Canadian Bird Trends

The Canadian Bird Trends Web site is a retrieval system that provides information on Canadian bird species, including population trends and taxonomy, with links to range maps and life history information, and national conservation designations. Population trends are derived from Breeding Bird Survey in Canada (BBS) data and are updated on an annual basis. For species or bird conservation regions for which BBS data are insufficient for statistical analysis, no trends are presented.

Disclaimer

The BBS is a large-scale survey of North American birds. It is jointly coordinated by the Canadian Wildlife Service, National Wildlife Research Centre and the U.S. Geological Survey, Patuxent Wildlife Research Center. The results at this Web site use data from Canadian routes only. Combined results for the United States and Canada are available on the U.S. Geological Survey Web site. For more information on the statistical methods used to produce these trends and annual indices visit BBS Statistical Methods

The BBS was designed to provide a continent-wide perspective of population change. Routes are randomly located in order to sample habitats that are representative of the entire region. Other requirements, such as consistent methodology and observer expertise, visiting the same stops each year, and conducting surveys under suitable weather conditions, are necessary to produce comparable data over time. A large sample size (number of routes) is needed to average local variations and reduce the effects of sampling error (variation in counts attributable to both sampling technique and real variation in trends).

The BBS data are very challenging to analyze. The survey produces an index of relative abundance rather than a complete count of breeding bird populations. The data analyses assume that fluctuations in these indices of abundance are representative of the population as a whole.

Any use of BBS data should acknowledge the hundreds of skilled volunteers in Canada who have participated in the BBS throughout the years and those who have served as provincial or territorial coordinators for the BBS.

Although the data presented here are the product of computer analysis at Environment Canada (EC), no warranty expressed or implied is made regarding the accuracy or utility of the data or their fitness for a particular purpose. It is strongly recommended that the user pay careful attention to the metadata file associated with these data. Environment Canada shall not be held liable for improper or incorrect use of the data described and/or contained herein.

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