I came home from an errand to find an immensely round and fat robin hopping around the leaves in my driveway. My first thought was that it might be injured, but it just kept hopping around with no apparent injuries to its wings or feet, and as I moved closer to get a better look, it hopped under the parked car to get away from my unwanted attention. My next guess was that such a fat robin was most likely a pregnant robin, but a quick search indicated that robins don’t lay eggs until the spring, and it’s only December now.
Generally, I don’t take too much interest in robins hanging around my yard, but the visual mystery of why this particular bird was so fat sparked my curiosity. I did find a resource which said not all robins fly south for the winter, and it suggested that they bulk up in order to have “fat reserves” during the winter. It makes sense, then, that this robin was initially seen hopping around in a pile of leaves (below left), as it was probably looking for small insects or worms in the decaying leaves. I saw one odd fact that a robin can eat up to 14 feet of earthworms in a given day!
To get a better sense of how fat this robin was, you can see it here compared to a picture of a standard-sized robin (shown below right).