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The Importance of Canada's Boreal Forest to Landbirds

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PART 2: HOW SIGNIFICANT ARE BOREAL LANDBIRDS THROUGHOUT CANADA, NORTH AMERICA AND THE WESTERN HEMISPHERE?

2.d. Where do boreal migrants go when they leave Canada?

The United States is home to an estimated one billion or more boreal migrants in winter (see Table 9). Mexico, Brazil and Colombia also provide wintering grounds for substantial numbers of boreal birds.² Each are estimated to house more than 100 million of them in winter. And most other countries of the Western Hemisphere are estimated to have an influx of boreal migrants that reaches or exceeds one million birds. In comparison, relatively few boreal migrants remain in the non-boreal southern parts of Canada.

Mexico is home to the highest concentration of wintering boreal species (see Table 9), followed by the United States and several Central American countries. During the spring and fall migration seasons, the United States is home to almost all of the boreal migrants.

Table 9: Estimated distribution of Canadian Boreal migrants on wintering grounds     Country / Islands Boreal Species * Millions of Migrants   Country / Islands Boreal Species * Millions of Migrants     Mexico 115 680   (continued)         Guatemala 70 34   Bolivia 31 39     U.S.A. 66 1,150   Cayman Islands 30 <1     Honduras 63 30   Haiti 26 4     Nicaragua 58 31   Dominican Republic 26 7     El Salvador 55 6   Puerto Rico 26 1     Belize 54 7   Trinidad & Tobago 24 <1     Costa Rica 54 12   Paraguay 24 11     Panama 53 15   Argentina 24 34     Colombia 53 110   Windward Islands 23 <1     Venezuela 46 62   Leeward Islands 22 <1     Brazil 42 200   Suriname 22 4     Cuba 40 22   French Guiana 19 2     Ecuador 40 15   Chile 18 4     Peru 40 52   Uruguay 17 2     Bahamas 36 3   Canada (non-boreal) 4 <1     Guyana 32 8   Bermuda 1 <1     Jamaica 31 2   Falkland Islands 0 0       * from 190 boreal species with estimated population sizes in Canada's Boreal

Overlaying Environment Canada's WildSpace winter range maps of boreal-breeding species, also illustrates their patterns of winter distribution. According to these maps, the areas of highest species richness are found across much of the United States, especially in the coastal and southern regions, and down through Mexico and Central America (Figure 3a). The areas of highest boreal bird density are similar, though they shift slightly southward, and higher numbers are found in Central America, Cuba and Colombia (Figure 3b). When each species range is weighted by proportion of global population that originates in Canada's boreal forest, the area of greatest concentration is much narrower, emphasizing countries all around the Gulf of Mexico and Caribbean Sea (Figure 3c).

a) Species Richness	b) Bird Density
c) Richness Weighted by % Global Population from Boreal
Figure 3: Distribution of Canada's Boreal landbirds in winter, shown in three ways

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²A combination of winter range maps and knowledge of the numbers and proportions of birds that migrate out of Canada's boreal forest were used to arrive at these estimated numerical distributions.

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