Every afternoon during winter months crows swarm together over our Santa Monica neighborhood, apparently from all over the LA's Westside, to select a location for a wild raucous party. Sometimes they even choose our house and, with lots of loud cawing, peck at the roof, frolic through lawns, carry stuff around and drop it, and generally act intimidating. They basically act like a bunch of bikers pulling into town to pillage. I've come to really enjoy it but it is still fun to raise my fist and shout obscenities at them like a cranky downstairs neighbor during a kegger.
After a few searches I couldn't find much about Los Angeles crows (but here is an excellent New York crow site ). So I contacted Kimball L. Garrett, Ornithology Collections Manager with the Natural History Museum of Los Angeles County. Garrett is the author of a new book, Birds of the Los Angeles Region, and though he is not a crow expert, he was able to offer a great overview of crows in L.A.
MSG: So, what are these birds doing?
KG: Crows (technically these are American Crows, Corvus brachyrhynchos — there are many other species of crows and ravens in the world) are very social birds. They tend to roost in groups, forage in groups, and gather for “socializing” at various times of the day. They also harass and chase predators (such as hawks) in groups. On the other hand, crows do not nest in large groups, but instead separate into pairs or small cooperative breeding groups of up to a dozen birds — in these groups there is usually a breeding pair, plus one to several “helpers” which are usually young from previous broods.
What you are seeing are social gatherings of wintering crows (social groups, as noted above, are much smaller in the breeding season). Some nighttime roosts may contain up to several hundred birds (thousands in some parts of the country). There is a lot of social interaction that goes on as birds gather near the roost sites — calling, chasing, jousting, etc. The seemingly useless behaviors such as pecking at roofs, picking up sticks, etc. may be “play” behavior mainly by juveniles — they’re just sort of acting out their repertoire of behaviors, getting more proficient at maneuvers and behaviors important for survival.
MSG: Are they having fun? It seems like it!
KG: I think we all agree that crows seem to be having fun in their social gatherings and “play” behaviors. It becomes a semantic and ethological issue of what “fun” is. I guess one can argue that if play behavior is adaptive (helps hone skills), then the bird is more likely to engage in skill-increasing activities if it is “having fun” (as we would put it) or whatever the biological equivalent is.
MSG: Where do they go during the day?
KG: Crows are mostly out foraging during the day. They’re omnivores and extreme generalists, so they might feed in a variety of areas and on many different kinds of foods. e.g., garbage at landfills, schoolyards, parks and beaches (we’re good at providing a lot of that), pet food left outdoors, fruits, walnuts (they’ve been observed dropping walnuts into streets and waiting for cars to run over them to crack the shells), insects, small vertebrates, bird eggs and nestlings (they’re notorious nest-robbers), etc. They fan out over a large area to feed, so you tend to see the large concentrations back toward the roost areas.
MSG: Is this a Westside phenomena or is this happening all around Los Angeles? Everywhere?
KG: American Crows are found over most of the US and temperate Canada (except for some of the southwestern deserts). In our region they’re pretty much everywhere on the coastal slope and foothills, but they’re scarce or absent from the deserts (where Common Ravens predominate). Crow behavior is more or less the same throughout the species’ range (though some northern migratory populations might not show cooperative breeding as frequently). Areas of high abundance of crows in the L. A. region include the interior valleys (San Fernando, San Gabriel, Pomona, etc., and most of the coastal lowlands (e.g. L. A. basin, Long Beach, etc.).
MSG: I read in your book that Crows are on the rebound — is that true? Were they endangered? Are they displacing other local birds or other fauna
KG: American Crows probably used to be less common overall and definitely more localized in their distribution than they are now. Basically they need trees — for nesting and for roosting. They prefer large stands of tall, dense trees for roosting. If you consider what much of the Los Angeles region looked like 200 years ago, you can understand why crows were probably relatively uncommon and localized — there were few if any trees in large expanses of the lowlands. Now we’ve planted trees everywhere, and the crows don’t care that they’re non-native eucalyptus, pines, ficus, deodars, silk-oaks, etc. So it’s probably not accurate to say crows “are on the rebound”. There are probably more than ever, and in fact most residents of the region who pay attention to such things feel that crows are far more abundant today than they were even 20-30 years ago. Not only have we changed the habitat in their favor and provided them with multiple sources of food, but we’ve done them one other big favor in the past few decades — we’ve stopped shooting them! Crows were often reviled by farmers and rural folks in general. They were harassed, shot, etc., sometimes legally with permits, sometimes illegally. As a result crows were quite wary of humans and tended to avoid area with high concentrations of people. Now we’re so urbanized that shooting is illegal in almost all of the region, crows are protected by law (as native “Migratory” birds), and crows have boomed. They’ve lost their tendency to avoid areas of dense human habitation.
Because crows have become so abundant, and because they do prey on eggs and young of a variety of other bird species, there is some evidence they are negatively impacting some of our local bird species. However, recall that crows are abundant because of our changes to the landscape — thus, we’re really the culprits (as expected) and the crows are the symptoms!
MSG: Are they considered a nuisance? They seem really intimidating and make quite a mess. I like them but I imagine others might not!
KG: Many find crows fascinating, and they are considered highly “intelligent” as birds go (insofar as we can really assess intelligence in birds). This stems from their adaptability and generalized ecology. That’s the up side. The down side is they can be noisy and their roost sites can be messy — some people don’t seem to be able to deal with such doses of nature.
MSG: Can you offer any other resources?
KG: We have a number of references here at the museum with more information on crows. One thing I would add (you didn’t ask about it) is the impact of West Nile Virus on crow populations. This virus, which arrived a few years back in the L. A. Region, has decimated crow populations in parts of the eastern and central U. S. Crows (and ravens, jays, and other relatives) have a much higher mortality rate from WNV than most birds. However, eastern and central US populations have largely recovered, so the population crash was more of a temporary blip. Here on the west coast population declines of crows don’t seem to have been as striking, though in some areas people have noticed declines. In any case, populations are likely to recover soon if they haven’t already.
And a couple of totally off topic and probably to-broad-to-answer questions…
MSG: I’ve seen that you did some work on the Los Angeles River. I’ve followed that a little over the years. How is that going?
KG: We did a biota study back in the early 1990s, but I haven’t kept up too closely with actual management developments along the river in recent years. It seems to be in the realms of politics, art and architecture right now, with the biology sort of relegated to the wings. There are still some very important environment/habitat battles to fight regarding the river (more riparian and wetland habitat, protection of riparian forests and alluvial scrub habitats in the upstream flood control basins and washes, protection and enhancement of critical shorebird habitat along the lower L. A. River in Long Beach, etc.
MSG: Do you know about any studies/info about the birds of the Venice canals. I was recently amazed at the variety of birds in the canals —egrets, pelicans.... It is like a reverse of the LA river — a manmade area that seems to serve as a refuge for wildlife.
KG: I don’t know of any detailed studies there, but a lot of birds that use the marina and the Ballona wetlands will move up into the canals. It’s actually not to hard to “create” good wetland habitat — this is just another example. We’ve done a far poorer job of protecting and restoring upland habitat such as sage scrub, grasslands, etc. — those have virtually disappeared from the L. A. Basin but it seems only the wetlands (which attract bigger birds that people notice) get the public attention.