The Impacts of Rainfall and Temperature on the Breeding Productivity and Foraging of Great Blue Herons in Southern Texas




Zannino, Marina Ann

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Rainfall and ambient temperatures can influence aquatic ecosystems such as wetlands, rivers, and lakes in semi-arid to arid regions. Seasonal changes such as these may impact the breeding productivity and foraging behavior of aquatic wading birds such as Great Blue Herons (Ardea herodias). Previous studies have used short-term datasets to research the effects rainfall and temperature that on the breeding productivity and foraging of Great Blue Herons. Though helpful, these studies do not allow for long term trend exploration. In this study, effects of rainfall and ambient temperature on the breeding productivity and foraging behavior of Great Blue Herons were evaluated over a 15-year period (2005-2019) at Cibolo Nature Preserve, Texas. First, I assessed the effects of rainfall and temperature on rookery size, lay date, brood size, nesting population, and nest success. Second, I used game cameras at six sites with different hydrological regimes and evaluated the effects of rainfall and temperature on the foraging behavior of herons (measured as the number of heron photos per week between July 2019 and March 2020). I found that rainfall and temperature had no effect on breeding productivity of Great Blue Herons. However, maximum daily temperature was inversely correlated to the number of photos captured of herons suggesting Great Blue Herons foraged less frequently during warmer temperatures. This study demonstrates that temperature has a significant impact on foraging activity of wading predatory birds.


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Breeding productivity, Great blue herons, Rainfall



Integrative Biology