WASHINGTON — Giving birth is the social event of the year for banded mongooses in Uganda. When females live in the same group, 60 percent bear their young together on exactly the same night — regardless of when they were impregnated.
To the casual observer, this synchronization may appear to be a remarkable feat of teamwork. But a study published recently in the journal Biology Letters suggests that the coordination is actually driven by cut-throat competition and murderous intent.
“There is a cost to giving birth early, and there is a cost to giving birth late,” said Sarah Hodge, a biologist at the University of Exeter in the United Kingdom.
Pups that emerge early tend to be easy targets for other females in the group that kill them to increase the odds for their own offspring. Those born late are also less likely to survive, presumably because they have more difficulty competing for food and for attention from young adult males that serve the community by pairing up with and protecting newborns that aren’t related to them.
Though no other species are known to practice such extreme coordination, close-timing of births has been observed in a wide range of creatures — from laboratory mice to nesting birds.
“We’re finding that the timing of reproductive cycles can be strongly driven by competitive social environments,” said Michael Cant, another University of Exeter biologist who was involved in the study.
The scientists have yet to determine how the mongooses achieve this extreme coordination but suspect that pheromones may be involved.