Crows - Of Mobbing and Murder

     We have two species of crows in the DC area: the common American Crow (Corvus brachyrynchus) and the slightly smaller Fish Crow (Corvus ossifragus), which is usually associated with water. The two are tough to differentiate (apart from the nasal like calls of the Fish Crow) and often flock together. Fish Crows have been expanding their range inland along waterways. American Crows are the largest of the true crows in North America at 16-20 inches, compared to the 14-16 inch Fish Crows. The rest of this article will be about American Crows, though much is also true of Fish Crows.
     All crows (called corvids because they're in the Corvidae family, the crows, ravens, magpies and jays) are considered among the smartest of birds, with good reason. American Crows are incredibly adaptable creatures with some amazing natural history allowing them to thrive.
     First of all, crows will eat just about anything. While they prefer animal protein (they love worms for example), they will eat quite a bit of plant material as well. And they won't be fooled by such scare tactics as scarecrows or fake owls to keep them away, being much too smart for that. The lengths corvids will go to get food are legendary, with some types of crows worldwide using tools, stealing fish caught ice-fishing, cracking nuts under car tires, using water to soften hard foods, and such. But our own crows are also very adept at getting food. Here's a short video of crows taking advantage of red cedar fruits:

https://www.youtube.com/watch?v=ia3-q1--mm8

     While they love to eat meat, crow beaks are not always strong enough to make them great scavengers. But they will take advantage of road kill, letting the car tires help them to not only kill their food, but break the skin open to allow them access to the softer insides. Crows will also raid bird nests, eating both eggs and young. This is one of the reasons you see birds gang up and mob them all the time. As they sometimes target poultry, this does not always endear them to many farmers. 
     They will also eat young animals, though again, it isn't easy for crows to dispatch potential prey with their beaks. It sometimes takes some great effort and time for them to finally kill their food. They will occasionally cooperate in order to do so. I've seen several crows all ganging up on a young rat, pecking at it, chasing and cornering it among each other until it finally died. Crows will also raid pet bowls, scavenge garbage and go after baby turtles. They will sometimes follow the edges of forest fires to catch whatever the flames force out into the open. I've seen them patrolling the edges of vernal pools, intercepting frogs as they make their way to the ponds to lay eggs. When they have enough food, they may cache leftovers for later use. If they eat something indigestible such as feathers, fur or bone, these get coughed up in pellets similar to owls. 

Crows are curious, and that occasionally gets them into trouble. We had to untangle this one when it got tangled up in line. 

     Some people think that curiosity is a sign of intelligence. Well, crows certainly are curious, but their inquisitiveness is tempered by lots of caution. Still, they do go out of their way to check out novel developments. I think it humorous when I see a crow sitting next to a fake owl meant to scare it away, for instance. They love to investigate shiny objects as well it seems. We had some who would regularly walk through our Arlington County native plant nursery and pull most of the plant tags and labels out of the pots and discard them on the ground. Here's a short video of them doing just that: 

