Why Birds Do That: Strange Bird Behaviors Explained
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Time to read 8 min
Birds aren’t just pretty to look at – their behavior is also endlessly fascinating. By “fascinating,” what we really mean is strange. If you’ve been a birdwatcher for any length of time, you’ve probably seen birds doing things that gave you pause. Perhaps it was a cardinal attacking a car mirror, or a downy woodpecker drumming on your home’s siding, or a gull dropping a clam dangerously close to your head. These and other seemingly strange behaviors are a mixture of instinct and adaptation, grounded in the drive to survive and reproduce.
Table of Contents
Why cardinals attack windows and car mirrors Why woodpeckers drum on houses Why cormorants stand with their wings spread Why other birds gang up on hawks Why Killdeers pretend to have a broken wing Why gulls drop clams on pavement Why Northern Shovelers swim in circles Why birds rub ants in their feathers What these strange bird behaviors tell us
Why cardinals attack windows and car mirrors
A male Northern Cardinal attacks its reflection in a car mirror, mistaking it for a rival during breeding season.
Some species of birds become highly aggressive during the breeding season. Northern Cardinals are a case in point. Always territorial, both males and females become even more so in the spring and summer, when pairs establish territories, build nests, incubate eggs and care for their young. Territorial actions include loud singing, puffing up feathers to look larger and fiercer, and physically attacking rivals.
That’s where attacks on windows and car mirrors come in. When a cardinal sees its reflection on a shiny surface, it interprets it as a rival and responds accordingly, flying at the interloper and attempting to peck it. It’s not unheard of for a cardinal to move up and down a row of parked cars, systematically attacking each side view mirror. While this behavior isn’t unique to cardinals, they are particularly well known for it.
Aggression triggered by reflections is a good reason to bird-proof your windows, following the tips in our guide to preventing window collisions.
Why woodpeckers drum on houses
When woodpeckers peck at trees, it’s for one of three reasons: they’re foraging for insects, they’re excavating a nest cavity, or they’re drumming. Drumming for woodpeckers is the equivalent of singing, a way to establish territory and attract a mate.
Your house is unlikely to be a good food source, nor a viable nesting site, but it makes an excellent drum. Flat surfaces, like siding, along with metal trim, like gutters and downspouts, offer woodpeckers a resonant instrument. Flickers and downy woodpeckers are especially given to drumming on houses. Not only are they enthusiastic drummers, they are also widespread in urban and suburban areas.
Why cormorants stand with their wings spread
A cormorant spreads its wings to dry after diving, a behavior that helps compensate for its less waterproof feathers.
Cormorants feed by diving for fish, crustaceans and other aquatic prey. When they’re not swimming or diving, they can often be found standing along the water’s edge with their wings outstretched like a long, black cape. Birders sometimes refer to this as “Dracula pose.”
What the birds are doing is air-drying their feathers. Unlike ducks and most other water birds, cormorants’ plumage is only partly waterproof. Their feathers lack the intricate interlocking structure that traps air and allows ducks to stay warm and dry even when they’re immersed in water.
The lack of an insulating layer of air makes cormorants less buoyant than ducks, something that’s evident when they swim. Unlike a duck, which rides high on the water, a cormorant swims with much of its body submerged, leaving its snake-like neck its most visible feature. This lack of buoyancy is an advantage when cormorants dive, allowing them to descend more rapidly and maneuver more agilely.
The price for cormorants’ enhanced diving ability is waterlogged feathers that leave them exposed to the cold. Air-drying is an adaptive solution.
Why other birds gang up on hawks
A Blue Jay mobs two Red-tailed Hawks, divebombing and calling to drive the predators away and alert other birds to danger.
Perhaps you’ve seen a group of birds screaming raucously at a perched hawk. You may also have watched smaller birds pursuing a hawk in flight, occasionally divebombing it and even making contact.
What you’ve witnessed is called “mobbing,” and it’s a defense against predators. Mobbing serves two purposes: driving the predator away and alerting other birds to danger. Blue Jays are famous for this behavior and often take the lead, but other birds participate as well. Even tiny birds, like chickadees, will join mobs, or even use their alarm calls to initiate one.
While alarm calls themselves are species-specific, they’re recognized and responded to by other species. This cross-species cooperation benefits the participants in several ways. Most immediately, there’s strength in numbers; group harassment generally results in the predator’s departure. But mobbing also serves a learning function. Alarm calls, including those of other species, teach young birds to recognize and avoid predators.
