[mou] Fwd: [BIRDCHAT] Boreal Bird Irruptions and Spruce Budworm

[Jim Williams]

Forward by Jim Williams, Wayzata, Minnesota

Begin forwarded message:

From: Jean Iron <jeaniron@SYMPATICO.CA>
Date: December 25, 2004 12:46:46 PM CST
To: BIRDCHAT@LISTSERV.ARIZONA.EDU
Subject: [BIRDCHAT] Boreal Bird Irruptions and Spruce Budworm
Reply-To: Jean Iron <jeaniron@SYMPATICO.CA>

Birders doing Christmas Bird Counts (CBC) will be interested in an
important article using CBC data just published in the 104th Christmas 
Bird
Count (2003-2004) issue of American Birds. An article by Nick Bolgiano 
is
titled "Cause and Effect: Changes in Boreal Bird Irruptions in Eastern
North America Relative to the 1970s Spruce Budworm Infestation". The 
most
recent budworm infestation of 1968-1985 defoliated approximately 55 
million
hectares (about 140 million acres) across Ontario, Quebec and the 
Maritime
Provinces. To get an idea of the size of the infestation, it was about 
as
big as the combined area of New York, Pennsylvania, Maryland, West
Virginia, Virginia, and North Carolina. Using CBC data, Bolgiano found
changes in irruption patterns of seven species: Evening Grosbeak, Purple
Finch, Black-capped Chickadee, Boreal Chickadee, Pine Grosbeak, Red
Crossbill, and White-winged Crossbill. Birders know about the rise and 
fall
of the budworm warblers (Tennessee, Cape May, Bay-breasted), but this 
study
emphasizes that "an understanding of population trends of many of 
eastern
North America's boreal birds must include the role of the 1970s budworm
infestation." Bolgiano asks if the 1970s infestation contributed to the
general declines of neotropical migrants in the 1980s and concurrent
decline of the Sharp-shinned Hawk. He ends by saying that the Christmas
Bird Count and Breeding Bird Survey have informed us that the spruce
budworm event of the 1970s apparently had a major impact on boreal 
forest
bird populations. I recommend that you read the entire article for its 
full
meaning. The author acknowledges the help of American and Canadian 
birders
and ornithologists and three Ontario Ministry of Natural Resources
foresters. If you don't have this issue of American Birds, perhaps you
could borrow it from your CBC compiler or from a member of the Audubon
Society or Bird Studies Canada. This 128 page issue also has several 
other
informative articles and the regional summaries of last year's 104th
Christmas Bird Count.

Reference: Bolgiano, Nicholis C. 2004. Cause & Effect: Changes in Boreal
Bird Irruptions in Eastern North America Relative to the 1970s Spruce
Budworm Infestation. American Birds 58: 26-33. This article is in The 
104th
Christmas Bird Count 2003-2004. Volume 58. 128 pages. American Birds.
Published by the National Audubon Society in association with the 
Audubon
Science Center and Bird Studies Canada.

Ron Pittaway
Ontario Field Ornithologists
Minden and Toronto ON
jeaniron AT sympatico.ca

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