White-breasted nuthatches are considered to be bold birds and will often perch nearby as a person fills up a bird feeder. Credit: Courtesy of Bob Duchesne

Social distancing — it’s not just for people anymore. Birds are migrating back into Maine. Their numbers will swell over the next several weeks. We humans could use a good outdoor distraction right now, and many Mainers have been looking forward to spring migration.

OK, we’re told that we should keep at least six feet away from our fellow humans. How much distance do the birds need from us? It’s fascinating. Different birds require different comfort margins, and sometimes those margins vary depending on what’s going on.

In general, birds that are accustomed to people require less distance from people. City birds, such as pigeons and house sparrows, barely budge when people are around.

Conversely, visitors from the far north don’t even know what you are, let alone think you’re a threat. You might be nothing more to them than a two-legged caribou. Rare owls can be so tolerant of human approach that it’s important for humans to take charge and maintain distance. Northern owls only migrate down here when stressed and undernourished. Even if they don’t seem to mind having people near, we may be scaring away their food. Other northern visitors, like pine grosbeaks, snow buntings and purple sandpipers, are also quite tolerant of people.

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Ducks are funny. Gamebird species are understandably skittish in the wild. But in an area where hunting is not allowed, they quickly adapt to having people around. Mallards will bring their babies right up to people in hopes of a handout. On marshes with boardwalks, even the wildest duck gets quickly accustomed to people, seeming to know that they are non-threatening when confined to the boardwalk.

Some birds are bolder by nature, especially birds that visit backyard feeders. Chickadees and nuthatches will practically perch on your shoulder while you replenish the sunflower seeds. Hairy and downy woodpeckers watch impatiently from the nearest tree as you refill the suet. Goldfinches and purple finches on a feeder are slow to scram as you approach.

Chickadees are so bold that they will seek you out and scold you, raising the alarm to let other birds know you’re around. The “chick-a-dee sound” is their call, often used to get attention and communicate alarm. Their song is “fee-bee” or “hey-sweetie,” used to claim territory and lure mates. I recently had occasion to listen to seven hours of audio recorded in a forest by a remote microphone. I heard a lot of birds, but what stunned me the most was this: I heard chickadees doing their “hey-sweetie” song a lot, but I briefly heard the “chickadee” calls only once. I’m beginning to think we humans hear the “chick-a-dee-dee-dee” often because they’re objecting to us! Considering I feed them, that’s kind of insulting.

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Resting flocks are easy, whether they consist of gulls, geese or shorebirds. Inevitably, they watch your approach. They’ll let you know when you’re getting too close. One will stand or begin to inch away. If you get any closer, expect the whole flock to skedaddle. I find that shorebirds are pretty tolerant, and if I pay attention to their slight movements, I know when to stop.

Nesting raptors are even easier. Ospreys start squawking while you’re still a significant distance away. Merlins wait a little longer before complaining loudly. Northern goshawks attack. There is never, ever, any confusion about when you’ve gotten too close. Run for your life.

Warblers, vireos and other small songbirds are harder. They have complete control over their distance from people. If necessary, they just sit a little higher into the tree. Warblers and sparrows that live near the ground are more likely to complain about your presence. Bush-dwelling common yellowthroats call the alarm more often than tree-dwellers. Low-nesting song sparrows and white-throated sparrows are both quick to call out their dismay upon your approach.

So, let’s examine the social distances right in our own backyards. Start simple. There’s a robin on the lawn, and you walk out the front door. What does it do? Does it flush immediately? Does it look at you? Ignore you? How close can you approach before it decides to find worms somewhere else?

Try it with a blue jay. How close are you when it reacts to your presence? Does it fly away or just jump higher in the tree? Does it squawk alarm? It’s good practice to notice when birds become uncomfortable with you. You learn how to avoid undue disturbance. Besides, watching birds is fun. Watching birds watch you – now that’s cool.

Bob Duchesne serves as vice president of Maine Audubon’s Penobscot Valley Chapter. He developed the Maine Birding Trail, with information at mainebirdingtrail.com. He can be reached at duchesne@midmaine.co