The American Crow (Corvus brachyrhynchos) is a common bird found throughout North America. Crows are extremely intelligent birds that exhibit complex social behaviors and have adapted well to living in human-populated areas. They are omnivorous scavengers and will eat almost anything. American Crows are perhaps best known for their loud, raucous “caw” vocalizations and their habit of gathering together in large communal roosts during winter months. Read on to learn more about what makes the American Crow such a fascinating bird!
Identification
The American Crow is an all-black bird with black feet, black legs, and a black bill. Their feathers often have a purple-blue iridescent sheen when viewed up close in good light. Adults measure 16-21 inches (40-53 cm) long with a wingspan of 33-39 inches (84-99 cm). Their tail is long and rounded or wedge-shaped. American Crows are very similar looking to the Fish Crow but can be identified by their slightly larger size, higher-pitched caws, and tendency to form larger flocks. The Fish Crow has a more rounded tail and a more doubled or croaking “caw-caw” call.
Range and Habitat
American Crows are resident year-round birds throughout most of the lower 48 United States and southern Canada. Their breeding range stretches across North America from coast to coast and as far north as Alaska and Canada’s tree line. American Crows thrive in a wide variety of habitats including woodlots, marshes, agricultural fields, parks, and urban/suburban neighborhoods. They are absent only from deserts and the Florida Keys.
During the summer breeding season, American Crows stick to nesting territories but may congregate in large foraging flocks. In winter, they form massive communal roosts numbering several thousand to even over a million birds in areas with abundant food. The record for the largest known American Crow roost was set in Fort Cobb, Oklahoma in the 1940s with an estimated 2 million crows!
Diet
The American Crow is an omnivorous and opportunistic forager, eating anything it can get its beak on. Their diverse diet includes:
- Insects
- Seeds and grain
- Fruits and berries
- Rodents
- Amphibians
- Reptiles
- Bird eggs and nestlings
- Carrion and roadkill
- Human fast food, pet food, and trash
Crows employ a wide range of foraging techniques to find food. They dig through leaf litter searching for insects, ransack trash bins, pick grain from agricultural fields, and even prey on small animals. Crows sometimes work together to herd fish and amphibians to the water’s edge to more easily capture and consume them.
Intelligence and Behavior
The American Crow is renowned for being one of the smartest birds in the world, rivaled only by their close corvid relatives the ravens, rooks, jays, magpies, and jackdaws. Their intelligence manifests in many observable ways:
- Large brains relative to body size
- Complex social systems and hierarchies
- Cooperative breeding and brooding
- Use of tools to solve problems
- Impressive learning and memory skills
- Communication through a vast repertoire of calls
- Ability to count, recognize symbols, and solve puzzles
Some specific examples of advanced crow behaviors demonstrating their high intellect:
- Using sticks or Pine needles to extract insects from crevices
- Dropping hard-shelled nuts onto roads and waiting for vehicles to crack them open
- Recognizing individual human faces and remembering those who have wronged them in the past
- Solving multi-step puzzles to get food rewards
- Imitating human voices, including words and phrases
- Interpreting traffic patterns and waiting for all lanes of traffic to stop before crossing roads, and even waiting at crosswalks for the walk sign
- Purposefully misleading other crows from food they have hidden for later
Reproduction
American Crows reach sexual maturity around 2 years old. They form monogamous pair bonds that may last for several years or for life, though they will find a new mate if one dies.
The breeding season lasts from early March through July, depending on latitude. Nests are built high up in the branches of trees by both male and female working together. The bulky nests are a bowl of twigs, bark, vines, moss, and lining feathers, well camouflaged in the dense canopy.
Females lay 3-7 pale greenish-blue eggs marked with brown speckles. She incubates the eggs for about 18 days while the male provisions her with food. Hatchlings are born blind, naked, and helpless. Both parents fiercely guard the nest and care for the young, who fledge at around 36 days old. Family groups may remain together for several months after fledging.
Vocalizations
The familiar loud, harsh “caw caw CAW” is one of the American Crow’s most distinguishable features. But they have a complex vocabulary of over 20 unique calls used to communicate different messages:
- “caw” – their typical contact call when interacting with flock mates
- Short “caws” strung together into phrases – alerts flock to interesting food sources or danger
- Harsher “caws” in series – signs of aggression and mobbing predators
- Soft warbling caws – given as feeding young
- Cooing calls – given between mated pairs as bonding
- Rhythmic knocking sounds – made with sticks or beak on wood, signals feeding sites or summons flock
Regional dialects occur in crow populations much like human regional accents. Crows in the west sound different than crows in the east. Young crows likely learn the local dialect from elders in their flock.
