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On Crows
I need to make good on a promise. I said I would post about corvids in exchange for a bowling for rhinos donation, months ago. I've been waiting to either get a great picture, or have some kind of divine insight.
I have said before that crows are my favorite urban animal. I used to watch them whenever I could, as they picked at carrion on the roadside or at insects in the crop fields at Drumlin Farm. There was even a crow roost, a nighttime gathering, that met in the trees near my house in Brighton. Thousands of birds would collect at dusk in the fall. They would chatter and caw all night, maybe not having conversations, but definitely learning about one another. The cleverest of them would notice who was most well-fed, and make a note to follow that one in the morning, to find a plump carcass or other food source.
At Drumlin farm, wild crows would wait over our heads as we brought buckets of compost (which contained dead mice and other meaty morsels from the live animal center) up to the pile in the woods. They came to recognize the buckets, anticipate the time, possibly even recognize the humans involved. They definitely recognized my boss' car, probably by sound first, then by sight. She would throw the wild crows handfuls of dry dog food in the morning. The wild crows gathered around the cage of our exhibit crow. They would caw to one another from either side of the mesh. Our captive crow would pass items of food from his dish to the mouths of the crows outside. He had joined their flock, even though he couldn't fly with them.
If I hear crow call, I look to see what's happening. They call to one another, and their calls all have meaning. I've never decoded completely, but if you pay attention you can hear the calls and responses in different situations. The most obvious calls are the braying hysterical caws at the high end of their voice, when a predator is in their midst. They will gladly join a red-tailed hawk in aerial battle. These hawks, like crows themselves, prey on baby birds still in the nest, and I have seen an adult crow brought down to be a red-tail meal. Once, at my in-laws house in Vermont I drank coffee on the back patio and listened to some upset crows. Through my binoculars I could see a family of black bears climbing a tree a short distance away. I don't know if the crows were in any immediate danger, but they let everyone in earshot know that a potential nest predator was in a tree.
Then in 2003 West Nile Virus swept through the area. In Boston and at Drumlin Farm, where I would routinely see groups of 5 to ten crows on any summer day, I stopped seeing them altogether. Mosquitoes could bite a bird like a robin, which may carry the disease without getting sick, and then pass it to a crow with a bite. Crows and their smaller cousins the blue jays disappeared for a while; other birds at risk included owls and eagles (our captive golden eagle at Drumlin died of WNV). The zoos began innoculating entire flamingo flocks and other birds on outdoor exhibit.
And the crows have begun to bounce back. There had to be some number of birds naturally resistant to the virus, and they passed on the resistance to their chicks. Corvids are some of the most adaptable birds in the world, and they tend to do very well around the edges of human activity. While I haven't seen the huge numbers of crows that I saw 10 years ago, they do appear to be back in force. At the zoo I see groups of 5 to 10 in open areas and up in the trees barking at the red-tailed hawks (both crows and red-tailed hawks nest in the zoo). The West Nile Virus event is probably a minor hiccup in the in the long history of crows, and the history that humans and crows share with one another.
I've posted about corvids a few times before:
365 urban species entries:
American crow
Northwestern crow
Blue Jay
Ravens are rare in Massachusetts. We did take a special trip to find the one place in Boston I know of, where ravens nest. Here it is. I was not able to photograph a raven there.
Wild corvids seem to be camera shy. They are smart and aware, so when a big predator stops and trains its one huge eye at them, they know not to stick around. I didn't get any pictures of ravens in Greenland or Iceland even though they were very common in both places.
Here's a couple cute videos of a captive crow at Drumlin.
A Canadian documentary team just produced a film called "A Murder of Crows," about crows in general and about a sanctioned crow massacre in Ontario in particular. It's showing on CBC tomorrow night. Those of us in the states may have to wait for the DVD.
I have said before that crows are my favorite urban animal. I used to watch them whenever I could, as they picked at carrion on the roadside or at insects in the crop fields at Drumlin Farm. There was even a crow roost, a nighttime gathering, that met in the trees near my house in Brighton. Thousands of birds would collect at dusk in the fall. They would chatter and caw all night, maybe not having conversations, but definitely learning about one another. The cleverest of them would notice who was most well-fed, and make a note to follow that one in the morning, to find a plump carcass or other food source.
At Drumlin farm, wild crows would wait over our heads as we brought buckets of compost (which contained dead mice and other meaty morsels from the live animal center) up to the pile in the woods. They came to recognize the buckets, anticipate the time, possibly even recognize the humans involved. They definitely recognized my boss' car, probably by sound first, then by sight. She would throw the wild crows handfuls of dry dog food in the morning. The wild crows gathered around the cage of our exhibit crow. They would caw to one another from either side of the mesh. Our captive crow would pass items of food from his dish to the mouths of the crows outside. He had joined their flock, even though he couldn't fly with them.
If I hear crow call, I look to see what's happening. They call to one another, and their calls all have meaning. I've never decoded completely, but if you pay attention you can hear the calls and responses in different situations. The most obvious calls are the braying hysterical caws at the high end of their voice, when a predator is in their midst. They will gladly join a red-tailed hawk in aerial battle. These hawks, like crows themselves, prey on baby birds still in the nest, and I have seen an adult crow brought down to be a red-tail meal. Once, at my in-laws house in Vermont I drank coffee on the back patio and listened to some upset crows. Through my binoculars I could see a family of black bears climbing a tree a short distance away. I don't know if the crows were in any immediate danger, but they let everyone in earshot know that a potential nest predator was in a tree.
Then in 2003 West Nile Virus swept through the area. In Boston and at Drumlin Farm, where I would routinely see groups of 5 to ten crows on any summer day, I stopped seeing them altogether. Mosquitoes could bite a bird like a robin, which may carry the disease without getting sick, and then pass it to a crow with a bite. Crows and their smaller cousins the blue jays disappeared for a while; other birds at risk included owls and eagles (our captive golden eagle at Drumlin died of WNV). The zoos began innoculating entire flamingo flocks and other birds on outdoor exhibit.
And the crows have begun to bounce back. There had to be some number of birds naturally resistant to the virus, and they passed on the resistance to their chicks. Corvids are some of the most adaptable birds in the world, and they tend to do very well around the edges of human activity. While I haven't seen the huge numbers of crows that I saw 10 years ago, they do appear to be back in force. At the zoo I see groups of 5 to 10 in open areas and up in the trees barking at the red-tailed hawks (both crows and red-tailed hawks nest in the zoo). The West Nile Virus event is probably a minor hiccup in the in the long history of crows, and the history that humans and crows share with one another.
I've posted about corvids a few times before:
365 urban species entries:
American crow
Northwestern crow
Blue Jay
Ravens are rare in Massachusetts. We did take a special trip to find the one place in Boston I know of, where ravens nest. Here it is. I was not able to photograph a raven there.
Wild corvids seem to be camera shy. They are smart and aware, so when a big predator stops and trains its one huge eye at them, they know not to stick around. I didn't get any pictures of ravens in Greenland or Iceland even though they were very common in both places.
Here's a couple cute videos of a captive crow at Drumlin.
A Canadian documentary team just produced a film called "A Murder of Crows," about crows in general and about a sanctioned crow massacre in Ontario in particular. It's showing on CBC tomorrow night. Those of us in the states may have to wait for the DVD.