Notes from Bronx Zoo Trip: American Robins

Dr. Sperling made special mention of the Robins (Turdus migratorius) and how 2 parents can produce 60 offspring in their lives while only 2 ever survive to replace them. According to the exhibit on Robins, only 1/2 of the chicks ever leave the nest and 10 survive out of 100 to become breeding adults. (The numbers don't exactly match-up, but Dr. Sperling insisted that Robin parents only ever replace themselves, otherwise we'd be up to our eyeballs in Robins.)

He said to make note of how the babies die. Reasons for such high mortality include ants, foxes, weasels, etc. (eating babies from the nest), babies falling out of the nest (into water and drowning & onto ground and getting eaten by scavengers like Turkey Vultures, ants, etc.), babies getting lost during migration, among others. Crows are known to steal baby birds from nests as well. Also, if one or both parents are killed (by feral cats, window/car strike, hawk attack, poisoning, etc.) obviously the babies would have little chance of surviving. In Spring and Summer, Robins tend to fly low along the ground (often right in front of cars) since they are hunting for worms.

Also note that Robins are thrushes. The babies have streaked breasts just like other thrushes and only get the "red (orange) breast" as they mature (after 1st year?) Robins ARE protected under the Migratory Bird Treaty Act of 1918, but they don't really migrate that far. They tend to migrate locally in winter to areas with berry bushes.

Robins are commonly referred to as the "first bird of Spring," but this is not exactly true. You can often find Robins around here in the middle of winter if you search around enough. Eastern Phoebes are the true first bird of Spring, as mentioned by Dr. Sperling. They are the first to arrive among the real migrants, usually appearing by mid-March. Remember, they are fly catchers, so it has to be just warm enough for insects to be out. My mom said that when Robins are sighted on the ground, it is a "sign of Spring" because that means that the ground is warm enough for worms to start moving around. (Remember: Eastern Phoebes bob their tail.)