Bluebird Trail, Week One

This was week one of flying solo on our bluebird trail. We have 10 locations, six with paired nest boxes (#1-12) and four singles (#13-16), for a total of 16 boxes. Nest boxes are often paired to give bluebirds a chance to use one of the two boxes when competing species are present. I wrote more about this last year in a post about one of the most frequent of those competitors, the tree swallow.

New nest this week - one of the singles

The first pair is by our house, so we'll be able to keep closer tabs on these than the others, which are a few miles away but which we'll check at least weekly. This weekend's findings:

1. Empty
2. Very small amount of moss - this may mean a black-capped chickadee is starting a nest here. Bluebirds use grasses, primarily, but moss is a common component of chickadee nests. On Sunday the moss was fresh and green. Today it was dry and barely detectable.
3. Empty
4. Empty
5. Empty
6. Empty
7. Empty
8. Empty
9. Bluebird nest (read more at #10)
10. Bluebird nest. These bluebirds (at paired boxes #9 and 10) seem to be trying to have two nests! A week ago, one of these was well developed and the other was just being started. We have been advised that if we see eggs laid in both we should move them from the second to the first to consolidate them. Two pairs of bluebirds would not tolerate each other so close, so these must be the same birds, and they can't successfully incubate two sets of eggs simultaneously. We'll have to keep a closer eye on this set.
11. Empty
12. Empty
13. Empty
14. Starter nest - a tree swallow buzzed Dave agitatedly as he checked this box, so it's likely this is a tree swallow nest
15. Bluebird nest - new this week
16. Bluebird nest - new this week

In Bluebird Trails: A Guide to Success by Dorene H. Scriven (1993, Bluebird Recovery Committee of the Audubon Chapter of Minneapolis), the nesting sequence is described thus: It can take anywhere from one to six days to build a nest (the second nest in a season is usually built faster than the first). One egg is then laid per day, with an average clutch being four or five eggs. First-year females have smaller clutches (three or four eggs), while second-year females may have as many as six or seven. (The average lifespan of a bluebird, sadly, is only two years, though some survive several years longer.) Incubation usually starts as soon as the last egg is laid. The incubation period is 12-14 days. Young birds typically fledge between 18 and 22 days. It will be very helpful to keep this timing in mind as we monitor the boxes.

Dave returning a nest box after checking it