Yellow-rumped Warbler (Dendroica coronata) Skye Christopher G. Haas
Rogers City, Presque Isle Co., MI June, 2009 © Willie McHale (Click to view a comparison of Atlas I to II)
Michigan's birdwatchers are lucky to have Distribution Yellow-rumped Warblers nest in the northern such a beautiful bird be so plentiful. This half of Michigan, are a low-density wintering abundant migrant is often the nucleus of mixed species in the southern third, and a common foraging flocks, and whether it is the arresting migrant throughout. While this species’ adult males with their dapper markings or the presence in Michigan likely dates back to the sublime brown streaks of the young of the year, Pleistocene when the last glaciers retreated, it Yellow-rumped Warblers are always a delight to was considered to be uncommon at the turn of behold. There may actually be two (or more) the 20th century (Barrows 1912). This is likely species within the complex of Yellow-rumped an artifact of the extensive logging that occurred Warbler. Currently recognized as a subspecies, in the late 19th century when northern Michigan the form found here in Michigan is known as was cleared of its mature pine forests. Extensive the Myrtle Warbler, aptly named for its habit of tracts of scrub brush-land were created, and consuming wax myrtle berries. Myrtle Warblers while many species thrived or even expanded range far, breeding from Newfoundland to their range into Michigan, many forest species Alaska, and from the treeline south to the Great undoubtedly suffered a decline in numbers Lakes and northern Appalachians. However the (Brewer 1991). By the mid-twentieth century, western counterpart, the Audubon's Warbler, their numbers had rebounded with the return of breeds along the West Coast and throughout the mature coniferous forest, and by MBBA I, Rocky Mountains from British Columbia south Yellow-rumped Warblers were considered to be into the mountain ranges of Mexico and one of the most plentiful breeding species in the Guatemala. Debate about the validity of two north woods. species continues, and the pair may be elevated to full status yet again. In Michigan, the There was no significant change in the Audubon's Warbler is only known as a rare distribution of Yellow-rumped Warblers vagrant, and confirming such individuals is between MBBA I and MBBA II but there was a difficult due to the existence of hybrids from a definite increase in the number of townships narrow hybrid zone in the Canadian Rockies. where the species was found, particularly in the
UP where there was a 9% increase from MBBA I, certainly suggestive of a population increase,
© 2011 Kalamazoo Nature Center Yellow-rumped Warbler (Dendroica coronata) Skye Christopher G. Haas though a similar increase in observer effort in the UP may also account for these trends. BBS Yellow-rumped Warblers are typically one of data show that they may be more abundant on the first species of warblers to be found singing Lake Superior watersheds, though significant on territory in northern Michigan. Nesting concentrations were found in the Sylvania occurs from June through late July (Eastman Recreation Area in Gogebic County, likely due 1991). Surprisingly, it is not known if there are to the extensive mixed mesic mature forests two clutches per season; it is certainly possible (Eastman 1991, Sauer et al. 2008, S. Haas and given the species early arrival to the breeding R. Rutherford pers. obs.). Yellow-rumped grounds, but more data are needed to test such a Warblers become more sparse as one travels hypothesis. Adults feeding prejuveniles on 24 southward in the Lower Peninsula. Breeding in August 1997 at McLain State Park, Houghton the NLP tends to be concentrated along the County was thought to suggest a second brood Manistee and Au Sable River watersheds. These (Binford 2006). The cup nest is typically placed cool water drainages, as well as the prevalence at a mean height of 6.1 m above ground, of red pine plantations on National Forest frequently on the outer half of a horizontal Service lands, likely contributes to their branch in a conifer tree. The clutch size is four abundance in these areas. The jack pine barrens to five eggs, and incubation takes just under two managed for Kirtland's Warbler in the eastern weeks from the last egg laid (Harrison 1975, NLP are also good places to locate breeding Hunt and Flaspohler 