Eastern Bluebird - Photo Earl Harrison

A study partially funded by Columbus Audubon shows that Eastern Bluebirds in Ohio struggle to take care of their young in less favorable environmental conditions.

Researchers at Ohio University monitored 76 bluebird nest boxes in Athens County in 2018 and 2019 to see if bluebird parents were able to overcome obstacles like lower food availability and higher levels of parasitic blow flies in their nests.

The results showed they could not.  Nestlings had lower growth rates when their nests were parasitized by blow flies and when they were in territories with lower food availability.

“Parents were unable to override the direct effects of negative environmental conditions on offspring growth,” the researchers wrote in their study, which was published online recently in the journal Ecology and Evolution.

The study was conducted by Madeline Sudnick, an undergraduate student in biological sciences; Bekka Broadie, assistant professor of biological sciences; and Kelly Williams, associate professor of biological sciences, all at Ohio University.

Sudnick and Williams received funding for the study in 2018 from the Columbus Audubon Conservation Grant Program. The Audubon funding was used to establish a new bluebird next box trail at the Land Lab on The Ridges in Athens County, one of four sites used in this research.

In their Ecology and Evolution paper, the research team said the findings should cause people to reconsider the belief that birds will be able to adjust their behavior to help deal with the negative effects of how humans have changed the environment.

For bluebirds, declines in worldwide insect populations in particular may be more than they can deal with.

“Human-altered habitats can present novel situations that parents are unprepared or unable to adapt to,” the researchers wrote.

In fact, “our work suggests that while parental care behavior is modified in relation to environmental factors, the changes in behavior do not completely compensate for the effects of the environment on offspring growth and condition.”