gulf These estimates result in a prespoil- Coast idle agricultural fields in rice age foraging value of 1,332 mal- rotations have been estimated at 149 lard-use-days for seasonal wetlands kg/acre (Davis et al. 1960), which is of the Laguna Madre Initiative area. slightly less than values that have been Under these assumptions of energetic reported for moist-soil habitats in the demand, prespoilage foraging value,

Figure 6. Semimonthly duck population objectives for the agricultural/rangeland portion of the Texas Laguna Madre Initiative area.

16 NAWMP Figure 7. Semimonthly expected numbers of geese for the agricultural/rangeland portion of the Texas Laguna Madre Initiative area.

Figure 8. Energetic demands of all waterfowl objectives (mallard-use-days) in inland seasonal wetlands of the agricultural/rangeland portion of the Texas Laguna Madre Initiative area. Figure includes ducks and a percentage of geese expected to occur in seasonal wetlands (25%).

GCJV 17 and monthly spoilage rate, we mod- flooded habitat that has occurred in eled habitat needs in the inland portion the recent past during dry years, we of the Laguna Madre Initiative area suggest that 50% of this need rep- based on two target flooding periods. resents flooding objectives for new The early flooding period (late August agricultural/rangeland enhancement through October) would serve the (Table 2). habitat needs of early migrants (Figs. These objectives are independent 6 and 7) and several shorebird species. of the earlier noted need for a nearby The late flooding period (November source of fresh drinking water for through March) coincides with the waterfowl that feed in hypersaline period of greatest habitat need (Fig. habitats. The use of adjacent fresh 8). We estimate a total need of 2,225 drinking water by redhead ducks acres of seasonal wetlands during the feeding in the Laguna Madre of Texas early period, and an additional 10,133 has been reported by Mitchell et al. acres during the late period to sustain (1994), Woodin (1994), and Adair et our objective waterfowl populations. al. (1996). The work by Adair et al. We emphasize that this habitat need (1996) also indicated that the coastal includes existing acres of habitat. ponds that were classified as high use Because our goal is to consistently by diving ducks were closer to feed- provide waterfowl foraging habitat, ing sites than the ponds classified as these should be viewed as minimum low use. Mitchell et al. (1994) reported amounts of managed and unmanaged that redhead herbivory on shoalgrass habitat (combined) that should be beds can occur at such a level that the available in the driest of years. Until plants do not recover to their previous we are able to estimate the amount of

Table 2. Flooding objectives (in acres) for new agricultural/rangeland enhancement within the Laguna Madre Initiative area. Early Late Seasonal wetlands/ 1,128 5,067 moist-soil American wigeon pair.

18 NAWMP level the following growing season. of waterfowl feeding in the Laguna Therefore, the presence and location of Madre. At the same time, efforts to freshwater coastal ponds are believed manage freshwater wetlands near ex- to be factors limiting waterfowl use of isting shoalgrass beds that are presum- seagrass beds in the Laguna Madre of ably suitable but are not presently be- Texas. ing used by ducks needs to be initiated A group of biologists recently came (Conservation of Freshwater Wetlands together to review the literature, docu- Adjacent to the Laguna Madre of Texas ment freshwater needs of waterfowl in and Mexico, unpublished report from the Laguna Madre, and develop guid- Laguna Madre Freshwater Wetlands ance for the conservation of freshwater Study Group, 2000). The GCJV will wetlands adjacent to the Laguna Madre seek to incorporate the study group’s (i.e., Laguna Madre Freshwater Wet- recommendations (Table 3) into on- lands Study Group). In its report, the the-ground efforts that are designed to study group concluded that efforts are meet the modeled habitat objectives needed to protect freshwater wetlands for new agricultural/rangeland en- that are near current concentrations hancement.

