Canadian Atlas of Bird Banding

General Overview – Volume 2: Seabirds, 1921–1995.
(Gaston et al., 2008)

Volume 2: Seabirds, 1921–1995 pdf

This volume covers the 58 species of seabirds that were banded or encountered in Canada from 1921 through 1995 (see full listing in Species Search). Of these,50 species are treated with a full species account.

For the 58 species covered in this volume, 905 588 individuals were banded in Canada between 1955 and 1995. (Numbers of birds banded prior to 1955 have not been entered into the electronic database.) The species banded most frequently during 1955–1995, comprising more than a quarter of all seabirds banded, was the Ring-billed Gull. All of the top four species (Ring-billed Gull, Herring Gull, Common Tern, Double-crested Cormorant) occur inland around the Great Lakes, where there is a big concentration of banders. Altogether, more than 10000 individuals were banded for 13 species, and more than 1000 individuals for an additional 10 species.

Of the 905 588 seabirds banded during 1955–1995, 31090 provided encounters up to 1995, for an overall encounter rate of 3.4%. The encounter rate for individual species varied from about 0.1% (Ancient Murrelet) to above 5% (Great Cormorant, Caspian Tern, Pigeon Guillemot), reaching a maximum of 9% for Glaucous-winged Gull. In addition to the 33 083 encounters of birds banded in Canada between 1955 and 1995, this volume covers an additional 7525 encounters of birds banded between 1921 and 1954.

Being generally rather large and often conspicuous (white plumage) and sometimes being cast up on well-used beaches after death, banded seabirds tend to be encountered much more frequently than small songbirds. Species where encounter rates away from breeding colonies are especially low are mainly those frequenting unpopulated coasts throughout the year (Northern Fulmar, Glaucous Gull, Ancient Murrelet, Rhinoceros Auklet). Unlike land bird corpses, those of seabirds may travel substantial distances between where they died and where they are found, carried by winds and tides. As seabird carcasses are large and sometimes buried in sand and later re exposed, a long time may elapse between death and encounter. Consequently, neither the exact finding location nor the date of encounter should be treated as indicative of the species' precise range in time or space.

Seabird banding, to a much greater extent than land bird banding, has been carried out mainly by professionals, with CWS permits accounting for the vast majority of the marine seabirds banded. This is partly because seabirds are accessible for banding almost exclusively when they are breeding, an activity that takes place mainly on remote islands and headlands that are difficult and expensive to access. It also reflects the professional concerns of a small number of CWS biologists. Inland banding of gulls, terns, cormorants, and pelicans has been less concentrated, but has still depended on a small number of highly motivated individuals, some amateur, some professional. For 28 species, just two banding permits accounted for more than 50% of birds banded! The comments of one bander on the kind of effort involved typify the spirit required (Rowan 1927):

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 amount of seabird banding in Canada has fluctuated greatly over the period between 1955 and 1995, the time period for which we have numbers (see Banding Summary). These fluctuations probably reflect the activities of particular individuals and the perceived management needs of CWS, rather than any changes in methods or equipment. Hence, the large numbers of Common Murres banded during 1955–1975 were mainly the responsibility of Leslie Tuck, whereas the peak of Thick-billed Murre bandings since 1985 reflects the ongoing CWS Coats Island project. Unlike the situation with land birds (Brewer et al. 2000), there has been no increase in numbers banded since 1955. In fact, for many species, peak banding occurred in 1955–1975 and has fallen since, perhaps reflecting a belief that we have amassed sufficient information on the species involved. The absence of any encounters since 1972 for Canadian-banded Franklin's Gulls illustrates the relative slowdown in the amount of inland water bird banding that has occurred in recent decades. It is worth noting that renewed banding for species that were heavily banded during the first half of the 20th century could provide interesting insights into changes in migratory patterns and wintering areas.

On top of the 40608 encounters of Canadian banded birds from 1921 to 1995, this volume also includes 9173 cases of birds banded in other countries but encountered in Canada during the same period. These encounters of foreign-banded birds are much more numerous than those for land birds (apart from those banded in the United States). This reflects the fact that seabirds inhabit oceans rather than continents. Most involve birds banded in Europe and encountered in eastern Canada, partly because there has been a great deal of banding carried out in Europe, and partly because the waters off eastern Canada are an important feeding area for many populations breeding in Europe. Southern ocean species, such as Sooty Shearwater and Wilson's Storm-Petrel, are not represented at all among Canadian encounters, although they are very abundant visitors to Canadian waters. This reflects both the small amount of banding in the Southern Hemisphere breeding areas and the tendency for these species to remain offshore most of the time, making encounters less likely.

Foreign-banded birds encountered in British Columbia have mainly been birds banded on the coasts of California, Oregon, and Washington. Many Alaskan birds undoubtedly visit B.C. waters in winter, but little banding has been carried out in Alaska, so encounters are few. Likewise, the lack of encounters of Canadian banded birds in Alaska should not be taken to indicate a lack of movement in that direction: the state has an enormous length of coasts that are rarely visited and are mostly very unsuitable for the accumulation of seabird carcasses.

An appreciable number of seabirds that breed in Canada make no clearly defined migration, in the sense that they exhibit no discrete and separate summer and winter ranges. This applies to most of the auks, many gulls, Northern Fulmar, and Great Cormorant. However, most disperse during the nonbreeding period, especially the younger cohorts; in the case of Arctic breeders, this dispersal is mainly southwards, away from areas of winter ice cover. Band encounters for these species are useful, not so much in identifying routes of migration as in defining minimum limits of dispersal.

Volume 2 should be cited as:

Gaston, A. J., A. D. Brewer, A. W. Diamond, E. J. Woodsworth, and B. T. Collins. 2008. Canadian Atlas of Bird Banding, Volume 2: Seabirds, 1921-1995. Canadian Wildlife Service Special Publication. Available from Environment Canada.

Date Modified: