May has been a busy month for the bluebirds at the Daniel Stowe Botanical Garden. The first brood of chicks from the nest boxes have fledged their nests and we are now seeing the second brood of the year. We noted that 8 of the nest boxes have a second brood and we counted a total of 28 eggs in those boxes. We also have one box with an active house wren nest.
If you are monitoring a bluebird box in your own back yard, do not be alarmed to see that the number of eggs in the second brood is smaller than the first. This is what we are seeing as well. We do have some smaller broods of just one, two or three eggs.
This year on the bluebird trail we had a slightly rare occurence in one of the nest boxes that we did not observe last year. During our monitoring of the boxes on April 30th we discovered that one nest box contained white eggs! The photograph above was taken on that day. After checking the box we drove a short distance away and waited. Sure enough a female bluebird flew right into the box. The eggs were also consistent with the size of the blue bluebird eggs that we are noting in the other boxes and the nest was consistent with the other bluebird nests.
According to www.sialis.org, up to 4 to 5 percent of bluebirds lay white eggs. The Sialis website also indicates that white eggs can occur in all three species of bluebirds and that the white eggs are just as fertile as the blue eggs. From what I read on this website, a female that lays white eggs will always lay white eggs. So, if we have blue eggs in the same nest box for the second brood, then another female has now inhabited the box. It will be interesting in the coming weeks to see if we have white or blue eggs in that same box.
As always, one other good thing about being outside monitoring the bluebird boxes is that it affords us the opportunity to see what new visitors we have flying around the garden. In addition to the usual suspects we saw a few new species of birds during May that we did not see in April. We observed the Indigo Bunting, American Goldfinch, Barn Swallow, Red-winged Blackbird, Orchard Oriole, Red-eyed Vireo and the Chimney Swift.
When you pay your next visit to the garden I hope you'll take some time and observe the birds as well as the beautiful plants and flowers. Please drop us a line if you see a species of bird that you do not normally see so that we can be on the lookout for them as well. Enjoy the garden and happy birding!