The summer 2016 nesting season in Nebraska was marked by extensive nest failures at colonies throughout the study area.
We are unsure of the cause(s) of the reduced reproductive success. Colonies where some nests were fumigated and others not showed higher success among fumigated nests, consistent with swallow bugs’ being responsible for the nesting failures.
Yet at those very sites, bug numbers were low and did not approach the same levels of past years when birds were successful. We think the hotter than normal season may have contributed in part to the nesting failures, as nightly low temperatures were much warmer than usual this summer.
This may have affected availability of flying insects, and the reduced food supply (plus additive effects of bugs) may have been enough to depress cliff swallow reproductive success. We predict a demographic consequence of these nesting failures: fewer breeding birds in 2017.
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