Understanding Bird Behavior

Birds exhibit a wide array of behaviors, so many that scientists regularly discover previously undocumented behaviors. If you are a beginner atlaser, or even if you’ve been studying birds for a long time, it’s unlikely that you will be familiar with all of the behaviors you will observe during the atlas project. This guide is intended to give you a primer on some of the common bird behaviors and help you classify breeding behaviors for the Atlas.

Some behaviors are used for self-care and feeding, others to elicit courtship or raise young, while others are used for self-defense. We also provide tips for learning bird behaviors.


These behaviors are not related to breeding but they are important to be familiar with so you can interpret what a bird is doing. They are also some of the most entertaining behaviors. Think of a bird taking a water or dust bath, squirming all around, flitting this way and that, shaking like a dog, and generally just getting all ruffled up. Other birds like herons and egrets will sunbathe by fanning out their wings in such a way that they catch the sun’s rays at the optimal angle. Jays can sometimes be observed laying on an ant hill with wings spread out so the ants can crawl over them. This is a behavior known as “anting” and is thought to help remove parasites. Preening is the more common behavior we see that birds use to keep their feathers in good condition for flight. Most birds rub the tip of their bill on their rump before realigning their feathers. They have a gland that excretes oil (the uropygial gland) on their rump and they rub the oil on their feathers for waterproofing. Since birds do not have sweat glands, they must regulate their body temperature in other ways. Vultures will defecate on their legs to cool off, loons will waggle their foot in the air to pass cool air over it much like a fan, and cormorants will vibrate their throat muscles with their bill wide open to expel heat (called “gular fluttering”) much like a dog panting.

Many birders are familiar with “Birds and Beaks”, the environmental education program that teaches children about different types of beaks and how they are used to feed on different items. Flycatchers have bristles at the base of their beaks to help them catch an insect when it sallies out from a perch. Kingfishers hover over the water until they see a good fish and then dive down to catch it in its spear-shaped bill. In addition to foraging styles, you may observe birds doing other food-related behaviors. Finches will do what is known as “gritting” where they land on a road to pick up salts, which is especially useful to get good looks at crossbills in a year with a good cone crop. Birds at your feeders will assess seeds before going through the trouble of cracking them open. Some seeds are rotten and so they are lighter, which they can detect. Jays can be observed caching seeds for use later in the year. They will usually stuff the seed somewhere and then fill in the hole with leaves or other debris to camouflage it. Yet some birds are smart enough to make tools to help them find food. If you are lucky enough to see that in the wild, make a video recording!

Types of Self-Maintenance Behaviors

  • Sleeping
  • Drinking
  • Foraging for food (use Atlas code CF if you observe a bird carrying food to young or a mate)
  • Beak cleaning/bill wiping
  • Bathing, in water or dirt
  • Oiling for waterproofing
  • Preening
  • Scratching
  • Sunning
  • Fluffing
  • Stretching

Courtship and Pair Bonds

The relationships between birds are complex and variable as are the behaviors they use to maintain these relationships (termed “pair bonds”). The most common mating system in birds is monogamy, meaning that birds mate with one bird per season. It’s rare that two birds will mate for life, but there are some cases of this. It’s more likely that they will mate one partner one year and a different one the next. This is particularly true in migratory species where annual survival is low. The second most common mating system is polygyny in which a male mates with multiple females. This is common in species that defend resources, such as good foraging areas and nest sites. You can observe this the next time you go to a marsh with lots of Red-winged Blackbirds. Notice how many different females fly in and out of the reeds near a single male. This is reversed in some species like phalaropes and Spotted Sandpipers where the males take on most of the chick rearing and females mate with multiple males (polyandry). Then there are a select few species where both sexes have multiple partners, called polygynandry. This is the case for Bicknell’s Thrush, which lives in an extreme environment and it’s difficult to find food and raise young. On top of this, scientists are starting to learn that many birds, even species once thought of as monogamous, exhibit extra-pair copulation where they mate with birds outside their pair bond. All of these mating systems evolved to take advantage of the available resources and fledge as many strong and healthy young as possible.

Within any of these mating systems, the partners can be more or less involved in raising young. Some pairs will stay together with both sexes helping to feed and educate the young, while others will merely come together to copulate and one bird is left to raise the young (usually the female, but not always). In species that brood multiple times in a single season, such as catbirds and grosbeaks, the males will care for the fledglings while the female builds a new nest and incubates the next clutch of eggs. On the other hand, waterfowl tend to have a long courtship period, but the males leave after copulation. Think about all those Common Merganser pairs you see in early spring and how all the males suddenly disappear. When atlasing, it helps to know which mating system a species has so that you know what behaviors to look for and when to look for them. For example, if you see a male Ring-necked Duck in the middle of summer, it’s likely not breeding there since the males don’t stick around after copulation.

