The “Nest Ecosystems” of Cavity Nesting Birds

Purple Martin gourd house being setup for the cavity nesting bird program.
Purple Martin gourd house being setup for the cavity nesting bird program.

Purple Martins, Eastern Bluebirds and Tree Swallows are all examples of cavity nesting birds which readily (or even exclusively in the case the Purple Martin) use man-made nest boxes. The nests in these boxes are far from sterile environments and are likely to contain a diversity of invertebrate and microbial species as well as the birds themselves. While the birds themselves are relatively well studied, we know very little about these uninvited residents and the effect they may have on the birds. Some of these species are likely detrimental to the birds, but others may not have any effect at all, or could even be positive.

Purple Martin Nest
Purple Martin Nest

Our research aims to characterize the entire nest ecosystem; discover which invertebrate and microbial species thrive there; and test what effects they might have on the birds. We will collect the invertebrates primarily by sampling the nest material and identifying species under the microscope. For the microbial part of the study we will swab the surface of eggs, the inside of the nest box and the nest material itself. We will then extract and sequence the microbial DNA to find out which species are present and determine whether or not they are likely to be harmful to the birds. As the community of invertebrates and microbes could be influenced by temperature and humidity we will use in-nest sensors to measure these variables and study how they vary depending on nest box orientation and design.

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Throughout our study we will of course also keep a close eye on the success of the nests’ avian inhabitants! We will record how many eggs are laid and hatched, how many nestlings fledge and the weight of the chicks at the time of fledging from each nest. We then hope to be able to link the breeding success of the birds back to the presence of certain other species in their nest ecosystem.

We are able to carry out this project thanks to generous financial support from the North American Bluebird Society, the New York State Bluebird Society and the Purple Martin Conservation Association.

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