point/counterpoint

 

Should Trumpeter Swans be Introduced to the Eastern United States and Canada?

 

by Bill Whan[1] and Gerry Rising[2]

 

No.

 

It seems we never learn. Conveniently disregarding ubiquitous Canada Geese and Mute Swans, we persist in importing species alien to our eastern states. As the more elusive native birds of our wetlands decline somewhere out of sight, we fill their places with larger, showier species, regardless of origin. Trumpeter Swans, for example, while impressive and beautiful in their native western range, seem not to have been a good fit for eastern North America as breeders. Less than perfectly matched to their adopted habitats, they are mostly non‑migratory. They can pose threats to native wildlife and overtax wetland resources. Far from their wild homelands, they all too often show up to beg crusts at city parks and farm ponds.

 

Until recently, all authorities agreed that the ancestral breeding range of the Trumpeter Swan extended east no farther than a line extending from James Bay to northwestern Indiana. Unsatisfied, swan advocates have advanced a case that the species once bred east to Nova Scotia and south to Florida. They over‑interpret fossils or archaeological remains of Trumpeters as proof of local breeding, even when such evidence tells us nothing of the kind for this widespread former migrant. Old reports of Trumpeter Swans during winter or migration are stretched to establish their presence during the nesting season. The absence of records of swans is not explained simply by the absence of swans, but rather by their secretiveness and inaccessibility during the breeding season, prior extirpations, or the poverty, illiteracy, or distractibility of observers. We have so few voucher specimens because hunters found them difficult to kill, we are told, but then we hear that swans were quickly eradicated as easy prey. Any odd swan mentioned in old travelers' accounts from May through August in the East they assume to be a Trumpeter, even though Ohio, for example, has at least 24 published records since 1936 of non‑breeding Tundra Swans during those months. Trumpeters, say the enthusiasts, must have bred quite far south because they require at least 142 frost‑free days to bring off a clutch of eggs, but we learn that the only remaining native population of Trumpeters in the Lower 48 breeds in areas of Wyoming averaging fewer than 80 frost-free days (Johnsgard 1978).

 

Unfortunately, we have allowed this ardent swan‑introduction movement to develop unchallenged. As a result, so-called restoration projects are well underway in Michigan, Ohio, New York, and southern Ontario. More are being discussed elsewhere in the Atlantic Flyway. Central to the movement's doctrine is a single publication, which circulated for twenty years in typescript among adherents before being sought by the Trumpeter Swan Society for the first issue of its bulletin North American Swans. "Ancestral breeding and wintering ranges of the Trumpeter Swan (Cygnus buccinator) in the eastern United States", by Philip M. Rogers and Donald A. Hammer, reported results of a search of the literature on swans in the East. It cites accounts of fossils and archaeological remains, environmental conditions, and sightings by explorers and naturalists in the region. The authors repeatedly admit that their findings fall short of conclusive proof that swans once bred in the East. Nevertheless, they hypothesize former breeding populations in "Florida, the Carolinas, Ohio, and the Lower Mississippi Valley". Their proposed breeding range map extends to West Virginia, Kentucky, Tennessee, and Mississippi, and their map of the wintering range includes the entire eastern U.S. save the southern half of Florida. They express hope that further research might provide firmer evidence for these provocative thought experiments.

 

After 23 years, however, no significant new evidence supporting these postulations has emerged, and they remain unconvincing. Not a single monograph on the birds of any state east of the accepted range considers the species a former nester, including the more recent ones, such as those for Massachusetts (Veit and Petersen 1993), Michigan (Grandlund et al. 1994), New York (Levine 1998), Pennsylvania (McWilliams and Brauning 2000), and Ohio (Peterjohn 2001). In view of this fact, it is regrettable that Carl D. Mitchell's 1994 account of the species in the prestigious Birds of North America series uncritically accepts the conjectures in Roger and Hammer's then‑unpublished paper as established fact. Mitchell's version of the Trumpeter Swan's former range differs radically from those accepted by all other ornithological authorities. He extends the wintering range "along the Gulf Coast to central Florida" and north from there along the Atlantic coast. He pushes the swan's Canadian breeding range all the way to the Atlantic, relying entirely upon a speculative 1984 paper by Harry Lumsden, a director of the Trumpeter Swan Society. Rogers and Hammer (1998) are his sole support for expanding it south into the Carolinas and Mississippi. Claims that swans were nesting in far‑flung locales like Nova Scotia in 1699, or the Carolinas in 1701, lack acceptable evidence, as do those that the species wintered coastally south of the Carolinas.

