While home on lunch break during the Christmas Bird Count (CBC) last year, I saw a flock of 20 trumpeter swans in a field slightly outside my assigned territory. I soon drove to confirm that the 24 trumpeters in my territory were a different flock. At day's end, I verified that both flocks had been counted.
With dozens of trumpeters around, it's easy to take them for granted, but that belies their history. A century ago, trumpeters had been hunted to near extinction, supporting trade in bird skins and feathers, in the lower 48
states. They came under the protection of the Migratory Bird Treaty Act of 1918.
Nevertheless, by 1935, U.S. experts knew of only 69 trumpeters.
Surprisingly, perhaps, trumpeters never made it onto the U.S. endangered species list, which was created in the 1960s. By then, a breeding population of 2,000 or so trumpeters had been discovered in Alaska.
Our local swans are part of that group. Migratory trumpeters found east of the Rocky Mountains are from a comparable group of swans that breed in a Canadian region that spans parts of northern British Columbia and the Yukon Territory.
The estimated U.S. population of trumpeter swans now exceeds 15,000 birds. Although a several-fold gain, that's still a modest number considering that we find nearly that many mallards and American wigeons in the 15-mile-diameter circle of our local CBC count.
Habitat, hunting, lead
Trumpeter swans face three primary risks: habitat, hunting and lead poisoning. As far as we know, neither hunting nor lead poisoning has been a problem in the Sequim area.
Notably, experts don't list DDT as a major threat. DDT contamination, which causes eggshell thinning, severely decreased populations of some other large birds during the 1900s, including bald eagles and ospreys.
Although trumpeter swans need wetlands for breeding territory, their winter grounds in western Washington are largely open fields. These are found locally and near Puget Sound north of Seattle, where trumpeters are flocking in the thousands this fall. Urban development continues to reduce vital habitat.
Hunting of trumpeter swans now is illegal. Nevertheless, accidental and deliberate shootings remain a problem in some areas.
Lead poisoning is a particular problem for trumpeter swans. They eat lead shot and fishing sinkers for grit to help digest hard grains. As few as three lead pellets can kill a swan.
Although lead shot is banned for hunting waterfowl, it remains legal for some other uses, and it has been found on grounds that trumpeters favor. Experts estimate, for example, that hundreds of trumpeters have died of lead poisoning in Whatcom County in the last decade.
Local flocks growing
CBC data indicate that local wintertime populations of trumpeter swans have been rising. Our count dates to 1975, but the first trumpeters weren't seen until 1982, when four were reported. Their numbers stayed in single digits through the 1900s with the exception of 1986 (21), 1994 (10), and 1999 (25).
They have been in double digits since 2005, peaking at 57 last year. A count in mid-February this year found 186 trumpeters locally, many of whom are thought to have arrived after the 2008 CBC.
Population growth of trumpeter swans is a slow process. Females don't nest until 4 to 7 years of age, yet they can live into their 20s. They lay a single clutch of 4 to 5 eggs in a breeding season.
The modest numbers of juvenile swans we see in local flocks show how few of those eggs resulted in swans successfully making their first migration. With good habitat preservation, the outlook for continued growth of our local trumpeter swan population is good.
Trumpeter swans occasionally are confused with tundra or mute swans. Wintering juvenile trumpeter swans have much darker plumage than their tundra counterparts, making it fairly easy to distinguish between flocks of these two species. In close-up views, adult trumpeter and tundra swans have subtle differences on their heads.
For details, refer to bird identification sources in books or online.
Mute swans, which are imports from Eurasia, have orange bills, whereas the other two species have mostly dark bills.
Trumpeter swans are named for their loud calls - a commendable choice of name considering that mute swans aren't mute.
Author: Dave Jackson, series coordinator and webmaster. Send comments to him at firstname.lastname@example.org or 683-1355.
Next OPAS meeting is at 7 p.m. Jan. 20 at the Dungeness River Audubon Center.