SPECIES

Blackpoll Warbler Setophaga striata Scientific name definitions

William DeLuca, Rebecca Holberton, Pamela D. Hunt, and Bonita C. Eliason
Version: 1.0 — Published March 4, 2020
Text last updated June 4, 2013

Movements and Migration

Migration Overview

Complete, annual obligate long-distance migrant, traveling between breeding areas in n. North America and wintering areas in n. South America. Generally leaves breeding areas in Aug and arrives on wintering grounds beginning in late Sep – early Oct. Leaves winter range in Apr and arrives on breeding range mid-May to early Jun. Often lingers south of breeding range into mid-summer. Both fall and spring migrations last longer than those of most other warblers.

Timing and Routes of Migration

Fall

See Figure 2. Most individuals leave breeding grounds in Alaska and the Yukon by late Aug (Gabrielson and Lincoln 1959, Sinclair et al. 2003); latest birds in Newfoundland early Oct (Peters and Burleigh 1951). Passage birds (non-breeders) begin moving through the Churchill, MB, area in late Jul through first half of Aug (RLH, unpubl. data). Western birds travel southeast across Canada and the n. U.S., passing through s. Alberta by mid-Sep (Sadler 1976). Peak Blackpoll numbers at Long Point, Ontario between mid-Sep and first half of Oct.

Further south, migration occurs primarily early Aug–early Oct in Minnesota (Janssen 1987), and the last half of Aug (rarely late Jul) through the second week Oct (rarely early Nov) in Ohio (Peterjohn 1989b). In the East, peak numbers in Nova Scotia during Sep and early Oct (Tufts 1986), and mid-Sep through mid-Oct in New England (Rimmer and McFarland 2000, Lloyd-Evans and Atwood 2004), with stragglers occurring regularly through late Nov in Massachusetts (Veit and Petersen 1993). 18% (18 out of 100 BLPWs) captured at coastal mid-coast Maine (Metinic I.) during October 2010 had deuterium isotope signatures indicating breeding origins from areas spanning e. Alaska to w. Hudson Bay region (Hobson, Holberton, Leppold unpubl. data).

In Cape May, NJ, migrants late Aug–early Nov, peaking early Sep–Oct (Sibley 1997); in Tennessee, primarily mid-Sep through mid-Oct (Robinson 1990a). In Florida, migrants observed 11 Sep through 14 Nov, with tower kills in Leon Co. recorded 24 Sep–7 Nov (Stevenson and Anderson 1994b). Generally rare or absent in se. and s.-central U.S. in fall (McNair and Post 1993a, eBird), where described as rare to uncommon in S. Carolina; very rare to rare in e. Missouri, Kentucky, Tennessee, and Alabama; and accidental in Arkansas and Louisiana. Most records from this region from late Aug to early Nov.

Occasionally common in Bermuda from late Sep to late Oct (Amos 1991). Passes over Hispaniola, Puerto Rico, the Virgin Is., and Lesser Antilles beginning in Sep, although not common until Oct (Raffaele 1989, Evans 1990a). Arrives in n. South America beginning in mid-Sep, with peak numbers in Oct (Paynter 1995). Rare in coastal Venezuela after Dec (Bosque and Lentino 1987). Regular vagrant to Pacific Coast of U.S. in Sep and Oct (average of 110/fall in California; Roberson 1980), but accidental elsewhere west of the Great Plains. Very rare in Costa Rica and Panama in Oct and Nov (Stiles and Campos 1983).

Most evidence supports the hypothesis that most individuals of this species undertake an overwater flight from the ne. U.S. and Maritime Provinces to n. South America (Nisbet 1970, Nisbet et al. 1995a, cf. Murray Murray 1965, Murray 1989). Birds from western breeding range travel southeast across Canada and the n. U.S., collecting along the coastal plain between Nova Scotia and Cape Hatteras, NC, and as far inland as w. Massachusetts (150 km) and W. Virginia (350 km), where they meet migrants moving south or southwest from the eastern breeding range. Most then head south or southeast over the Atlantic Ocean, at which point they are assisted by periodic northwest winds (Williams et al. 1978). As they approach the Tropic of Cancer, they encounter the northeast trade winds, which deflect them south and southwest toward the South American mainland. This route varies from 2,500 to 3,500 km and is estimated to take up to 88 h (Williams et al. 1978). Small numbers also appear to migrate through the se. U.S. and reach South America via the Greater Antilles (see below).

