Birds are pros at social distancing

A flock of barn swallows rests on a utility line, each bird such an even distance from the others it's as if they carried a tape measure.

Chickadees may arrive in a small flock near a bird feeder, but only one bird comes in at a time, while the others wait their turns nearby.

Dark-eyed juncos move over the ground under feeders, staying a foot or more from each other even as the flock moves around.

Although humans have had to learn to stay at least 6 feet apart in this time of contagion, birds have always kept their distance — but this isn't related to disease avoidance (at least as far as we know). No, birds are masters at giving each other space in order to maximize foraging for food, raising their young and aerodynamics in flight.

"Chickadees are great at social distancing," says Laura Erickson, who studies birds from her Duluth home base. She calls them the "Norwegian bachelor farmers of the bird world" for their habit of each grabbing a seed and then eating it alone. One of the most common reasons for having "wide elbows" is that birds need to divvy up the available resources. If one chickadee forgets its place, a brief conflict ensues.

Those swallows sitting on a wire are also sharing a resource — flying insects — and their spacing allows each to sweep off in pursuit of a meal without bumping into other swallows.

Great blue herons and great egrets provide another example of birds splitting up a foraging territory: These large wading birds work the shorelines of streams, ponds and lakes as they hunt for fish and frogs. Even if there's a good "fishing hole" in one spot, the herons stay far apart as they slowly pace the water's edge.

"Their nests are generally 6 to 8 feet apart," Henderson said. "This is about how far a nesting pelican needs to be from other pelicans to avoid being pecked by their neighbors." This gives each pelican enough room for its nest and a runway for comings and goings.

Birds like Canada geese seek to get the most distance in the air for the least effort, resulting in the awe-inspiring "V" formations we see at migration time, with each goose precisely distant from its flying companions. Each bird benefits from the uplift from its neighbors' wings, allowing them to save energy during long, exhausting flights.

Many of us have seen a starling flock wheeling and swooping in coordinated flight across the sky, hundreds or even thousands of birds turning on a dime but keeping an exact distance apart. This phenomenon, called a murmuration, confuses predators, such as hawks. Scientists aren't yet clear on how the starlings manage this aerial ballet, but it is amazing to watch.

Whatever their reasons — splitting up a food source, stymieing a predator, protecting their young, saving energy — birds are old hands at not encroaching on one another. When food or nest sites are involved, fights break out when one bird intrudes on another.

Birds know things about being birds that we humans may never fathom, such as what mechanism keeps those swallows so equally apart. Humans have been chary about acknowledging intelligence in birds, but when we study their lives we turn up so many shrewd and purposeful actions. That's a definition of intelligence, in my book.

Remember when West Nile virus hit bird populations hard, starting in 1999?

That virus has killed millions and millions of birds, from blue jays to sparrows to finches, and it turns out that many species are still suffering from this killer disease, which is spread by mosquitoes.

Some species, such as downy woodpeckers, field sparrows and red-eyed vireos, died off at high rates early on, but their populations seem to have recovered. However, for birds like the Swainson's thrush, purple finch and tufted titmouse, their populations have never come back to pre-virus levels.

Chickadees and crows seem to be especially vulnerable to this mosquito-borne disease in our area, and in both cases, numbers are noticeably down. And the virus is still circulating, spread by mosquitoes.