Calendars provided by this tool are based on predictions derived from a set of models developed for studying the nesting phenology of bird species breeding in Canada (Rousseu & Drolet 2015). The project used the vast amount of nest observations contained in the Project NestWatch database (Bird Studies Canada 2013) to estimate through backcalculations first egg and nest departure dates for about 200,000 nest records representing 311 species. Based on the National Ecological Framework for Canada (Marshall et al. 1999), the modelling procedure used the mean annual temperature of ecodistricts and nest locations to predict when the nesting period should occur. Specifically, for every ecodistrict where a species is found, models were designed to predict the bulk of the nesting season of each species which is defined as the period between the date when 10% of first eggs have been layed and the date when 90% of nests have been left by young. In general, the uncertainty around the estimated nesting dates could vary within a period of up to 10 days, or more, due to the natural variability in the timing of nesting events between regions, individuals, and years and due to the sampling and the constraints associated with the method used.

The nesting calendars are built using the bulk of the nesting season for each species in each ecodistrict. Calendars sorted by bird species show the percentage of ecodistricts selected in which a species is predicted to be actively nesting. Calendars sorted by ecodistrict show the percentage of species actively nesting in each ecodistrict selected. Calendars sorted by compilations of several species and ecodistricts in different regions show the percentage of species-ecodistrict combinations in which there is active nesting, which can be interpreted as a measure of nesting intensity across the regions of interest.

The category “Open Habitat” includes a variety of habitats such as urban environments, farmland, clearings, mountain meadows, coastal areas, cliffs, and tundra. The classification of species by habitat is still somewhat subjective and debatable, especially considering the variety of habitats used by some species within their breeding ranges and the unclear distinction between some types of wetland in comparison with open and/or forest habitats.


Federally Protected Birds


Bird Conservation Regions (Map)

Nesting Zones (Map)

Recommended citation:

Rousseu, F. and B. Drolet. 2015. Prediction of the nesting phenology of birds in Canada. In: J. Hussell and D. Lepage. 2015. Bird Nesting Calendar Query Tool. Project NestWatch. Bird Studies Canada / Études d’Oiseaux Canada, URL: warning.jsp visited [date of consultation]


Bird Studies Canada (BSC). 2013. Project NestWatch. Bird Studies Canada / Études d’Oiseaux Canada, URL: [visited February 29th, 2013]

Ecological Stratification Working Group. 1995. A National Ecological Framework for Canada. Agriculture and Agri-Food Canada, Research Branch, Centre for Land and Biological Resources Research and Environment Canada, State of the Environment Directorate, Ecozone Analysis Branch, Ottawa/Hull. Report and national map at 1:7500000 scale.

Rousseu, F. and B. Drolet. In preparation. The Nesting Phenology of Birds in Canada. Technical Report Series. Canadian Wildlife Service, Quebec Region, Environment Canada, Québec City.