Cumulative and interannual effects of reproduction in eastern grey kangaroos.

Reproduction can reduce energy allocation to other life-history traits such as survival and growth. Resource constraints give rise to (co)variation in life-history traits and to heterogeneity in energy acquisition and allocation. At each reproductive opportunity, females face a choice between allocation to current reproduction or to maintenance.

Early-life behavior, survival, and maternal personality in a wild marsupial.

Individual behavior varies for many reasons, but how early in life are such differences apparent, and are they under selection? We investigated variation in early-life behavior in a wild eastern gray kangaroo () population, and quantified associations of behavior with early survival. Behavior of young was measured while still in the pouch and as subadults, and survival to weaning was monitored. We found consistent variation between offspring of different mothers in levels of activity at the pouch stage, in flight initiation distance (FID) as subadults, and in subadult survival, indicating similarity between siblings.

Post-weaning survival in kangaroos is high and constant until senescence: Implications for population dynamics.

Large herbivores typically have consistently high prime-aged adult survival and lower, more variable, juvenile, and senescent survival. Many kangaroo populations undergo greater fluctuations in density compared with other large herbivores, but age- and sex-specific survival of kangaroos and their response to environmental variation remain poorly estimated. We used long-term capture-mark-recapture data on 920 individuals to investigate the survival component of eastern grey kangaroo (Macropus giganteus) population dynamics.

Tall young females get ahead: size-specific fecundity in wild kangaroos suggests a steep trade-off with growth.

When resources are limited, organisms face allocation conflicts. Indeterminate growth creates a persistent conflict with reproduction, as growth may enhance future reproduction, but diverts resources from current reproduction. Little is known about allocation trade-offs in mammals with indeterminate growth.

Mother-offspring distances reflect sex differences in fine-scale genetic structure of eastern grey kangaroos.

Natal dispersal affects life history and population biology and causes gene flow. In mammals, dispersal is usually male-biased so that females tend to be philopatric and surrounded by matrilineal kin, which may lead to preferential associations among female kin. Here we combine genetic analyses and behavioral observations to investigate spatial genetic structure and sex-biased dispersal patterns in a high-density population of mammals showing fission-fusion group dynamics.

Adoption in eastern grey kangaroos: a consequence of misdirected care?

Adoption is rare in animals and is usually attributed to kin selection. In a 6-year study of eastern grey kangaroos (Macropus giganteus), 11 of 326 juveniles were adopted. We detected eight adoptions by observing behavioural associations and nursing between marked mothers and young and three more by analysing the relatedness of mothers and young using microsatellite DNA.

Determinants of reproductive success in female Columbian ground squirrels.

We studied the reproductive success of female Columbian ground squirrels (Spermophilus columbianus) in southwestern Alberta for nine years. We defined reproductive success as the number of offspring surviving their first hibernation, classified as yearlings. The number of weaned juveniles explained one third of the variance in number of yearlings at emergence from their first hibernation the following spring, and much of the variance in individual reproductive success originated after weaning.