Crows are a group of birds belonging to the genus Corvus and family Corvidae. There are over 40 different species of crows around the world, with some key differences between them in terms of size, coloration, range, behavior, and calls. Two of the most well-known crow species in North America are the American crow (Corvus brachyrhynchos) and the northwestern crow (Corvus caurinus). While these two species look very similar, there are some notable differences between them.
Quick Facts
Here is a quick overview of the key differences between American crows and northwestern crows:
- Range: American crows are found across much of North America, while northwestern crows are limited to the northwest coastal regions from southwest British Columbia through Washington state.
- Size: Northwestern crows are slightly smaller on average than American crows.
- Voice: The calls/caws of northwestern crows are higher pitched and raspier compared to the deeper, rangier caws of American crows.
- Feathers: Northwestern crows have more glossy, purplish-blue iridescent feathers around the head, wings and tail.
- Beak Shape: Northwestern crows have slightly slimmer, straighter beaks compared to American crows’ stouter, curved beaks.
We’ll now go over these differences in more detail.
Geographic Range and Habitat
The most noticeable difference between American and northwestern crows is their geographic distribution and habitat preferences.
American crows are one of North America’s most widespread bird species. They are found from southern Canada down to Florida, and can be seen across the United States. American crows thrive in a variety of open habitats including agricultural fields, parks, pastures, and backyard settings in both rural and urban environments.
In contrast, the northwestern crow is only found along the Pacific coast, from southwest British Columbia in Canada down through western Washington and Oregon in the United States. The northwestern crow sticks closely to coastal regions and is rarely found more than 50 miles inland. Unlike American crows, northwestern crows prefer more forested habitats and are most abundant in coniferous forests and along shorelines.
Range Comparison
Species | Range |
---|---|
American Crow | Across much of North America from southern Canada to Florida |
Northwestern Crow | Pacific northwest coast from southwest British Columbia to western Washington/Oregon |
As you can see, while the American crow occupies a wide swath of North America, the northwestern crow has a much more limited range confined to coastal northwest regions.
Physical Differences in Size, Coloration, and Beak Shape
In addition to differences in range, American crows and northwestern crows show some subtle physical differences in terms of size, coloration of their feathers, and beak shape that can help distinguish these two species.
Size
Northwestern crows are slightly smaller on average than American crows, although there is some overlap in size. American crows measure around 17-21 inches in length with a wingspan of around 33-39 inches. They weigh between 12-21 oz. Northwestern crows measure 16-20 inches in length, have a wingspan of 32-36 inches, and weigh 11-16 oz.
Coloration
While both species are glossy black overall, northwestern crows tend to show more iridescent, purplish-blue tones in their feathers, especially around the head, wings and tail. The throat feathers of northwestern crows may also appear slightly grayish. American crows exhibit more violet-purple iridescence on their body feathers compared to the colder blue-purple sheen of northwestern crows.
Beak Shape
American crows tend to have stouter, arched beaks compared to northwestern crows that have slimmer, straighter beaks. However, beak shape can vary quite a bit between individuals of both species so this is not a completely reliable distinction.
Comparison Table
Feature | American Crow | Northwestern Crow |
---|---|---|
Size | 17-21 in. length 33-39 in. wingspan 12-21 oz. weight |
16-20 in. length 32-36 in. wingspan 11-16 oz. weight |
Coloration | Glossy black with violet-purple iridescence | Glossy black with bluish-purple iridescence |
Beak Shape | Stouter, arched beak | Slimmer, straighter beak |
Differences in Calls and Vocalizations
One of the most reliable ways to distinguish American and northwestern crows is by their vocalizations. While crows of both species make a familiar “caw caw” sound, the quality of their calls is noticeably different.
The caws of American crows are deeper, raspier, and have a bit of a ringing, gargling quality. They make a wide variety of calls ranging from single caws to complex strings of caws in various pitches and rhythms. American crows also make rattling sounds and clear bell-like notes.
In contrast, northwestern crows produce higher-pitched and raspier cawing sounds compared to American crows. Their calls are scratchier with a bit of a stuttering quality. Northwestern crows make more simple, single caw sounds and do not produce the complex vocalizations of American crows.
