Canada Warbler Cardellina canadensis
Version: 2.0 — Published May 7, 2020
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Movements and Migration
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Dispersal and Site Fidelity
Natal Philopatry and Dispersal
Two birds first captured as juveniles were caught in subsequent years in the same location (123). In New Hampshire, 13 individuals banded as nestlings returned to the same breeding population including at least 3 females (LRR, unpublished data) and 3 males, sometimes returning late as presumed nonbreeding floaters. A male banded as a nestling in one site in New Hampshire came back to breed 5 km north of its birth site (LRR, unpublished data).
Fledgling telemetry conducted in New Hampshire documented high variation in distances initially dispersed by fledglings. Some leave detection range in less than 1 wk of fledging and others persist for the life of the transmitters (12 days).
Adult Fidelity to Breeding Site and Dispersal
In New Hampshire study initiated in 2003, > 50% overall fidelity of males to breeding sites; individuals return to within 25–35 m of previous territory centers in subsequent years (98). Females also exhibited site fidelity in this study, returning to same general area to breed, generally 0.5–1.0 km from previous year's mate's territory. In southeastern Massachusetts, marked adults observed returning to same breeding location for up to 4 subsequent yr (123).
Frequency and distance of dispersal from breeding sites unknown. One breeding female in central New York returned 2 yr later to same general location to breed again, then was subsequently recovered 5 yr later (25 May 1971) near Cleveland, Ohio, 800 km west of original breeding site after flying into window (R. Pantle, personal communication).
Fidelity to Overwintering Home Range
Fidelity to overwintering grounds unknown.
Complete, Neotropical–Nearctic migrant; traveling annually between breeding areas in northern and eastern North America and overwintering areas in northern South America. Compared to other warblers, arrives breeding areas late in spring and departs early in fall (see Figure 1; 94, 28, 124, 125, 126); the last warbler to arrive and first to leave in Alberta (127, 128, 129).
Timing and Routes of Migration
Typically departs breeding areas mid-July to late August in British Columbia (126). Recent tracking data documented departure by males from Alberta, Manitoba, and New Hampshire in late August (130). Using a coordinated radio-telemetry network, birds were documented departing one hour after sunset in late August from breeding grounds in Quebec (M. Bégin, unpublished data). Manitoba birds arrived in South America past mid-October with two-thirds overwintering in Columbia and one-third in Venezuela. Alberta birds arrived in early November with half in Columbia and half in Venezuela. Males from New Hampshire all overwintered in Columbia and arrived in early November. On average, females leave northern Alberta before males (3 August vs. 10 August; 128).
Main passage is rapid and compressed, extending locally over about 3 wk (131, 132). Peak is late August to early September in Ontario (133, 134), 30 August in southern Maine (135), 26 August–4 September in western Pennsylvania (136), 29 August–11 September in New Jersey (137), 18 August–3 September in central Illinois (138), 5–15 September in coastal Alabama (139; F. Moore and D. Cimprich, unpublished data), 11–20 September in Texas (15, 124), 8–27 September in Oaxaca, Mexico (61), 21–30 September in Veracruz, Mexico (124) and on Cozumel Island, Mexico (140). Regular but rare vagrant during September (extremes 24 August and 16 October) in Bermuda (83). Rare (25 September–16 October) in Florida (141), very rare transient during September and October (extremes early August and 20 November) in California (142), and extremely rare (4 records) during September and October in Oregon (143).
First individuals reach Central America by early September (132, 144). Rare migrant in Belize 15 September–14 October (63, 145), 8 September–7 October in Guatemala, 21 September–7 October in Honduras (62), and early September–early November in Costa Rica (144). Peak is late September–early October (extremes early September and late November) in Panama (60). Begin to arrive on overwintering grounds end of September in Colombia and early October in Peru (59). Data from geolocators indicates that fall migration (departure to arrival) lasts over 50 d (130).
As in fall, main passage is rapid and compressed. Most birds leave overwintering grounds by late March in Peru, early April in Ecuador, and mid-April in Colombia (14, 59). Peak migration late April–early May in Panama (6, 60), mid-April in Honduras (62), 22 April–12 May in Oaxaca, Mexico (61), 1–10 May in Veracruz, Mexico (124), 2–20 May in Texas (15, 124), 25 April–7 May in coastal Alabama and Mississippi (F. Moore and D. Cimprich, personal communication), first two weeks of May in Kentucky (55), 29 May in Chicago (138), last two weeks of May in Michigan (146, 90, 90), late May in Minnesota (147), mid to late May in New Jersey (137), second week of May in Massachusetts (52) and Vermont (97), 11–18 May in New Hampshire (Reitsma et al., unpublished data 2003–2019), 28 May in Maine (135, S. Morris, personal communication), last week of May in Ontario (148, 125, 134), final days of May to early June in British Columbia, Saskatchewan, and Alberta (149, 150, 127, 126). In northern Alberta, older males arrive first (May 30, on average) followed by young males (June 1), old females (June 2) and eventually young females (June 3) (128). Extremely rare transient (< 1 record/season) 20 May–20 June in coastal California (142). Light-level geolocator data from one male documented a total time of 30 days from departing Colombia to arriving in New Hampshire (130). This same individual took 55 days to complete fall migration between New Hampshire and Colombia the previous fall.
During migration commonly occurs west to eastern North Dakota, eastern Nebraska, eastern Kansas, western Oklahoma, central Texas, and eastern Mexico (12, 67). Rare but regular in California, mainly in fall (early September through October), also in northeastern Montana. Relative to adults, young of the year appear to migrate more along the coast in their first southbound migration; e.g., the majority of birds captured during spring (99.4% of 161) and fall (86.5% of 245) migration in southeastern coastal Maine were young birds (135, 151).