 

But let us join Mitchell, himself a former director of the Trumpeter Swan Society, and suppose that Trumpeter Swans once nested and wintered far and wide across eastern North America. Would re‑introductions be either justified or wise 200 years later? How much of the pre‑settlement habitat conceivably inviting to the species still remains? In Ohio, for example, over 90 percent of the primeval wetlands has disappeared, and much of the rest stagnates in diked impoundments. Does it make sense to add Trumpeter Swans to habitats that seem increasingly to have trouble supporting rails, bitterns, Black Terns, and other birds known as numerous breeders in the past? Trumpeters are a conspicuous and handsome sight in the local marsh, but they take up a lot of room, and they can be aggressive. A 1988 study by Lawrence Gillette in a Trumpeter Swan Society publication recounted following two pairs in Minnesota. He observed that "broods of ducklings were attacked by the swans, and ducklings were killed on several occasions". The evidence, it appears, does not favor the neighborliness of swans.

 

Concerns have been voiced about habitat destruction along the mid-Atlantic coast by exotic Mute Swans, and even by native wintering Tundra Swans. How much more degraded would these wetlands be with the year‑round presence of an even larger swan? In bygone days, vast coastal marshlands there supported both Trumpeter and Tundra Swans in winter, but they are now much reduced in size and productivity. Because a single Trumpeter can consume twenty pounds of sub-aquatic vegetation per day, and because their feeding habits involve considerable cratering and gouging of the landscape, their potential to adversely affect scarce wetland ecosystems is ominous.

 

The movement to plant Trumpeter Swans everywhere has troubling resemblances to that on behalf of the "giant" Canada Goose. In the mid‑twentieth century, game agencies dedicated intense efforts to introducing populations of this subspecies in areas far to the south and east of ancestral breeding grounds. Questionable evidence ‑ in some cases identical to that adduced for Trumpeters ‑ was elicited to prove that the species once had a more extensive range than previously recognized. Breeding stock came from captive birds, and the "re"-introductions were spectacularly successful, contributing to our huge semi-domesticated resident populations of geese ‑ birds that have come to prefer golf courses, suburbs, and corporate lawns to wilder settings.

 

Like those for geese, swan introduction projects have produced manipulated non‑migratory populations, with too many showing up in less‑than‑wild settings. Many of the swans in these projects were released as captive‑raised cygnets or foster‑reared by Mute Swans, banded, tracked, and fed (at least 80 percent of the 900+ birds in the interior population receive supplemental food in winter), and are hence in many ways wards of the state. They lack migratory traditions, and attempts to instill such traditions have repeatedly failed, as very likely will the most recent one, a seemingly bizarre scheme to induce migration by transporting swans via balloons.

 

In recent years, many landowners have installed Mute Swans in their ponds to chase off nuisance Canada Geese. Ironically enough, advocates are now promoting another reason to introduce Trumpeter Swans in the East: perhaps they will chase off nuisance Mute Swans. Trumpeter Swans are the world's largest waterfowl species, however, and there will be no bigger bird to bully them into departing should they, too, outlive their welcome.

 

"Restored" birds cost upwards of two thousand dollars apiece to install and maintain in the East. It is worth considering whether these millions might better go to support efforts to restore, foster, and protect the wild native populations of the West, birds on behalf of which biologists and other wildlife managers have been struggling for decades. Important studies go unfunded in the West, where potential wintering habitat is threatened, as are the birds themselves by legal swan hunters along the migratory pathway.

 

Birders who want to enjoy the genuine experience of this magnificent species on its wild homeland are well advised to visit its haunts in the prairie potholes, mountain lakes, and muskeg wetlands of the western U.S. and Canada. It is depressing, however, to see them delivered by truck and shoehorned into a landscape, chasing after flung clods as if they were tidbits, and playing a starring role as pond ornaments in the public relations fantasies of game managers. Trumpeters seen in the East are dubious beneficiaries of artificial introduction projects, strangers in a strange land.

 

Literature Cited

 

Grandlund, J., G. McPeek, R. Adams, P. Chu, J. Reinoehl, C. Nelson, R. Shinkel, M. Kielb, S. Allen, and A. Trautman. 1994. The Birds of Michigan. Indiana University Press, Bloomington.

Johnsgard, P.A. 1978. The triumphant trumpeter. Natural History 87(9):72‑77.

Levine, E., ed. 1998. Bull's Birds of New York State. Cornell University Press, Ithaca.

McWilliams, G.M. and D.W. Brauning. 2000. The Birds of Pennsylvania. Cornell University Press, Ithaca.