The evidence for an overwater route is varied. Distributional data are equivocal, but indicate that the species is usually rare in the se. U.S. in fall (Nisbet 1970, McNair and Post 1993a, Roberts and Tamborski 1993, eBird, cf. Murray 1989). In contrast, it can be one of the most common warblers at coastal stations north of N. Carolina. Radar studies have detected large numbers of passerine birds departing over the ocean along the coast, or actually passing over ship-based radar far out to sea (Drury and Keith 1962, Drury and Nisbet 1964, Williams et al. 1977a, Williams et al. 1978). Observers on boats have directly seen hundreds of Blackpoll Warblers over the ocean, often moving at the same time as other known transoceanic migrants such as shorebirds (Cherry et al. 1985, Brady 1992a, Brady 1992b). Other species of passerines have generally been rare at these times (but see Mcclintock et al. 1978).

The species is a common fall migrant at Bermuda (Amos 1991), which lies directly in the proposed migratory route, but is a very rare fall visitor in the Caribbean west of Hispaniola (Pashley 1988c). All large concentrations in Florida and the Bahamas have coincided with unusual weather systems that probably forced birds to the west of the normal migration route (Kale II et al. 1969, Nisbet 1970, Roberts and Tamborski 1993).

Ratios of adult to yearling birds are higher along the ne. U.S. coast than ratios for other warblers: 61% (Nisbet et al. 1963), 33% (Able 1977), and 25% (Morris et al. 1996). If adult ratios are higher near the center of a species' fall migration route (Ralph 1981), then these data also support the overwater migration hypothesis. This is further supported by the observation that only 44% of Blackpoll Warblers captured in Bermuda were yearling birds (Ralph 1981).

In further support for a trans-oceanic fall migration route, analysis of a 15-year period of the breeding abundance, as measured by Breeding Bird Survey, of eastern populations of the Blackpoll warbler found a negative correlation with the frequency of storms over the western Atlantic; such patterns were not found for most other songbird migrants similarly examined (Butler 2000).

Body-mass data are somewhat harder to interpret. Nisbet et al. (Nisbet et al. 1963) give fat-free mass of 11.2 g and state that birds leave New England at 20–23 g. Grounded birds in Bermuda weigh 13–16 g, suggesting that these birds would normally have continued over the island (Nisbet et al. 1963). Birds captured in coastal New Jersey ranged from 8.5 to 22.1 g, with weights on average lower than other studies (Murray and Jehl 1964). This, plus low fat levels, may indicate that birds were coming in from longer flights (perhaps from New England). Birds captured in Puerto Rico and Hispaniola in Oct are often emaciated and below fat-free weight (M. Baltz and S. Latta pers. comm.), as are those arriving in n. South America (Nisbet et al. 1963). In laboratory studies, Blackpolls rapidly gain dramatically more mass (increase from 12.0 g to 24+ g) and maintain much higher levels of fat and plasma triglycerides during the autumn migration period compared to the shorter-distance primarily overland migrant, the Yellow-rumped warbler (S. coronata; Holberton & Dufty 2005). Altogether, these data suggest the capacity for long flights uninterrupted by opportunities for foraging and weight gain.

There are, however, some data that suggest that not all Blackpolls fit this hypothesis. Murray (Murray 1965, Murray 1989, pers. comm.) has pointed out that the timing of arrival on Bermuda does not match peak departures from the mainland. He also stated that radar in the Caribbean has not detected any passerine arrivals from over the ocean, and that bird movements detected on ship-based radar do not always show a consistent orientation. Murray also commented on the use of relative-abundance estimates in the se. U.S. as a potential source of bias or error. Finally, weights of birds from Florida average 16.5 g (Murray 1989), which Murray views as higher than expected for birds diverted from long overwater flights (but not too high for birds traveling from closer points such as West Virginia; I. Nisbet pers. comm.). These are all valid criticisms, and it is worth considering the possibility that some Blackpoll Warblers do follow the coast south through the se. U.S. in fall. More detailed data on abundance and migration timing in this region, including age ratios and physical condition, are needed before the importance of this alternate migration route can be assessed.