https://www.youtube.com/watch?v=TjZpsj2_2J8

     American Crows will also make use of tools, a trait most other animals don't share. One example is of a captive crow who learned to use a shallow container as a cup to carry water over to its dish to moisten the dry mash it was fed. Another involves one that shaped a stick so it would fit into a fence post to pry food out. Others have learned to pick up mollusks and drop them from great heights to break them open. In another example, a captive crow would use a slinky toy as a head-scratcher. One learned to drop pine cones and other tree parts onto the heads of climbers getting too close to its nest. Some crows use another bird behavior called "anting" where they stir up an ants' nest and let the ants swarm them, or pick up individual ants in their beaks to preen their feathers. The belief is that the ants not only kill parasites on the birds, but by spraying formic acid also reduce the presence of pests on their bodies. In what may be a unique use of a "tool", a crow was famously photographed hitching a ride for a while on the back of a flying bald eagle. Crows are capable of learning and even teaching one another, as some examples below will show. Some crows have even learned to be mimics, including saying some words and copying voices. 
     Crows have a very complex communication system. They make many other sounds in addition to the common "caw", but the same "caw" can mean a variety of different things based on how quickly it is repeated, how many times it's made, and the context as well. Many people are most familiar with the 3 sharp caws given by sentry crows that are keeping watch over the flock. It also seems that each crow sounds different enough from one another that they can tell individuals apart. Crow calling is a favorite study subject among researchers studying animal communication due to its complexity. 
     Crows not only learn, but appear to have remarkable memories and can teach one other. One experiment showed that when researchers captured crows, once they returned to the area, the crows could recognize them and tell them apart from other people. They would harass the researchers and warn each other of their presence. They did this even 9 years later, and amazingly birds who had not been handled themselves learned to recognize the researchers and warn others years later. Hunters and farmers have even tried to accustom crows to their presence, carrying broom sticks as gun-props in the hopes that they would learn not to fear them. But the crows are able to tell the difference of when they are carrying a gun instead of broomsticks. Many hunters and farmers have tried to trick crows with fake-gun props, and the crows always seem to figure it out. It is little wonder that scarecrows, fake owls and other scare tactics are useless, even when changing their clothes or imparting motion. 

Crows love to bathe and will do so almost daily even in winter, frequently in large numbers.

     Mobbing is a common defensive behavior among birds, and crows use it quite often. This is when birds gang up and harass a potential predator. They may not actually strike their perceived enemy, but they don't let it rest or hunt, eventually causing it to leave the area. Crows may use this as a means to teach their young what predators to avoid as well. 
     I've used crows mobbing as an educational demonstration many times. My set-up is a bit more elaborate in order to trick them, if only briefly. I use a fake owl that I place out there as the predator (sometimes a large great horned owl puppet, sometimes a stuffed taxidermy mount). At its feet, I place a crow puppet, usually on its back with feet up in the air and wings spread in as dramatic a death-pose as I can achieve. I then hide nearby and use a mouth call along with a recording of crows mobbing. The first few are apprehensive when they appear, and I need to be well hidden or they quickly notice something is amiss. But as their numbers increase, so does their daring. It is sometimes like a scene from Alfred Hitchcock's "The Birds" movie, so many aggressively gather and scream bloody murder. But this is very short-lived. Soon they see through the ruse and leave. I can rarely get away with dong this in the same area more than a couple of times a year before they get wise that it's a trick.
     It appears that crows also learn how to be good parents. Crows normally are not sexually mature until after their second year, and many don't breed until their fourth year or even later. During the interim after they themselves leave the nest, most assist their parents in raising their younger siblings. Each year, the previous years' young assist in feeding and protecting the nest. In this way some think they learn the best ways of being successful as parents, and the extra helps helps more young crows survive. It is not uncommon for families of up to 15 crows covering 5 generations to all be present raising young.

A pair of crows

     So during the late winter and early spring, crows pair up, often with the previous year's same mate and often mating for life. While they have interesting courtship displays, (preening one another, males bowing and spreading their wings for the females, and showing off with diving and circling), this is not often seen. Once the pair has bonded, they tend to not have as many courtship displays anymore in the years that follow. 
     Once paired up, the pair builds a nest, preferring evergreens as a nest site when they're available. It is often hidden, with the normally noisy birds keeping quite quiet around the nest. From 3-9 (though 4-5 is most common) dull bluish green eggs are laid, incubated solely by the females, hatching about 18 days later. With lots of help from their older siblings, young leave the nest 3-5 weeks later. The young crows tend to have bluish eyes at first. crows only nest once a year, but after their first successful attempt, they tend to be fairly successful in raising young most years that follow. Being so smart and adaptable, they have been recorded as living over 16 years in the wild, and the record is of one that lived 59 years old in New York as a captive.
     While their extended families and clans form the basis of their flocks, and while they tend to use a set family territory, this can be quite variable. Crows living in urban areas have much smaller territories for instance. During the day, family members may leave and join larger flocks before coming back to join their families. While in the larger flocks, family members also don't seem to hang out together very much either.
     Crow behavior changes quite a bit in the winter though. Crows tend to join flocks more, particularly before dusk. These can be huge aggregations, some 2 million strong per roost have been recorded, though of course numbers are usually much smaller. Some historic roosts have also been around for over 100 years. There's safety in numbers. 

