Posted in carnivores, tagged Canada lynx, lynx on October 8, 2009 |
It’s in a cage trap, but it’s a good close up view!
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Posted in carnivores, tagged bobcat, Canada lynx, lynx on October 7, 2009 | 3 Comments »
The bobcat is a generalist.
In North America, we have two species in the genus Lynx. For some reason, most people do not realize that the bobcat is actually a species of lynx, and the Canada lynx is not the same species as the Eurasian (“Siberian”) lynx. However, there are actually four species of lynx, and the bobcat and Canada lynx make up the North American representatives of this genus.
The bobcat’s ancestors were very similar to the Eurasian lynx, and it is believed to have entered North America as early as 2.6 million years ago. The bobcat’s ancestors came to North America when the ice sheets receded. They then returned, cutting off the ancestral bobcats from Eurasia.
It is thought that bobcat became smaller in size because of competition from other large carnivores that lived in North America at the time. Most bobcats are are under 30 pounds in weight, although a few exceptional individuals can exceed 40 pounds.
As the Pleistocene ice sheets receded once again, another wave of lynx-type cats entered North America from Eurasia. These became rather specialized to hunt snowshoe hares. This species became the Canada lynx.
On average, it weighs more than a bobcat, but the biggest bobcats are actually larger than the Canada lynx. Bobcats are also much more aggressive than Canada lynx are, so where their ranges overlap, the bobcat usually has the upper hand.
The Canada lynx’s range in the US has been greatly reduced. Canada lynx have had a very hard time recolonizing their former range in part because of territorial issues with the bobcat. The fact that snowshoe hares, its main prey species, are very cyclical in their population sizes means that Canada lynx numbers are always limited to snowshoe hare cycles. That certainly does prevent it from returning to its former range.
The fortune of the Canada lynx is tied to the snowshoe hare.
To make matters worse, bobcats and Canada lynx can hybridize. Hybrid specimens have been found in New Brunswick, Maine, and Minnesota.
The bobcat and Canada lynx are good examples of two different strategies for survival.
The bobcat evolved as a generalist. It eats lots of different prey species. If the winter weakens the deer and the snow fall is too heavy, the bobcat will try to make a meal out of them.
The Canada lynx has hitched its wagon to the snowshoe hare’s star. Things were good for the Canada lynx, for it could adapt to the wild cycles in snowshoe hare populations. It was bust and boom for the hares, and boom and bust for the Canada lynx.
Canada lynx then suffered from overtrapping by humans. It couldn’t handle that sort of pressure. As a result, Canada lynx are on the Endanger Species List in the United States.
So in this tale of two kitties, the generalist’s wager paid off, while the specialist’s wager has not paid off so well.
Posted in carnivores, tagged clouded leopard on October 1, 2009 | 1 Comment »
Well, it took all day, but someone finally got it.
It is a clouded leopard skull.
What’s a clouded leopard?
It’s probably the coolest big cat in the world.
This is what it looks like as a living animal:
You can read more about them here.
Posted in carnivores on October 1, 2009 |
A few days ago, I happened to mention that polar bears were actually somewhat hard to classify. They do represent a specific niche in a specific ecosystem, but they are very closely related to brown bears (European brown bears, grizzlies, and Kodiak bears are subspecies of the brown bear [Ursus arctos]). Indeed, there are populations of brown bear that are more closely related to polar bears than they are to other brown bears. (I can give you the source if you’d like. I can’t get it to link here.)
Comparison of polar and brown bear MtDNA suggests that polar bears and brown bears diverge 200,000 years ago. However, the oldest known fossil from a polar bear is 130,000 years old.
All of this evidence suggest that that a polar bear is basically a modified brown bear. It has a smaller head, larger body (although roughly equal to that of a Kodiak brown bear), sharper and more hooked claws, and a different metabolism. Only pregnant female polar bears hibernate, but all brown bears hibernate, unless they are in captivity and are fed all winter long.
Polar bears can better utilize littoral and marine environments than brown bears can. They are almost entirely carnivorous, while the brown bears are omnivores. They have become different animals– usually considered separate species.
However, their links to the brown bear as still strong enough for the two to hybridize. In 2006, one was shot on Banks Island in the Northwest Territories, and the ephemeral and mysterious “MacFarlane’s bear,” which was documented in 1864, was probably a similar hybrid.
***
I should mention here that the term polar bear is a bit of a misnomer. Today the animal is found in areas around the Arctic Ocean, but historically the bear’s range was far more southerly. In Europe they were found as far south as Bergen (Norway) and the Gulf of Bothnia, which is an arm of the Baltic Sea.
