Abstract Title
The Influence of Seasonality and Migration Strategy on the Reproductive Pace of American Kestrels (Falco sparverius)
Additional Funding Sources
This research, conducted at the Raptor Research Experiences for Undergraduates site, was supported by the National Science Foundation and Department of Defense under Grant No. DBI-1852133 and by Boise State University.
Abstract
Variation in reproductive pace (the time span from egg laying to fledging young) may be attributable to seasonal patterns in primary productivity and prey availability that affect both breeding season energetic investments and nonbreeding season migration strategies. As growing seasons shift in timing and duration, information on reproductive pace and its underlying mechanisms are necessary to predict how populations will respond to climate change. We studied breeding American kestrels with different migration strategies at two sites in southern Idaho with distinct seasonal resource patterns. At the site near Fairfield, ID, where the breeding Kestrels are migrants, the growing seasons are brief with high peaks in primary productivity, suggesting a short window of high prey abundance. In Kuna, ID, where the breeding Kestrels are partial migrants, the growing seasons are longer with low, prolonged peaks in habitat productivity, suggesting a long window of moderate prey abundance. We examined variation in reproductive pace and its dependence on site or migration strategy. We predicted that Kestrels nesting near Fairfield would have an accelerated nesting pace compared to Kestrels nesting in Kuna because of the short window of high prey availability they experience. Alternatively, we predicted that migratory Kestrels, regardless of site, would have an accelerated nesting pace because they arrive later at the breeding grounds and have a shorter nesting period than resident Kestrels. We collected information about the length and productivity of the growing season using NDVI values. We identified individual migration strategies of breeding adults based on stable hydrogen isotope analysis of talon tissue, and collected nesting event information with images taken by nest box cameras to determine the pace of each reproductive stage. Results will determine how resource availability and wintering decisions influence the nesting pace of Kestrels.
The Influence of Seasonality and Migration Strategy on the Reproductive Pace of American Kestrels (Falco sparverius)
Variation in reproductive pace (the time span from egg laying to fledging young) may be attributable to seasonal patterns in primary productivity and prey availability that affect both breeding season energetic investments and nonbreeding season migration strategies. As growing seasons shift in timing and duration, information on reproductive pace and its underlying mechanisms are necessary to predict how populations will respond to climate change. We studied breeding American kestrels with different migration strategies at two sites in southern Idaho with distinct seasonal resource patterns. At the site near Fairfield, ID, where the breeding Kestrels are migrants, the growing seasons are brief with high peaks in primary productivity, suggesting a short window of high prey abundance. In Kuna, ID, where the breeding Kestrels are partial migrants, the growing seasons are longer with low, prolonged peaks in habitat productivity, suggesting a long window of moderate prey abundance. We examined variation in reproductive pace and its dependence on site or migration strategy. We predicted that Kestrels nesting near Fairfield would have an accelerated nesting pace compared to Kestrels nesting in Kuna because of the short window of high prey availability they experience. Alternatively, we predicted that migratory Kestrels, regardless of site, would have an accelerated nesting pace because they arrive later at the breeding grounds and have a shorter nesting period than resident Kestrels. We collected information about the length and productivity of the growing season using NDVI values. We identified individual migration strategies of breeding adults based on stable hydrogen isotope analysis of talon tissue, and collected nesting event information with images taken by nest box cameras to determine the pace of each reproductive stage. Results will determine how resource availability and wintering decisions influence the nesting pace of Kestrels.