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Population increase in Kirtland's warbler and summer range expansion to Wisconsin and Michigan's Upper Peninsula, USA

Oryx

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Abstract

The threatened Kirtland's warbler Dendroica kirtlandii breeds in stands of young jack pine Pinus banksiana growing on well-drained soils in Michigan, USA. We summarize information documenting the range expansion of Kirtland's warbler due to increased habitat management in the core breeding range in the Lower Peninsula of Michigan during 1990?2000. We collected records and conducted searches for the species in Michigan's Upper Peninsula and Wisconsin over 1978?2000. During that time 25 males were found in Wisconsin and 90 males in the Upper Peninsula. We documented colonization of Michigan's Upper Peninsula by six ringed males from the Lower Peninsula of Michigan. Four ringed birds also moved back to the core breeding range, including two males that made two-way movements between the core breeding range and the Upper Peninsula. Thirty-seven females were observed with males from 1995 to 2000, all in Michigan. Nesting activities were noted for 25 pairs and at least nine nests fledged young. One male ringed as a fledgling returned to breed in two subsequent years. After a 19-year period of population stability, the Kirtland's warbler population increased four-fold during 1990?2000, most likely in response to a tripling in habitat area. This increase in sightings and documented breeding may be related to habitat availability in Michigan's Upper Peninsula and to saturation of habitat in the main breeding range. The increase in extra-limital records during 1995?1999 corresponds to the time when the population went from the minimum to the maximum projected population densities, and a decline in natural wildfire habitat was just offset by new managed habitat for the Kirtland's warbler.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Population increase in Kirtland's warbler and summer range expansion to Wisconsin and Michigan's Upper Peninsula, USA
Series title:
Oryx
Volume
37
Issue:
3
Year Published:
2003
Language:
English
Contributing office(s):
Patuxent Wildlife Research Center
Description:
365-373
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Oryx
First page:
365
Last page:
373
Number of Pages:
9