The Worm Whisperer

The Worm Whisperer

American Robins (Turdus migratorius)are skilled assassins. Of my earthworms. I don't know how it is that I still have any left after the carnage of the last few weeks, but there you go. Nature is amazing.

Our robins (yours too, of course) are a member of the Thrush family, as are all our named thrushes (like Hermit Thrushes) and our bluebirds. Taxonomy of the thrushes has changed in the last couple of decades, so birds that used to be believed to be of the family Turdidae may no longer be classified in that manner.

Robins are very widespread in North America--familiar to the suburbs and farmlands, but also to cities where grassy greenspace has been set aside--even if that set-aside was intended as a dog park. Robins also enjoy forests and woodland wherever short grasslands are close at hand. They breed in nearly all of the Lower 48. They are, for the most part, carnivores (bug and worm eaters) in the spring and summer, but will also eat fruit when it is available--and switch to mostly fruit in fall and winter. The nests themselves are constructed from twigs, grasses, leaves and mud.

You can tell the adult male from the adult female pretty easily if you watch a group of them in the winter. Even in non-breeding plumage (which doesn't change much in this species), the males have darker, richer coloring than the females--darker gray or brown on their backs, more vibrant russet coloring on their bellies. Heads of the males are nearly black (like the one above), while females have gray heads. The white crescents above and below the eye are seen in both sexes. Western versions of the American Robin are a bit more subdued. Juveniles have spotty breast feathers to add to their generally unkempt appearance. Of course, when their heads are buried in a birdbath it is difficult to make a determination of sex. :)

As the Latin name would indicate, American Robins are conspicuously migratory, though some populations in Baja California stay put. Large groups move together and are much more restless than breeding pairs. Crack a window in winter and they'll take off in a heartbeat--do the same in late spring and you're likely to be ignored!

The robin's diet tells you all you really need to know about what to plant to ensure yourself a breeding pair in spring, or a flock in winter. In spring, there must be short grasses. This can be traditional lawn, or it can be a short-grass meadow area you've created.

[A note on this--evidently they do not listen for the worms, they see minute traces of activity and react accordingly.]

According to the one study available to BNA (cited below), 78% of a robin's diet is insects gleaned from vegetation, while only 15% was gleaned from the ground. That being said, whatever habitat is available locally is sure to impact these proportions. Another fun finding was that newly-mown lawns were indeed exploited as a "vulnerable prey" source. Worm stealing, however is frowned upon and will be met with agitated hopping and sharp vocalizations--as long as the perceived thief is another robin. If the thief is a more aggressive species, such as a starling, robins will drop their prey and run.

If you are looking for guidance on what to plant (besides non-tall fescue lawn), chokeberries figured heavily in the consumption patterns of robins in one study. Chokeberry is also an excellent rain garden plant. Juniper species were another fruit heavily consumed by robins and they have the further benefits of being evergreen and walnut tolerant. In my own yard, I have observed them consuming winterberry holly (ilex verticillataand green hawthorn (crataegus viridis).

Exposure to pesticides, as you might expect, reduces bird weight and breeding success. High levels of exposure can lead to death. DDT is apparently a highly successful way to kill robins if you're so inclined. The species takes between 10 and 17 years to recover when an area has been treated with DDT. Ironically, earthworms are immune to DDT, but that doesn't stop the poison from taking out the consumer of the earthworm, who may have levels of the poison 5 times higher than the surrounding soil.

Robins are in no danger of dying out--the urbanization of America has increased the resources that these birds can use. Because of this success, they are sometimes considered a pest--they are capable of extensive crop damage to fruit orchards!

For more great pictures of robins, check out Steve Creek Outdoors--great series of shots of a nesting robin.

Sources:

Birds of North America (a subscription site), All About Birds (Cornell's non-subscription site)

Favorite Spring Thing #3

Favorite Spring Thing #3

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Favorite Spring Thing #2