Dispersal patterns in breeding Mountain Plovers (Charadrius montanus)
The rapid multi-clutch mating system of the Mountain Plover Charadrius montanus provides an opportunity to examine sex differences in natal, within-, and between-year breeding dispersal. We used nest locations from a Montana breeding population over a 14-year period to examine patterns of sex bias in natal and within-year breeding dispersal. Additionally, we modeled between-year dispersal distance with sex, previous nest fate, and presence of sylvatic plague as covariates. We found no sex bias in natal dispersal (mean = 12.96 km for 16 males; mean = 10.18 km for 22 females) or within-year breeding dispersal (mean = 2.81 km for 22 males; mean = 2.97 km for 26 females). The mean dispersal distance was 2.74 km (n = 115, SE = 0.60) for males nesting in consecutive years and 4.32 km (n = 87, SE = 0.87) for females. On average, birds that were successful moved 2.99 km (n = 149, SE = 0.55) between nesting attempts, while those whose nests had failed moved 4.63 km (n = 53, SE = 1.18). Sex of the tending adult and prior nest fate had the strongest effects on between-year breeding dispersal with a positive effect on dispersal distance for both females and birds whose nests had failed the previous year; there was a weak year effect but no effect of sylvatic plague. Our work provides 1) a better understanding of dispersal in an uncommon shorebird, 2) additional insight into a novel mating system, and 3) a basis for testing theories of avian dispersal.