TEXAS PARKS AND WILDLIFE WoodManaging Ducks for in East Texas WOODMANAGING DUCKS FOR IN EAST TEXAS by Carl Frentress Regional Waterfowl Biologist, Retired – East Texas Acknowledgements The following persons are due special recognition for their contributions to this publication: Vernon Bevill, Dr. Brian Davis, DeAnna Faulk, Dr. Eric Frasier, Hayden Haucke, Robert L. Jessen, Kevin Kraai, Dr. James C. Kroll, Mary Lane, David Lobpries, Brad McCool, M. D. Marks, Dave Morrison, Dale Prochaska, Dr. Dean Ransom, Anne Storey, Charles Stutzenbaker, and Dr. Raymond C. Telfair II. Thanks also are due the numerous private cooperators who participated in the nest box project. Finally, the Wetland Habitat Alliance of Texas and Ducks Unlimited are recognized for financial contributions for nest box materials and conservation of wood duck habitat. Information in this bulletin includes findings from studies funded by Pittman-Robertson federal aid projects and Texas duck stamp funds. Design by Tim Peterson, Creative Services Branch Chief, Texas Parks and Wildlife Department Cover Photo: Wood Duck, TPWD © 2005 TPWD PWD BK W7000-1045 (7/05) SAVED FROM THE VERGE OF EXTINCTION In the early 1900s, wood ducks were on the verge of extinction due to habitat loss from over-harvesting of timber, drainage of swamps and marshes, and excessive exploitation by man for its meat and feathers. The Migratory Bird Treaty Act of 1918, which was enacted for the protection and well being of all FIGURE 1 Wood Duck migratory birds, gave protection to Aix sponsa woods duck by closing the season until 1941. Since that time this beautiful bird has remained the subject of substantial attention by waterfowlers, birders, aviculturists and biologists. 2 MANAGING FOR WOOD DUCKS IN EAST TEXAS IDENTIFICATION AND RANGE The wood duck, which belongs to the perching duck tribe, is the only member of this tribe found in North America. It is closely related to the elaborately colored mandarin duck of Asia. Like the mandarin, adult male wood ducks have beautiful plumage. In fact, the scientific name, Aix sponsa, is interpreted from the Latin as “betrothed duck,” alluding to the extravagance of a bride’s dress in similarity to male wood duck plumage. As with other North American duck species, the females and juveniles have generally drab, gray-brown plumages (see Figure 1). It is no surprise that a bird of such extravagant appearance and extensive range is known to many people, and has been given a variety of colloquial names. Names such as summer duck, woods, acorn duck, black brancier, gray duck, plumer, squealer, swamp duck, tree duck, wood widgeon, crested wood duck and Carolina duck attest to its unique habits, features and haunts. The commonly used name “wood duck” denotes its affinity for trees. Wood ducks spend most of their life in or near forested areas. They often perch in trees during the spring and summer; females use tree cavities as nesting sites; during winter all wood ducks feed heavily on the mast of bottomland hardwood trees. Wood ducks are not shy with their vocalizations. If you have approached a Photo: Kevin J. Kraai group of feeding wood ducks, you are familiar with the squeals, clucks and squeaks they make while foraging. At other times different sounds are made by both the male and female birds. Generally, the male’s calls are softer and less The commonly used audible than those of female wood ducks. In fact, the calls of the females have name “wood duck” earned the species the widespread local name of “squealer.” In comparison to other North American duck species, wood ducks are mid-sized denotes its affinity birds. Adult males weigh slightly more that 1-1/2 pounds, while adult hens average 1-1/4 pounds. Juveniles weigh about one pound when they reach for trees. Wood ducks flight stage at eight weeks of age. Ducklings one to two weeks old weigh about six ounces. spend most of their In summer (June or July) males molt into drab eclipse plumage and replace the flight feathers in their wings. In August or September the drake molts from its life in or near eclipse plumage into full winter plumage. Females begin their post-nesting molt later than males since they must remain active while incubating and brood forested areas. rearing. During these summer molts, wood ducks are vulnerable from loss of the flight feathers. They become secretive because they temporarily are flightless at this time. Juveniles molt body feathers in their first fall of life. Adult plumage is perfected during the second spring. 