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Biodiversity and Global Change

Evaluating risk of parasitism from Brown-headed Cowbirds

Brown-headed Cowbirds are obligate nest parasites, which means they rely on birds of other species to incubate their eggs and raise their young. Nest parasitism can reduce the reproductive success of the host species, so management of endangered species and populations often includes removal of cowbirds from important breeding grounds. Kirtland's Warblers, which were considered endangered until 2019, breed in a small region in northern Michigan and Wisconsin. For decades, cowbirds have been removed from their breeding grounds to improve reproductive success. We used conditional prediction to determine whether Kirtland's Warblers and other birds in the region are at risk of nest parasitism due to high co-occurence. 

We learned that in areas where Kirtland's Warblers breed, there are fewer cowbirds than expected. This means that Kirtland's Warblers are probably at low risk of nest parasitism. We also learned that there are more cowbirds than expected where Bell's Vireos breed, meaning they are at higher risk of nest parasitism. We suggest that Bell's Vireos populations be monitored to understand how parasitism affects reproductive success.

This manuscript is currently in review; for more information, please email me.

Predicting biodiversity with GJAM

As part of the Predicting Biodiversity with Generalized Joint Attribute Modeling (PBGJAM) project, I developed predictions of suitable habitat for 100 bird species in current conditions and under two future climate change scenarios. These predictions combine information from the current abundances of species across different environmental conditions with projected environmental conditions under climate change. For example, if we know the temperature range of the areas where a species lives today, and we know what regions will fall within that temperature range in 100 years, we can predict where the species will live in 100 years. It is important to remember that these are maps of habitat suitability, not actual species range. If there is suitable habitat in an area that a species can’t get to, it will not actually be found there.


Interactive maps on the PBGJAM website show current habitat suitability for each species. Use the toggles in the menu to view the expected habitat suitability at two time periods in the future for both RCP 4.5 and RCP 8.5. Current and past lab members have developed similar interactive maps for beetles (Christopher Kilner), trees (Shubhi Sharma), and small mammals (Amanda Schwantes), all of which are available on the website.

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