Snow-white Trumpeter Swans present a truly spectac-ular sight. With a - PDF document

Snow-white Trumpeter Swans present a truly spectac-ular sight. With a wingspan of more than 7 feet and aheight of about 4 feet, the Trumpeter Swan ( Cygnus buc- ) ranks as the largest native waterfowl species inNorth America. Because the Trumpeter Swan disappeared as a breed-ing bird in the Midwest, several states have launchedrestoration programs to reintroduce it to the region. Thispublication will provide you with background informa-tion on the Trumpeter Swan픀s status and life history, andon restoration efforts being conducted in the upperMidwest. rumpeter Swans, along with ducks and geese, belongto the avian Order Anseriformes, Family Anatidae.Trumpeters have broad, flat bills with fine tooth-likeserrations along the edges which allow them to strainaquatic plants and water. The birdsÕ long necks andstrong feet allow them to uproot plants in water up to 4feet deep.Most Trumpeter Swans weigh 21Ð30 pounds,although some males exceed the average weight. Thein its first year is called a cygnet or juve-The Trumpeter is often con-more commonTundra Swan (formerlyWhistling Swan, Cygnus columbianus) the only other native swan foundroutinely in North America. TundraSwans can be seen in the upperMidwest only during spring andYou can distinguish between the two native speciesmost accurately by listening to their calls. Observers havedescribed the Trumpeter픀s call as resonant, deep, loud,sonorous and trumpet-likeÑhence the bird픀s name. TheTundra Swan has a high-pitched, quavering call resem-bling that of a Canada Goose (Branta canadensis) Snow Goose (Chen caerulescens) . From a distance, thecalls of a flock of Tundra Swans may be likened to the The Trumpeter Swan by Sumner Matteson, Scott Craven and Donna Compton Trumpeter Swan hats. By the late 1800s, it was widely believed that theFortunately, a small nonmigratory population sur-vived in the remote mountain valleys of Montana, Idahoand Wyoming. Two nests were found in YellowstoneNational Park in 1919; and in 1932, 69 Trumpeters weredocumented in the region. In 1935, the U.S. government established Red RockLakes National Wildlife RNWRNWRontana픀sCentennial Valley to protect the remnant Trumpeter pop-ulation. Managed by the U.S. Fish and Wildlife Service,habitat conditions quickly improved when refuge person-nel restricted livestock grazing and hay cutting in marsh-es, protected the muskrat population (muskrat housesfurnish nesting sites for Trumpeters), provided winterfood, controlled predators, and more recently prohibitedthe use of lead shot and lead fishing sinkers to reduce theWith protection at Red Rock Lakes NWR and in theadjacent Yellowstone National Park, the Tristate (south-western Montana, east central Idaho, and northwesternWyoming) subpopulation of Trumpeter Swans increasedto 640 birds by the late 1950s.In an attempt to expand their range and improve theirchances of survival, some Trumpeters were relocated fromthe Tristate area to a suitable habitat outside of theregion. In 1938, four cygnets were taken to the NationalElk Refuge in Jackson, Wyoming. Over the next 30 years,Trumpeters were moved to several national wildliferefuges as well as to the Midwestern site of HennepinParks in Minnesota. A total of 40 Trumpeters from RedRock Lakes NWR formed the core of the Midwest픀srestoration effort in the late 1960s.Between the mid-1960s and the mid-1980s, theTristate subpopulation declined. Productivity plunged inthe late 1970s, and by 1986 only 392 birds remained.Concern over the decline led to an extensive study thatdemonstrated a close relationship between swan survivaland productivity and the availability of winter food sup-plies (native foods and supplemental grain) at Red RockLakes NWR. The policy of providing supplemental feedon NWR lands, however, led to erratic artificial feedingpractices. Because Red Rock Lakes NWR was designed topromote the welfare of Trumpeter Swans, it was deter-mined that Trumpeters wintering in the Tristate shouldbe redistributed. Plans to achieve that objective are cur-rently underway.We now know that in the 1930s, when Red RockLakes NWR was established, remnant Trumpeter Swanflocks survived in remote parts of Alaska and westernCanada. Those flocks have grown substantially and nowcomprise the most secure population of Trumpeters inNorth America.For management purposes, Trumpeters are dividedinto three populations based on where they breed andspend the winter (figure 2). The Rocky Mountain popu-flock that migrates to the Tristate for the winter, and theTristate Subpopulation, a year-round resident flock.These two subpopulations total approximately 2,500. There are nearly 15,000 Trumpeter Swans in thePacific Coast Population