The Christmas count, first held in 1900, will see bird watchers in teams across the country count as many birds as possible in a 24-hour period in a 15-mile-diameter circle that stays the same for each group of watchers from year to year, The Province newspaper in British Columbia reported Thursday.
"This is not just about counting birds," Dick Cannings, Bird Studies Canada's program coordinator, said in a release.
"Data from the Christmas Bird Count are at the heart of hundreds of peer-reviewed scientific studies and inform decisions by wildlife managers across Canada."
Previous counts have highlighted the impact of climate change on birds and a disturbing decline in Canada of common bird species, researchers said.
"Because birds are early indicators of environmental threats to habitats we share, this is a vital survey of North America," Cannings said of the count, which runs Dec. 15 to Jan. 5.