Incubation behavior and dispersal patterns in the Mountain Plover (Charadrius montanus)
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The rapid multi-clutch mating system of the Mountain Plover (Charadrius montanus) provides an interesting opportunity to examine sex differences in natal and breeding dispersal. I used nest locations from a breeding population of plovers in north-central Montana over a 13-year period (1995-2007) to examine patterns of sex bias in their dispersal. Additionally, I looked at the influence of prior experience and sylvatic plague on breeding dispersal in successive years. I also modeled successive nest fate using breeding dispersal distance with sex, previous nest fate, and presence of sylvatic plague as covariates in the model. I found no sex-bias in natal dispersal or within-year breeding dispersal. The mean dispersal distance of male plovers in consecutive years was 2.75 km (95% CI 1.51 to 4.00) and for females was 4.64 km (95% CI 2.76 to 5.52). Birds that were successful moved 3.02 km (95% CI 1.87 to 4.17) on average between nesting attempts, while those whose nests had failed moved 5.06 km (95% CI 2.53 to 7.58). The best model of between-year breeding dispersal contained the full set of parameters, with sex of the tending adult and prior nest fate having the strongest effects. The estimate of dispersal distance for females was positive ( Female = 0.86, 95% CI 0.67 to 1.05) as well as the estimate of dispersal distance for birds whose nests had failed the previous year ( Fail = 0.82, 95% CI 0.52 to 1.13). There was a year effect but no effect of sylvatic plague on dispersal. This study not only provides a better understanding of dispersal in an uncommon mating system but also is important in understanding the movements of a species of conservation concern. I also monitored incubation activity of Mountain Plovers in Montana using a combination of video monitoring and temperature data-logging. The rapid multi-clutch mating system of the Mountain Plover provides an interesting opportunity to examine sex-specific differences in uniparental care. To explore possible sex differences in breeding behavior I modeled the duration of departures of incubating adults to see if activity patterns differed between sexes. In addition, the effects of time of day, nest age, day of season, and year were also included. I recorded 857 hours of video of 24 incubating Mountain Plovers at 25 nests during the 2007 field season and >10,000 hours of temperature data from 117 individuals at 142 nests during the 2006-2008 nesting seasons. Video data revealed that males on average made 1.48 departures hour-1 over the course of a 24-hour period (n = 6 deployments, SE = 0.35) and females made 1.41 departures hour-1 (n = 26 deployments, SE = 0.11). From the combined video and temperature data males contributed 1,925 nocturnal departures with a mean duration of 0.38 hr (SE = 0.01) while females contributed 2,716 nocturnal departures with a mean duration of 0.36 hr (SE = 0.01). The quadratic effect of the time of departure was the most important factor in the length of nocturnal off-bouts. Other effects that were included in competitive models were the cubic and linear effects of time of departure and the highest ambient temperature the previous day. The day of incubation and the day of the season were also important in explaining duration of off-bouts. Sex was not an important predictor of duration of departure. This study not only provides further information about incubation patterns in an uncommon mating system, but also is important to gaining a better understanding of behavior in this species of conservation concern.