In Sea of Slaughter, Canadian author Farley Mowat contends that the polar bears had an extensive southerly range in North America. The bears were common in the Gulf of St. Lawrence. A bear was killed in the Gulf of Maine in the eighteenth century, and supposedly one was killed in Delaware Bay in the seventeenth century. (Take that last one with a grain of salt. Albino black bears are not unknown).
To bolster his claims, Mowat points to a large population of polar bears that were found far to the south of Churchill, Manitoba, on the same line of latitude as the city of Calgary. The bears had been undiscovered, but they were utilizing both the land and sea for food.
Because of Mowat feels that they are a more southerly species, he no longer calls them polar bears. In the text, he calls them “white bears” or “water bears.” I think that this is a pretty fair assessment.
***
Now, the polar bear is threatened by climate change. It no longer can range across the ice in the Arctic Sea for as many months out of the year as it once did. As a result, polar bears are left stranded and hungry for more months and weeks out of the year.
One wonders why they don’t start foraging like brown bears do, eating what they can find.
However, brown bears learn their foraging habits from their mothers. The knowledge of how to eat certain foods and when they are available is passed on through the generations.
Polar bear mothers have taught their cubs how to live on seals on the sea ice. That is the knowledge they pass on.
When that opportunity disappears, the bears have no way of adapting in the short term.
However, I think it will be just a matter of time before some polar bears figure out how to forage on the land. Hunger is a powerful motivator, and all bears seem able to utilize new food sources all the time.
My guess is it won’t be long before they start foraging like brown bears.
Over the generations, these bears will gradually evolve to be like brown bears again, which may be further facilitated by crossbreeding.
Then the reason for them to be different from brown bears will disappear. They will gradually meld into the brown bear soup, and they will be gone.
So the likely future of the brown bear is for it to return to its past.
Posted in animal behavior, carnivores, tagged skunks, spotted skunk, striped skunk on September 29, 2009 | 2 Comments »
For those of you who don’t live in North America, here’s a very good video on skunks. This show was on PBS not long ago, and the striped skunks were awesome.
I can’t describe what skunk musk smells like. I really can’t.
It’s really not the smell that is bad.
It’s how it irritates your eyes and mucous membranes.
I say this as someone who has been skunked.
I had a dog that reveled in killing skunks, and she attacked one that was maybe 10 feet away from me one evening. As she shook it, the skunk wound up spraying me as “collateral damage.”
In some states, people can keep these animals as pets, but most states ban it because skunks have their own strain of rabies.
Incidentally, skunks are not weasels (Mustelids). They used to be classified with the weasels, ferrets, mink, otters, badgers, martens, and wolverines (gluttons). But now skunks and stink badegrs are in their own family called Mephitidae. Both skunks and Mustelids are members of the superfamiy Musteloidea, which includes the raccoon family (Procyonidae) and the red panda (Ailuridae). This suborder Caniformia within the order Carnivora. This suborder also includes dogs, bears, seals, sea lions and fur seals, and the walrus.
Finally, we supposedly have Eastern spotted skunks in West Virginia, but I have never seen one here. Those are the skunks that do handstands.
Posted in carnivores, dogs, Uncategorized, tagged dog domestication, foxes, red foxes, Timothy Treadwell on September 21, 2009 | 3 Comments »
As regular readers of this blog know, I found Timothy Treadwell’s relationship with foxes far more interesting than his relationship with bears. (Here he is with his beloved “Timmy.”)
If he’d only stayed with foxes, he’d probably be alive today, and we’d call him the “Red Fox Man.”
The real reason why I find his intimate relationship with these foxes fascinating is quite simple:
I think we can glean some insights into dog domestication from his relationship with his fox friends.
Now, I do disagree with Mr. Treadwell on the merits of fox hunting and trapping. If foxes become too densely populated, they will succumb to disease or mange and will die horrific deaths. It is better to have a controlled cull of foxes to prevent these diseases from causing a lot of suffering.
However, these foxes in Katmai National Park have never been hunted or persecuted. They have no reason to fear people. They not only scavenge and beg for food from people. Some of them, like “Timmy,” became extremely tame and even a bit bonded to people.
I think it is very likely that before we began our intense and often bizarrely creative persecution of wolves that they were rather like these foxes. They were curious and bold animals that were opportunists that would approach people without any fear. These animals were probably easily imprinted as puppies, and they were probably kept as pets by hunter-gatherers.
We know that most hunter-gatherers today keep all sorts of interesting pets, and it is very likely that wolves were kept as pets by these ancient hunter-gatherers. How long ago this happened is still up for debate– anywhere from 14,000 years ago to 135,000 years ago.
Modern wolves are generally very hard to tame, even if bottle-reared from any early age. They don’t typically make good pets, but it is very possible that this nervousness and reactivity that so marks this species is the result of a few centuries of intense persecution from our species.
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