This is Scientific American 60 Second Science. I'm Emily Schwang.

Over the last few decades,

Cannag East had been wintering further and further north,

which was interesting because the winters have gotten

a little more mild over the last few years but still it's pretty cold out there

and lots of snow. University of Illinois ornithologist Mike Ward.

So you would wonder why these geese are deciding to spend the winter in Chicago when they could

have the opportunity to fly down to Arkansas, Louisiana Louisiana somewhere warmer.

Geese who continue south often land in agricultural fields and other wide open areas,

which makes them visible to hunters in those states who can bang the birds until the end of January.

There's definitely a lot of geese that are seeing the winters in Chicago, and not just

Chicago, lots of urban areas throughout the Midwest.

And one reason they're doing that is they're trying to avoid hunters it looks

like. Of course staying in cities is no easy life either. It probably would be

easier to find food if they would fly somewhere else and to go to a cornfield or somewhere else.

But they're hanging out in the city and they're acting very strangely.

We found that they were using parks like you might expect, but when the weather got bad and it snowed they were hanging out on top of

roofs, so large factories and flat rooftops, they'd spend a large amount of time just sitting there.

We also found that they would go to areas like

transfer stations for rail cars that had spilled grain and so they would be

walking around railroad tracks trying to find spilled grain. And the effects of that changed behavior are significant.

They're a lot skinnier.

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