Blackpoll warbler

Blackpoll warbler
File:Dendroica striata MN.jpg
Conservation status
Least Concern (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Passeriformes
Family:	Parulidae
Genus:	Setophaga
Species:	S. striata
Binomial name
Setophaga striata (Forster, 1772)
File:Dendroica striata map.svg
Range of S. striata      Breeding range     Wintering range
Synonyms
Dendroica striata

The blackpoll warbler (Setophaga striata) is a New World warbler. Breeding males are mostly black and white. They have a prominent black cap, white cheeks and white wing bars. The blackpoll breeds in forests of northern North America, from Alaska, through most of Canada, the Great Lakes region and New England. They are a common migrant through much of North America. Come fall, they fly South to the Greater Antilles and the Northeastern coasts of South America in a non-stop long-distance migration over open water, averaging 2500 km, one of the longest distance non-stop overwater flights ever recorded for a migratory songbird. Rare vagrants to western Europe, they are one of the more frequent transatlantic passerine wanderers.

Description

File:Blackpoll Warbler PJT.JPG

Blackpoll warbler

The blackpoll warbler is a fairly small bird which attains the weight of a ball point pen. However, it is one of the larger of the diverse Setophaga genus (formerly Dendroica). In the species, body length can vary from 12.5 to 15 cm (4.9 to 5.9 in) and wingspan can range from 20 to 25 cm (7.9 to 9.8 in). Body mass can vary from 9.7 to 21 g (0.34 to 0.74 oz), with an average bird anywhere between 12 and 15 g (0.42 and 0.53 oz). Among standard measurements, the wing chord is 6.6 to 8 cm (2.6 to 3.1 in), the tail is 4.5 to 5.4 cm (1.8 to 2.1 in), the bill is 0.8 to 1.2 cm (0.31 to 0.47 in) and the tarsus is 1.8 to 2 cm (0.71 to 0.79 in). The summer male blackpoll warblers have dark-streaked brown backs, white faces and black crowns. Their underparts are white with black streaks, and they display two white wing bars. The adult females essentially resemble washed-out versions of the summer males, and in particular, the females lack the strong head patterns, and their crowns and faces are shades of gray. Another outstanding physical characteristic of the species are the bright orange, pink legs.

Non-breeding birds of this species have greenish heads, dark-streaked greenish upperparts and yellowish breasts, with the yellow extending to the belly in young birds. Their wing bars are always present.

Habitat

File:BlackpollWarbler.jpg

In fall plumage

In the southern portion of their breeding range, blackpoll warblers can be found on the higher elevations of mountains in woodland or brushy areas. They also spend their summers on the wooded coastal islands of Maine and the Maritime Provinces. Farther north they have been reported throughout the boreal coniferous forest. Blackpolls breed nearer to the tundra than any other warbler.

Behavior

Although fairly large for a warbler, blackpoll warblers are fairly easy to miss because of their relatively inactive foraging style and tendency to perch in dense foliage near the canopy of the trees. They are more often heard than seen, though their song is one of the highest pitched known. Their songs are simple repetitions of high tsi notes. Their calls are thin sits.

Foraging and diet

The blackpoll has a deliberate feeding style with occasional flitting, hovering and hawking around branches. They are primarily insectivorous. The species appears to be quite a generalist, preying on a great diversity of adult and larval insects and spiders. Documented insect prey for the species includes lice, locusts, cankerworms, mosquitoes, webworms, ants, termites, gnats, aphids and sawflies. It has been suggested that this species may be a spruce budworm specialist, but there is no obvious connection between population trends of the two species. The blackpoll will opt for berries in migration and during winter. They often forage high in trees, and sometimes catch insects while in flight.

Reproduction

Their breeding habitats are coniferous woodlands, especially those in which spruce trees grow. The bird's breeding ranges extend to the taiga. Blackpoll warblers commonly nest in a relatively low site of a conifer. They lay 3–5 eggs in a cup-shaped nest, rarely up to 9. The eggs are incubated for around 12 days and the young leave the nest when they are only 10 days old, before they can fly well. Their parents feed them for a total of around two weeks. Mated females usually begin second nests right away and leave post-fledging parental duties to their mates. The high incidence of double brooding, coupled with and partly a function of low nest predation and parasitism rates, results in high annual productivity for this species.

