Sunday, May 18, 2008
Purple and Blue All Over
I spent some time sitting quietly under an apple tree today, watching all the action going on at the various nest boxes and gourds. The main goal was to sort out the ages and sexes of the martins nesting in the gourd rack. I am trying to figure out how many are ASY (After Second Year) birds and how many are SY (Second Year.) There were too many distractions to get a complete count, but I did get some photos to help you see the differences.
[Aside: The year the young are hatched and fledge is their Hatch Year. They migrate to South America for the winter, where they molt, and return the next year as subadult or SY birds. This is their second summer, or their first breeding season, and they are basically teenagers. They migrate again that fall and acquire their adult plumage, returning as adult or ASY birds.]
This is an ASY, or adult male Purple Martin. He's the easiest to sex and age - he's purple all over. You can see how the species got its common name. Isn't he gorgeous?
I have seen at least 3 ASY males so far this year, maybe more. (Won't everybody just line up and sit still for a head count, please?) Last year's colony was started by one ASY male, so at least two of these guys are probably my SY's from last year, all grown up and come back home from South America.
This is an ASY female. She has some purplish coloration on her head and back, but her breast and belly are pearl gray.
Another ASY female. An SY female would have a whiter breast, but the big key to distinguishing subadult from adult females is the undertail coverts (feathers under the tail.)
Here is a close-up of the undertail coverts in this ASY female. In an adult female, the feathers have a gray center. In a SY female, they would be all white. I haven't seen an SY female yet, so I don't have a photo of one for comparison.
An SY male. Subadult males look an awful lot like adult females, which is one reason why my census is going so slowly. Look for a dark throat and irregular purple blotches on the breast and/or belly to ID a subbie male. If you can hear one sing, that clinches the ID, since females don't sing, but there is a lot of noise in a martin colony, and it can be hard to tell who the songster is.
I have been a bit lax in my martineering duties so far this spring, and today was my first complete nest check. Imagine my surprise to find that all 12 of my main gourds have nests and three of those have eggs!
Notice the mud dam in front of the nest cup, which is lined with green leaves. I find martins make these barriers in the larger plastic Super Gourds.
I also have a pair of martins interested in a Super Gourd that is hung on a shepherd's crook (the one that was intended for tree swallows and where I trapped a starling.) I'm surprised they would choose to nest so low, but all the prime spots are taken. I have seen 3 different martins exploring the aluminum house, but as far as I can tell these are all bachelor subbie males.
[Aside: Most colonies end up with extra SY males. These boys hang around the colony, trying to usurp already attached females. Juvenile males are the same all over the animal kingdom, always causing trouble.]
This is the best look I can give you of the female.
The male isn't shy about being photographed, though.
The bluebird couple has a new nest, which looks to be nearly complete.
I haven't seen the fledglings from the first clutch yet, but I got some great pictures of Papa today.
And, for the ultimate in nestbox cams, go here to see the Columbus, Ohio, peregrine falcons. Live streaming video of Orville and Scout's clutch of 4 babies.