Spring

See Figure 2. Leaves n. South America in early to mid-Apr (Paynter 1995), with rare stragglers into mid-May (Thomas 1993). Spring migration route poorly known south of the U.S. Most spring migrants appear to pass through the w. Caribbean (Pashley 1988c, O. Garrido and A. Kirkconnel unpubl. data). Rare or accidental in the e. Caribbean (Pashley 1988b, Raffaele 1989, Pashley and Hamilton 1990), Jamaica (Downer and Sutton 1990), Mexico, and Central America (Ridgely and Gwynne 1989, Howell and Webb 1995), with most records in Apr.

Evidence from the Caribbean and Central America suggests overwater flight from South America to Cuba, the Bahamas, and the se. U.S. Arrives in Florida by mid-Apr (rarely late Mar) with tower kills in Leon Co. peaking 21 Apr–10 May but extending to 26 May. Sight reports through late Jun and early Jul could pertain to late migrants or summering birds (Stevenson and Anderson 1994b). In Tennessee, migrants seen mostly late Apr–late May (Robinson 1990a), early May–early Jun in Cape May, NJ, with extreme dates of 28 Apr and 22 Jun (Sibley 1997), and early May through late May, peaking 15 May–25 May in Ohio, with a few stragglers into Jun (Peterjohn 1989b). The bulk of migrants occur mid-late May in Massachusetts (Veit and Petersen 1993, Lloyd-Evans and Atwood 2004) and in Minnesota (Janssen 1987). Arrive in maritime Canada and British Columbia by mid-May (Peters and Burleigh 1951, Tufts 1986, R. W. Campbell pers. comm.), and Alaska by early Jun (Gabrielson and Lincoln 1959).

Most spring migration occurs east of the western Great Plains. Rare but regular west of the Rocky Mtns. in mid-May through Jun, especially in California (Small 1994). Regularly recorded into early Jun south of the breeding range. No difference in timing of males and females in s. Ontario (Francis and Cooke 1986), although males arrive before females at breeding areas in New Brunswick and at Churchill, MB (Eliason 1986b). Males observed on breeding territories at Churchill, MB, by the end of May, often before significant snow melt has occurred, with first females arriving during the first week in Jun (RLH, unpubl. data).

Nonbreeding birds seen on Kent I., New Brunswick (NB), up to 10 d earlier than birds that breed there (Eliason 1986b). In most north temperate regions, locally breeding individuals of a species arrive before conspecific passage migrants (Phillips 1951a). The reversal in coastal New Brunswick may stem from the maritime climate there -- phenologically less advanced than inland breeding sites farther north. It may be feasible for birds to take up residence on these inland sites earlier than in coastal areas (Eliason 1986b).

Vagrancy

Perhaps due to its wide breeding range, vagrants of this species are regularly recorded outside of the normal migration route in w. North America, primarily in spring. Several fall records for Greenland, Iceland, and the British Isles add credence to the possibility of regular overwater flights from the ne. U.S. and maritime Canada. Scattered records on the Pacific slope of Mexico in both spring and fall (Howell and Webb 1995, Almazán-Núñez 2009).

South American records away from known wintering areas include the Galapagos Is., 16 May 1976 (Boag and Ratcliffe 1979), and n. Chile, 17 Jun 1858 (Bent 1953b). Given the dates and locations of these two records, they may represent reversed spring migrants. Experiments on captured vagrants in California suggest that these birds arrive in the w. U.S. largely as a result of mirror-image misorientation across the north-south axis (DeSante 1973). Study of fall warbler vagrancy patterns in California in relation to budworm outbreaks in ne. U.S. makes no mention of the Blackpoll (Patten and Burger 1998). Single record from Cornwallis I., Northwest Territories, on 23 May 1971, > 1,000 km north of the nearest known breeding population (Caron 1974), was likely an overshooting spring migrant. See also Distribution: outside the Americas, above.

Migratory Behavior

Migrates primarily at night, although diurnal movements are often necessary during long overwater flights and at high latitudes in spring and fall, most likely due to shorter periods of darkness during the migration periods. (Holberton, unpubl data). Captive Blackpolls placed in Emlen funnels showed significantly southerly oriented activity during daytime tests in early Sep at Churchill, Manitoba (Holberton, unpubl data). Based on radar data (not necessarily this species), in autumn most depart from New England coast between 18:00 and 24:00 (Drury and Keith 1962). Blackpolls returning to land after shorter overwater flights or offshore drift generally make landfall before noon (Murray 1976b). Radar data show average flight altitude of overwater passerine migrants at 400–800 m within 4 h after sunset in New England (Nisbet et al. 1963). Over entire course of autumn overwater flight, altitude rises from 1,000–2,000 m at Bermuda to 3,000–6,000 m over Antigua, then drops below 800 m as birds approach South America over Tobago (Williams et al. 1977a). Average flight speed of 38–43 km/h based on radar observations (Nisbet et al. 1963, Williams et al. 1978). One bird banded in Michigan was recaptured in Connecticut 6 d later, thus traveling a minimum of 186 km/night (Walkinshaw 1976).

