Date of Award


Document Type


Degree Name

Master of Science (MS)


College of Science and Mathematics




The American Kestrel (Falco sparverius) recently has been discovered to be in decline and the reason is still unknown. Many studies have shown climate’s effect on migratory birds, but the relationship between climate and kestrel ecology has received little attention. This study sought to determine whether the climate in northwestern New Jersey and kestrel reproductive efforts have changed over the course of 20 years as well as determining whether these two factors are related. Monthly temperature, rainfall, and snowfall data were obtained from online databases. Breeding variables, including percentage of nest boxes used, clutch and brood size, percentage of successful attempts, and mean number of fledglings per successful attempt (MFPSA), were obtained from a nest box program established in 1995. Correlative statistics and a principal component analysis were conducted. Weather variables changed little through the study period. Regarding breeding variables, earlier laying dates were strongly correlated with larger clutch sizes. Of the climate variables, temperature exhibited the most variability and had the strongest relationships with breeding variables, warmer temperatures being associated with higher reproductive success. Weather did not seem to influence how many kestrels reached the breeding grounds, but once the birds arrived, temperature may have had a significant impact on when the birds lay their eggs, which has a positive relationship to clutch size, brood size, and therefore the number of fledglings that live to banding age, the standard measure of reproductive success.

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