Migration

The blackpoll warbler's transoceanic flight has been the subject of over twenty-five scientific studies. Sources of data include radar observations, bird banding and weights taken, dead birds recovered from field sites and fatal obstacles. It is unknown if they feed on insects while in flight. Blackpoll warblers have the longest migration of any species of New World warbler. This is likely the reason that they are one of the later warblers to appear in spring migration, after one or more short overwater flights and a relatively prolonged movement overland after through North America anytime from early May to mid-June. The peak of their migration is in late May, when most warblers are on their breeding grounds.

In the fall the birds migrate from their breeding grounds across the northern latitudes. They converge on the Northeastern United States south to Virginia starting in mid-August. Most blackpolls fly directly from northeastern North America over the Atlantic Ocean to their winter range. Data from nocturnal accidents, banding stations and sightings have shown that blackpolls are rare autumn migrants south of Cape Hatteras, North Carolina, whereas north of Cape Hatteras they are common. Part of the fall migratory route of the blackpoll warbler is over the Atlantic Ocean from the northeastern United States to Puerto Rico, the Lesser Antilles, or northern South America. Island stopovers at Bermuda and other places are evidence of migratory pathways. To accomplish this flight, the blackpoll warbler nearly doubles its body mass in staging areas and takes advantage of a shift in prevailing wind direction to direct it to its destination. When they fly southward over the Atlantic they burn, 0.08 g of fat every hour. This route averages 3,000 km (1,900 mi) over water, requiring a potentially nonstop flight of around 72 to 88 hours. They travel at a speed of about 27 mph (43 km/h). Blackpolls can weigh more than 20 g (0.71 oz) when they leave the United States and lose 4 or more grams by the time they reach South America. Some of the blackpolls land in Bermuda before going on. Some birds, often with lower body weights, do not make it.

Using a tiny light level geolocator biologists have proven that the black poll flies an average of 2540 km (2270 to 2770 km) non-stop over an average of 62 h, up to 3 days, corresponding to about 41 km/h. In 2013, 37 blackpolls from Vermont and Nova Scotia carried a miniaturized geolocator weighing 0.5 g with harness on their back. The device recorded light-levels, from which longitudes and latitudes could be estimated, and in 2014 the scientists recovered five of the original 37. Four of the five birds departed from western Nova Scotia between September 25 and October 21, and traveled at speeds between 10.7 and 13.4 meters per second. The study revealed that the spring migration overland and the autumn routes overwater were "dramatically different". When the flight distance per body mass was compared to other birds, only the ruby-throated hummingbird might travel more kilometres per gram (estimated around 210-280 km/g vs. 233 km/g for blackpolls).

Further reading

Books

• Blackpoll Warbler. The Cornell Lab of Ornithology: All About Birds. Access: May 20, 2011
• Hunt, P. D., and B. C. Eliason. 1999. Blackpoll Warbler (Dendroica striata). In The Birds of North America, No. 431 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.

Thesis

• Baltz ME. Ph.D. (2000). The nonbreeding season ecology of neotropical migratory birds in the dry zone of Puerto Rico. University of Missouri – Columbia, United States, Missouri.
• Chisholm SE. M.Sc. (2005). The impact of precommercial thinning on abundance of Bicknell's Thrush and other high elevation birds. Dalhousie University (Canada), Canada.
• Davis AK. M.Sc. (1999). The stopover ecology of migratory landbirds on Bon Portage Island, Nova Scotia. Acadia University (Canada), Canada.
• Eliason BC. Ph.D. (1986). MATING SYSTEM, PARENTAL CARE, AND REPRODUCTIVE SUCCESS IN THE BLACKPOLL WARBLER (DENDROICA STRIATA) (POLYGYNY, KENT ISLAND, NEW BRUNSWICK, CANADA, BREEDING BIOLOGY). University of Minnesota, United States, Minnesota.

