I've had 9 nest boxes on my property for going on three years. All have
been occupied by Tree Swallows and Bluebirds (as well as a couple by House
Sparrows, a problem I'm trying to solve now).
My understanding is that smooth walls more commonly cause problems for Tree
Swallows than for Bluebirds, because the swallows have weaker legs. And the
problem is that the fledglings can't get out. I've never heard of adult
birds of either species having any such problem.
We lost a large number of swallow nestlings to cold rainy weather two
summers ago, but the Bluebirds did not have a problem. The knowledgeable
bluebirders I consulted attributed this discrepancy to the fact that
Bluebirds eat insects from the ground, but the swallows catch them on the
wing, and rain suppresses insect activity. This means the swallows have to
travel much farther for food and either can't get enough to feed the
nestlings, or can't keep them warm enough, or both.
But these are all problems that occur AFTER nesting and breeding are
underway. Based on what I'm hearing and seeing, what's happening right now
is that the Bluebirds are not showing up or nesting in the first place.
As of yesterday, we still had our one pair of Bluebirds (I saw the female
for the first time yesterday) aggressively defending a nest box from
swallows. I did not see the Bluebirds today--but it was also very quiet on
the swallow front.
From: Vermont Birds [mailto:[log in to unmask]] On Behalf Of Lynette Reep
Sent: Sunday, April 29, 2007 9:08 PM
To: [log in to unmask]
Subject: Re: [VTBIRD] Bluebirds/fatalities
I think it was Bryan Pfeiffer (excuse me if I am wrong here, Bryan)
who pointed out to a group of us some years back that bluebird boxes
that are planed and sanded smooth on the inside can become death
traps, since the birds can get in, but cannot climb back out (nothing
to grab onto). Does this sound right, those of you with bird house