Factors contributing to osprey use of great blue heron rookeries for nest sites in southeastern New Hampshire

Horne, Christopher
Jon Atwood, PhD
Department of Environmental Studies
New Hampshire's Osprey (Pandion haliaetus) population has recovered steadily since active management of the species began in 1980, following its addition to the state's list of Threatened Species. In 1988 a pair nested within a Great Blue Heron (Ardea Herodias) colony, or heronry. Since then, seven other pairs of Ospreys have established nests in five other heronries located in southeastern New Hampshire. To determine what characteristics of Great Blue Heron breeding colonies may attract nesting Ospreys, I measured nest site and landscape characteristics at eighteen heronries, six of which also had nesting Ospreys. The measured characteristics for the 18 sites varied widely, making comparisons statistically unreliable given the relatively small sample sizes involved. Nonetheless, this study provides baseline documentation of the use of Great Blue heron colonies by Ospreys; as New Hampshire's Osprey population recovers, heronries may become increasingly important in providing natural nesting sites for the species.

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