Blue Grosbeak

A Blue Grosbeak (Passerina caerulea) sings on a nippy 36 F morning. Yesterday morning I stopped by a Ross County site where I've seen this species in year's past, and this male was immediately evident. Blue Grosbeaks deliver a distinctive rich warbling song, reminiscent of a Purple Finch. The vast majority of birds that I've found have alerted me to their presence by their song, which carries for quite some distance.

Probably due to the cold, he was foraging down low and even spent time on the ground. Here he poses on old stalks of Indian Grass in a prairie meadow. Henslow's Sparrows were singing nearby.

This southern species is expanding northward and is much easier to find - at least in Ohio - than in the not-too-distant past. When I was a kid, Blue Grosbeak was pretty much an Adams County specialty. Away from there, it was a great rarity. Not now.

During the first Ohio Breeding Bird Atlas (1982-87), Blue Grosbeak was found in only eleven counties, and was locally frequent in only Adams and Lawrence counties - two of our southernmost Ohio River counties. Their numbers and distribution had spiked by the time of Atlas II (2006-11). Surveyors found Blue Grosbeaks in nearly 70 counties and in much higher densities than occurred during the Atlas I period. Scattered pairs have made it all the way to the Lake Erie region, and it would not be especially surprising to turn one up anywhere in the state.

Blue Grosbeak numbers have skyrocketed in southern Ohio. Anywhere that their favored habitat of open meadows interspersed with scattered trees and brushy areas occurs, there is a great chance of finding this stunning relative of the Indigo Bunting.

Why are Blue Grosbeaks moving north and increasing in numbers? If one takes the long view, this species of semi-open country probably began its northward march following the opening up of the formerly vast eastern deciduous forest several centuries ago. Widespread clearing created much favorable habitat. However, that does not explain the fairly recent and obvious ongoing expansion. Forest clearing has been going on far longer than Blue Grosbeaks have been actively expanding northward, at least at the pace of the past few decades. This species clearly did not join in the boom-and-bust expansions of a trio of other open country songbirds in the late 19th and early to mid-20th centuries: Bachman's Sparrow, Bewick's Wren, and Loggerhead Shrike. Despite the apparent availability of suitable habitat, those three have crashed and the sparrow and wren are extirpated from the state. The shrike barely holds on. Yet the grosbeak is growing in numbers and conquering much new ground.

One big difference between the aforementioned shrike, sparrow, and wren and the Blue Grosbeak is that the latter is a Neotropical migrant, with nearly the entire population wintering in the Caribbean and especially in Central America. Ohio-nesting grosbeaks are traveling up to several thousand miles south to wintering grounds. The others were/are short-distance migrants or even year-round residents, wintering almost exclusively in the U.S. Who knows, perhaps upward shifts in mean temperatures is the catalyst for the northward sweep on grosbeaks. It will be interesting to watch their continued expansion.