Courtship evolved to show off the dominant individual’s assets, almost exclusively the male in our region. Males often show off their fitness, how good they are at procuring food, and the quality of the resources found within its territory. So you many see a male flaunt its bright colors and follow that behavior by feeding its potential mate, all the while singing its typical song. This shows the female how fit he is and demonstrates that he can provide for her young. Females will show their interest by remaining in the vicinity or by begging for food. Pairs may sit close to each other and even preen each other (“allopreening”) after they have chosen their mates. In sexually dimorphic species it’s easy to tell the males and females apart, but in monomorphic species like Song Sparrows the males act aggressively towards the female before making advances so that he can be sure it is a receptive female. But the most dramatic signs of courtship are dances and flight displays. Sandhill Cranes are known for their trumpeting and courtship dances, and many birders make it a point each April to go to a field at dusk to watch the extravagant courtship display of American Woodcocks on their leks (male display grounds). Many other species also have elaborate and entertaining courtship behaviors and have been given equally elaborate names by scientists: “Grunt-whistle”, “Head Up-Tail Up”, “Horizontal Head Pump”, “Twig Shake”, “Penguin Dance”, “Head Throw”, “Preen-behind-the-wing”, “Nod Swim”, “Parade”, “Scraping”, “Dive Display”, and “Shuttle Display”. Species that remain together throughout the breeding season will often maintain their pair bond by touching their bills, duetting, or going through ritualized displays like greeting ceremonies.

Types of Courtship and Pair Bond Behaviors

  • Singing (use Atlas code S)
  • Duetting (C)
  • Elaborate dances and flight displays (C)
  • Greeting Ceremonies (P)
  • Begging for food (use C if part of courtship)
  • Mate feeding (C)
  • Bill touching (P)
  • Allopreening (P)
  • Chasing and aggression towards mate (use C if part of courtship)

Raising Young

Some of the easiest behaviors to observe during an atlas project are those related to rearing young. The breeding season is short and their drive to breed is so strong that they become single-minded. They are often distracted in their busy search for nesting materials or finding food for their young and themselves. It’s difficult to find an actual nest, and it’s not really necessary for an atlas project since you can often tell that a bird is nesting without having to get that close. You may encounter warblers peeling birch bark or moss from trees, goldfinches gathering fluffy plant seeds to line their nest, robins gathering clumps of mud and leaves, or larger birds carrying sticks. Orioles will weave their nest and usually out in the open so you can often find them.

When the young hatch, they are either precocial or altricial. Precocial birds are ready to swim or walk or run almost immediately after hatching, like terns and plovers. You might see waterfowl diving for their own food when they are still balls of fluff or loons riding on their parents’ backs. Yet other species like Common Eiders will pool their young together in a creche so they can take advantage of safety in numbers. Altricial birds are naked and helpless for several weeks and will remain in the nest, like most of our songbirds. After the eggs hatch, the adults will carry away the egg shells and fecal sacs to keep the nest clean so it doesn’t attract predators. Canada Jays are an example of a species that uses helpers to raise young. The young from previous years will remain with the parents and help raise their younger siblings until they find a suitable territory of their own.

Whether precocial or altricial, most young will stay with their parents and be fed by them for several weeks until they are big enough and experienced enough to care for themselves. Fledglings beg loudly and the noise can be a good way to find breeding birds during an atlas. As the fledglings grow, you may observe them play fighting, playing with unusual objects, experimenting with different foods, or just making awkward landings. Later in the summer you will start to hear unusual songs given by young trying to learn their parents’ vocalizations. It will usually sound vaguely familiar but not quite right and can be quite a challenge to identify! Just remember that young birds can look, behave, and sound different from their parents.

Types of Parental Behavior

  • Nest building (use Atlas code B or NB if building nest, CN if carrying nesting material)
  • Incubation (ON)
  • Brooding (ON)
  • Feeding young (FY or NY)
  • Nest cleaning, removing eggshells and fecal sacs (FS)
  • Defending young (DD)
  • Nest helpers
  • Creches (FL)


Birds are constantly vigilant for potential threats. During the nonbreeding season, many birds are more likely to flee than to fight. If they are cryptic, or well camouflaged, they may crouch down or freeze in place. Others will give an alarm call signaling to the potential threat that they have been spotted while simultaneously alerting other birds in the area of the threat. Alarm calls are often different for ground versus aerial predators so that other birds can take the proper action. Some species will even gang up on predators like owls and hawks and mob them by flying at them and calling loudly until the predator leaves. This is why birders “pish”; they imitate an alarm call so that birds nearby will come in to investigate the threat. A few species are so vigilant that they post sentinels who keep watch and alert their relatives when danger nears.

Birds living in densely vegetated areas, like sparrows, will often duck into the vegetation and scurry on the ground like a rodent until they are out of harm’s way. Chickadees in a roost or nest hole will pretend to be a snake if a squirrel comes near them, hissing and thrusting their head out of the hole like a snake attacking. Yet other birds will flock together for safety in numbers or to help them find new food sources. They may stay together all day or, like crows, just come together to roost at night.

Some species have elaborate distraction displays that they use during the nesting season. Killdeer, Black Skimmer, and Common Yellowthroat are some of the species that will pretend to be injured if you or a predator comes close to their nest or young. A general rule of thumb is that if you see a bird make itself look larger, it feels threatened (threat displays), while if it makes itself look smaller, it is trying to hide or show submission to a potential threat (appeasement displays).