of Trumpeter Swans. Most ofthese birds nest in Alaska and winter along the coasts ofBritish Columbia and Washington.The third population, the Interior Population,includes all Trumpeters east of the Rocky Mountains. Allof these birds have been part of restoration projects andare widely distributed. Since the first recovery efforts in the 1960s whenTrumpeters were all but extinct, until now, with the birdpopulation totalling nearly 900, major strides have beenmade in restoring the species to the continental interior. Figure 2. Current regional populations of Trumpeter Swans. A cygnet픀s first flight in late September is ordinarilyshort. Daily practice prepares cygnets to migrate withtheir parents just before the temperature reaches freezing.Family groups and mated pairs keep to themselves on thewintering area, although they may be part of a larger con-gregation of swans. Parents and their cygnets return yearafter year to the same winter feeding sites. The qualityand quantity of winter foods influences productivity dur-ing the next breeding season. Cygnets remain with their parents throughout theirfirst winter, migrating with them back to the breedingarea. Shortly afterwards, cygnets are driven away by theirparents. They remain together in sibling groups untilabout 2 years of age when they seek mates and a new lifein a remote marsh. Trumpeter Swans, though protected from huntingthroughout their range, are sometimes shot by mistake.Snow Geese, hunted in some areas frequented byTrumpeters, are significantly smaller, with a wingspan ofonly about 3 feet and prominent black wing tips. TheTundra Swan is hunted in North Carolina, Virginia,North and South Dakota, Montana, Nevada and Utah.Where both Tundra Swans and Trumpeters dwell, TundraSwan hunts are limited to areas and times whenTrumpeters are not commonly present. Midwestern swan restoration programs windling Trumpeter Swan populations have impelledsome Midwestern states to launch restoration pro-grams to reintroduce the birds. So far, the results ofthese programs have been encouraging. Minnesota픀s Hennepin Parks pioneered the effort toreestablish Trumpeter Swans in 1966. By the 1980s, thestate natural resourcesÕ agencies of Wisconsin, Minnesotaand Michigan had initiated Trumpeter Swan recoveryprograms. In 1994, Iowa began a cooperative restorationproject. Working together, these states are now establish-ing flocks that will help create a breeding and migratorypopulation of Trumpeter Swans in the Midwest.Wisconsin, Minnesota (including Hennepin Parks),Michigan and Iowa (as well as the province of Ontario)are attempting to reestablish Trumpeter Swans by rearingcygnets in captivity. After 2 years, unrelated birds arepaired and released at selected wetlands. Birds are kept incaptivity for 2 years because it is believed that survival ismost difficult in the cygnet픀s first 2 years of life. Releasedbirds usually ÒimprintÓ on the release area; that is, theyare most likely to return to that area to nest at age 3 orolder. The sites where cygnets and yearlings are held arecalled captive-rearing or overwintering sites. Wisconsin,for example, has 3 such sites where Trumpeter cygnets aremaintained. To prevent the swans from flying away, theirwings are clipped in the summer. Within a year, theswans molt and regrow their flight feathers, necessitatinganother clipping since the young swans must remain atthe overwintering site for a second year. Another important approach in restoration efforts isthat of maintaining flightless, breeding pairs that con-tribute young to the restoration programs. Several zoos,game farms, private propagators, and the DeltaWaterfowl Research Station in Manitoba, Canada, haveprovided cygnets for Midwestern restoration programs.These cygnets are held in captivity for 1Ð2 years, thenreleased at selected sites. To determine the most effective techniques for achiev-ing a wild, free-flying Trumpeter Swan population,Wisconsin initiated research in 1989 to compare therelease of 2-year-old birds with the release of cygnetsimprinted on a swan decoy. Decoy-reared cygnets learn toavoid potential predators through responses to tapedvocalizations from a swan decoy. The cygnets live in aremote marsh setting for about 4 months until they canfly. They are then allowed to fly free as they would in thewild. Preliminary results suggest that decoy-rearing is aneffective technique in establishing breeding pairs as earlyas 2 years of age. Observations on live birds and the recovery of deadbirds provide wildlife managers with valuable data onswansÕ movements and survival. To monitor the survivaland movements of released swans, Minnesota biologistsattach orange wing tags with black numbers on each birdreleased. Wisconsin and Hennepin Parks have used yel-