Survival and Breeding Transitions for a Reintroduced Bison Population: a Multistate Approach

Abstract

The iconic plains bison (Bison bison) have been reintroduced to many places in their former range, but there are few scientific data evaluating the success of these reintroductions or guiding the continued management of these populations. Relying on mark‐recapture data, we used a multistate model to estimate bison survival and breeding transition probabilities while controlling for the recapture process. We tested hypotheses in these demographic parameters associated with age, sex, reproductive state, and environmental variables. We also estimated biological process variation in survival and breeding transition probabilities by factoring out sampling variation. The recapture rate of females and calves was high (0.78 ± 0.15 [SE]) and much lower for males (0.41 ± 0.23), especially older males (0.17 ± 0.15). We found that overall bison survival was high (>0.8) and that males (0.80 ± 0.13) survived at lower rates than females (0.94 ± 0.04), but as females aged survival declined (0.89 ± 0.05 for F ≥15 yr old). Lactating and non‐lactating females survived at similar rates. We found that females can conceive early (approx. 1.5 yr of age) and had a high probability (approx. 0.8) of breeding in consecutive years, until age 13.5 years, when females that were non‐lactating tended to stay in that state. Our results suggest senescence in reproduction and survival for females. We found little support for the effect of climatic covariates on demographic rates, perhaps because the park's current population management goals were predicated from drought‐year conditions. This reintroduction has been successful, but continued culling actions will need to be employed and an adaptive management approach is warranted. Our demographic approach can be applied to other heavily managed large‐ungulate systems with few or no natural predators.

Survival cost to relocation does not reduce population self‐sustainability in an amphibian

“…The ability of individuals to accommodate novel environmental conditions may also depend on individual factors such as sex and age (Teixeira et al 2007). The effect of sex has been investigated (Le Gouar et al 2008, Pyne et al 2010, Armstrong et al 2017), but reduced survival during the establishment phase and related consequences for relocation success remain poorly understood (but see Le Gouar et al 2008, Aaltonen et al 2009).…”

State‐space modeling to support management of brucellosis in the Yellowstone bison population

“…Choices of age and sex classes (Table 2) were guided in part by knowledge of bison life history. We chose two age classes for non-juvenile females because pregnancy and birth rates do not show any effect of age beyond age three years (Fuller et al 2007) and because it is reasonable to assume that adult survival is high and constant with age in adults (Eberhardt 2002, Pyne et al 2010. Our choice of classes was also influenced by the data available to fit the model.…”

Generation of multistate release–recapture models using a graphic user interface (GUI)

“…Releaserecapture methodology was used by Aars and Ims [15] to explore the effects of habitat corridors on populations of root voles (Microtus oeconomus). More recently, a multistate model was used by Pyne et al [16] to estimate survival rates stratified by age, sex, and breeding status for a reintroduced population of plains bison (Bison bison).…”