3 BBS Limit 101 and above 31 to 100 11 to 30 4 to 10 2 to 3 One and below None counted The breeding range of wood ducks encompasses all the United States east of the FIGURE 2 Great Plains (see Figure 2). Wintering grounds are along the Atlantic seaboard Breeding Range and the Gulf coasts. A separate and disjunct population breeds in the Pacific Patuxent Wildlife Northwest and winters in California. In Texas the ducks live primarily in the Research Center eastern portion of the state, but may be found beyond the Edwards Plateau. A small population extends into the Panhandle via the Canadian and Red River drainages. Winter migrants are most numerous in East and Southeast Texas; however, they have been encountered in the Panhandle, west to El Paso and south to Brownsville. It is important to note that two separate populations of wood ducks occur in Texas. During the fall and winter, adult birds that nested in Texas generally remain in the state. This also holds true for the young birds that were produced in the state during the spring and summer. Together all of these birds form a resident wintering population. Texas also is the winter terminus for wood ducks migrating from states and provinces to the north. Consequently, the state hosts a migrant, non-resident, wintering population of wood ducks. Both populations, the residents and the migrants, mix into one large, composite wintering population. As spring migration draws near (usually in late winter) these birds begin to sort themselves into the two distinct breeding populations. Wood ducks reach breeding age the first spring after hatching. Most wood ducks court and establish pair bonds during winter. This seems to be particularly true 4 MANAGING FOR WOOD DUCKS IN EAST TEXAS Texas also is the for resident wood ducks. Some out-of-state birds may pair in the autumn and migrate south as mates. During most of the year the drakes normally are tolerant of each other; however, during courtship the males often peck each winter terminus for other and chase drakes that come too close to the hen of interest. The actual pair-bonding behavior involves a series of specific movements and activities wood ducks migrating (known as courtship displays) that are exhibited by both the drakes and hens. from states and After the pair bond is established, drakes and hens remain mated for the duration of the nesting season. If either of the pair is lost before the nest is provinces to the north. started, the remaining duck may select a new mate. Later in the breeding season when fewer individuals remain unmated the likelihood of acquiring a new mate Consequently, decreases. Wood ducks select new mates each year. the state hosts a A noteworthy aspect of wood duck biology is the fact that breeding populations for any given geographic area are maintained by strong homing tendencies in the migrant, non­ hens. This behavior is strongest in older adult hens. A high percentage of the hens return to nest in the area where they were hatched and reared. This is an important fact in the management of wood duck breeding populations since resident, wintering studies have shown that homing wood duck hens nest within five miles of their original rearing area. If the local population of hens is lost for some reason, population of considerable time may elapse before nesting wood ducks reoccupy the vacant breeding habitat. Drakes do not have this strong homing tendency; they follow wood ducks. their mates to their breeding areas. Consequently, any given drake may spend successive breeding seasons at various locations around the country. The breeding populations of wood ducks in Texas are composed of females that were raised in the places where they are nesting and males that come from anywhere in the continental wood duck range. The hens maintain the geographic integrity of the breeding population while the drakes provide for exchange of genetic material within the continental population. As nest initiation nears,Texas hens take their mates to their respective locales within the state while out-of-state hens begin migration with their mates to nesting areas where they were reared. Late winter habitat conditions strongly affect the success of breeding wood ducks. Shallow flooding in bottomland hardwood forests is a key factor for production success. This flooding stimulates population explosions of aquatic invertebrate animals that are required for wood duck hens to achieve optimal breeding condition and to lay sufficient clutches of eggs.This situation, therefore, is one of the reasons conservationists strive for protection and management of bottomland hardwood ecosystems. The proper functioning of bottomland hardwoods is essential to the multitude of wildlife species that occupy them. Wood ducks are significant among the types of animals that depend on these forested wetlands. 5 After pair bonding the nesting season begins with the search for a suitable cavity in which the hen may nest. In Texas this activity may start in late January or early February. The search begins in the morning with the male accompanying the female. While the hen inspects a prospective natural cavity in a tree or an artificial nest box, the male waits outside perched on a nearby limb or other vantage point.