Curiously, of the ten recognized subspecies of Bewick's Wren, only the 
nominate bewickii of the east has declined.   The other subspecies are stable or 
increasing.   Could there be a genetic susceptibility factor?   Just curious.

Paul O'Brien
Rockville, Mont. Co., MD

In a message dated 1/23/07 3:55:13 PM,  writes:


> From what I understand, Bewick's Wren is essentially gone everywhere east 
> of the Mississippi River. It is one of the most dramatic range losses of our 
> lifetime, yet no one ever really had a handle on what was happening or what 
> could be done about it. Speculation has focused on competition with House Wren 
> and changing forests. According to Birds of North America (BNA), Bewick's 
> Wren prefers open brushy woodlands. Our woodlands tend to be more closed-canopy 
> than they used to be, and to have less underbrush (because of deer 
> overbrowse). House Wrens seem to like the forests and edges that we have now. The BNA 
> account suggests an initial colonization of the East by Bewick's Wren in the 
> late 1800s right after a major deforestation, then a replacement of Bewick's 
> Wren by House Wren from 1920 to 1980. House Wrens peck holes in the eggs of 
> species that nest nearby, plus they prefer a more mature forest than does 
> Bewick's Wren.
> 
> Retreat of Bewick's Wren may be similar to the retreat of Golden-winged 
> Warbler, which has retreated behind an expansion of Blue-winged Warblers.
> 
> There has been no cold weather worth mentioning since the late 1970s in the 
> United States east of the Mississippi and most songbirds that winter in the 
> Eastern USA that are sensitive to cold weather have been expanding their 
> ranges, not contracting (including Carolina Wren).
> 
> Bewick's Wrens have stable populations out west, according to the Breeding 
> Bird Survey, so the species as a whole is doing fine, although the chances 
> that it will ever re-colonize the East seem very low (although they did colonize 
> the East from the West in the second half of the 1800s). The Ozark Mountains 
> of Missouri seem to be the eastern-most stronghold for the species now.
> 
> Greg Butcher
> Director of Bird Conservation
> National Audubon Society
> 1150 Connecticut Avenue NW, Suite 600
> Washington DC 20036
> Tel.: 202-861-2242, ext. 3034
> Fax: 202-861-4290
> 
> 
> Protecting our Great Natural Heritage through the Important Bird Areas 
> program,<http://www.audubon.org/bird/iba>,
> and the WatchList, <http://www.audubon.org/bird/watchlist>.
>