Trumpeter Swan Population Rising in Ontario
Thursday October 14 2010
Volunteers Report Trumpeter Swan Wing Tags – Revealing a Self-Sustaining Population in Ontario
A team of vigilant observers has helped biologist and TTSS board member Harry Lumsden to track and tally what is now a successful, self-sustaining population of Trumpeter Swans in Ontario. Ontario’s Trumpeters are marked with yellow wing tags. In a typical year, observers report 300-360 individuals. Once a number is read and reported, the data can be entered to help track that bird’s movements, habitat use and reproductive success. Data from tagged bird sightings allows biologists to produce a genetic family tree and to record population growth and range extension. This past year 116 birds were marked in Ontario — 70 of them caught by hand by the team of Bev and Ray Kingdon, Julie Kee and Kyna Intini in the wintering flock that feeds at La Salle Park and other areas near Burlington on the west end of Lake Ontario. Peak numbers recorded for this wintering group were 160 Trumpeters along with 100 Mute Swans. Smaller congregations, where other birds were marked, included Bluffer’s Park, Frenchman’s Bay, Whitby Harbour and Wye Marsh.
Tag sightings by observers across the southern part of the province proved useful even when the number was not recorded. Ontario observers have been asked to keep track of the proportion of marked to unmarked birds in groups observed (even if number is not read). The last four year’s analysis of reported proportions reveals a steady increase in the wild population. As the population grows, the percent of total marked birds has declined. In 2005, it was 54%. By 2006 it had declined to 46%, 2007, 44% and in 2008, 39%. In 2007-08 364 tagged birds were reported. By using this calculated annual percentage rate, with an adjustment for marked birds missed (based on year to year variance in reports of known live tagged birds) along with the percentage ratio of marked to unmarked birds, biologists estimate the population.
Doing the numbers, Harry Lumsden recorded quadruple figures for the Sept. 2007 to Aug. 2008 report — a total of 1018 birds. The milestone of 1000 birds had been passed! This number is for adult and sub-adult birds. Cygnets of the year averaged 39% for this period. Applying this ratio to overall numbers, Ontario’s breeding population estimate registers a remarkable 1415 birds. When Harry Lumsden started Ontario’s Trumpeter Swan Restoration program in 1982, Trumpeters had not been seen for almost 100 years, since 1886 when a hunter at Lake Erie’s Long Point shot the last known individual. The Ontario Field Ornithologists honored Lumsden with their Distinguished Ornithologist award for 2008. Among his many career achievements, leading the successful restoration of Ontario’s Trumpeter Swans must bring great satisfaction.
Trumpeter Swan Society
Photography Doug Worrall