American Robins in winter
by Stan Tekiela
January 31, 2010
Photo by Stan Tekiela©
Each winter it seems to surprise a lot of people to see American Robins (Turdus migratorius) eking out a living in the snow and cold. Well, actually it's not uncommon at all. In fact a small percentage of the entire population of American Robins don't migrate at all. I have always estimated that between 1 and 5% of the population of robins simply puts up with winter and stays put in the northland.
The reasons behind the lack of migratory motivation are multifold. First, nature is always testing the boundaries or pushing the envelope as some people are so fond of saying. Individuals within a population will always be different and not follow the normal behavior patterns. For example in the case of robins some will not migrate thus allowing for an alternative to migration. These hardy individuals sacrifice in some aspects of their lives but gain advantage in others. This kind of exploratory behavior by some individuals is how nature adapts to a changing environment.
Male robins are far more likely to not migrate than females. Turns out there are some good reasons for this. Every study on migratory birds indicates that the first males to return to the breeding grounds get their choice of the prime territories. Possessing the prime territories insures more success in breeding and reproducing. And in nature that is the name of the game.
The male robins that don't migrate will have a huge advantage over the migratory males when spring rolls around. The wintering male robins will occupy the best territories weeks before the migrating males return. This will ensure they will attract the best females for mates.
So how do the robins survive the cold, snow, and more importantly the lack of food? Robins switch their diet from insects and earthworms in the summer to fruit in winter. The only trick is they need a source of water to help process the strict fruit diet. So you will often find wintering robins near an open water source such as a creek.
So you might wonder how the birds handle the extreme cold. Well, back in autumn the birds started to grow extra feathers. Up to one third more feathers than during summer. These extra feathers help to insulate the bird and reduce any heat loss. You can see this by noting that falling snow doesn't melt on the backs of the birds.
Robins gather in fairly large flocks during winter unlike summer. The reason for this is a simple rule of "more eyes find more food". Flocks of robins roam around in winter looking for fruit on the trees. Once a tree is located they often spend several days feeding. When the food supply is gone they fly off to find another tree. This continues all winter.
So let the snow fall, the wind whip and the temperatures plummet, our wintering robins will do just fine. Until next time
Stan Tekiela is an author/naturalist and wildlife photographer who travels the US to study and photograph wildlife. He can be contacted at his web page at www.naturesmart.com
Column List | Back to top