2013 Blue Bird Update


Eastern Bluebird 2012 2013
Number of Eggs 545 531
Percent of Hatch Rate 83% 85%
Number of Live Young 455 453
Percent of Fledge Rate 89% 88%
Number of Fledged 404 398
Tree Swallow 2012 2013
Number of Eggs 549 561
Percent of Hatch Rate 83% 75%
Number of Live Young 453 418
Percent of Fledge Rate 83% 78%
Number of Fledged 375 324
House Wren 2012 2013
Number of Fledged 30 49
Black-capped Chickadee 2012 2013
Number of Fledged 7 2
House Sparrow 2012 2013
Number of Eggs 33 26
Purple Martin 2012 2013
Number of Fledged 2 17

With nearly 400 bluebirds fledged, 2013 was another great year for Holden’s bluebird program. And despite some weather-related challenges, our tree swallows also did quite well.


Extended cold weather during the breeding season caused a relatively high number of unhatched eggs and dead young in our tree swallow nests. This can be seen in the percentage of hatched and fledged numbers, which were much lower this year than in 2012. But the record high number of eggs meant that our overall number of fledglings was still quite good.


This weather did not affect bluebirds nearly as much; in fact, percentage of hatched eggs was higher in 2013 than in 2012. The reason the cold weather isn’t as much of a problem for bluebirds is likely due to the fact that they eat bugs from the ground. Tree swallows eat flying insects. When the weather turns cold, the flying insects just don’t fly and the tree swallows have a hard time finding enough to eat. And bluebirds, which often spend the winters here, might just be tougher than tree swallows, which migrate south for the winter.


As you can see, 2013 ranks as the fifth best year on record for number of bluebirds fledged. And the fourth best year for tree swallows.


Holden’s bluebird program has reached another milestone this year. The total number of bluebirds fledged over the entire history of the program is now more than 10,000. To be precise, Holden has fledged 10,101 bluebirds since 1965.


Thank you to all the volunteers, past and present, who have helped make this such a successful conservation program.


For more details on the volunteer bluebird monitoring program contact Mike Watson at 440.946.4400 or mwatson@holdenarb.org.