A murder of crows...

     There are quite a few generally accepted names for flocks of crows. The most popular is to call them a murder. But they're also sometimes called a congress, a cauldron, a muster, or a horde. These noisy (and sometimes messy) aggregations may be very unpopular near people, leading to some jurisdictions trying harassment tactics to discourage them in certain areas. Crows being as smart as they are, these are not always very successful, leading to more lethal means of controlling numbers and trying to break up roosts. Dynamite has even been used in the past.

Attempted murder of crows...

     Recently, crow numbers in some areas took a dramatic drop, with some surveys showing a 45% drop in their population numbers. West Nile Virus when it was accidentally introduced into our area took a huge toll on them. Crows are more susceptible to it than any other bird, with most infected birds not lasting even a week. But those that survived, due to their adaptability and intelligence, have made a huge come back. A 2014 survey estimated there were 27 million crows in North America. 
     Crows may not be every one's favorite bird, and indeed to some they're a nuisance or even a pest. but there's no denying their adaptability and intelligence. People may grudgingly admire these large, common birds. Around the world, corvids have been part of folklore and legend, be it the crows in Aesop's fables, or the mythical ravens in Norse mythology. I'll leave you with one tale of our own crows, a legend attributed to the Delaware tribe, the Lenni Lenape. Back in my stoyteller days, my version was part of a much longer creation story, but here are the elements at least regarding crows.  One of many versions, the story of the Rainbow Crow:
     It starts with a long, bitter and dark winter. The deep snow and darkness finally worried all the animals, who were tired of stumbling in the darkness and suffering from the cold. They all gathered to see what they could do about it. In the most common version of the tale, it is decided that a messenger should go to the great spirit and ask for help. The journey would be long and dangerous with the darkness and snows. As they were fearful of disturbing the spirits, and since only a very intelligent creature would be able to find the way, there were not a lot of volunteers. But the most beautiful of all birds, the Rainbow Crow, volunteered to speak on their behalf and ask for aid. Having one of the most elegant of voices, this was seen as fitting as well.
     After a perilous voyage, Rainbow Crow eloquently made his point, asking for help on behalf of all the animals, and providing a gift to the spirits of his song. The great spirit provided a magical gift called Tindeh (fire) for him to take back as a present for the animals, to provide light and warmth until the season changed. It was burning at the end of a stout branch for the beautiful messenger to carry.
     Rainbow Crow grabbed the fire stick by the end in his strong beak and returned to the people. Again, the journey was a long one. Soon the fire stick started to burn down to the end he was holding, yet he could not let go lest he lose this precious gift. So he ignored the heat and smoke and flew on. Soon the flames were scorching his beautiful feathers. He could not help but breathe in the fumes. When he arrived back at the animal village, his beautiful feathers had burned black, covered in soot and ash. When he tried to speak, his speech  was hoarse from the smoke, his eloquent voice forever gone. 
     All the other animals rejoiced for Rainbow Crow's sacrifice had provided them with a great gift providing light and warmth, All rejoiced that is except for Rainbow Crow, who had gone from the most beautiful of voice and feather to now being among the ugliest. But the great spirit appeared to him in a smoky vision. He reminded Rainbow Crow that his daring deed had saved the people, and he would always be remembered for his bravery and intelligence. He added that he also would not be hunted for food, for the smoke had made his flesh burnt and ill tasting, no one would want to eat crow (more on how this saying came to be in the comments below). Since his voice was also not attractive anymore, few would want to cage him for he had no song to offer rather than a hoarse "caw". But seeing that Rainbow Crow was still suffering, the spirit gave him another gift. His black feathers were not just dull black any longer, but under the right light would have a beautiful iridescence all their own. So it would ever be for the descendants of Rainbow Crow: always to be admired, if sometimes grudgingly, for all their remarkable abilities for those who take the time to look for them.