Peterjohn, B.G. 2001. The Birds of Ohio. The Wooster Book Company, Wooster.

Rogers, P.M. and D.A. Hammer. 1998. Ancestral breeding and wintering ranges of the Trumpeter Swan (Cygnus buccinator) in the eastern United States. North American Swans 27(1):13‑29.

Veit, R.R. and W.R. Petersen. 1993. Birds of Massachusetts. Massachusetts Audubon Society, Lincoln.

 

Note: The authors maintain a web site that extends the issues of this column and includes an extensive bibliography at http://www.acsu.buffalo.edu./~insrisg/ nature/swans.html.

 

                                          from the August 2002 Birding 34(4):338-340

 

____________________________________________________________

 

point/counterpoint

 

Should Trumpeter Swans be Introduced to the Eastern United States and Canada?

 

by Ruth E. Shea[3]

 

Yes.

 

For over 30 years, The Trumpeter Swan Society (TTSS) has worked to assure the vitality and welfare of wild Trumpeter Swan populations, and to restore the species to as much of its former range as possible. TTSS supports their restoration in eastern, as well as in central and western North America, because:

 

• Trumpeter Swans were indigenous to eastern North America from at least the late Pleistocene until they were extirpated by human activities that now can be controlled.

 

• Suitable habitat is still present.

 

• Re‑colonization is unlikely without human assistance, and successful restoration techniques have been developed.

 

• And finally, Trumpeter Swan restoration provides highly visi­ble affirmation that North Americans can restore extirpated wildlife and conserve wetland habitats that also benefit a host of less conspicuous species.

 

Prior to European settlement, Trumpeter Swans were abundant and widespread in North America, including eastern portions of the continent. By 1900, they were nearly extinct and survived only in remote parts of Alaska, Alberta, and the Greater Yellowstone region (Banko 1960). After over 80 years of curtailed harvest and restoration programs in the U.S. and Canada, Trumpeters had increased to about 23,650 in North America by the summer of 2000, with most (17,550) summering in Alaska (Caithamer 2001). Across Canada and the lower 48 states, however, Trumpeter Swans are still among the rarest of our native waterfowl, totaling only about 6,100 as of the summer of 2000 (Caithamer 2001). Rebuilding their migrations and expanding nesting and winter distribution in eastern North America would help increase the security of this depleted species outside of Alaska.

 

When considering restoration of Trumpeter Swans in eastern North America, it is helpful to understand the factors that led to their early extirpation from that region. In many long‑lived species, such as swans, population health is strongly influenced by adult mortality rates (Sovada et al. 2001). Modeling of a nesting population in Montana showed that an increase in annual adult mortality from 15 to 20 percent would cause its eventual extinction, with population size halving every 20 years (Page 1976). To successfully restore a self‑sustaining population, adult mortality from factors such as shooting, lead poisoning, powerline collisions, and environmental pollution must be carefully controlled.

 

 Trumpeter Swans were extirpated primarily by human harvest, beginning thousands of years ago and reaching devastating levels after the arrival of Europeans and firearms (Banko 1960, Lumsden 1984, Rogers and Hammer 1998). The impacts of subsistence hunting by Native Americans and settlers for meat, quills, skins, and eggs were compounded by over 125 years of commercial swanskin harvest, which began before 1772 (Banko 1960, Houston et al. 1997). Habitat degradation, such as marsh drainage in northwestern Indiana (Schorger 1964), also eliminated nesting in some locales. In most areas, however, suitable habitat remained long after Trumpeters had been extirpated.

 

Prior to the spread of firearms, Trumpeter Swans were most vulnerable during summer when molting adults and developing cygnets were flightless. Those nesting in accessible temperate areas were particularly vulnerable. When Native Americans and settlers gained firearms, Trumpeters were pursued year-round, and southerly nesting populations were the first to be destroyed (Banko 1960). Writing in 1912, Edward Howe Forbush, State Ornithologist of Massachusetts, said: "Persecution drove it from the northern parts of its winter range to the shores of the Gulf of Mexico; from all the southern portions of its breeding range toward the shores of the Arctic Ocean; and from the Atlantic and Pacific slopes toward the interior.... [A] swan seen at any time of the year in most parts of the United States is the signal for every man with a gun to pursue it. The breeding swans of the United States have been extirpated, and the bird is pursued, even in its farthest northern haunts, by the natives, who capture it in summer, when it has molted its primaries and is unable to fly."

