Blackburnian Warbler (Dendroica fusca) Robert Doepker
Jordan River Valley, Antrim Co., MI. 6/11/2008 © John Van Orman This species sponsored by Sharon Johnson.
(Click to view a comparison of Atlas I to II)
The faint and ascending trill from the top of the time period preceding European settlement, but it has changed little in the last half century tallest conifer is a clue to the presence of the (Wood 1951). Barrows (1912) reported the bird male Blackburnian Warbler – a small bird with as common in the northern two-thirds of a flaming orange throat and breast. The Michigan and present in suitable habitat in the Blackburnian is one of several wood warblers southern LP. The decline from the pre- that co-exist by partitioning foraging niches settlement period is related to a reduction in based on the vertical structure of forested forested area and a change in species habitats (MacArthur 1958, Morse 2004). In the composition and developmental stage of the northern two-thirds of Michigan, the remaining forest (i.e., from mature mixed or Blackburnian Warbler is a fairly common conifer dominated forest to young deciduous Neotropical migrant. It is strongly associated dominated forest). with mature, conifer dominated forests throughout its breeding range which The Blackburnian Warbler’s preferred habitat corresponds to the southern boreal forest and throughout its breeding range is forest hemlock-white pine-northern hardwoods forest dominated by hemlock, white spruce, balsam fir region identified by Braun (1950). The and white pine (Beals 1960, Morse 1976, breeding range encompasses the southern half of Collins 1983, Doepker et al. 1992). In northern eastern Canada, the northern portions of portions of its breeding range, the presence of Minnesota, Wisconsin and Michigan, and New mature, coniferous-dominated stands that England southward through the Appalachian possess over 75% tree canopy cover and greater Mountains into northeastern Georgia (Morse than 60% coniferous canopy cover are important 2004). The birds leave Michigan in autumn to breeding habitat attributes (Titterington et al. return to their wintering areas in southern 1979, Collins 1983, Doepker et al. 1992). Central America and northwestern South
America. The distribution of Blackburnian Warblers in
the Lower Peninsula changed only slightly over Distribution the 20-year period between MBBA I and The breeding range of the Blackburnian Warbler MBBA II. During both Atlas efforts, breeding in Michigan has been reduced compared to the
© 2011 Kalamazoo Nature Center Blackburnian Warbler (Dendroica fusca) Robert Doepker activity was recorded in about four percent of (containing the UP and NLP), respectively. The townships in the southern LP and about 20% of mean annual increase over the 1966 – 2007 townships in the northern LP. In contrast, this period was 1.7% for Michigan, and 0.9% for the warbler appears to have expanded its Northern Spruce – Fir Region. In Michigan distribution in the UP. Fifty-four percent of during the more recent, 20-year period between townships had recorded breeding activity during MBBA I and MBBA II (1983 – 2007), the MBBA I, and this percentage increased to 70% Blackburnian Warbler decreased at an annual of townships during MBBA II. The stronghold rate of 0.08% (Sauer et al. 2008). of the warbler remains the Ottawa and Hiawatha National Forests, likely a result of their forest Conservation Needs management policies which includes a On the breeding grounds, Blackburnian component of older forest including increased Warblers are strongly associated with mature numbers of hemlock, white pine, white spruce conifer dominated forests of hemlock, white and balsam fir. spruce, balsam fir and white pine growing in an uneven-aged condition. Red-eyed Vireos and Breeding Biology Ovenbirds, which inhabit mature deciduous The Blackburnian Warbler arrives in the Lower forest, are 15 and seven times more abundant, Peninsula in early May and a few days later in respectively, than Blackburnian Warblers on the Upper Peninsula. Nesting is usually BBS routes in Michigan. Mature conifer initiated by late May, and most nests are dominated forest must be provided to ensure a established by early to mid-June. The nests are sustainable Blackburnian Warbler population in almost exclusively built in conifers, usually high Michigan. The major threat on the breeding in the canopy (Morse 2004). Little information grounds is intensive timber harvest emphasizing is available on the incubation, hatchling and even-aged management and shortened rotation fledging periods. However, the incubation periods. Such harvesting methods result in period is probably 12 - 13 days (Morse 1989), decreased proportions of conifers in uplands and and only the female incubates. Both parents a lack of mature trees growing in an uneven- feed the young. Blackburnian Warblers forage aged condition. primarily by gleaning insects from conifers and deciduous tree species. They have also been observed hawking insects.
Abundance and Population Trends (Click to view trends from the BBS) The number of singing Blackburnian Warblers detected on BBS routes in Michigan increased from about one per route in the late 1960s and early1970s, to about 1.4 per route since 2000 (Sauer et al. 2008). Although the trend line suggests an increasing population, it is not statistically significant.
The mean number of Blackburnian Warblers counted per BBS route over the period 1966– 2007 was 1.2 and 2.8 for Michigan and the Northern Spruce–Fir Physiographic Region
© 2011 Kalamazoo Nature Center Blackburnian Warbler (Dendroica fusca) Robert Doepker
Literature Cited Michigan Museum of Zoology. Ann Arbor, Michigan, USA. Barrows, W.B. 1912. Michigan Bird Life. Special Bulletin. Michigan Agricultural Suggested Citation College. Lansing, Michigan, USA. Beals, E. 1960. Forest bird communities in the Doepker, R. 2011. Blackburnian Warbler Apostle Islands of Wisconsin. Wilson (Dendroica fusca). in A.T. Chartier, J.J. Bulletin 72: 156-181. Baldy, and J.M. Brenneman, editors. The Braun, E.L. 1950. Deciduous Forests of Second Michigan Breeding Bird Atlas. Eastern North America. Blakiston Co. Kalamazoo Nature Center. Kalamazoo, Philadelphia, Pennsylvania, USA. Michigan, USA. Accessed online at: Collins, S.E. 1983. Geographic variation in
© 2011 Kalamazoo Nature Center