Willow Flycatcher (Empidonax Traillii) Robert B

Willow Flycatcher (Empidonax traillii) Robert B. Payne

(Click to view a comparison of Atlas I to II) © Jerry Jourdan Distribution Willow Flycatchers are widespread in late Willow Flycatchers are common summer spring and summer in northeastern North residents in southern Michigan and are sparsely America and in much of the northern plains and distributed in northern Michigan. In Michigan in the west. The species was known in earlier they are generally more southern than Alder records in Michigan as "Alder Flycatcher" and Flycatchers, but the two species overlap in their "Traill's Flycatcher" (Barrows 1912, Wood breeding range throughout the SLP and NLP. 1951), and the early records did not distinguish Willow Flycatchers live in a variety of habitats between two distinct species, Willow Flycatcher of upland brush and lowland swamps, in and Alder Flycatcher. Only about 80-90% of overgrown uplands, dry marsh with unplowed birds of the two species can be distinguished in brushy grassy fields, old pasture land and morphology, but their behavior is distinct. thickets, shrubs along the edges of streams, and Willow Flycatchers give two song themes in wet thickets of willow, alder and buckthorn. In irregular alternation, "FITZ-bew!" and "FEE- southern Michigan most birds arrive from 7 to BEOO!" As they sing, Willow Flycatchers toss 17 May. The birds remain on their breeding back their heads further for the first note (in grounds from May through August and some "FITZ-bew!") or the same distance for the first birds are seen there in early September and second notes (in "FEE-BEOO!"). The (Walkinshaw 1966). second song theme is sometimes mistaken for the "knee-DEEP!" single song theme of Alder Breeding Biology Flycatchers. The call of the Willow Flycatcher In Michigan, as many as 45 nesting pairs of is a liquid "whit" (Stein 1958, 1963). Willow Willow Flycatchers have been observed locally Flycatchers are long-distance migrants and in 100 ha in a breeding population (Berger winter in the Pacific lowlands in southwestern 1957). The average territory size in southern Mexico, in the Caribbean and Pacific lowlands Michigan is 0.84 ha Birds build their nests from of Central America and in northern Colombia. early though late June; some active nests are They do not sing in winter; their winter range in found into mid-July and young are fledged as the Neotropics has been determined in part by late as the first half of August. The late nests are their response to a playback of their songs in of birds that failed an earlier breeding attempt Central America (Gorski 1969, Sedgwick 2000). and no second nesting attempts were found after birds had reared successfully an earlier brood

(Walkinshaw 1966). Their nests are often built northern Wisconsin they have been reported in in shrubs and small trees of dogwood, hawthorn, three counties bordering the UP (Cutright et al. rose, honeysuckle, alder and willows. Nests are 2006), although not in the counties bordering open cups of grass and large amounts of cotton- Gogebic Co. where Willow Flycatchers were like material or shredded fiber and feathers, mapped in MBBA I and MBBA II. In Ontario much like nests of Yellow Warblers and they occur in abundance as far north as the American Goldfinch; nests are compact on the southern Georgian Bay region, about the same underside and without a trailing streamer and in latitude as in the NLP of Michigan and on this way they differ from nests of the Alder Manitoulin Island in Lake Huron east of the UP, Flycatcher. The eggs usually differ from eggs of and their distribution has moved northward onto Alder Flycatcher and are a deeper buff color the Southern Shield region (Cadman et al. with larger and more diffuse spots (Fargo 1928, 2007). In Michigan during MBBA I, the Stein 1958, 1963). The nests often are brood- proportion of surveyed townships where the parasitized by Brown-headed Cowbirds (Berger flycatchers were detected was 80% in the SLP, & Parmelee 1952, Berger 1957, 1967, 27% in the NLP and 3% in the UP; and in Walkinshaw 1966). Adult flycatchers return to MBBA II their numbers were nearly the same the same area from year to year: 41% of adult (77%, 21% and 3%). In the Breeding Bird males banded in one year were seen again in the Surveys from 1996 to 2006, Willow Flycatchers next year, all on their old territory, one bird have undergone a small but significant decrease returning each year into its fifth year. Only 23% in numbers both in Michigan and throughout the of females returned to their old territory; the range of the species. In the combined data for missing numbers were likely both birds that did both Alder and Willow Flycatchers, there has not survive and birds that returned and settled in been no significant change in numbers in a new area. A few young flycatchers return to Michigan or throughout North America (Sauer their natal area in a later breeding season: two et al. 2008). In contrast to Michigan, Ontario were found at a distance 500 and 1600 m from and elsewhere in the Lower Great Lakes, the the territory where they were born (Walkinshaw numbers of flycatchers in Quebec, New York, 1966). the Appalachian Mountains, the Atlantic Northern Forest, New England and the Mid Abundance and Population Trends Atlantic Coast appear to have increased in (Click to view trends from the BBS) recent years (Cadman et al. 2007, McGowan & The atlas surveys show that Willow Flycatchers Corwin 2008, Sauer et al. 2008). are widespread in the SLP, scattered in the NLP, and sparsely distributed in the UP. Earlier than Conservation Needs the 1960s the Willow Flycatcher and Alder No conservation concerns are evident. Flycatcher were not recognized as two distinct species, so it is not possible to compare the distribution of the two in the early 1900s. In the past few decades there has been no clear evidence of an expansion of the range of Willow Flycatcher into northern Michigan. In the northernmost NLP locality (Dingman's Marsh, Cheboygan Co.) where Willow Flycatcher was reported in both MBBA I and MBBA II, their songs were tape recorded in the 1970s. In the UP nearly all of the few reports of Willow Flycatcher are along the southern border. In