1998). populations of Yellow-rumped Warbler. The species remains nearly absent from the SLP Abundance and Population Trends with only two Possible breeding records noted; The status of Yellow-rumped Warblers in not surprising considering the lack of coniferous Michigan is that of a year-round resident, albeit forest. in low numbers during the wintertime. As a migrant, fewer warbler species are more readily Breeding Biology observed, or have as protracted of a migration Yellow-rumped Warblers are dependent upon period, particularly in the fall. Spring migrants mature coniferous or mixed forest, however return early. Yellow-rumped Warblers are within this broad designation Yellow-rumped regularly seen throughout the state by the end of Warblers will use a wide variety of forest April and males have set up territory by mid- composed of differing coniferous species. May. In the fall post-breeding dispersal is noted Yellow-rumped Warblers tend to use mature as early as late July and early August (pers. mesic forest habitats, though xeric forests that obs.). Flocks of juvenile birds are noted at are composed of white, red, and jack pine also migration locations along the Great Lakes in seem to concentrate this species. They also use northern Michigan during this early period, hemlock groves located within tracts of northern however the bulk of migrants, possibly from hardwood forest. Hunt and Flaspohler (1998) further north in Canada, move through in late indicate that they prefer mature forests, though September and early October (Chartier and in Michigan the species is regularly found in Ziarno 2004). Birds are regularly seen into young jack pine managed for Kirtland's Warbler November, even in the UP, and by December (pers. obs.). They are also generalists when most have left the state except for the small foraging, gleaning for insects in trees and number of birds that will attempt to overwinter. shrubs, hawking for aerial insects and consuming fruit and berries, though the latter Partners in Flight have estimated that a healthy food source may be used more during migration total of 400,000 Yellow-rumped Warblers nest and on the wintering grounds. in Michigan, 0.3% of the world's total
© 2011 Kalamazoo Nature Center Yellow-rumped Warbler (Dendroica coronata) Skye Christopher G. Haas population (PIF 2007). BBS data found a 0.6% per year national increase from 1966-1999 (Sauer et al. 2008). Binford found an even more striking increase on the Bootjack BBS route in northern Houghton County with a 310% increase between the periods of 1967-1973 (1.29 birds per count) and 1992-2005 (5.29 birds per count), thought to be a direct result of forest maturation, especially of the required scattered conifers within mesic mixed forest (Binford 2006). While there was only a 3.5% increase in the number of townships between atlases in Michigan, Ontario experienced an 11% increase in the probability of detection between their two atlases (Crins 2007).
Conservation Needs The state of the Yellow-rumped Warbler in Michigan appears to be good, both currently and for long-term trends. Possible threats to this species are logging of mature forest, particularly selective cuttings of conifers for pulpwood, and collisions with communications towers. It was considered to be the most abundant warbler in tower kills in Florida, constituting 7% of all causalities (Hunt and Flaspohler 1998). No management plan is currently required for this species; any program to enhance other coniferous forest species will likely benefit Yellow-rumped Warblers as well.
© 2011 Kalamazoo Nature Center Yellow-rumped Warbler (Dendroica coronata) Skye Christopher G. Haas
Literature Cited 5.15.2008. USGS Patuxent Wildlife Research Center. Laurel, MD. Barrows, W.B. 1912. Michigan Bird Life. Special Bulletin. Michigan Agricultural Suggested Citation College. Lansing, MI. Binford, L.C. 2006. Birds of the Keweenaw Haas, S. C. G. 2011. Yellow-rumped Warbler Peninsula, Michigan. MP 195. University of (Dendroica coronata). In Chartier, A.T., J.J. Michigan Muzeum of Zoology. Ann Arbor, Baldy, and J.M. Brenneman (eds.). 2010- MI. 2011. The Second Michigan Breeding Bird Brewer, R. 1991. Original Avifauna and Atlas. Kalamazoo Nature Center. Postsettlement Changes. In Brewer, R, GA Kalamazoo, MI. Accessed online at: McPeek, and RJ Adams Jr. (eds.). 1991.
© 2011 Kalamazoo Nature Center