Forward by Jim Williams, Wayzata, Minnesota Begin forwarded message:
From: Jean Iron <[email protected]> Date: December 25, 2004 12:46:46 PM CST To: [email protected] Subject: [BIRDCHAT] Boreal Bird Irruptions and Spruce Budworm Reply-To: Jean Iron <[email protected]> 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 BirdChat Guidelines: http://www.ksu.edu/audubon/chatguidelines.html Archives: http://listserv.arizona.edu/archives/birdchat.html