 

In the eastern U.S., Trumpeter Swan fossils are known from Pleistocene deposits in Illinois and Florida (Banko 1960). After the last ice sheets ‑ which reached nearly to the Ohio River Valley ‑ began to recede about 10,000 years ago, the Trumpeter Swan's range began to expand northward (Banko 1960, Rogers and Hammer 1998). The only known factors limiting their breeding distribution would have been their need for at least a 145‑day ice‑free period for incubation and brood rearing and the availability of fertile, shallow ponds and marshes with sufficient food for brood rearing (Hansen et al. 1971, Lumsden 1984).

 

Further clues to their pre‑extirpation distribution in the eastern U.S. come from at least 23 Native American archaeological sites in Illinois (n=7), Ohio (n=4), Pennsylvania (n=5), West Virginia (n=2), Arkansas (n=2), and Tennessee (n=3), where Trumpeter Swan bones have been reported (Banko 1960, Rogers and Hammer 1998). In Illinois, the archeological record spans >1,500 years, ending just before the arrival of Europeans. In Ohio, the oldest remains date back about 2,377‑2,750 years (Banko 1960). In Canada, the easternmost evidence of Trumpeter Swans comes from the Port aux Croix burial site in Newfoundland, dated 2000+ B.C. Bones dating from 1000 B.C. up to 1,000 A.D also were found in Quebec, upstream from Montreal (Lumsden 1984). Suitable breeding, as well as wintering, habitat was available in many of these locations (Lumsden 1984, Rogers and Hammer 1998).

 

Trumpeter Swans were not officially described as a species until 1832, although in 1709, Lawson clearly described "great flocks" of Trumpeters wintering in the Carolinas and departing in February "when they go to the Lakes to breed" (Banko 1960). Suitable nesting habitat occurred in the Carolinas, but Lawson provided no details regarding breeding‑lake locations (Rogers and Hammer 1998). Forbush (1912) concluded that Trumpeters had frequented the Atlantic seaboard from New England as far south as Georgia during the 1600s, and summarized later reports from New Hampshire, Connecticut, Massachusetts, Ontario, the Chesapeake and Delaware Bays, and the last New England record from Maine in 1901 (Forbush 1925).

 

Rogers and Hammer (1998) and Lumsden (1984) reviewed early Trumpeter records in the eastern U.S. and Canada and discussed the problems inherent in reconstructing early distribution. They delineated likely pre-European breeding and wintering distribution, which they based upon early reports, their extensive knowledge of Trumpeter habitat requirements, and the location of suitable habitat. Hansen et al. (1971) performed a similar analysis for Alaska and western Canada.

 

 Reports of swans present at locations and times when Tundra Swans were much farther north suggest that breeding Trumpeters persisted at least until 1535 along the St. Lawrence River east of Montreal (Lumsden 1995), 1679‑1701 in the vicinity of the Detroit River and Lake St. Clair (Lumsden 1984), 1700 in the Bay of Fundy region where eggs were gathered (Lumsden 1995), 1805‑1808 in the marshes bordering the Mississippi River near Memphis, Tennessee (Rogers and Hammer 1998), 1860 near Eastmain Fort, Quebec (Banko 1960), and 1872 in remote marshes of northwestern Indiana (Schorger 1964). Forbush (1912) noted that hunters had reported that "[s]wans remained all through the year in the remoter portions of New York state" but gave no year or further details.

 

The potential to restore Trumpeter Swans in eastern North America is good because substantial suitable habitat remains. Although vulnerable to human disturbance during nesting, Trumpeters are relatively adaptable birds that prefer shallow and productive ponds, lakes, and marshes for nesting. They feed on a wide variety of aquatic plants. Nesting density is limited by their strong territoriality and intolerance of other nesting swans. Trumpeters winter primarily in freshwater where shallow depths, slow currents, and ice‑free conditions provide access to aquatic vegetation. They may also use brackish coastal habitats, and they can learn to feed in fields and use various crop residues. Although some northern breeding populations migrate long distances to wintering areas, in temperate areas some birds may move only as far as necessary to find ice‑free foraging areas.

 

In their discussion of the probable ancestral range of Trumpeter Swans in the eastern U.S., Rogers and Hammer (1998) showed the major areas in which 90 percent of all waterfowl use of wetlands occurs. Many of these important waterfowl wetlands, particularly in Michigan, Indiana, Ohio, northwestern Pennsylvania, New York, western Kentucky, and eastern Arkansas, could support nesting Trumpeters today if mortality factors and human disturbance can be adequately controlled.

