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Research & Reports
Reports
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. c. What proportion of landbirds, and what number of landbirds, migrate from the boreal and from Canada after the breeding season?
Overall, boreal landbirds tend to be highly migratory. An estimated 93% of Canada's boreal landbirds
migrate from the boreal after the breeding season (Table 6). Based on an average of two juveniles per
family surviving to migration age, an estimated 2.5 billion landbirds migrate from Canada's boreal forest in the fall. This number could be as high as five billion landbirds if BBC estimates were used. 1
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Table 6: Number and Proportion of Landbirds Migrating from Canada's Boreal Forest |
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# of Boreal Birds * |
Proportion of Population Migrating out of Boreal |
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Landbird Family |
# of Spp |
|
Migrating |
Remaining |
%Boreal
Pop'n |
%Canadian
Pop'n |
%WHem
Pop'n |
%Global
Pop'n |
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Emberizidae (Sparrows & Allies) |
25 |
|
910,000,000 |
6,600,000 |
99% |
68% |
46% |
43% |
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Parulidae (Wood-Warblers) |
27 |
|
610,000,000 |
0 |
100% |
76% |
53% |
53% |
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Turdidae (Thrushes) |
10 |
|
390,000,000 |
1,700,000 |
100% |
67% |
36% |
36% |
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Vireonidae (Vireos) |
5 |
|
170,000,000 |
0 |
100% |
66% |
42% |
42% |
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Tyrranidae (Flycatchers) |
14 |
|
110,000,000 |
0 |
100% |
69% |
34% |
34% |
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Regulidae (Kinglets) |
2 |
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110,000,000 |
1,500,000 |
99% |
68% |
55% |
55% |
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Icteridae (Blackbirds & Allies) |
10 |
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55,000,000 |
0 |
100% |
32% |
5% |
5% |
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Troglodytidae (Wrens) |
4 |
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51,000,000 |
15,000 |
100% |
57% |
33% |
22% |
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Hirundinidae (Swallows) |
7 |
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46,000,000 |
0 |
100% |
46% |
10% |
6% |
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Fringillidae (Finches) |
8 |
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29,000,000 |
64,000,000 |
31% |
20% |
13% |
7% |
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Picidae (Woodpeckers) |
8 |
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20,000,000 |
16,000,000 |
56% |
39% |
18% |
17% |
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Bombycillidae (Waxwings) |
2 |
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11,000,000 |
250,000 |
98% |
53% |
32% |
29% |
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Corvidae (Jays, Crows & Allies) |
5 |
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9,900,000 |
35,000,000 |
22% |
14% |
6% |
4% |
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27 other Landbird Families |
63 |
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32,000,000 |
72,000,000 |
30% |
9% |
2% |
1% |
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Total Landbirds |
190 |
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2,550,000,000 |
200,000,000 |
93% |
59% |
27% |
20% |
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* assumes 2 young produced per breeding pair, on average |
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Several entire, or nearly entire, families of boreal landbirds leave the boreal for the winter (see Table 6). Among these species, the number of birds migrating from Canada's boreal forest often represents a
substantial proportion of their global population. For example, the estimated one-half billion warblers
migrating from the boreal represents about one-half of the global population of those 27 warbler species.
Those families that largely remain in the boreal, including finches, woodpeckers, jays and chickadees, tend to have smaller overall breeding numbers than many of the largely migratory families (Table 6).
Table 7 lists those boreal landbirds whose estimated migration numbers are highest. As in Table 3, most of these species are sparrows or warblers.
Canadian boreal migrants comprise a substantial portion of the global population of many species. Table 8 shows that for 16 landbirds, boreal migrants comprise 70% or more of their global population.
