Population-level response of coyotes to a pulsed resource event

From foraging theory, generalist predators should increase consumption of prey if prey availability increases. Pulsed resource events introduce a large influx of prey to predators that may exhibit a functional response of increased consumption rate on, or specialization to, this abundant food resource. We predicted that coyotes (Canis latrans) would respond functionally to numerical increases of neonate white-tailed deer (Odocoileus virginianus) during the pulsed resource event of parturition. We used howl surveys and deer camera surveys with occupancy modeling to estimate densities for coyotes, adult deer, and fawns, respectively, in Upper Peninsula of Michigan, USA, 2009-2011. We estimated biomass of adult and fawn deer consumed by coyotes during 2 periods [fawn limited mobility period (LMP) and social mobility period (SMP)] in May-August each year. Coyote densities were 0.32 and 0.37/km(2) for 2010-2011, respectively. Adult deer densities (3.7-3.9/km(2)) and fawn densities (0.6-1.3/km(2)) were similar across years. Overall, fawn hair occurrence in coyote scats was 2.3 times greater in LMP than SMP. Estimated consumption of fawns between periods (n = 157-880) by coyotes varied, suggesting a functional response, with increasing consumption of fawns relative to their availability. Coyotes, on average, consumed 2.2 times greater biomass of fawns than adults across years, and consumed 1.5 times greater fawn biomass, on average, during LMP than SMP. We suggest that consumption rates of coyotes is associated positively with increases in fawn density, and fawn consumption by coyotes follows predictions of optimal foraging theory during this pulsed resource event.