Humans unknowing midwives for pregnant moose

When it’s time for moose to give birth in the Greater Yellowstone Ecosystem, they head to where it is safest from predators – namely closer to people, according to a new study by the Wildlife Conservation Society.

Published in the Royal Society’s journal Biology Letters, the study says that moose avoid predation of their calves by grizzly bears by moving closer to roads and other infrastructure prior to giving birth. Wildlife Conservation Society researchers tracked both moose and bears, finding that pregnant moose in Greater Yellowstone have shifted their movements each year for the past decade about 125 meters closer to roads during calving season, specifically to avoid road-shy brown bears, which can prey heavily on moose calves.

“Given that brown bears avoid areas within approximately 500 meters of roads in Yellowstone and elsewhere, moose mothers have apparently buffered against predation on offspring using roadside corridors,” said Wildlife Conservation Society biologist Dr. Joel Berger, the study’s author.

Berger also cited similar examples where prey species tend to use humans as cover from predation, including vervet monkeys in Kenya and axis deer in Nepal that avoiding big cats by staying close to ranger stations.

“The study’s results indicate that moose and other prey species find humans more benign and hence move to humans for safety whereas predators do not because we humans tend to be less kind to predators,” Berger added.

According to Berger, the results also reveal that national parks are not necessarily showcases of natural ecosystems, but instead can actually affect natural biological events in ways park managers haven’t yet imagined.

Source: Wildlife Conservation Society

Explore further

Why jackals thrive where humans dominate

Citation: Humans unknowing midwives for pregnant moose (2007, October 9) retrieved 17 July 2019 from
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

Feedback to editors

User comments

Oct 10, 2007
This past September while visiting Yellowstone, I witnessed two moose in separate locations just tens of meters from the side of the road. The male stayed in that one location for over a week.

Interestingly, when viewing a video I took of the male, I noticed in the background, perhaps 100 meters away, a female black bear and her cub walking by. I, and the entire moose audience, including a park ranger, completely missed seeing that bear.

Perhaps moose aren't afraid of black bears. Or maybe the moose really felt impervious in the proximity of 100 human beings.

Oct 21, 2007
and the interesting question is: does this constitute "selection pressure" leading to an evolutionary effect, or is it just "cultural" and they've "learned" to associate lower predation with proximity to human spoor? In other words, would calves brought up away from their families make the same choice because they now have a genetic predisposition, or would they and their descendantes have to learn the same lessons all over again?

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more