Southerly fall route mainly in and west of the Appalachian Mountains (avoiding southeastern states), through south coastal Texas, through highlands in eastern Mexico (generally absent from Yucatan peninsula), Guatemala, southern Belize (rarely), northern El Salvador, Honduras, Nicaragua, Costa Rica, Panama and on to South America (14, 2, 124, 5). Midwest and central Canada breeders proceed straight to Texas coast (2). Rarity of records on eastern Gulf Coast and in Florida, West Indies, Bahamas, Bermuda, Puerto Rico, Jamaica, and Cuba (73, 8) suggests individuals do not cross Caribbean directly (4). Western breeders fly east before turning south (130). Breeding males from Alberta, Manitoba and New Hampshire converge in northeastern Mexico, fly over a portion of the western Gulf of Mexico and proceed through eastern Central America before arriving in South America (130).
Rare migrant along California coast (especially during fall in south) and very rare during fall migration in coastal and south-central Oregon (143, 142). In southern Mexico, birds apparently cross over to Pacific slope of Central America and proceed along narrow coastal route or move south along montane areas of Central America to overwintering grounds in northwestern South America (124, 5).
In spring, populations overwintering in the western part of the overwintering range may cross the eastern Pacific Ocean south of Central America proceeding directly to southern Mexico (124). Once in North America, the spring migration route is largely similar to the southerly fall route with a possible eastward shift (2). More abundant during spring than fall migration in coastal Texas (124, 7). Longer stopovers in fall compared to spring in Maine (135). One male used similar routes between Colombia and New Hampshire in both directions (130). Migration period is longer in fall than in spring.
Nocturnal migrant (152); possibly migrating as pairs (but see A. F. Skutch in Bent ). Observed from Pacific coast up to 1,980 m elevation during fall migration in Central America (A. F. Skutch in Bent ). Stopover periods longer during fall (3.4 d ± 2.3 SD, range 1–10, n = 20) than spring in Maine (135, 151). Greater numbers captured during spring migration (447) than in fall migration (261) over a 13-year study in western Pennsylvania (136).
Speed, Method of Orientation, Response to Weather
Degree of Flocking
During fall migration, observed in mixed-species flocks that were often lead by Black-capped Chickadees (Poecile atricapillus) and Tufted Titmouse (Baeolophus bicolor), and occurring most often along mature forest edges and in shrub/sapling-stage forests (153). Observed in mixed-species flocks lead by Tufted Titmouse during fall in Michigan, along with American Redstart (Setophaga ruticilla) and Magnolia (S. magnolia), Black-throated Green (S. virens), Blackburnian (S. fusca), Bay-breasted (S. castanea), Chestnut-sided (S. pensylvanica), and Black-and-white (Mniotilta varia) warblers (154). Often associated with Wilson's Warbler (Cardellina pusilla) during migration (8). In Panama, occur exclusively as single birds or pairs within mixed-species flocks of small insectivorous birds with antwrens (Microrhopias quixensis and Myrmotherula spp.; 6). Proportion of mixed-species flocks observed containing 1–2 Canada Warblers: 40 of 67 flocks during spring and 21 of 50 during fall (6). In Ecuador, individuals observed regularly both alone and in flocks with some joining flocks for short periods as the flock passes through the bird’s territory (MTH, LR, personal observations). A greater proportion of territorial individuals in primary forest were older males (P. Benham, unpublished data).
Differential Migration of Age/Sex Classes
Majority of migrants at an island stopover site in Maine were hatch-year/second-year birds; 99.4% of 161 birds during spring, 95.7% of 47 birds during fall (135). Fifty-seven percent of 288 fall migrants in coastal Texas were immatures (124); 79% of 224 fall migrants in western Pennsylvania were immature (hatch-year) birds (136).
Mean arrival dates for males slightly earlier than for females at banding stations along migration route (126) and on established breeding grounds with high site fidelity. In southern coastal Maine, males arrive 4 d earlier than females in spring, but no difference during fall migration (S. Morris, personal communication). In New Hampshire, males arrive on territories an average of 5 d before females with a high degree of variation among individuals of both sexes (L. Reistma et al., personal observation). No detectable difference in fall passage dates between sexes in coastal Alabama (F. Moore and D. Cimprich, unpublished data). Males arrive earlier than females on breeding grounds in Quebec (155) and Ontario (3.2 d earlier [P < 0.01]; 125). Evidence suggesting adult males arrive earlier in spring than immature (second-year) males in Ontario (wing length negatively correlated with arrival date; 125). Older males arrive on average at least one week prior to second-year males on breeding grounds in New Hampshire, but with considerable individual variation within age classes (L. Reitsma et al., personal observation).
Mean fall passage for immature (hatch-year) birds occurs significantly earlier compared to adult birds in coastal Alabama (F. Moore and D. Cimprich, unpublished data), further corroborated by early dispersal of fledglings with transmitters from natal grounds in New Hampshire (L. Reitsma et al., unpublished data). Peak for adults 5 d after peak for immatures in western Pennsylvania (136).
Control and Physiology of Migration
Little information. Most birds captured during spring (84.2% of 177) and fall (71.7% of 46) migration at a Maine stopover site had little or no fat; comparatively higher percentages than 8 other species of migrant warbler (135). Fall migrants gained an average of 0.1 g/d ± 0.4 SD (151). Analysis of energetic condition (calculated as a scaled mass index [SMI] based on wing length and body mass) at a stopover site on the south shore of Lake Ontario in New York found that females had significantly greater energetic condition than males, and both sexes showed increases in energetic condition between fall and spring migration. Later arriving birds in spring exhibited greater energetic condition than earlier arriving birds corresponding to an increase of SMI by 0.3 per day (156).