How Do Robins Find Worms? Sight, Hearing and Head Tilts

The run, stop and tilt routine

Watch an American robin on a lawn and you will see the same pattern again and again: a quick run or a few hops, a sudden stop with the body upright, a tilt of the head, then either another run or a lunge into the grass. This “run-and-stop” style of foraging is typical of thrushes.

Each stop gives the robin a moment to scan the ground while its body is still. Movement blurs vision, so standing motionless makes it easier to spot small changes, such as the end of a worm poking out of a burrow or a slight twitch in the soil.

When the robin finds a target, it drives its bill into the ground, grabs the worm and pulls it out with steady tugs, bracing backward with its legs. Long worms sometimes break, and a robin may pull for several seconds before the worm comes free.

Why do robins tilt their heads?

Like most songbirds, a robin has eyes on the sides of its head. That gives it a wide view to watch for predators, but only a narrow zone where both eyes look forward together. To inspect a small patch of ground in detail, the robin turns its head so that one eye points almost straight down.

That sideways tilt is what makes robins look as if they are “listening” to the lawn. In fact, early researchers argued that the tilt is mainly about seeing. In a well-known study published in 1965, ornithologist Frank Heppner tested captive robins and concluded that they located worms mainly by sight, not by hearing or smell.

Can robins hear worms?

Later experiments added a twist. In a study published in 1997 in the journal Animal Behaviour, biologists Robert Montgomerie and Patrick Weatherhead set up careful tests with captive robins and earthworms buried in trays of soil.

They removed one possible cue at a time. The robins could not see the worms, the soil surface gave no visual clues, and the researchers controlled for smell and for vibrations that the birds might feel through their feet. Even so, the robins found worms far more often than they would by chance. When the researchers played background noise, however, the robins’ success fell sharply.

The study concluded that robins can use hearing to locate worms underground, probably by picking up the faint sounds of worms moving through soil. Today, scientists think robins use a mix of senses: sight is the main tool, and hearing helps, especially when worms are just below the surface.

When are worms easiest to find?

Earthworms come close to the surface when the soil is moist and cool. That is why robins hunt most actively:

• In the early morning, when grass is damp with dew
• After rain, when worms move up through wet soil
• On lawns that have just been watered or mowed, where short grass makes worms easier to see

In hot, dry spells, worms burrow deeper and robins catch fewer of them. In winter, frozen ground makes worms almost impossible to reach, and robins switch to berries, as explained in where robins go in winter.

What else do robins eat?

Earthworms are a signature food, especially for feeding chicks, but robins have a broad diet:

• Spring and summer: earthworms, beetle grubs, caterpillars, grasshoppers, flies, spiders and small snails.
• Fall and winter: fruit and berries such as holly, juniper, dogwood, sumac, crabapple and mountain ash.

Over a full year, fruit often makes up more than half of what a robin eats. On the Pacific coast, some robins even feed on beaches, picking up insects and small mollusks.

Feeding the chicks

During the nesting season, earthworms become even more important. Robin parents feed their nestlings mainly on worms and soft-bodied insects, and a busy parent may arrive at the nest with several worms dangling from its bill at once. Nestlings grow fast and leave the nest at about two weeks old.

Parents hunt the same lawns again and again during this period, which is why robins are such a familiar sight in gardens in late spring. Once the chicks hatch from their famous blue eggs, the parents spend much of each day running, stopping, tilting and pulling.

Robin hunting myths

“Robins listen for worms with their heads tilted.” Partly true. The tilt is mainly to look with one eye, though robins can use hearing too.

“Robins stamp on the ground to bring worms up.” Some birds, such as gulls, do patter their feet to disturb prey. Robins mostly rely on watching and listening rather than stamping.

“The early bird gets the worm.” There is some truth in the saying. Robins are busy hunters at dawn, when dew keeps the soil damp and many earthworms are still close to the surface.