A Northwoods Almanac for February 11-24, 2011
David Schmoller in Minocqua observed the following in December: “Some ruffed grouse took up residence in one of my crab apple trees. It started with one grouse. Each day around 4 pm he would land in the tree and gorge himself with apples. One day, while writing reports, 4 pm came around, and so did the grouse, and the tree is directly in front of my office window so naturally, the actions of the bird posed a grave threat to my train of thought, the discharge of my duties, and the noble cause of Science. So I was compelled to take leave.
“The bird stood still for about 15 minutes on a stout branch, sizing up the layout of the apples. Then he did a tightrope act, balancing along the thinner branches, sliding sideways, hopping to another branch, sliding sideways again and then stretching his neck, he stabbed at the apples. He did this for about 5 or 10 minutes. I counted the apples; he ate 48 of them. Then, he paused, looked at a tree in the woods about 60 feet away, and launched himself into the air. He quickly dropped about 4 feet, all the while flapping furiously, then, like a cartoon character running in mid-air, he slowly gained altitude, enough so that he was able to plunge into the lower branches of the target tree. Do not try this at home.
“A few days later, four grouse showed up. Word had spread. They stripped it of all that they could. The last remaining apples, out of reach of heavier birds, were taken a few days later by a red squirrel that had, on an earlier date, filled my woodshed with enough pine cone debris to heat my house for several years. This is war.”
We have had around 50 goldfinches visiting our feeders all winter, but we have nothing on Helene Sleight on Island Lake in Manitowish Waters who estimates that she has 200 or more flocking to her feeders.
Vicki Shanahan in Lac du Flambeau recently sent me a photo of a bobcat that had just caught a gray squirrel near her bird feeders. For squirrel-haters everywhere, bobcats may now have attained wildlife royalty status.
But do bobcats eat that many squirrels? Well, it’s hard to say given that bobcats are opportunistic predators. While a bobcat’s diet mostly consists of rodents and rabbits, with deer making up a larger portion in the winter, their diet can be very diverse. A Florida study examined the stomachs of 413 bobcats and found 18 different mammal species, 14 kinds of birds, and even two reptiles. In an Oregon study of bobcats, four hundred ninety-four bobcat scats were analyzed with snowshoe hares most commonly found, followed by black-tailed deer and then mountain beaver.
So, a bobcat’s prey varies by region. In the eastern United States, cottontail rabbits are at the top of the menu, but further north the snowshoe hare takes precedence.
Less commonly, bobcats will feed on larger animals such as foxes, minks, and skunks, the occasional domesticated dog or cat, and farm animals from poultry to sheep. Out West, bobcats have been documented consuming pronghorn antelopes, mule deer, and bighorn sheep Interestingly, bobcats are considered the major predatory threat to the endangered whooping crane.
As a deer predator, one study in Florida’s Everglades showed a large majority of kills (33 of 39) were fawns, but that prey up to eight times the bobcat's weight could be successfully taken.
Bobcats cannot supplement their diet with plants because their stomach physiology is specialized for meat, and thus they are called hypercarnivores, the quintessential carnivore. Every aspect of their physical body, ecology, and social structure is geared towards capturing and consuming animals. For example, their relatively short digestive tract weighs less, enhancing greater acceleration to capture their prey. And their teeth are so specialized for consuming meat that their premolars and molars do not have any flat surfaces, limiting their ability to grind up plant cell walls.
As for whether importing a bobcat to your backyard could assuage your grudge against the local squirrel population, you might want to reconsider. Since bobcats consume more than 50 species throughout their range, they might consume a few other things you might want not want them to. Better, perhaps, to suffer the squirrels.
Great Backyard Bird Count
The 2011 Great Backyard Bird Count, an annual four-day event, will take place Friday, February 18, through Monday, February 21. Participants count birds to create a real-time snapshot of where the birds are across the continent. Anyone can participate, from beginners to experts, and it takes as little as 15 minutes on one day, or you can count for as long as you like each day of the event.
