Tracking Nesting Success
in Canada

Note : Ce texte n'est pas disponible en français

Have you ever found a bird's nest, and watched in fascination as the parents built the nest, patiently incubated the eggs, then frantically fed their chicks until they were old enough to fly? Or perhaps the ending was not so happy, and the eggs or young disappeared, eaten by a predator such as a jay, squirrel, or raccoon. Or maybe the chick they raised was not their own, but that of a Brown-headed Cowbird, a social parasite that lays its eggs in nests of other birds instead of making its own nest. Such events are all part of the natural cycle, but if they start happening too often, we begin to worry. 

Cowbirds were formerly restricted largely to the prairies in western North America, where their nomadic lifestyle - following herds of bison - probably led to their unusual behaviour. With the spread of agriculture, they expanded their range and now parasitize nests of hundreds of different species. Other human-induced changes in the landscape, such as forest fragmentation, garbage dumps, and surplus grain crops, have led to increased populations of raccoons, skunks and other nest predators. Climate change could affect the food supply and hence growth rate for nestling birds, through changing the timing of insect emergence. Can our native songbirds cope with these changes? 

People like you can help to find out, by tracking the fate of each nest you find, both the successes and the failures, and reporting the results on a nest record card. Regional nest record schemes have been established right across Canada, from British Columbia to Newfoundland, some as early as the mid-1950s. These schemes gather data on bird nests from volunteers and professionals alike. Nest records have been extensively used to study many things, including the breeding distribution, nesting habitat and ecology of individual species. In Britain, they have widely been used for monitoring, as part of an integrated approach to monitor and conserve bird populations, but they have been less used for this purpose in Canada.

To promote development of the nest record schemes, and to enhance their value for population monitoring, Bird Studies Canada (BSC) convened a meeting in December 2000, bringing together representatives from many of the nest record schemes in Canada, along with scientists from the British and U.S. nest records schemes and the Canadian Wildlife Service (CWS). The meeting was highly productive, with many ideas exchanged on ways to computerize data bases with suitable standards (critical to use of the data for monitoring), develop appropriate analysis methods, and encourage greater public participation. BSC, CWS and individual schemes are now working closely together entering historical data, designing new nest record cards that are more computer friendly, building web-based data entry programs, and finding ways to encourage greater participation. 

So, next time you find a bird's nest, even a common species, follow its progress, record what you find, and fill out a nest record card. You'll be contributing to our knowledge and understanding of birds, and helping with their conservation. For addresses of individual nest record schemes, and to obtain nest record cards, check the national programs section of the BSC web page: www.bsc-eoc.org/bscmain.html

                                                                                                  by Charles M. Francis