Half the monitors this year blamed the long wet spring (from March to September) for the poor productivity of nest-box inhabitants. My email was full of comments like Ron Reist’s “…huge number of failed TRES nests due to inclement weather (lack of food for both adults and young.)” The weather was harder on Tree Swallows (TRES) especially as they require mainly air insects. Mountain Bluebirds (MOBL) can adapt by eating ground and air insects, berries, etc. I suspect many parents simply gave up as they could find barely enough food for themselves – and even then there were more dead adults this year than usual. The cold contributed to hypothermia, and the excessive rain and hail probably caused some deaths as well. None of us enjoy opening a box to find several dead hatchlings, but there isn’t much we can do. Lynda Alderman comments that this “was a very confusing and sad year to do the route. [the Bluebirds’] struggle in June was hard to witness......rain, cold, snow, no bugs and then the swallows. Nature took its toll.”
We may not be able to help our avian friends in the cold weather, but they sometimes help each other. Shonna McLeod relates this story:
This box was occupied by a family of Mountain Bluebirds and they had successfully hatched 6 fledglings which I had previously banded the trip before.
Checking the box to see if baby Bluebirds had fledged, I was astonished to find an adult female TRES with wings spread out over the young hatchlings of another species, dead on top of them.
It was a picture I will never forget and it made me very sad to realize that the instinct of the TRES female to protect the young from the cold was intact even though the babies were not her own young.
I wonder if anyone else has ever documented anything like this.