Table 3. Recommended characteristics of restored or created freshwater wetlands adjacent to the Laguna Madre of Texas for optimum wildlife benefits (fromConservation of Freshwater Wetlands Adjacent to the Laguna Madre of Texas and Mexico, unpublished report from Laguna Madre Freshwater Wetlands Study Group, 2000). Factor Recommended Value Size 1-5 ha (2-12 acres) Open water 75% of surface area Salinity Less than or equal to 15 ppt; ideal is 6 ppt Depth About 0.5 m; ideal is 43 cm, maximum is 1 m Distance to shoalgrass Within 6 km, 10 km maximum Number of wetlands At least two wetlands per shoalgrass meadow

GCJV 19 Specific Activities dietary freshwater. Additionally, part- The wetland habitat objectives of ners will initiate activities described the GCJV will be addressed through in this initiative as other opportunities various projects that focus on coastal become available. An evolving pack- marsh and agricultural lands. A pack- age of actions designed to meet some age of actions designed to meet some of the Laguna Madre Initiative/GCJV of the Laguna Madre Initiative/GCJV objectives, as well as contribute to the objectives and contribute to the ful- fulfillment of the NAWMP goals, has fillment of the NAWMP goals will be been developed and will be continually developed. Projects in the estuarine updated. environment of the Laguna Madre Other Programs Initiative area will concentrate on We recognize and support other protecting existing seagrass beds from conservation efforts that contribute mechanical damage, dredging, and to goals and objectives of this plan. dredge disposal, and on restoring lost Coastal marsh projects implemented meadows. Projects on lands adjacent to under the Coastal Wetlands Planning, the Laguna Madre will be designed to Protection and Restoration Act could provide landowners with financial and possibly contribute to the maintenance technical assistance to develop fresh- and restoration objectives of this plan water wetlands for foraging habitat and through the National Coastal Wetlands to ensure the availability of necessary

American wigeon pair.

20 NAWMP Conservation Grant Program in Texas. conservation along the Laguna Madre Similarly, shallow flooding provisions of Tamaulipas. of some Natural Resources Conser- Communication and vation Service programs contribute to Education agricultural enhancement objectives. Public awareness of the importance The Laguna Madre of Tamaulipas, of the Gulf Coast to waterfowl and with similar physical and climatic other renewable resources is key to the features as the Laguna Madre of Texas, success of the GCJV. Communications provides important habitat for a great efforts will be developed to educate number of waterfowl including red- decision makers, resource managers, heads, Northern pintails, American landowners, conservation organiz- wigeons, and greater and lesser scaup. ations, and the general public about The north end of this lagoon lies about wetlands conservation in the Laguna 75 km south of the Laguna Madre Madre Initiative area. The GCJV of Texas. Any discussion of the La- will also work with existing commu- guna Madre Initiative area’s transient nication and education efforts (e.g., and wintering waterfowl populations Texas Sea Grant, Coastal Bend Bays would be incomplete without consid- and Estuaries Program, and The Nature ering the valuable wintering areas of Conservancy’s Coastal Conservation Mexico’s east coast. The GCJV will Education Program) that address wet- pursue coordination and cooperation land conservation. with those involved with wetlands

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 gaps require numerous assumptions a mechanism for feedback to, and about both the basic framework for refinement of, Initiative Area Imple- planning habitat conservation (i.e., mentation Plans. The initiative plans food limitation) and specific variables will therefore be updated periodically, used in energetic modeling of habitat as evaluation feeds the planning and needs (e.g., relative importance of implementation 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 midwinter survey were in the Missis- Objectives sippi Flyway (see Fig. 3 for a similar Although the coordinated midwin- example). The NAWMP continental ter survey is an inaccurate count of breeding population objective for mal- total wintering birds, and not cor- lards is 11 million, so we estimate the rected for visibility bias, it provides proportion of the continental breeding a reasonable approximation of the population objective from the Missis- relative distribution of birds across sippi Flyway to be 42.9% of that, or broad regional and temporal scales. 4.72 million. Expanding this number Therefore, we used averages from the to account for 10% mortality between 1970-79 midwinter surveys for each January and May yields a midwinter species to determine the proportion of objective of 5.24 million in the Mis- surveyed ducks that occurs in each of sissippi Flyway. Because 9.8% of all the initiative areas. (For greater and Mississippi Flyway mallards were lesser scaup, offshore counts were counted in the Louisiana Chenier excluded due to inconsistent survey Plain, we apply that percentage to the coverage, resulting in “inland-only” flyway goal and obtain a midwinter scaup objectives.) We then applied population objective of about 516,000 those species-specific proportions to for mallards in the Louisiana Chenier the NAWMP continental breeding Plain. This method yields midwinter 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% average of all con- tinental mallards counted during the

Lesser scaup pair.