Literature Citations Kroodsma, D.E. 1984. Songs of the Alder Berger, A.J. 1957. Population density of Alder Flycatcher (Empidonax alnorum) and Flycatchers and Common Goldfinches in Willow Flycatcher (Empidonax traillii) are Crataegus habitats of southeastern innate. Auk 101: 13-24. Michigan. Wilson Bulletin 69: 317-322. Lovell, S.F. & M.R. Lein. 2004a. Song variation Berger, A.J. 1967. Traill's Flycatcher in in a population of Alder Flycatcher. Journal Washtenaw County, Michigan. Jack-Pine of Field Ornithology 75: 146-151. Warbler 45: 117-123. Lovell, S.F. & M.R. Lein. 2004b. Neighbor- Berger, A.J. & D.F. Parmelee. 1952. The Alder stranger discrimination by song in a Flycatcher in Washtenaw County, Michigan: suboscine bird, the Alder Flycatcher. breeding distribution and brood parasitism. Behavioral Ecology 15: 799-804. Wilson Bulletin 64: 33-38. Lovell, S.F. & M.R. Lein. 2005. Individual Binford, L.C. 2006. Birds of the Keweenaw recognition of neighbors by song in a Peninsula, Michigan. Miscellaneous suboscine bird, the Alder Flycatcher Publications, Museum of Zoology, Empidonax alnorum. Behavioral Ecology University of Michigan, no. 195. and Sociobiology 57: 623-630. Cadman, M.D., D.A. Sutherland, G.G. Beck, D. McGowan, K.J. & K. Corwin, eds. 2008. The Lepage & A.R. Courtier, eds. 2007. Atlas of Second Atlas of Breeding Birds in New York the Breeding Birds of Ontario, 2001-2005. State. Cornell University Press, Ithaca, NY. Bird Studies Canada, Port Rowan, Ontario. Sauer, J.R., J.E. Hines & J. Fallon. 2008. The Cutright, N.J., B.R. Harriman and R.W. Howe. North American Breeding Bird Survey, 2006. Atlas of the Breeding Birds of Results and Analysis 1966 - 2007. Version Wisconsin. Wisconsin Society for 5.15.2008. USGS Patuxent Wildlife Ornithology, Waukesha. Research Center, Laurel, MD. Dunn, J.L. and J. Alderfer, eds. 2006. National Sedgwick, J.A. 2000. Willow Flycatcher Geographic Field Guide to the Birds of (Empidonax traillii). In The Birds of North North America, fifth edition. National America, No. 533. Geographic Society, Washington, D. C. http://bna.birds.cornell.edu.bnaproxy.birds.c Fargo, W.G. 1928. Traill's Flycatcher in ornell.edu/bna/species/533. southern Michigan. Wilson Bulletin 40: 218- Stein, R.C. 1958. The behavioral, ecological and 221. morphological characteristics of two Gorski, L.J. 1969. Traill's Flycatcher of the populations of the Alder Flycatcher, "fitz-bew" songform wintering in Panama. Empidonax traillii (Audubon). New York Auk 86: 745-747. State Museum and Science Services Bulletin Gorski, L.J. 1971. Traill's Flycatcher of the "fee- 371: 1-63. bee-o" songform wintering in Peru. Auk 88: Stein, R.C. 1963. Isolating mechanisms between 429-431. populations of Traill’s Flycatchers. Hussell, D.J.T. 1991. Spring migrations of Proceedings of the American Philosophical Alder and Willow Flycatchers in southern Society 107: 21-50. Ontario. Journal of Field Ornithology 62: Walkinshaw, L.H. 1966. Summer biology of 69–77. Traill's Flycatcher. Wilson Bulletin 78: 31- Johnson, N.K. & C. Cicero. 2002. The role of 46. ecological diversification in sibling speciation of Empidonax flycatchers (Tyrannidae): multigene evidence from mtDNA. Molecular Ecology 11: 2065-2081.