Ruffled Grouse, Bonasa umbellus, Bob Agar Photographer 2015

Billions of birds nest and raise their young in Canada and the majority are migratory. By 2010, bird species spending the entire year in Canada increased in population on average by 68% since 1970. On average, Canadian breeding bird populations declined by 12% between 1970 and 2010, but trends vary among species, depending, in part, on where they winter.Footnote [1]

Bird species migrating farther from home generally declined, and birds migrating the farthest – to South America – showed the most severe declines, with populations declining by 53%. Birds migrating to the United States had 10% declines on average, while birds migrating to Central America declined by 14%.

Trends in Canada’s migratory bird populations by primary wintering area, 1970–2010

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Note: There are 451 regularly occurring native bird species in Canada. The annual composite population index for “all species” reports on 318 bird species for which there are sufficient population data, including birds that winter in more than one area. Annual indices by primary wintering area report on 292 bird species with sufficient population data and exclude birds that winter across more than one area. Central America includes Mexico and the Caribbean.
Source: North American Bird Conservation Initiative-Canada [NABCI-Canada] (2012) State of Canada’s Birds.

Blue Jay - March 2015 -  Bob Agar, Photographer.

Blue Jay – March 2015 –
Bob Agar, Photographer.

Within each wintering area, there are increasing and decreasing species. While trends reflect the overall patterns, individual species or species groups respond to different environmental factors. For example, grassland birds in Canada are generally declining and raptors are generally increasing.Footnote [1]

Status of Canada’s migratory bird populations within each primary wintering area, 1970–2010
Primary wintering area Strong increase
(number of species)
Increase
(number of species)
Little change
(number of species)
Decrease
(number of species)
Strong decrease
(number of species)
Total
Canada 18 6 10 7 11 52
United States 19 17 32 18 25 111
Central America 12 9 21 13 19 74
South America 5 5 7 7 31 55

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How this indicator was calculated

Note: Bird species whose populations increased by more than 33% from 1970 to 2010 are classified as increasing. Species that have declined by more than 25% are classified as decreasing.  Species that have experienced smaller increases or decreases are assigned to the little-change category.
Source: North American Bird Conservation Initiative-Canada [NABCI-Canada] (2012) State of Canada’s Birds.

Pine Grosbeak Bob Agar Photographer 2015

Pine Grosbeak Bob Agar Photographer 2015

Travelling hundreds or even thousands of kilometres in search of food, shelter and safe passage, both en route and at their destinations, is risky for birds. The State of Canada’s Birds 2012 lists the greatest threats to migrating birds travelling outside of Canada as follows:

  • Habitat loss – Growing development pressures and demand for products in many countries in the Caribbean, Central and South America are destroying natural habitats. Agriculture is replacing both natural forests and grasslands. Logging has significantly reduced the forest habitats of Central America and the Caribbean. Beach tourism and shrimp aquaculture are replacing coastal habitats, including mangroves and salt marshes.
  • Pollution – Oil spills, pesticides, industrial chemicals and heavy metals degrade the quality of air, water and terrestrial habitats, and may sicken or kill birds. Many toxic pesticides now banned in Canada and the U.S.A are still in widespread use elsewhere.
  • Incidental Take such as collisions with towers, windows, vehicles and power-lines kill millions of birds each year as they migrate between breeding and wintering areas. In addition, millions of birds are killed by domestic and feral cats.
  • Uncontrolled hunting and trapping remains a concern for birds in some countries. Many shorebirds are hunted in the Caribbean, while songbirds are trapped for the caged bird trade in many areas.
  • Climate change will have particularly strong effects on long-distance migrants because changes anywhere along their migration routes can disrupt their life cycle. Mismatches between migration timing and food availability can lead to reduced nesting success. Changing sea levels will flood coastal stopover habitats. More frequent, stronger storms can lead to major mortality on migration.

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