Spreading their Wings

It is that time of year when a lot of chicks are leaving the nest and a lot of juvenile birds are spreading their wings for the first time. Just today we say the 4 bluebird chicks raised in our backyard birdbox leave the nest. Above is what I believe is juvenile blue grosbeak (Guiraca caerulea) based upon its size and the shape of its beak. The pic with the cardinal is for scale.

Another Grosbeak

Ironically, this Rose-breasted Grosbeak (Pheucticus ludovicianus) that visited my feeders regularly a few weeks ago is NOT closely related to the Blue Grosbeak I have already featured. These guys breed mostly in northern North America and spend the winters in central and northern South America. They are occasionally seen in Europe. Interestingly, these birds migrate at night in small flocks or alone. Unlike many of the more common birds, Rose-breasted Grosbeaks have no sub-species. Females will lay one egg per day until clutch size is reached (average 4 eggs). Both males and females incubate the eggs and take turns feeding crushed insects to the chicks. These birds have been reported to live up to 13 years in the wild and 24 in captivity. Populations are stable.

Blue Grosbeak

When I was taking Ornithology in college this bird was placed in its own genus, Guiraca. However, with the advent of DNA technology it has been shown that the Blue Grosbeak (Passerina caerulea) is close kin to the Indigo Bunting (Passerina cyanea). DNA sequence comparisons (which is what I did in graduate school and still do with my research students) has really changed the way scientist now construct phylogenetic (family) trees for many organisms, not just birds. As far as looks, the Blue Grosbeak can be distinguished from the Indigo Bunting very easily by the two broad rusty wing bars and conical beak.

I caught this fellow during bath time (kind of). The Grosbeak was in the midst of a good preening. The act of preening is the way birds repair and waterproof their feathers. Feathers can split apart (actually become unzipped) and by starting at the base and working toward the tip, birds "rezip" their features. Additionally, most birds have a preen gland, or uropygial gland, at the base of the tail. The gland produces uropygial oil, a waxy substance used to waterproof and condition feathers. Rubbing the preen gland with the beak, a bird picks up the oil and then distributes it onto feathers by rubbing the beak over the feathers. I found this fellow at the Iron Mountain marina on Lake DeGray. Although I have regular visits from the Rose-breasted Grosbeaks and Indigo Buntings at my backyard feeders, I have not seen the Blue Grosbeaks. So I was happy to see this guy and get some pics.