The Bio-Indicator

Bird of the Day Series, Social Media Content

White-Throated Dippers don’t move around much, but they are found all over the place, from Ireland to Iraq to India to Italy, always near fast-flowing water and often in mountains. They feed by walking underwater—they dive in, then walk along the bottom, poking around for something to eat. Then they pop their heads up, chomp away, and go back under for something else. At seven inches and three ounces, you’d think they’d get swept away, but they stabilize themselves by holding up their wings.

These birds are dangerous, to each other. They are usually monogamous, although up to half of males play around, and males compete via pushing contests. The problem arises when a Dipper has no mate—he or she will kill the chicks of another couple and force mating with one of the parents.

Dippers build their nests on hard-to-reach places like rock faces, cliffs and bridge supports, but they are still vulnerable to crows and rats. In many communities, humans try to protect them because they are valuable bio-indicators. These birds will not live near polluted streams, so no Dippers means a stream is being polluted. If there are a lot of empty nests, rodent control is required. Coniferous tree debris decreases the pH of streams; the Dippers’ prey can’t live under acidic conditions, so poor breeding by Dippers indicates that too much foresting is occurring upstream. Various communities have always known this; would that we all paid such attention.