GCJV 23 objectives for most species of ducks ratio of the total population to the total that commonly occur in the GCJV area harvest (U.S. Fish and Wildlife Service (Table 1). estimate) equals the ratio of the banded Exceptions to this method include population to the banded harvest derivations for blue-winged teal and (direct recoveries/band reporting rate redhead objectives, and estimation of estimate; band reporting rates are as- the expected number of mottled ducks. sumed to be 33% for 1994-95 and 59% For blue-winged teal, the continental for 1996-97). Preseason population breeding population was first reduced estimates were then averaged, and an by 79% to account for the proportion estimated fall/winter mortality rate of estimated to winter outside the range 30% was assumed to be evenly distrib- of the U.S. midwinter survey, mainly uted September through March. The in Mexico and both Central and South resulting midwinter estimate was then America. apportioned to initiative areas by the Population objectives for redheads midwinter survey (Table 1). were determined directly from aver- Migration Patterns age winter population estimates from Louisiana migration patterns for the Special Redhead Cruise Survey for ducks were determined by using pe- the same time period (1970-79). Us- riodic coastwide aerial surveys along ing direct estimates from aerial winter established transects that generally surveys is appropriate for determin- were flown one to two times per month ing objectives for redheads, but not September through March, 1970-1998 other ducks, because (1) wintering (Louisiana Department of Wildlife redheads occur almost exclusively in and Fisheries coastal transect survey, known locations of offshore seagrass unpublished data). Chandeleur Sound, habitat with good visibility, (2) visibil- the primary redhead area in Louisiana, ity bias has been estimated and found is not covered by these coastal tran- negligible for portions of this special sects, so for Louisiana redheads we survey, and (3) redhead habitats are not instead used 1987-92 periodic redhead consistently surveyed during the mid- surveys from that region (Thomas winter survey, precluding the method- C. Michot, U.S. Geological Survey, ology applied for most species. unpublished data). Each survey was To estimate the number of mottled assigned to a half-month period. For ducks expected to occur during win- each species, each survey of a given ter, we used mark-recapture analyses year was expressed as a proportion of of direct recoveries from bandings in that year’s peak. These proportions Louisiana and Texas during 1994-97. were averaged across all years to yield Preseason population estimates were derived from the assumption that the

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

Blue-winged teal males.

GCJV 25 2 s d n a l t e W

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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

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

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a

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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. Data are not available for Coastal Mississippi Wetlands proportion of the annual peak, relative to January (midwinter) survey. Average Southeast Louisiana. 1 2