Why Killdeers pretend to have a broken wing
If you spend much time walking through open areas in the spring and summer, you may have been taken aback to see a bird with a boldly striped chest and rusty rump in apparent distress, running and hopping with its wing at an awkward angle, seemingly unable to fly.
No, the bird is not injured. It’s a Killdeer protecting its young.
Killdeers lay clutches of 3-5 eggs in rudimentary nests on the ground, often in areas close to human habitation. Their fluffy chicks begin to run and feed within hours of hatching, but they won’t be able to fly for another month or so. This means Killdeer eggs and chicks are especially vulnerable to predators, from raccoons to outdoor cats and unleashed dogs to blundering humans. The broken wing display is a way to distract and misdirect a potential threat. Once the predator is a safe distance from the nest or young, the bird will drop its ruse and fly away normally.
Why gulls drop clams on pavement
A Glaucous Gull carries a clam in flight, about to drop it onto pavement to crack the shell and access the meat inside.
Gulls often drop hard-shelled mollusks on paved parking lots and concrete piers from a considerable height. This behavior can seem vaguely threatening if you happen to be standing below them. But it’s not directed at you; it’s the gulls’ way of cracking open a meal.
Not all species of gulls engage in this behavior. It’s limited to larger gulls (for example, herring or western) with the size and strength to carry heavy, awkwardly shaped shellfish. The behavior also depends on proximity to shellfish-rich water and hard surfaces, be they rocky shorelines or, in an increasingly human-altered environment, piers, parking lots and flat roofs. If those conditions are met, gulls’ adaptability, intelligence and ability to learn from one another make shellfish-dropping highly likely.
These same factors – adaptability, intelligence and ability to learn – help gulls thrive in human environments. That’s something to ponder the next time one tries to steal your fried clam strips.
Why Northern Shovelers swim in circles
Northern Shovelers are surface-feeding ducks, common across North America. Even when they’re too distant to get a good look at their distinctive shoehorn-shaped bills, shovelers are easy to identify by their behavior. You will often see them swimming around and around in tight circles that can include dozens of birds.
What they are doing is feeding cooperatively. Shovelers feed by submerging their bills and sweeping them from side to side, separating small invertebrates and plant matter from the water through built-in comb-like strainers. While shovelers sometimes do this as individuals or in pairs, it’s more effective when done as a group. Swimming in circles stirs up and concentrates food particles, benefiting all the participants.
Why birds rub ants in their feathers
Some birds eat ants; some use them as grooming aids. The latter is known as “anting,” and while discussions of this behavior can be found in the writings of early 19 th century naturalists, it’s still not entirely understood.
What we do know is that anting is common and cuts across a wide range of species. Sometimes anting is passive. A bird – in North America, often a crow – sits on a swarm of ants and allows the insects to crawl over its body. More often, anting is active. A bird picks up an ant in its beak and instead of eating it immediately, rubs it into its feathers. Blue Jays, robins and starlings are just a few of the birds that do this.
Because ants secrete formic acid, most explanations for birds’ anting behavior focus on it. One hypothesis is that the substance protects birds from harmful parasites; another that it soothes skin irritation; yet another that it supplements birds’ own preen oil. Or perhaps anting is not a grooming aid at all, but a way to make ants more palatable. Or maybe it’s all of the above.
The bottom line is that we still have a lot to learn about anting, and about birds in general.
What these strange bird behaviors tell us
Bird behavior that seems strange to us is not just random weirdness. It reflects strategies that allow birds to survive and reproduce. In some cases, the behavior is a relatively recent adaptation to changes we humans have made in birds’ natural environments.
Paying attention to bird behavior adds another dimension to birdwatching. It’s a great way to hone your powers of observation, making you a better birder in the process. It’s also, dare we say, a lot of fun.
FAQs:
Is woodpecker drumming harmful to houses?
Drumming itself may cause superficial damage, such as dents or chipped paint. Reflective streamers or shiny mobile-type objects have been shown to discourage woodpeckers. Digging for food or excavating a nest cavity can cause more serious damage, but this generally reflects an underlying problem, such as insect infestation or rot.
What time of year are strange bird behaviors most common?
Because so many behaviors that look strange to us are related to breeding, from attracting a mate to defending nests to protecting young, it’s fair to say that strange bird behavior peaks in the spring and summer. But if you pay attention, you can see birds acting strangely year-round.
Are strange bird behaviors a sign that something is wrong?
Generally, the answer is no. Most strange behaviors serve a survival purpose. But if you see a bird acting lethargic or unsteady, it may indeed be injured or ill. In that case, the best response is to contact a local wildlife rehabilitator. Humane World for Animals (formerly the Humane Society) maintains a list of resources by state.
