Crows are best known for cawing, but they also make a dry clicking or knocking sound that surprises many people who hear it up close. That sound has a name, the rattle call, and it appears to be made mostly by one sex, yet even the scientists who study crows say they don’t know what it means.1Corvid Research. Crow Vocalizations Part II: Q&A A crow clicking overhead may not be using its voice at all, because some clicks come from the bill itself.
The Rattle Call Is What You Are Most Likely Hearing
If you heard a rapid, throaty series of clicks rather than separate notes, it was probably this call.2Corvid Research. Crow Vocalizations Part II: Q&A3Corvid Research. Crow Vocalizations Part II: Q&A In the moment, it comes across as a fast run of knocks or clicks, often wooden or hollow. It is usually quieter than a caw, so you often hear it only when the bird is close. The crow may bob or hunch its body while making it, and it often comes from a perched bird rather than one in flight.
A caw is a single loud note, repeated, often to call others or raise an alarm. The rattle is a rapid string of short pulses joined together. Crows switch between the two, so the same bird may caw and then rattle. Crows have a large set of calls beyond the familiar caw, and rattle calls occur across the crow family and in their close relatives, the nutcrackers.4The Condor. Comparative Analysis of the Rattle Calls in Corvus and Nucifraga: The Effect of Body Size, Bill Size, and Phylogeny Traffic, wind, and conversation can drown the rattle out, so you may only catch it when you are nearly beneath the bird.
Many people first guess a woodpecker tapping or a squirrel chattering, and the clicks can seem to come from a branch rather than a bird. Looking for a crow sitting still nearby usually solves the puzzle.
If you hear clicking and can’t see the source, stand still and scan nearby perches such as fence tops, lamp posts, and mid-level tree branches. Once you spot a crow, watch its throat and body rather than its bill alone; a vocal rattle usually comes with a bird that looks tense or is shifting its posture. If the bird flies off and the clicks stop with it, that fits a crow better than an insect or a branch creaking in the wind.
What Crow Clicking Means
Scientists who study crow calls say plainly that they don’t know what the rattle call means.5Corvid Research. Crow Vocalizations Part II: Q&A It is hard to link one sound to one purpose when birds use it in varied situations.
Who makes the call offers a clue. There is evidence that the rattle call is made mainly or only by female crows.6Corvid Research. Crow Vocalizations Part II: Q&A So it may play some role tied to females, such as pair or family life, though that link is unproven.
You can gather your own clues. Note whether another crow is nearby when the rattle starts, what season it is (crow pairs nest in spring), and whether the bird seems calm or agitated. Repeated observation over weeks shows patterns no single sighting can.
Why Your Crow May Be a Female
The crow you heard rattling was very likely a female.7Corvid Research. Crow Vocalizations Part II: Q&A Male and female crows look alike, though, so you can’t confirm it by sight.8The Condor. Comparative Analysis of the Rattle Calls in Corvus and Nucifraga: The Effect of Body Size, Bill Size, and Phylogeny
Size is easier to hear. Across crow species, bigger birds tend to give rattles with lower-pitched tones,9The Condor. Comparative Analysis of the Rattle Calls in Corvus and Nucifraga: The Effect of Body Size, Bill Size, and Phylogeny so a raven’s rattle sounds deeper than a small crow’s. Pitch can’t settle the sex, though: a deep rattle could come from a female of a large species.
Clicks Made With the Bill
Some birds give clicks, probably from snapping the bill, while diving at predators.10The Auk. A Comparative Analysis of Passerine Mobbing Calls Bill clapping has been recorded in hooded crows, a close relative of the American crow.11Ornis Norvegica. Documentation of bill clapping in Hooded Crow Corvus cornix Clicks heard while crows chase a hawk, owl, or cat may therefore be bill snaps rather than calls. Crows dive at a hawk, owl, or cat to drive the predator away from their area.
Several crows often join in, taking turns diving while others perch nearby and call. If the commotion is around a tree, a predator is often sitting in it, so looking there may explain the clicks.
A few clues point to the bill. It happens during a dive or swoop at a threat, and each click is sharp and single rather than a smooth rattle. You may see the bill open and shut with each sound, and loud caws from a mob of crows often surround it.
Even so, it is often unclear to an observer whether a bird’s sound is vocal or made mechanically.12Ornis Norvegica. Documentation of bill clapping in Hooded Crow Corvus cornix Some mechanical bird sounds closely resemble vocal ones,13Ornis Norvegica. Documentation of bill clapping in Hooded Crow Corvus cornix so researchers sometimes need high-speed cameras to see how a sound is made.14Ornis Norvegica. Documentation of bill clapping in Hooded Crow Corvus cornix
If crows are diving at you or a pet, know that they mostly do this near nests in spring and early summer. Walk away from the area rather than waving your arms. Wearing a hat or using another route for a few weeks usually ends it.
When the Click Is an Imitation
Members of the crow family have mimicked many kinds of birds, including hawks, owls, woodpeckers, and ducks.15PubMed Central. Vocal mimicry in Corvids They have also copied mammals, including human voices, plus frogs and insects,16PubMed Central. Vocal mimicry in Corvids and human-made sounds like bells, lawnmowers, and motorbikes.17PubMed Central. Vocal mimicry in Corvids An unusual click near a busy street could be a copy of something the bird hears often.
Mimicry usually sounds like a specific outside source, such as a camera shutter or a gate latch, instead of the generic hollow rattle. The rattle sounds broadly similar across many crows, while a copied sound often repeats something you can hear nearby. If the odd sound doesn’t match a recording of a standard rattle call and you can name what it resembles, mimicry is the likelier answer. Pet or tame crows living near people mimic most often. Why crows mimic is still debated, so a copied click has no known message either.
Why Crows Sound Different in Different Places
American crows west of the Cascade Mountains have harsher, lower-pitched calls than those elsewhere in the country.18Corvid Research. Crow Vocalizations Part II: Q&A They probably descend partly from interbreeding with Northwestern crows long ago.19Corvid Research. Crow Vocalizations Part II: Q&A If you live in western Washington or Oregon, your local crows may sound deeper than online clips.
To check what you heard, look for recordings labeled “rattle call” from your own region. Compare rhythm and texture more than pitch, since pitch varies by place. Listen for the same rapid, hollow, pulsed texture you heard outside; if the rhythm matches, you have likely found the right call even if the pitch is different. If the recording has a clear caw but your sound was only clicking, search for rattle-specific clips instead of general crow calls. Recording the bird on your phone lets you compare later.
Your own ears can mislead you. Higher sounds fade first over distance, so a crow farther away may seem deeper and softer than the same bird up close. Wind and buildings can muffle or echo clicks, making them seem to come from somewhere other than the bird. Judging a call is more reliable when you hear it several times from a similar distance.