GCJV 27 Literature Cited

Adair, S.E., J.L. Moore, and W.H. Kiel. 1996. eutrophication survey, volume 4: Gulf of Wintering use of coastal ponds: Mexico region. U.S. Department of Com- an analysis of alternative hypotheses. Jour- merce, National Oceanic and Atmospheric nal of Wildlife Management 60:83-93. Administration, Office of Ocean Resources Cowardin, L.M., V. Carter, F.C. Golet, and Conservation and Assessment (ORCA). 77 E.T. LaRoe. 1979. Classification of wet- pp. lands and deepwater habitats of the United Neely, W.W. 1956. How long do duck foods States. U.S. Fish and Wildlife Service, last underwater? Transactions of the North FWS/OBS - 79/31, Washington, D.C. American Wildlife and Natural Resources Davis, J.P., C.H. Thomas, and L.L. Glasgow. Conference 21:191-198. 1960. Foods available to waterfowl in Onuf, C.P. 1995. Seagrass meadows of the fallow rice fields of southwest Louisiana, Laguna Madre of Texas. Pages 275-277 in 1960-1961. Proceedings of the Annual E.T. LaRoe, G.S. Farris, C.E. Puckett, P.D. Conference of the Southeastern Association Doran, and M.J. Mac, editors. Our liv- of and Fish Commission 15:60-66. ing resources: a report to the nation on the Handley, L.R. 1995. Seagrass distribution distribution, abundance, and health of U.S. in the northern Gulf of Mexico. Pages plants, animals, and ecosystems. U.S. De- 273-275 in E.T. LaRoe, G.S. Farris, C.E. partment of the Interior, National Biological Puckett, P.D. Doran, and M.J. Mac, editors. Service, Washington, D.C. Our living resources: a report to the nation Petrie, M.J. 1994. True metabolizable energy on the distribution, abundance, and health of waterfowl foods. M.S. thesis, University of U.S. plants, animals, and ecosystems. of Missouri, Columbia. 138 pp. U.S. Department of the Interior, National Quammen, M.L., and C.P. Onuf. 1993. Laguna Biological Service, Washington, D.C. Madre: seagrass changes continue decades Kendeigh, S.C. 1970. Energy requirements for after salinity reduction. Estuaries 16:302- existence in relation to size of bird. Condor 310. 72:60-65. Reinecke, K.J., R.M. Kaminski, D.J. Moor- McAdams, M.S. 1987. Classification and wa- head, J.D. Hodges, and J.R. Nassar. 1989. terfowl use of ponds in south Texas. M.S. Mississippi Alluvial Valley. Pages 203-247 thesis, Texas A&M University, College in L.M. Smith, R.L. Pederson, and R.M. Station. 112 pp. Kaminski, editors. Habitat management for Michot, T.C. 1997. Carrying capacity of sea- migrating and wintering waterfowl in North grass beds predicted for redheads wintering America. Texas Tech University Press, Lub- in Chandeleur Sound, Louisiana, USA. bock. Pages 93-102 in J.D. Goss-Custard, R. Ru- Spiller, S.F., and J.D. French. 1986. The value fino, and A. Luis, editors. Effect of habitat and status of inland pothole wetlands in loss and change on waterbirds. Proceed- the Lower Rio Grande Valley, Texas. U.S. ings of the 10th International Waterfowl Department of the Interior, U.S. Fish and Ecology Symposium, University of Aveiro, Wildlife Service, Special Report, Corpus Portugal, 18-21 September 1995. Institute Christi, Texas. of Terrestrial Ecology Symposium No. 30, Stutzenbaker, C.D. 1999. Aquatic and wetland Wetlands International Pub. No. 42. plants of the western Gulf Coast. Texas Michot, T.C. 2000. Comparison of wintering Parks and Wildlife Press, Austin. 465 pp. redhead populations in four Gulf of Mexico Texas Parks and Wildlife. 1999. Seagrass con- seagrass beds. Pages 243-260 in F.A. Co- servation plan for Texas. 79 pp. min, J.A. Herrera, and J. Ramirez, editors. U.S. Environmental Protection Agency (USE- Limnology and aquatic birds: monitoring, PA). 1999. Ecological condition of estuaries modelling, and management. Universidad in the Gulf of Mexico. EPA 620-R-98-004. Autónoma de Yucatán, Mérida (Mexico). U.S. Environmental Protection Agency, Of- Mitchell, C.A., T.W. Custer, and P.J. Zwank. fice of Research and Development, National 1994. Herbivory on shoalgrass by wintering Health and Environmental Effects Research redheads in Texas. Journal of Wildlife Man- Laboratory, Gulf Ecology Division, Gulf agement 58:131-141. Breeze, Florida. 71 pp. Moulton, D.W., and D.M. Dall. 1998. Atlas Woodin, M.C. 1994. Use of saltwater and of National Wetlands Inventory Maps for freshwater habitats by wintering redheads Nueces County, Texas. 58 pp. in southern Texas. Hydrobiologia 279/280: National Oceanic and Atmospheric Adminis- 279-287. tration (NOAA). 1997. NOAA’s estuarine

