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!

Martin nest.

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.

Martin nest with 5 eggs in a natural gourd.

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.]

The Tree Swallow couple has five eggs.
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.

Please indulge my bluebird addiction:

One last photo of an adult male Purple Martin.

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.


NCmountainwoman said...

Great photos. Truly lovely birds.

Mary C said...

Hi Kat Doc - I'm so enthralled with the number of birds you have nesting. That is truly wonderful. Do you think the martin eggs will hatch before the tree swallow eggs? Or will they all hatch about the same time? Your hard work in keeping those gourds and other nesting boxes clean has certainly paid off.

KatDoc said...

NCMountain: Thanks! Aren't they the best?

Mary C:

Hatching is going to be going on for quite a while this spring and summer. The Tree Swallow eggs should hatch around Memorial Day weekend. I calculated her "due date" as somewhere between May 29 and June 1.

The bluebird clutch has just started; the first egg was May 21. That bunch should hatch around June 6, give or take a day. ("Don't count your nestlings before the eggs are laid," or something like that.)

And the Purple Martins are impossible to predict right now. PUMA can lay between 4 and 7 eggs, depending on the age/experience and health of the adult birds, also the food supply. Incubation starts on the day the next-to-last egg is laid and takes about 2 weeks. But, I only have 3 nests with eggs so far (doing a nest check today, so that number may change) and I haven't any idea yet when all those babies will start to hatch.

Gonna be a 3-ringed circus for a while!


Mary C said...

Thanks, Kat Doc. I was thinking the same thing (3-ringed circus). Well, you and the mama birds will be busy for the next few weeks. But I'm sure it will be worth the wait, too. It's so exciting to see baby birds, and more exciting to see them in the nest - something I haven't seen in a very long time.