Articles

• Bledsoe AH. (1988). Nuclear DNA Evolution and Phylogeny of the New World Nine-Primaried Oscines. Auk. vol 105, no 3. pp. 504–515.
• Boag PT & Ratcliffe LM. (1979). 1ST RECORD OF A BLACKPOLL WARBLER FOR THE GALAPAGOS. Condor. vol 81, no 2. pp. 218–219.
• Boag PT & Ratcliffe LM. (1979). Blackpoll Warbler Dendroica-Striata New-Record for the Galapagos. Condor. vol 81, no 2. pp. 218–219.
• Boal CW, Sibley FC, Estabrook TS & Lazell J. (2006). Insular and migrant species, longevity records, and new species records on Guana Island, British Virgin Islands. Wilson Journal of Ornithology. vol 118, no 2. pp. 218–224.
• Bosque C & Lentino M. (1987). The Passage of North American Migratory Land Birds through Xerophytic Habitats on the Western Coast of Venezuela. Biotropica. vol 19, no 3. pp. 267–273.
• Cherry JD, Doherty DH & Powers KD. (1985). An Offshore Nocturnal Observation of Migrating Blackpoll Warblers Dendroica-Striata. Condor. vol 87, no 4. pp. 548–549.
• Darveau M, Beauchesne P, Belanger L, Huot J & Larue P. (1995). Riparian forest strips as habitat for breeding birds in boreal forest. Journal of Wildlife Management. vol 59, no 1. pp. 67–78.
• Davis AK. (2001). Blackpoll Warbler (Dendroica striata) fat deposition in southern Nova Scotia during autumn migration. Northeastern Naturalist. vol 8, no 2. pp. 149–162.
• Desgranges JL & Rondeau G. (1995). CHANGES IN THE BIRD COMMUNITIES OF A BALSAM FIR WHITE BIRCH FOREST FOLLOWING AN INSECT PEST EPIDEMIC. For Chron. vol 71, no 2. pp. 201–210.
• Deviche P, Greiner EC & Manteca X. (2001). Interspecific variability of prevalence in blood parasites of adult passerine birds during the breeding season in Alaska. Journal of Wildlife Diseases. vol 37, no 1. pp. 28–35.
• Dowie MI. (1993). Blackpoll warbler in Shetland. British Birds. vol 86, no 5. pp. 206–209.
• Eliason BC. (1986). Female Site Fidelity and Polygyny in the Blackpoll Warbler Dendroica-Striata. Auk. vol 103, no 4. pp. 782–790.
• Graves GR. (1996). Hybrid wood warblers, Dendroica striata X Dendroica castanea (Aves: Fringillidae: Tribe Parulini) and the diagnostic predictability of avian hybrid phenotypes. Proceedings of the Biological Society of Washington. vol 109, no 2. pp. 373–390.
• Holberton RL, Wilson CM, Hunter MJ & Lee AW. (2000). An endocrine basis of different migratory strategies in long- and short-distance neotropical migrants. American Zoologist. vol 40, no 6.
• Hunt PD & Eliason BC. (1999). Blackpoll Warbler: Dendroica striata. Birds of North America. vol 0, no 431. pp. 1–24.
• Hussell DJT & Lambert AB. (1980). New Estimates of Weight Loss in Birds During Nocturnal Migration. Auk. vol 97, no 3. pp. 547–558.
• Jobson GJ. (1978). BLACKPOLL WARBLER IN ISLES OF SCILLY. British Birds. vol 71, no 4. pp. 186–187.
• Latta SC & Brown C. (1999). Autumn stopover ecology of the Blackpoll Warbler (Dendroica striata) in thorn scrub forest of the Dominican Republic. Canadian Journal of Zoology. vol 77, no 7. pp. 1147–1156.
• McNair DB, Arendt WJ & Massiah E. (1996). Sightings of the blackpoll warbler in the West Indies during winter. Florida Field Naturalist. vol 24, no 3. pp. 81–82.
• McNair DB, Massiah EB & Frost MD. (2002). Ground-based autumn migration of Blackpoll Warblers at Harrison Point, Barbados. Caribbean Journal of Science. vol 38, no 3-4. pp. 239–248.
• McNair DB & Post W. (1993). Autumn migration route of blackpoll warblers: Evidence from southeastern North America. Journal of Field Ornithology. vol 64, no 4. pp. 417–425.