Threat Displays

Threats can come from predators or potential competitors, and may be of the same or different species. Accordingly, the degree of the threat display will increase with the severity of the perceived threat. Imagine watching a Common Loon on the other side of a lake. It sits high on the water and has a smooth forehead. As you approach, the loon will sink lower and lower in the water and it will raise it’s eyebrows. If you get even closer, it will probably start calling and may stand up in the water and flap its wings or even try to attack you. The closer you get, the more threatened it feels, and the more it is forced to defend itself. In the breeding season this threat display will escalate faster than in the nonbreeding season. In general, adult birds are most sensitive when they have eggs near hatching until the time their young are fledged.

Typical threat displays usually involve making the bird look bigger and more threatening. They will raise their bill up, extend their head forward or upward, raise their wings, fan their tail, sway back-and-forth, puff up their feathers (as they do in the winter to stay warm), snap their bill, raise their crest, or stab with their bill in the direction of the threat. These behaviors are often accompanied by calls or mechanical noises made with their wings. It’s rare for birds to attack each other since it is so dangerous but you may very well see woodpeckers pulling each other’s feathers out during a tussle. Yet other birds appear very brave and will attack larger predators. Red-winged Blackbirds and Eastern Kingbirds will chase away raptors without hesitation. Terns and swallows will attack humans that get too close to their nests and young. In fact, terns will also vomit and defecate on you as they come in to stab the crown of your head.

All of these behaviors, from small warning signs to outright attacks, can clue you in to your surroundings. If you hear alarm calls or mobbing, it’s likely that a corvid or raptor is nearby. If you see a distraction display, a nest is nearby. If you see a fight, the birds are probably fighting over a potential mate that is watching the spectacle nearby and after the fight is over you are likely to observe pair bond behaviors between the winner and the mate. Threat displays are also critical behaviors to hone in on to determine if you yourself are threatening a bird and causing undue stress. If you observe any of these behaviors directed at you, you are too close to the bird or its nest and should back off. It’s very unlikely the bird will resume its normal behaviors until you move away and conceal yourself, only then will you see potential signs that would confirm breeding.

Appeasement Displays

Just like a dog will roll onto its back and expose its vulnerable belly, birds will also signal their submission to other birds. Some birds will actually roll onto their back, but that’s rare. It’s more likely to see birds fold their wings, flatten their feathers so they look very sleek, and lower or turn their head away. They may also point their bill down or away and even point their tail down. You may even see them lean their body away or simply fly off. You can study these interactions at a bird feeder where dominance hierarchies are easy to observe.

Types of Defensive Behaviors

  • Group and social behaviors
    • Flocking for safety in numbers
    • Vigilance, use of sentinels
    • Alarm calls
    • Distraction displays, such as broken-wing (use Atlas code DD if protecting nest or young)
    • Mobbing (A)
  • Individual threat displays—appearing larger and more threatening
    • Tail fanning
    • Puffing feathers out
    • Bill snapping
    • Raising bill upward
    • Lifting head
    • Swaying back-and-forth
    • Raising wings
    • Raising crest
    • Bill stabbing
    • Vocalizing
    • Vomiting
    • Defecation
    • Chasing (use Atlas code T or A)
    • Physical attacks (T or A)
    • Fighting (T or A)
  • Individual appeasement displays—appearing smaller and less threatening
    • Crouching
    • Folding wings
    • Flattening feathers
    • Lowering head
    • Turning head away
    • Pointing bill down and away
    • Leaning away
    • Fleeing

Tips for Learning Bird Behaviors

You will start to pick up on many of these behaviors experientially through atlasing. You will slowly learn which species exhibit which behaviors and in what circumstances. Try these tips for learning more about bird behavior.

  • Discuss. Share your discoveries on the Atlas Discussion Group on Facebook, on your local birding listserv, and with your local bird club. For unusual behaviors, try to find out if others have seen the same thing. You can also post questions about any behaviors you’ve seen on Facebook or ask your Regional Coordinator.
  • Research. There are a lot of resources available to help you understand bird behaviors. Aside from just googling something, good resources are All About Birds, the Audubon Bird Guide, and Birds of the World (subscription). Handy books include The Birder’s Handbook, Nests, Eggs, and Nestlings of North American Birds, and the Stokes Guides to Bird Behavior. A lot of times you can find videos of interesting behaviors on YouTube and at the Macaulay Library.
  • Watch. If you have bird feeders, you can become familiar with a lot of these behaviors right in your own backyard. If you don’t have a feeder of your own, you can watch a Bird Cam. When you sense that a bird feels threatened, ask yourself what evidence you observed that told you this. When you see what you think is a pair of birds, ask yourself how you can be sure that they are a bonded pair and not just two birds of the same species in the same location. Similarly, when you have young birds coming to your feeders, study their plumage and sounds so you will recognize them when you see them elsewhere. You can learn a lot about bird behavior before ever heading out in the field this way.

The more you pause to watch bird behavior, the more you will discover and understand. Read more tips on taking these skills into the field.