Below is a table summarizing the differences in vocalizations between the two species:
Species | Call Description |
---|---|
American Crow | Lower-pitched, deep caws with a gargling quality. Complex strings of caws of varying pitches and rhythms. |
Northwestern Crow | Higher-pitched, raspy caws. Simple, single caw sounds lacking complexity. |
When heard side-by-side, the differences in the cawing voices of American and northwestern crows are quite apparent. Listen for the deeper, ringing caws of American crows versus the higher-pitched, scratchy calls of northwestern crows.
Differences in Behavior and Sociality
American and northwestern crows also exhibit some general differences in their behavior and social dynamics.
American crows are highly social and gather in large flocks outside of breeding season. They roost together at night in huge communal roosts that can number in the thousands or even millions of crows in some areas. American crows actively harass and mob potential predators as a group.
Northwestern crows are a bit less social than American crows outside of the breeding season. They form looser winter flocks that don’t amass in the same huge numbers as American crows. Northwestern crows still mob predators as a group but maybe not quite as aggressively as American crows.
During breeding season, American crows tend to nest in looser colonies while northwestern crows nest in tighter clusters. So northwestern crow nest sites may have a higher density of nests grouped closely together compared to American crow nesting sites.
In terms of feeding and foraging, American crows are supreme generalists and opportunists. They will eat almost anything, readily adapting to human-provided food sources. Northwestern crows are a bit less adaptable and do most of their foraging along shorelines.
Here’s a summary table of some of the behavioral differences:
Behavior | American Crow | Northwestern Crow |
---|---|---|
Sociality | Highly social, massive communal winter flocks | Loosely social, smaller winter flocks |
Nesting | Loose colonies | Dense clusters |
Foraging | Opportunistic generalists | Specialize along shorelines |
Range Overlap Between the Species
American and northwestern crows generally occupy distinct ranges with little overlap. However, their distributions do come into contact along the northwest coast.
In coastal Washington state, particularly in the Puget Sound region, American crow populations mix and intergrade with northwestern crows. Individual crows in this hybrid zone show intermediate features between the two species in terms of size, vocalizations, coloration, and behavior.
Northwestern crows appear to be dominant in the Puget Sound hybrid zone, as the center of abundance for American crows in Washington is pushed eastward away from the coast. However, pockets of pure American crows still remain in some urban and agricultural areas of western Washington, rather than intermixing with northwestern crows.
There is also a narrow zone of overlap between the species that runs along the immediate Pacific coastline of southwest British Columbia. Here again, hybrid American-northwestern crows occur.
In Oregon, interbreeding is rare, with American and northwestern crow distributions meeting but not really overlapping. The ranges of the two species sit side-by-side but do not intermix much in Oregon.
So while interbreeding does happen in limited hybrid zones, overall the distinct ranges of American and northwestern crows remain largely separate apart from a bit of overlap in parts of coastal Washington state.
Identification Tips to Tell the Two Species Apart
Telling apart American and northwestern crows can be tricky given their physical similarities, but by paying attention to geographic location along with vocalizations, some key identification tips emerge:
- Location – Only northwestern crows occur along the northwest Pacific coast and immediate inland forests. Seeing a crow on the coasts of southwest BC, western Washington/Oregon almost certainly means it’s a northwestern crow. American crows within this zone occur only in some urban/agricultural areas.
- Vocalizations – Listen for the deep, gargling “caw” of American crows or the higher-pitched, raspy calls of northwestern crows. Recordings of typical calls for each species can help identification.
- Iridescence – Northwestern crows show more colorful bluish-purple iridescence vs. the violet-iridescence of American crows.
- Beak Shape – The slimmer, straighter bill of northwestern crows contrasts with the arched bill of American crows but has lots of variation.
- Behavior – Seeing crows in huge winter flocks suggests American crows, while crows nesting in tight clusters indicates northwestern crows.
Using location as a starting point, along with vocalizations, coloration, beak shape, and behavior, birders can confidently identify whether a crow in the Pacific northwest is an American or a northwestern crow.
Conclusion
While American and northwestern crows appear very similar at first glance, important differences set these two species apart. The limited coastal range of the northwestern crow contrasts sharply with the widespread distribution of the American crow across North America. Northwestern crows also have a smaller body size, more colorful bluish-purple iridescence, higher-pitched vocalizations, and a slimmer beak. Behaviorally, northwestern crows are a bit less social and congregate in tighter nesting clusters.
Paying attention to location, along with vocalizations, slight physical differences, and behavior, allows observers to confidently differentiate between these two all-black corvid species. So next time you see a crow on the northwest coast, listen and look closely to determine if it is an American crow or a northwestern crow!