It’s free, easy, and it helps the birds. Participants tally the highest number of birds of each species seen together at any one time. To report your counts, you fill out an online checklist at the GBBC website (http://www.birdsource.org/gbbc/). As the count progresses, anyone with Internet access can explore what is being reported. You can also see how this year's numbers compare with those from previous years. The 2010 Great Backyard Bird Count broke the participation record – bird watchers submitted more then 97,200 checklists from all 50 states in the U.S. and from all 10 provinces and 3 territories of Canada. Participants reported 602 species in 11.2 million individual bird observations. In terms of overall numbers of birds counted, the American robin led the way by a huge margin with 1,850,082 individuals reported. Canada goose was a distant second with reports of 748,356 birds. Snow goose, American crow, and European starling all came in with about 500,000 individuals each.
Texas, with its size, habitat diversity, and dedicated birders, was the species diversity hotspot with 347 species. Tiny unincorporated Tivoli, Texas, took the honor of having the most species recorded at any locality with 175 species. Saint Petersburg, Florida, led in sheer numbers for the second year in a row with 1,476,478 birds reported, of which, rather amazingly, 1,450,058 were robins.
In terms of human participation, Mentor, Ohio, led the way with individuals submitting 709 checklists. In Canada, Clearwater, British Columbia, with a population of only 4,960, was the standout performer with locals submitting 329 checklists. In Wisconsin, participants submitted 2,385 checklists and reported sighting 124 bird species.
This would be a particularly neat event for local communities to embrace. I would think our larger towns like Minocqua, Eagle River, and Rhinelander could easily make the top ten participants category (couldn’t we get 300 people to count birds at their feeders for 15 minutes?), but it would take someone in each town to champion the cause.
Hibernating Snapping Turtles Eaten by Otters
On 1/24, Joe Mastalski discovered 10 adult snapping turtles on the ice next to a pool of open water, an area that in Joe’s experience otters often visit during the summer. Most of the turtles were just shells and claws. The heads were not eaten, but the throats were.
Joe wrote again a few days later when a friend went to see the turtle remains and saw an otter enjoying a turtle meal. The friend noted that the turtles were mostly thoroughly eaten but at least two had just had their throat sliced.
All of this led Joe to ask whether the turtles actually eat and stay "awake" in moving water during the winter, or do they hibernate near areas of thin ice where otters could hunt them?
As for hibernation, I knew that snappers, despite being air-breathing reptiles, bury themselves typically in groups in pond mud, and hibernate for six months without ever coming up for air. Their body temperature drops to 34°F and they stop breathing entirely. While hibernating, snapping turtles can get oxygen by pushing their head out of the mud and allowing gas exchange to take place through the membranes of their mouth and throat, a process known as extrapulmonary respiration.
However, some snappers do not bury themselves in pond mud – I’ve received several e-mails over the years from people who, looking through clear ice, have seen snappers simply laying on the bottom of a shallow lake bed. Presumably they were hibernating as well, but failed for some reason to bury themselves, an adaptation researchers speculate they utilize to reduce predation from animals like raccoons and otters. Researchers speculate that snappers choose very shallow water because shallow waters heat up most quickly in spring, thus reducing the length of hibernation.
Richard Vogt in his book Natural History of Amphibians and Reptiles of Wisconsin further expands the hibernacula options by noting, “Snapping turtles often congregate in large numbers to hibernate in muskrat tunnels, springs, and holes in banks.”
So, snappers clearly hibernate, but in a variety of locations.
What about otters predating on them? I had never heard of this prior to Joe’s observation, but in doing some research I found that at the site of a long-term study of snapping turtles in Algonquin Park, Ontario, the whole study population of snapping turtles was effectively exterminated during a single winter, when otters ate the viscera out of the hibernating and defenseless turtles.
And so Joe’s question has an answer: otters do eat snappers that they can find under the ice. Which leads to the next questions: how common is this? And how in the world do the otters find them? If I uncover answers, I’ll fill you in.
On 2/17 we will receive 10 ½ hours of daylight. We’re gaining around three minutes of daylight every day now.
The “Snow/Hunger” full moon occurs on 2/18.
To find the planets in the night sky in February, look after dusk for Jupiter high in the southwest. Saturn rises around midnight in the east, and then is high in the south before dawn. Also before dawn, look for Venus low in the southeast.