Monday, April 27, 2009

What are the answers to the most recent quizzes appearing on the right side of this home page as you scroll from top to bottom?

Beyond Michigan's breeding population, where else do researchers believe the Kirtland's Warbler regularly to periodically breeds?

Answer: WI & Ontario


Which common wood-warbler's breeding range is split into an eastern and western subspecies breeding population?

Answer: Nashville


Which sequence of weather conditions typically result in a "fallout" of wood-warblers during the spring on the Gulf Coast?

Answer: Warm, southerly breezes followed by a cold front/northerly winds.


If it's not a wood-warbler, then into which taxonomic placement has Yellow-breasted Chat previously been proposed?

Answer: Tanager family

Which "New World" wood-warbler species has the most extensive breeding area?

Answer: Yellow


Unlike Blackpoll that undertake a long migration (see 1/8/09 article), which wood-warbler has populations that do NOT migrate?

Answer: Common Yellowthroat

Tuesday, April 21, 2009

Where in Michigan might I see Kirtland’s Warbler and what are the best dates to go?

Thanks for the question, Laurie in Detroit, MI


Given the good news (from a Michigan DNR news release from September, 2008) that Kirtland’s Warbler populations are at an all-time high of 1,791 singing males, your chances of detecting them are excellent. Most of the population nests in 12 lower Michigan counties within central-northcentral Michigan (Alcona, Clare, Crawford, Grand Traverse, Iosco, Kalkaska, Montmorency, Ogemaw, Oscoda, Otsego, Presque Isle, and Roscommon) and five upper Michigan counties (Chippewa, Delta, Luce, Marquette, and Schoolcraft). (However, nine individuals were detected in WI in 2008 and one in Ontario.).

The initial two weeks of June are the ideal time to visit the Kirtland’s breeding grounds, but a later visit through the first week of July could also yield viewing results.

Note that guided tours to view the Kirtland’s Warbler leave from various locations. To find out the schedule, contact the DNR Wildlife Division, Natural Heritage Program, Box 30180, Lansing, MI 48909, or visit the DNR Web site:

Wednesday, April 8, 2009

Why is the diversity of wood-warblers greater in eastern than western USA forests?

Excellent question, Don Y. of Houston, TX.


Although different perspectives for this phenomenon have been initiated by researchers, a summary of the leading ones follow:

1. The epicenter of wood-warbler colonization occurred initially in eastern USA forests, so over time more wood-warbler species have evolved in this area in comparison to western habitats.

The above statement is an oversimplification of a theory that is based on two million years of bird movement/migration in North America since the Pleistocene glaciation episodes occurred. In this regard, theorists believe the eastern wood-warbler species were present before the most recent four glacial advances. As the ice sheets advanced, separation of some species may have occurred or movement was enhanced, so that the splitting off of sibling wood-warbler species occurred. However, this process is slow and, thus, colonization of western USA areas has occurred with less diversity of species than those remaining (and continuing to evolve) in eastern habitats areas.

2. Moisture is generally far more abundant during the breeding season in eastern forests than western ones. As a result, more insect prey resources occur in eastern than western foliage where many species of wood-warblers forage.

3. Related to the above, #2, the foraging method called “foliage-gleaning” is specific to the largest quantity of wood-warblers occurring in North America, namely the Dendroica genus of wood-warblers. More than half of this area’s 52 annually occurring wood-warblers in North America (north of Mexico) are members of this genus. Given the far greater opportunity for “foliage gleaning” to occur in eastern forests than western ones (due to the composition of forests and the tree species they host), more wood-warbler species were able to establish themselves and evolve in eastern USA habitats.