28 NAWMP Appendix For More Information

Scientific Names of Plants and North American Waterfowl Management Plan. 1986. U.S. De- Animals Mentioned in This Plan partment of the Interior and Environment Canada. 19 pp. I. Plants alphabetical by common name. Laguna Madre Initiative Gulf Coast Joint Venture North Ameri- Common Name Scientific Name can Waterfowl Management Plan. 1990. Laguna Madre Annual sumpweed Iva annua Initiative Team. 50 pp. 1994 Update to the North American Waterfowl Management Brownseed paspalum Paspalum plicatulum Plan: Expanding the Commitment. 1994. U.S. Department Cattail sp. of the Interior, Environment Canada, and Secretaria de De- Drummond’s rattle-bush Sesbania drummondii sarrollo Social Mexico. 30 pp. + appendixes. Flatsedge Cyperus sp. Expanding the Vision 1998 Update North American Waterfowl Knotroot bristlegrass Setaria geniculata Management Plan. 1998. U.S. Department of the Interior, Manateegrass Syringodium filiforme Environment Canada, and Secretaria de Medio Ambiente, Olney bulrush americanus Recursos Naturales y Pesca. 32 pp. Seashore dropseed Sporobolus virginicus Seashore saltgrass or inland saltgrass Distichlis spicata Acknowledgments Shoalgrass Smartweed Polygonum sp. This planning document benefited from the input of numerous Spikerush Eleocharis sp. individuals. Star grass Cynodon plectostachyus Turtlegrass Thalassia testudinum The Waterfowl Working Group of the Gulf Coast Joint Ven- Widgeongrass maritima ture’s Monitoring, Evaluation, and Research Team—A.D. Afton, W.P. Johnson, M.T. Merendino, T.C. Michot, T.E. Moor- II. Waterfowl alphabetical by common name. man, and M.J. Petrie—provided initial direction, review of the Common Bird Name Scientific Name biological foundation, and identification of critical underlying Anas rubripes assumptions for the plan. American wigeon Anas americana Black-bellied whistling duck Dendrocygna autumnalis Laguna Madre Initiative Chairpersons S. Labuda and D. Curtis Blue-winged teal Anas discors were instrumental in organizing team members for discussing Canada goose Branta canadensis this plan and/or reviewing drafts. Initiative team members also Canvasback valisineria participated in discussions and reviewed drafts. Cinnamon teal Anas cyanoptera Fulvous whistling duck Dendrocygna bicolor The Gulf Coast Joint Venture Management Board provided Gadwall Anas strepera input during plan development and commented on completed Greater scaup Aythya marila drafts, as well as provided the impetus and encouragement to Greater white-fronted goose Anser albifrons initiate and complete this effort. Green-winged teal Anas crecca Lesser scaup Aythya affinis K.E. Gamble, D.A. Haukos, T.C. Michot, R.N. Helm, J.E. Mallard Anas platyrhynchos Neaville, D. Orr, and B.D. Sullivan gathered and provided Mottled duck Anas fulvigula unpublished waterfowl survey data for use in this document. Northern shoveler Anas clypeata Northern pintail Anas acuta The publishing staff at the U.S. Geological Survey’s National Wetlands Research Center provided significant advice to im- Redhead Aythya americana prove the readability and attractiveness of this document. C.A. Ring-necked duck Aythya collaris Manlove and J. Holden provided early drafts of Fig. 1. Ross’ goose Chen rossii Lesser Chen caerulescens Financial or substantial in-kind support for the preparation and Aix sponsa publication of this plan was provided by Ducks Unlimited, Inc.; III. Other animals alphabetical by common name. the North American Waterfowl and Wetlands Office and Re- Common Name Scientific Name gion 2 (Gulf Coast Joint Venture) of the U.S. Fish and Wildlife Service; the Texas Parks and Wildlife Department; the U.S. Alligator mississippiensis Geological Survey’s National Wetlands Research Center; and Ondatra zibethicus the Gulf Coast Joint Venture Management Board. Nutria Myocastor