According to the theory of sexual selection, members of one sex compete for the access to the other. The sexual selection hypothesis for infanticide proposes that a male taking over a new group of unrelated females will kill the infants. By doing so, the invader removes a competitor’s offspring while speeding up the opportunity to mate with the victimised mother. However, several requirements must be met in order to categorise infanticide as sexually selected (SSI): 1) a male should not kill his own offspring; 2) killing of infants must shorten the time period to a female’s next estrus and shorten the interbirth interval; and 3) the male should sire the mother’s next offspring. SSI benefits the fitness of the male, but is very costly to the fitness of the mother, and thus female counterstrategies have evolved. SSI has been studied in the Scandinavian brown bear, in which it can induce up to 30 % cub loss per year. Evidence for all three requirements of the SSI hypothesis has been documented in Scandinavian brown bears, and females show evidence of behavioural counterstrategies to SSI. Hunting of especially male bears seems to increase the probability of SSI and can limit population growth, because bear cub mortality increased significantly six months and especially one and a half years after an adult male bear was killed in an area. However, this mechanism is controversial and cannot be generalised among bear species and populations.
Sexually selected infanticide as a mating strategy in brown bears
Pages: pp. 129-136


Bear and Human: Facets of a Multi-Layered Relationship from Past to Recent Times, with Emphasis on Northern Europe
Publisher: Brepols Publishers
Published: January 2023
ISBN: 978-2-503-60611-8
e-ISBN: 978-2-503-60613-2
https://doi.org/10.1484/M.TANE-EB.5.133678
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