Date: Fri, 20 Apr 2001 09:53:43 EDT Reply-To: Maryland Birds & Birding Sender: Maryland Birds & Birding From: Marshall Iliff Subject: Yellow-throated Warbler subspecies in MD and their habitats MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit MDOsprey, I have been very pleased to see the recent discussion on Yellow-throated Warbler habitats and subspecies in Maryland. I have been looking into this question especially closely recently as part of another project, so may be able to add somewhat to the discussion. Yellow-throated Warblers in Maryland break down in to two subspecies: _Dendroica dominica dominica_ and _D. d. albilora_. The most often cited difference in the subspecies is that _dominica_ has a yellow forehead (leading portion of the supercilium) while _albilora_ has a totally white supercilium, hence its specific epithet. _Albilora_ is also noticeably shorter-billed than _dominica_. Several sources (e.g. Dunn & Garrett 1997) caution against over-reliance on the color of the lores, since _dominica_ can sometimes have much reduced yellow that is hard to see in the field and since _albilora_ can occasionally have a yellow wash there. Bill length may be a better field character. I have not noticed a difference in the songs of the two, but would not be surprised to hear that they differ... Subspecies _dominica_ breeds on the Coastal Plain of Maryland. It is especially common along the Pocomoke River on the Lower Eastern Shore (Worcester, Somerset, Wicomico Counties) but breeds locally throughout the Eastern Shore. On the Western Shore it is considerably scarcer but breeds locally in Anne Arundel, Prince George's (e.g. Jug Bay), Charles, Calvert (e.g. Flag Ponds), and Saint Mary's Counties. I am not sure of its status in Baltimore or Harford Counties, but presumably a few breed along the Bay Shore. Preferred habitat on the Eastern Shore is almost exclusively Loblolly Pine or Pond Pine woods, though Bald Cypress and Atlantic White Cedar are used as well. In addition to riverside and floodplain habitats, they frequent marsh edge, in some places right up to the shore of the Bay (e.g. Jim Stasz and I had a couple singing on Poplar Island, in the central Bay of Talbot County, last year). On the Western Shore Loblolly Pines (especially at marsh edges) are probably preferred but Virginia Pine forests are used as well. They are NOT found in deciduous woods to my knowledge, although the forests are obviously often mixed pine and deciduous. They probably arrive a bit earlier than _albilora_ and quit singing a bit earlier. Subspecies _albilora_ is the one that is sometimes called the Sycamore Warbler, and rightly so. This is the one that is strictly tied to riparian areas, and to my knowledge in Maryland it is found _only_ in close association with streams and rivers of the Piedmont and along the Potomac River as far upstream as Allegany County (e.g. Oldtown, Spring Gap). Healthy populations exist along the upper Patuxent and Patapsco Rivers, along Monocacy Creek, and along a number of other large, Sycamore-lined Piedmont watercourses. Good numbers occur along the Potomac in Montgomery and Frederick Counties, though it is scarce in Washington and local in Allegany County. A recently discovered population (ca. 5 pairs) exists below Youghigheny Reservoir in Garrett County, where the river below the lake is lined with Sycamores. I am especially interested to wonder how close these two subspecies come to meeting in the state. Along the upper Patuxent breeders will be referable to _albilora_ while those on the lower Patuxent are _dominica_. Each subspecies seems to cutoff abruptly at the Fall Line. Both subspecies may breed in Prince George's, Anne Arundel, Baltimore, and Harford counties. I'd be interested in comments from anyone who has seen YT Warblers in both habitats in any Maryland County. We also know very little about migrant records of either subspecies away from their breeding habitat. Jim Stasz has reported an _albilora_ from Blackwalnut Pt., Talbot County, in Fall migration, but I am unaware of other records of _albilora_ in MD away from breeding grounds. One final note of interest is that Dunn & Garrett (1997) specifically comment that breeding _dominica_ on the Delmarva peninsula are significantly longer-billed than birds from the rest of the breeding range. Best, Marshall Iliff Literature Cited: Dunn, J.L. and K.L. Garrett.1997. A Field Guide to the Warblers of North America. Houghton Mifflin Co., Boston, MA. *********************** Marshall Iliff miliff@aol.com Annapolis, MD ************************ ======================================================================= To leave the MDOsprey list, send e-mail to listserv@home.ease.lsoft.com with the following message in line 1: signoff mdosprey ======================================================================= =========================================================================