Maternal care is stressed because it helps to increase the chances of survival when overcrowding

(new study) - A new study has found that animals can speed up the development of their offspring to help ensure young offspring can compete for residence when number The amount becomes too crowded. Surprisingly, stress rather than eating more is the key to the gift of mothers, scientists said.

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Larger young squirrels have a better chance of mapping out an exclusive area, where it can freely enjoy the seeds lurking in the spruce. Juvenile squirrels without control of a territory before their first winter will often not be able to survive.

'When the density is high, only the fastest growing young can survive,' said researcher Andrew McAdam. Andrew McAdam is a researcher at Guelph University in Canada.

Andrew McAdam and colleagues studied North American red squirrels living in the Yukon. In the experiment, they turned on the audio tapes of squirrels emitted when they determined the territory to deceive the mother, so that they thought the forest was too crowded.

All sounds made pregnant squirrels produce more cortisol stress hormones, and therefore the squirrels are born to grow faster. Increased cortisol even motivates the born calves to be slightly larger, leading to a slower growth trend.

'Although we all know that stress is a bad thing for our health, our research shows that high levels of stress hormone in mothers can actually help their babies , ' says Ben Dantzer, currently a postdoctoral researcher at Cambridge University said in a statement. (Dantzer studied with McAdam when both were at Michigan State University).

But there is a compromise here. Faster squirrels also consume faster, often dying earlier than later adults. When the forests are wide, the growth rate is slower. The study is detailed online in Science magazine on Thursday, April 18