Monday, January 23, 2012

Evening Grosbeaks

A friend who was around Sax Zim the same day I was asked me what my favorite bird was that I saw that day. Hands down - the Evening Grosbeaks. Here is a bird that I can usually find a single individual of if I make a trip to the Duluth and related area, but not always. This past trip found four adult males and several females at one time. Talk about a ray of sunlight in an otherwise dreary weather day!

Since this bird has interesting natural biology related to its migration, I copied this from Cornell Lab of Ornithology's Birds of America online: "An irruptive migrant across much of its range, it makes roughly biannual appearances at winter feeding stations throughout much of the coterminous United States. Often moving in large flocks, this boldly colored bird with the massive bill is difficult for observers to miss. During the breeding season, however, the species is quite secretive, and courtship occurs without elaborate song or display. This secretiveness, together with a spare, flimsy nest placed high in a tree, makes it a difficult subject of study. As a result, comparatively little is known of the species’ life history.
The breeding range of the Evening Grosbeak underwent a significant expansion in historic times. The contemporary scientific literature documented eastward movement, with the species regularly appearing in areas east of its known range, perhaps a result of the establishment of box elder (Acer negundo) in eastern cities as an ornamental planting. The abundant seeds of the box elder persist on the tree through the winter, providing a stable food supply. Outbreaks of forest insects may also have allowed this bird to extend its breeding range to the east."

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