Influence of prey abundance on raptors in tallgrass prairie

TitleInfluence of prey abundance on raptors in tallgrass prairie
Publication TypeJournal Article
Year of Publication2004
AuthorsReed, AW, Kaufman, GA, Rintoul, DA, Kaufman, DW
JournalPrairie Naturalist
Pagination23 -32
Accession NumberKNZ00968
KeywordsANPP, microtine rodents, predator-prey, raptor, tallgrass prairie

We examined relationships between winter abundance of diurnal raptors (red-tailed hawk, Buteo jamaicensis; rough-legged hawk, B. lagopus; ferruginous hawk, B. regalis; and northern harrier, Circus cyaneus) and both the abundance of microtine rodents (prairie vole, Microtus ochrogaster; and southern bog lemming, Synaptomys cooperi) and aboveground net primary productivity (ANPP) in tallgrass prairie. We used Christmas Bird Count data for each year during 1975 through 1999 from Manhattan, Kansas to index winter raptor abundance (number of hawks per party hour). Microtine rodent abundance (average number of microtine rodents per trapline in burned and unburned prairie) was estimated by using long-term data gathered from autumn and spring surveys along 14 permanent traplines from autumn 1981 to spring 2000 in tallgrass prairie on the Konza Prairie Biological Station. An estimate of ANPP for each year during 1975 through 1999 was provided by the Konza Prairie Long-Term Ecological Research Program. Winter raptor abundance was related positively to ANPP during the preceding growing season (P = 0.01) and to microtine abundance in the previous spring (P = 0.03). Based on a stepwise regression, 39% of the annual variation in winter raptor counts was explained by ANPP and the log of spring microtine abundance. Overall, our analyses suggested that winter raptor abundance was higher in years with higher than lower prey availability, but that other factors also influenced winter raptor abundance.