Most fall migrants leave coast of ne. North America on northwest tailwinds following passage of cold fronts (Williams et al. 1977a). As they approach the Tropic of Cancer, the winds shift to the northeast, allowing for drift south toward the Lesser Antilles and South America. During this time, individuals apparently maintain a southeast orientation (Williams et al. 1977a). Over the Lesser Antilles, flight above 4,000 m results in lower wind speeds and less headwind than at lower altitudes (Williams et al. 1977a).

Four of 5 captive Blackpoll Warblers showed southerly orientation in fall in s. New England, in contrast to other species tested at the same time (Able 1977). Orientation experiments with vagrants in California showed that birds exhibited 4 main orientation directions: the “correct” orientation of SE, the mirror orientation of SW, the reverse orientation of NW, and the mirror of the reverse at NE (DeSante 1973). DeSante further speculated that mirror-image orientation errors were the cause of this species' vagrancy to the coast of California.

Migratory restlessness in captive birds in California increases slightly between late Sep and mid-Oct and decreases markedly by mid-Nov (DeSante 1973). Average length (minimum) of stopover of 1.8 d in fall on Appledore I., ME (Morris et al. 1996). Some birds stayed for 2–3 wk in e. Massachusetts (Nisbet et al. 1963).

Control and Physiology of Migration

Little information, primarily limited to studies of weight loss and fat deposition. Rates of weight loss are apparently very low during migration: 0.062 g/h (Nisbet et al. 1963). Blackpolls may experience a 15-fold lower rate of mass loss (0.008g/h, n= 214) in flight compared to other species (e.g. Yellow-rumped warbler: 0.124 g/h, n = 636), while actively migrating overland in autumn (Hussell and Lambert 1980), suggesting physiological adaptation for long flights. Birds kept in captivity initially lost weight, but subsequently gained >3 g in 12–23 d; deposited more fat than congeners (Nisbet et al. 1963).

In preparation for extensive non-stop flights, Blackpolls may experience a greater increase in metabolic activities that support dramatic gains in body mass and lipid reserves compared to shorter distance migrants. Yarbrough (Yarbrough 1970a) documented an increase in lipid levels in late July in n. Manitoba, probably in preparation for fall migration. Holberton and colleagues (Holberton and Dufty 2005, unpubl. data) found that during early autumn migration studies at Churchill, MB, free-living Blackpolls showed similar body mass, fat reserves, and plasma levels of triglycerides as Yellow-rumped Warblers. Similarly, when held in captivity during the early onset of migration, Blackpolls gained no more mass than Yellow-rumps did but rapidly doubled in body mass in 7-10 d later in the migration period.

Blackpolls can maintain extraordinarily high body mass and fat reserves, as well as high levels of plasma triglycerides, compared to Yellow-rumped Warblers (Holberton and Dufty 2005). Blackpolls in captivity can gain as much as 20 g above fat free mass (32 g total body mass). Similarly, captive vagrants in California gained 11 g in 40 d (DeSante 1973). Nisbet et al. (Nisbet et al. 1963) proposed a departure weight of at least 20 g for overwater flight to be successful. Estimated caloric cost of flight 1.02 kcal/h (Nisbet et al. 1963).

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Blackpoll Warbler

Setophaga striata

Abundance

Estimates of relative abundance for every week of the year animated to show movement patterns. Relative abundance is the estimated average count of individuals detected by an eBirder during a 1 hour, 1 kilometer traveling checklist at the optimal time of day for each species.   Learn more about this data

Relative abundance
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Week of the year

Recommended Citation

DeLuca, W., R. Holberton, P. D. Hunt, and B. C. Eliason (2020). Blackpoll Warbler (Setophaga striata), version 1.0. In Birds of the World (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.bkpwar.01