Wednesday, June 16, 2010

It's A Poor Day When You Don't Learn Something New...

I've long been a firm believer that it would be a poor day when I went out into the field and didn't learn something new. The same can be true of a post to a web blog, especially when the post is done in a hurry! Yesterday I posted a photograph of a Sandhill Crane which I glibbly called a second calendar year bird, based on an assumption that brownish birds were youngsters and adults were grey. Thanks to those who emailed me and questioned this assumption! So this evening I did some research (a man has to do something whilst his wife is away!) and it took an amazing amount of digging before I got something concrete. It is generaly accepted that the red-brown coloration of Sandhill Canes actually comes from iron staining from the soil. This can easily be demonstrated by close examination of feathers but there could be two reasons for this - deliberate or accidental - and tracking this down is what took the time. Some birds use iron-staining as a form of cosmetic and deliberately color their feathers in a way that seems to make them more attractive to members of the opposite sex. The Lammergeier is a classic example of this. Other birds, such as Mute Swans and Snow Geese acquire rusty staining to the head and neck (as do ducks - remember the possible Cinnamon Teal of 2009?!) and this seems to be accidental and merely acquired during normal feeding behavior. So it seems that Sandhill Cranes get their rusty coloration by applying it with the bill. This is apparent from the fact that all of the plumage except the head and neck - which can't be reached by the bill - acquires the staining. According to Handbook of Birds of the World, the birds do this by deliberately rubbing iron-rich mud onto the plumage and they do this not for cosmetic reason but to camouflage themselves whilst sitting on the nest - a time when they are most vulnerable to predators. Another longer look at our Sandhill Crane surely shows it to be an adult from the amount of red on the head. Here endeth today's lesson!

As for today's bird sightings, our regular Wednesday walk at Cape May Point State Park was low on species but rich in experiences this morning as we had up close and personal views of a pair of Orchard Orioles feeding chicks in the nest and watched Cedar Waxwings nest-building. Our regular Yellow-breasted Chat proved elusive - though we did hear him and it perhaps won't be long now before his singing stops for another season. Less expected was a fine adult male Baltimore Oriole on the red trail. The Rips were quiet but for a scattering of Forster's Terns, but a Common Eider was a surprise, drifting east along the bay.

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