Building a Nest in the Middle of a Desert

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Darlene Francis, Behavioral Neuroscientist, University of California, Berkeley:

We’re watching this mother do the best that she can. Her stress hormone levels are through the roof.


It’s like trying to build a nest in the middle of the desert. Not the most hospitable place. Split screen of rat mothers trying to build nests.

NARRATOR: Rat mothers like to build nests for their pups with soft materials. But these moms have only been given hard, scratchy, inferior building supplies. It’s a replication of an experiment first conducted by David Swett.

Darlene Francis:

They really devote a lot of resources to trying to build nests, because we took their nesting materials away, horrible researchers that we are. A mother rat with bad materials neglects her pups as she pushes around materials.

Darlene Francis:

I think it’s obvious that she’s trying really hard, and she’s tried really hard to provide as much of a nest as she can to her litter.

NAR: The stressed mothers spend as much time with their pups as unstressed moms. But they lick and groom far less. The strain of providing shelter with few resources impeded the rats’ efforts to care for their young.

Darlene Francis:

It wasn’t a time issue, but the quality of what they were doing and how they were interacting with their pups was different, and we were able to identify that that directly related to measures of the stress response.

NAR: A stressful environment led to a low-licking mother. That low-licking mother produced offspring that had trouble turning their stress response off. And this triggered a cascade of health and behavioral effects.

NAR: But laboratory rats are one thing. Would the same pattern hold true for humans?