I arrived home from school today to find an intruding female tree swallow.
Or what I thought was the intruder (I for some reason, when it's needed,
don't remember what color plumage my TS has). One bird was in the nest hole
entrance. The other, was flying to the hole, and trying to pull the bird out
by the forhead. After a few minutes, the bird barreled into the hole pushing
the intruder into the box where they had a brief but intense fight. I
normally would have let it be but the eggs needed to be cooled and I didn't
want any being crushed so I opened the box, one was on top of the other. The
thing is, one bird was nicely colored, the other had blotches of grey in
with the blue/green plumage. As opposed to the all blue/green bird. If I
remember right, both female and male tree swallows, adults, look similar.
But the male is more intensely beautiful. But I don't remember if the birds
that have some grey are first year birds or what, and if they're male of
female. This bird that had the blotches of grey I thought was the intruder.
But now she is going in and out as she pleases. I had taken her and blew on
her chest to expose her brood patch making sure she was a female. Now I
can't figure out whether she's the actual female or not. I had THOUGHT the
more brightly colored female was mine, but I don't know now. Do females
(first years possibly or adults) sometimes take over egg duty and so on of
another nest if they themselves have a nest. I've never read or seen this
behavior so those that are experienced TS's landlords could you give me some
info.? Thanks so much!



Blake Iverson
Arlington, WA
coopershwk at Hotmail.com

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