Population Status
The American Crow is considered a species of Least Concern by the International Union for Conservation of Nature (IUCN). Their global population is estimated at 31 million individual birds. Their numbers dropped in the mid 1900s due to DDT pesticide use but have rebounded since DDT use was banned. West Nile Virus has also suppressed numbers in hard hit areas. Overall the American Crow remains widespread and adaptable to human activity. In fact, they have thrived alongside humans and expanded their range over time. Their high intelligence and willingness to exploit human food sources ensures they are here to stay.
Threats and Predators
For such a ubiquitous bird, the American Crow has relatively few natural predators as adults due to their large size, swift flight, loud alarm calls, and tendency to flock together. However, eggs and nestlings are vulnerable to:
- Snakes
- Cats
- Raccoons
- Jays
- Ravens
- Hawks
- Owls – especially Great Horned Owls
West Nile Virus has been an emerging threat, killing millions of American Crows since it arrived in North America in 1999. Crows are considered a sentinel species for West Nile detection as they succumb rapidly to the disease and signal when the virus arrives in an area.
Collisions with vehicles and manmade structures like powerlines take a toll. Hunting pressure also contributes to mortality as they can be legally hunted as game birds in most states. However, their high reproductive rate means they bounce back quickly despite these threats.
Relationships to Humans
The American Crow has a mixed relationship with humans. On one hand they thrive in human-altered environments. They dine on our garbage and crops, using our settlements as extensions of their natural habitat. Their population has exploded thanks to resources we inadvertently provide.
On the other hand, some consider crows pests for raiding crops and making noise in urban areas. They cause damage when scavenging and can spread trash. Their droppings are acidic and damage property. Crows sometimes eat songbird eggs and are blamed for songbird declines, despite limited evidence to support this claim.
Regardless, these adaptable, intelligent birds are here to stay alongside humans. Their antics provide endless fascination. With some tolerance on our part, there is space enough for both crows and humans to coexist successfully.
Notable Crow Gatherings
Here are some of the most impressive known gatherings of American Crows:
Location | Estimated Crow Count |
---|---|
Fort Cobb, Oklahoma | 2 million crows (largest on record) |
Crowley, Louisiana | 1 million crows |
Danville, Illinois | 500,000 crows |
Lancaster County, Pennsylvania | 275,000 crows |
Kalamazoo, Michigan | 250,000 crows |
Glide, Oregon | 200,000 crows |
John’s Island, South Carolina | 150,000 crows |
These astounding crow gatherings reflect their highly social nature. During winter, they form huge communal roosts for warmth, protection, and exchange of information on food sources.
Notable Crow Research
The fascinating intelligence and behaviors of American Crows have made them frequent research subjects over the years. Here are some of the most pioneering and important crow studies:
- John Marzluff – University of Washington professor who has conducted groundbreaking research on crow cognition, facial recognition, language, and urban ecology.
- Bernd Heinrich – Studied crow use of tools and problem solving.
- Kevin McGowan – Ornithologist who exhaustively studied crow roosting behaviors.
- Kaeli Swift – Current PhD student focusing on crow social networks and communication.
- Alex Taylor – Discovered crows understand analogies and use tools in the lab.
We have learned more about crow intelligence and behaviors thanks to these researchers’ devoted work unraveling the mysteries of the American Crow mind. Their findings continually impress both the scientific community and public.
Notable Crow Encounters
- In 1871, the town of Kilkenny, Ireland entered into a battle with a murder of crows that lasted 3 days. They tried to remove a crow nesting colony but the crows fought back viciously.
- During WWII, despite extreme adversity and rationing, a little girl in France befriended the crows in her town. She fed them and they brought her gifts like buttons, beads, and pieces of cutlery in return, likely stolen from German soldiers.
- In Seattle, Washington, local crows recognized and mobbed an unmasked man who had been capturing and killing crows. The entire murder scolded him loudly whenever he was in their territory, forcing him to mask up to hide his identity.
- Joshua Klein, a technologist, trained crows to deposit coins into a machine in exchange for peanuts. The coins could be collected and the value donated to corvid conservation. He tested the Crow Box in locations around the world.
- In 2020, a murder of crows in Ottawa, Canada perched along the driveway of the Saudi embassy to poop on cars in protest after Saudi Arabia assassinated journalist Jamal Khashoggi.
These stories showcase the intellect and memories of crows, their ability to recognize faces, their complex social bonds, and their knack for grudges.
Conclusion
The American Crow is an amazing bird that has adapted seamlessly to life alongside humans. We have still only scratched the surface of understanding their impressive cognitive abilities. Crows deserve appreciation and continued study as a unique window into the animal mind. By respecting these intelligent creatures and making room for them in our urban ecosystem, we can coexist to everyone’s benefit. The American Crow’s future remains bright and intertwined with our own.