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Table 7: Number and Proportion of Landbird Species Migrating from Canada's Boreal Forest |
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# of Boreal Birds * |
Proportion of Population Migrating out of Boreal |
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Species |
Migrating |
Remaining |
%Boreal
Pop'n |
%Canadian
Pop'n |
%WHem
Pop'n |
%Global
Pop'n |
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Dark-eyed Junco |
330,000,000 |
6,500,000 |
98% |
87% |
65% |
65% |
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White-throated Sparrow |
220,000,000 |
0 |
100% |
87% |
85% |
85% |
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American Robin |
180,000,000 |
1,700,000 |
99% |
60% |
28% |
28% |
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Yellow-rumped Warbler |
160,000,000 |
0 |
100% |
84% |
63% |
63% |
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Red-eyed Vireo |
140,000,000 |
0 |
100% |
74% |
52% |
52% |
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Swainson's Thrush |
110,000,000 |
0 |
100% |
77% |
59% |
59% |
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Ruby-crowned Kinglet |
90,000,000 |
0 |
100% |
83% |
68% |
68% |
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Chipping Sparrow |
89,000,000 |
0 |
100% |
78% |
45% |
45% |
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Hermit Thrush |
72,000,000 |
0 |
100% |
90% |
72% |
72% |
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White-crowned Sparrow |
70,000,000 |
0 |
100% |
74% |
48% |
48% |
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Lincoln's Sparrow |
60,000,000 |
0 |
100% |
93% |
84% |
84% |
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Alder Flycatcher |
59,000,000 |
0 |
100% |
88% |
63% |
63% |
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Orange-crowned Warbler |
58,000,000 |
0 |
100% |
81% |
47% |
47% |
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Magnolia Warbler |
46,000,000 |
0 |
100% |
78% |
77% |
77% |
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Nashville Warbler |
43,000,000 |
0 |
100% |
76% |
63% |
63% |
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Tennessee Warbler |
42,000,000 |
0 |
100% |
97% |
97% |
97% |
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Savannah Sparrow |
39,000,000 |
0 |
100% |
38% |
25% |
25% |
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Winter Wren |
38,000,000 |
15,000 |
100% |
59% |
49% |
24% |
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Mourning Warbler |
27,000,000 |
0 |
100% |
82% |
75% |
75% |
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Yellow Warbler |
27,000,000 |
0 |
100% |
71% |
36% |
36% |
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Blackpoll Warbler |
26,000,000 |
0 |
100% |
94% |
65% |
65% |
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* assumes 2 young produced per breeding pair, on average |
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Table 8: Landbird species whose Boreal migrants are a very
high proportion of Global population |
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Species |
Global Abundance
post-breeding |
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Canadian Boreal
Migrants |
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% of Global Pop'n
Migrating from
Canada's Boreal |
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Palm Warbler |
17,000,000 |
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17,000,000 |
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98% |
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Tennessee Warbler |
44,000,000 |
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42,000,000 |
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97% |
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Connecticut Warbler |
6,300,000 |
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5,800,000 |
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92% |
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Smith's Longspur |
1,300,000 |
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1,200,000 |
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89% |
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Yellow-bellied Flycatcher |
12,000,000 |
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11,000,000 |
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87% |
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Philadelphia Vireo |
8,200,000 |
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7,000,000 |
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86% |
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White-throated Sparrow |
260,000,000 |
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220,000,000 |
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85% |
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Lincoln's Sparrow |
71,000,000 |
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60,000,000 |
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84% |
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Cape May Warbler |
6,500,000 |
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5,400,000 |
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83% |
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Bay-breasted Warbler |
6,000,000 |
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4,900,000 |
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82% |
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Swamp Sparrow |
18,000,000 |
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15,000,000 |
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80% |
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Magnolia Warbler |
60,000,000 |
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46,000,000 |
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77% |
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Mourning Warbler |
36,000,000 |
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27,000,000 |
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75% |
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Hermit Thrush |
100,000,000 |
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72,000,000 |
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72% |
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Rusty Blackbird |
4,900,000 |
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3,400,000 |
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70% |
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Le Conte's Sparrow |
5,600,000 |
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3,900,000 |
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70% |
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