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Why Are Robins So Big in the Spring?

  • 3/5/2015 10:24:00 AM
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Learn why robins are bigger in the spring | Iowa DNRJust like the first sighting of a robin marks spring for many people, so does the arrival of animal babies. But in this case, robins aren’t big in the spring because they’re ready to lay eggs. They’re not bigger at all – just really cold.

On cool spring mornings and chilly days, robins puff out their feathers – called rousing – to stay warm. It fluffs air into the bird’s down feathers, giving some insulation to help the robin maintain its body temperature. Other times, that large-looking robin could be a male puffing up his chest to display his territory or to attract a female for breeding.

But what about those eggs? It doesn’t take long for a robin to create and lay a clutch of three to five eggs. A robin can produce one egg a day, but you’d never know she was a mama by looking at her.

She then sits on the eggs for 16 to 17 days and spends another 16 to 17 days at the nest feeding the little hatchlings. Iowa robins usually try for two successful nest attempts between April and August.

You might even catch a glimpse of a cold and “fat” robin in the winter. While most Iowa robins still head south for the winter, robins may stick around in years with good fruit and berry supplies.