Canadian Atlas of Bird Banding

General Overview – Volume 3: Raptors and Waterbirds, 1921–1995.
(Dunn et al., 2009)

Volume 3: Raptors and Waterbirds, 1921–1995 pdf

There are 63 species covered by this volume (full listing in Species Search). Of these, 51 had at least one record of an encounter more than 100 km from the site of banding, thereby meriting a full species account.

For the species covered in this volume, there were 234736 individuals banded in Canada between 1955 and 1995. Of these, 6980 were later encountered, for an overall encounter rate of 0.3%. However, this rate includes 11 species for which there were no encounters at all between 1955 and 1995, including secretive marsh birds such as Least Bittern and Sora, as well as several small owl species. Ironically, the highest encounter rate for any species was for King Rail, with one encounter out of only three birds banded. Encounter rates were >1% for most other species and on the order of 5–10% for the larger raptors, herons, and owls.

The birds covered by this volume are generally large and therefore conspicuous when dead, so it is not surprising that their encounter rates are relatively high. Reports from South America, in particular, are much more common in this volume than in the volume covering small songbirds (Brewer et al. 2000).

Banding effort for many of the species covered here has increased greatly over time, rising from under 12000 individuals banded during 1955–1965 to over 100000 during 1986–1995. Some of the largest increases are in species captured at raptor migration stations, whereas others reflect increased study of particular species (e.g., Burrowing Owl) or increased population size (e.g., Merlin). Encounter rates often have not kept pace, as has also been found for small landbirds (Dunn 2001).

In addition to the 6980 encounters of birds banded in Canada between 1955 and 1995, this volume includes 828 encounters of birds banded from 1921 to 1955 and another 1173 records for birds banded in other countries but encountered in Canada.

Words cannot describe the labour of our second visit. Every step in the sticky ooze…was an effort to begin with, but towards the end it felt as though 50 lb weights were tied to our feet… Each band placed that day involved mental as well as physical effort and one bander after another dropped out from sheer exhaustion; by eleven o'clock the effort had automatically come to a conclusion. The last bander was played out…. Five of us, in spite of all handicaps and unexpected difficulties, placed over 500 bands each in five hours.

The main fall migration routes of passerines (Brewer et al. 2000) are southward from British Columbia along the Pacific coast, southeast from the Prairie provinces towards the southeastern United States, and southwestward from the Maritime provinces (also towards the U.S. southeast). Ontario forms a transition zone between east and west. By contrast, hawks from the Prairie provinces move much more directly south through the U.S. Great Plains, where conditions for open-country hunters are much more congenial than they are for woodland songbirds. Some owls also follow regular migratory paths, but others show a high degree of wandering (such as Snowy Owl). Most raptors are reluctant to fly over water, and this volume includes many records that demonstrate movement around the edges of the Great Lakes rather than directly across.

Waterbirds, the last group of species covered by this volume, often have migration patterns distinct from those of raptors, in part because they are following (or heading towards) large water bodies used for stopover or as wintering areas. Western Grebe is perhaps the most striking example, with birds from Manitoba heading towards the Pacific coast — one of the few North American species that regularly migrates across the Rocky Mountain chain. Cranes and some herons (e.g., Great Blue Heron), however, typically migrate through the U.S. Great Plains, just as hawks do.

This volume lists many individual records of birds encountered at some distance within a few days of banding, including a Sharp-shinned Hawk that travelled 169 km between two captures on a single day. The maximum distance between banding and encounter location of any individual of a species included in this volume was 12807 km, for a Peregrine Falcon banded in the Yukon as a chick and recovered in Argentina 15 months later.

Volume 3 should be cited as:

Dunn, E. H., A. D. Brewer, A. W. Diamond, E. J. Woodsworth, and B. T. Collins. 2009. Canadian Atlas of Bird Banding, Volume 3: Raptors and Waterbirds, 1921-1995. Canadian Wildlife Service Special Publication. Available from Environment Canada.

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