Weathering the storm: Most maternal and environmental drivers of individual reproductive success do not scale up to population recruitment in a large herbivore
5 affiliations
- 1Département de Biologie Université de Sherbrooke Sherbrooke Quebec Canada
- 2Centre for Conservation Ecology and Genomics, Institute for Applied Ecology University of Canberra Bruce Australian Capital Territory Australia
- 3Department of Primary Industries & Regional Development Orange New South Wales Australia
- 4Evolution & Ecology Research Centre The University of New South Wales Sydney New South Wales Australia
- 5Research School of Biology The Australian National University Acton Australian Capital Territory Australia
Abstract
Population growth depends upon individual survival and reproduction, but do drivers of individual reproductive success scale up to population recruitment? Factors affecting individuals may have little effect on population dynamics if individuals within a population experience different conditions. When seasonal resource availability is unpredictable and breeding season long, average conditions over a breeding cycle may poorly reflect the environment experienced by many individuals.
We compared the drivers of individual reproductive success and population recruitment in an asynchronously breeding large herbivore, the eastern grey kangaroo (Macropus giganteus). We analysed 18 years of individual‐based data using multivariate hierarchical Bayesian models to first identify the causal mechanisms relating population density, environmental conditions and maternal traits to individual success. We then assessed whether the drivers of individual reproductive success scaled up to determine population recruitment.
Most maternal and environmental covariates strongly influenced individual reproductive success, with distinct effects on juvenile survival before and after pouch exit. Maternal traits had a greater influence in the pouch, whereas environmental conditions became increasingly important once young exited the pouch. Most drivers of individual reproductive success did not affect population recruitment. Recruitment decreased with population density and increased with mean body condition of adult females. Weather harshness had a weak positive effect on recruitment, which appeared independent of female age structure, previous recruitment or forage.
Most drivers of individual reproductive success did not scale up to population recruitment. Birth asynchrony could buffer population recruitment against environmental variation such that variables affecting individual reproduction have little impact at the population level. Large herbivores that reproduce asynchronously may therefore be more resilient to environmental variability than synchronous breeders.
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BibTeX
@article{bergeron2026weathering,
title = {{Weathering the storm: Most maternal and environmental drivers of individual reproductive success do not scale up to population recruitment in a large herbivore}},
author = {Rachel Bergeron and Richard P. Duncan and David M. Forsyth and Wendy J. King and Marco Festa‐Bianchet},
journal = {The Journal of Animal Ecology},
year = {2026},
month = sep,
doi = {10.1111/1365-2656.70341},
url = {https://doi.org/10.1111/1365-2656.70341},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - Weathering the storm: Most maternal and environmental drivers of individual reproductive success do not scale up to population recruitment in a large herbivore
AU - Rachel Bergeron
AU - Richard P. Duncan
AU - David M. Forsyth
AU - Wendy J. King
AU - Marco Festa‐Bianchet
PY - 2026
DA - 2026/09/03
JO - The Journal of Animal Ecology
DO - 10.1111/1365-2656.70341
UR - https://doi.org/10.1111/1365-2656.70341
AB - Population growth depends upon individual survival and reproduction, but do drivers of individual reproductive success scale up to population recruitment? Factors affecting individuals may have little effect on population dynamics if individuals within a population experience different conditions. When seasonal resource availability is unpredictable and breeding season long, average conditions over a breeding cycle may poorly reflect the environment experienced by many individuals. We compared the drivers of individual reproductive success and population recruitment in an asynchronously breeding large herbivore, the eastern grey kangaroo (Macropus giganteus). We analysed 18 years of individual‐based data using multivariate hierarchical Bayesian models to first identify the causal mechanisms relating population density, environmental conditions and maternal traits to individual success. We then assessed whether the drivers of individual reproductive success scaled up to determine population recruitment. Most maternal and environmental covariates strongly influenced individual reproductive success, with distinct effects on juvenile survival before and after pouch exit. Maternal traits had a greater influence in the pouch, whereas environmental conditions became increasingly important once young exited the pouch. Most drivers of individual reproductive success did not affect population recruitment. Recruitment decreased with population density and increased with mean body condition of adult females. Weather harshness had a weak positive effect on recruitment, which appeared independent of female age structure, previous recruitment or forage. Most drivers of individual reproductive success did not scale up to population recruitment. Birth asynchrony could buffer population recruitment against environmental variation such that variables affecting individual reproduction have little impact at the population level. Large herbivores that reproduce asynchronously may therefore be more resilient to environmental variability than synchronous breeders.
SN - 0021-8790
SN - 1365-2656
ER -