• Morris SR, Holmes DW & Richmond ME. (1996). A ten-year study of the stopover patterns of migratory passerines during fall migration on Appledore island, Maine. Condor. vol 98, no 2. pp. 395–409.
• Morse DH. (1979). Habitat Use by the Blackpoll Warbler Dendroica-Striata. Wilson Bulletin. vol 91, no 2. pp. 234–243.
• Murray BG. (1979). Fall Migration of Blackpoll Warblers Dendroica-Striata and Yellow-Rumped Warblers Dendroica-Coronata-Coronata at Island Beach New-Jersey USA. Bird Banding. vol 50, no 1. pp. 1–11.
• Nisbet ICT, McNair DB, Post W & Williams TC. (1995). Transoceanic migration of the Blackpoll Warbler: Summary of scientific evidence and response to criticisms by Murray. Journal of Field Ornithology. vol 66, no 4. pp. 612–622.
• Norman DM. (1978). BLACKPOLL WARBLER IN DEVON. British Birds. vol 71, no 1. pp. 41–42.
• Ralph CJ. (1981). Age Ratios and Their Possible Use in Determining Autumn Routes of Passerine Migrants. Wilson Bulletin. vol 93, no 2. pp. 164–188.
• Rimmer CC, McFarland KP, Evers DC, Miller EK, Aubry Y, Busby D & Taylor RJ. (2005). Mercury concentrations in Bicknell's thrush and other insectivorous passerines in Montane forests of northeastern North America. Ecotoxicology. vol 14, no 1-2. pp. 223–240.
• Rimmer CC & Tietz JR. (2001). An adult male Blackpoll Warbler in female-like plumage. Journal of Field Ornithology. vol 72, no 3. pp. 365–368.
• Roberts RE & Tamborski CV. (1993). Blackpoll warbler mortality during fall migration at a tower in southeastern Florida. Florida Field Naturalist. vol 21, no 4. pp. 118–120.
• Sabo SR. (1980). Niche and Habitat Relations in Subalpine Bird Communities of the White Mountains of New-Hampshire USA. Ecological Monographs. vol 50, no 2. pp. 241–260.
• Stewart PA. (1986). Fall Migration of Twelve Species of Wood Warblers through Coastal Virginia USA. North American Bird Bander. vol 11, no 3. pp. 83–88.
• Stiles FG & Campos RG. (1983). Identification and Occurrence of Blackpoll Warblers Dendroica-Striata in Southern Middle America. Condor. vol 85, no 2. pp. 254–255.
• Swanson DL, Carlisle HA & Liknes ET. (2003). Abundance and richness of Neotropical migrants during stopover at farmstead woodlots and associated habitats in southeastern South Dakota. American Midland Naturalist. vol 149, no 1. pp. 176–191.
• Thorup K, Ortvad TE & Rabol J. (2006). Do nearctic Northern Wheatears (Oenanthe oenanthe leucorhoa) migrate nonstop to Africa?. Condor. vol 108, no 2. pp. 446–451.
• Walley WJ. (1989). Breeding Blackpoll Warblers Dendroica-Striata in Duck Mountain Provincial Park Manitoba Canada. Canadian Field Naturalist. vol 103, no 3. pp. 396–397.
• Whitaker DM, Carroll AL & Montevecchi WA. (2000). Elevated numbers of flying insects and insectivorous birds in riparian buffer strips. Canadian Journal of Zoology. vol 78, no 5. pp. 740–747.
• Wigh RJ. (2003). Blackpoll Warbler at sea. Oriole. vol 68, no 3-4.
• Woodrey MS & Moore FR. (1997). Age-related differences in the stopover of fall landbird migrants on the coast of Alabama. Auk. vol 114, no 4. pp. 695–707.

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External links

• Blackpoll warbler species account – Cornell Lab of Ornithology
• Blackpoll warbler – Dendroica striata – USGS Patuxent Bird Identification InfoCenter
• Stamps for: Grenada, Guyana at bird-stamps.org
• Blackpoll warbler videos, photos, and sounds at the Internet Bird Collection
• Blackpoll warbler photo gallery at VIREO (Drexel University)