 

Lumsden (1984) concluded that potential Trumpeter Swan breeding range in eastern Canada was largely confined to post‑glacially flooded land with high calcium levels, with the northern limit bounded by the 145‑150 day ice-free isopleth. Such areas included parts of the Hudson Bay Lowlands of Manitoba, Ontario, and Quebec; most of southern Manitoba and western Ontario; parts of central Ontario and Quebec in the clay belts and where large marshes exist; extreme southern Ontario around the shores of the Great Lakes; the shores of the St. Lawrence at least as far as Quebec City; parts of Anticosti Island; and locally in New Brunswick, Nova Scotia, and Newfoundland. Much of this area still contains suitable breeding habitat (H. Lumsden personal communication).

 

Due in part to their strongly traditional behavior and fidelity to natal areas, Trumpeters are slow to re‑occupy vacant habitat without human assistance. Fortunately, captive‑rearing, capture, and translocation methods are well developed. Much information is available from TTSS and the states and provinces currently involved in active restoration programs. During the 40+ years of restoration efforts, most potential difficulties have been identified and solved. Lead poisoning, however, remains one of the most tenacious problems in some areas.

 

Finally, TTSS also supports Trumpeter Swan restoration in eastern North America because these magnificent and vulnerable birds inspire public support for wetland conservation that benefits a myriad of less conspicuous species. Trumpeter Swans are powerful ambassadors for wildlife and wetland conservation. Their restoration, after decades or sometimes centuries of absence, provides highly visible affirmation that recovery of extirpated species is possible, not just in the remote wilderness of Alaska, but even near human population centers.

 

Literature Cited

 

Banko, W.E. 1960. The Trumpeter Swan. North American Fauna 63. U.S. Fish and Wildlife Service, Washington.

Caithamer, D.E. 2001. Trumpeter Swan Population Status, 2000. Unpublished report, U.S. Fish and Wildlife Service, Division of Migratory Bird Management, Laurel.

Forbush, E. H. 1912. A History of the Game Birds, Wild‑fowl, and Shore Birds of Massachusetts and Adjacent States. Massachusetts State Board of Agriculture, Boston.

Forbush, E. H. 1925. Birds of Massachusetts and other New England States. Part I. Water Birds, Marsh Birds, and Shore Birds. Massachusetts Department of Agriculture, Boston.

Hansen, H.A., P.E.K. Shepherd, J.G. King, and W.A. Troyer. 1971. The Trumpeter Swan in Alaska. Wildlife Monograph 26.

Houston, C.S., M.I. Houston, and H.M. Reeves. 1997. The 19th‑century trade in swan skins and quills. Blue Jay 55:24‑34.

Lumsden, H.G. 1995. History of Trumpeter Swans in Ontario. pp. 11‑17 in: W.A. Rapley, E. Christens, and T.P. Birt, eds. Proceedings of the Trumpeter Swan Symposium. Metro Toronto Zoo, Toronto.

Lumsden, H.G. 1984. The pre‑settlement breeding distribution of Trumpeter, Cygnus buccinator, and Tundra Swans, C. columbianus, in eastern Canada. Canadian Field Naturalist 98:415‑424.

Page, R. 1976. The ecology of Trumpeter Swans on Red Rock Lakes National Wildlife Refuge, Montana. Ph.D. dissertation. University of Montana, Missoula.

Rogers, P.M. and D.A. Hammer. 1998. Ancestral breeding and wintering ranges of the Trumpeter Swan (Cygnus buccinator) in the eastern United States. North American Swans 27(l):13‑29.

Schorger, A.W. 1964. The trumpeter swan as a breeding bird in Minnesota, Wisconsin, Illinois, and Indiana. Wilson Bulletin 76:331‑338.

Sovada, M.A., R. M. Anthony, and B.D.J. Batt. 2001. Predation on waterfowl in arctic tundra and prairie breeding areas: a review. Wildlife Society Bulletin 29:6‑15.

 

 

                                       from the August 2002 Birding 34(4):341-343,345


[1] Bill Whan, 223 East Tulane Road, Columbus, OH 43202, <danielel@iwaynet.net>. BW is a writer from Columbus, Ohio. He edits The Ohio Cardinal, the state journal covering birds and birding.

[2] Gerry Rising, 295 Robinhill Drive, Williamsville, NY 14221, <insrisg@acsu.buffalo.edu>. GR, former editor of the New York state journal, The Kingbird, now writes a weekly natural history column for the Buffalo News.

[3] Ruth E. Shea, The Trumpeter Swan Society, 3800 County Road 24, Maple Plain, MN 55359, <ruthshea@srv.net>. RES has studied the distribution and ecology of Trumpeter Swans since 1976 and is currently Executive Director of The Trumpeter Swan Society.