A Northwoods Almanac for Aril 15-28, 2016 by John Bates
Watching ducks and geese standing on lake ice makes my feet feel very cold. A friend recently said that the feet of ducks and geese don’t freeze in the winter because no blood circulates through them. But that’s not the case.
The blood moving through the naked portions of a bird’s leg would lose enormous amounts of heat in the winter, which has forced birds to compensate by employing a countercurrent heat exchange mechanism. It works like this: the main artery that carries warm blood down the leg is positioned next to a large vein that brings cooler blood back from the foot to the heart. A shunt near the base of the toes allows most of the arterial blood to pass directly into the vein and return without going through the toes and webs, and thus losing even more heat.
The blood returning to the heart absorbs heat from the warmer arterial blood next to it. So, heat is exchanged all the way from the bottom to the top of the leg with the blood arriving back in the body only slightly cooler than what originally left to go to the legs.
To get blood into the feet, some of the blood at the bottom of the leg bypasses the shunt and runs through a capillary network into the toes, which is just enough to keep the blood a few degrees above freezing. It makes for cold feet, but not frozen feet.
|hooded mergansers - photo by Bev Engstrom|
Become a Landlord
Now is the time to become a bird landlord and “rent out” homes to new tenants. Some 85 species nest in tree cavities in North America, of which about three dozen will nest in birdhouses. In our area, the most common tenants will be black-capped chickadees, eastern bluebirds, house wrens, purple martins, wood ducks, common and hooded mergansers, kestrels, and most of our woodpeckers.
Birds won’t rent your houses unless you fulfill their needs. The size of the entrance hole limits which species can enter – and which pest species such as starlings cannot – and the floor plan must accommodate the species' nest. For example, to attract chickadees, which typically nest in dense stands of small trees, put up birdhouses that have 1 1⁄4-inch diameter holes, centered 6 inches above the bottom of the nesting floors, in small tree thickets.
Bird renters would like a home security system on their digs, and you can offer this by putting a stovepipe baffle below the house to keep out raccoons, house cats and other predators that steal eggs and chicks. One writer says, “If you put a birdhouse up on a pole without a guard, you are basically serving lunch.”
Remember, too, that dying and fallen trees make excellent homes for cavity nesters. One unusual example is the brown creeper which nests between strips of loose bark and the trunk of a tree.
Prairie Chicken Dancing
I haven’t visited a prairie chicken lek for many years now, but I still vividly remember the experience. Sarah Krembs reminded me of this when she sent me some photos and a description of her recent visit to a lek near Wisconsin Rapids. She wrote, “We had to be in the blinds at 5:30 and wait for the chickens to show up. First one, and then about a dozen more all at once.
“The sound is most unusual . . . like a mourning dove crossed with a morning barnyard hen. Only one female was there yet, so it was mostly the males who were defending their territory and fighting with each other . . . When they puff their neck sacks out and drum their feet, it is sure a sight to see. Sometimes when the males were puffed up they also did a kind of walk in the funniest way. It was like they were sliding in a straight line . . . as if they were gliding across the ground on ball bearings. It was such a “non-natural” motion that it truly fascinated me.”
If you’re interested in reserving a blind to watch these remarkable birds, go to: www.uwsp.edu/wildlife/pchicken/Pages/viewing.aspx
|prairie chicken dancing - photo by Sarah Krembs|
The Big Thaw
Five species of frogs in northern latitudes freeze during the winter: wood frog, chorus frog, spring peeper, gray tree frog, and Cope’s gray tree frog. In the next few weeks, they’ll all thaw out, and the first to begin singing will be the wood frog, followed almost immediately by spring peepers.
Wood frogs and peepers hibernate by hiding under the leaf litter on the forest floor. By hibernating on land, the frogs can become active as soon as the snow melts and breed in temporary ponds formed by meltwater.
But frogs can't dig underground like toads do. Their water-permeable skin is no barrier to ice, and so they freeze. Their eyes even turn white because the lenses freeze. Their blood stops flowing and as much as 65% of the frog's total body water is converted to ice. Breathing, heart beat, and muscle movements all stop, and the frog lives in a virtual state of suspended animation until it thaws.
They survive largely by building up high concentrations of sugars to keep the insides of their cells from freezing. Ice forms all around their internal organs, but not in the cells.
So, when you hear the first wood frog or spring peeper in the next few weeks, consider that they have been frozen for nearly six months. The pandemonium of their calling makes all the more sense in that light.
Spring Break for Black Bears
Black bears should all be emerging from hibernation now. While some will undoubtedly smash a few bird feeders this spring, according to data from the National Center for Health Statistics, only about 36 human deaths from black bears occurred across North America in the 20th century. For every person killed by a black bear in North America in the same period, 60 were killed by domestic dogs, 180 by bees, 350 by lightning, and 90,000 were murdered. So, while always being wary and cautious, enjoy their awakening!
With the arrival of spring snow melt, this is the time of year when salmonella bacteria can affect birds at your feeders. The smaller songbirds, such as pine siskins, redpolls and goldfinches that weigh only a half ounce, are most at risk.
Salmonella presents itself via a bird at your feeder that appears constantly “fluffed up” and is lethargic and easily approached. While the bird may appear “fat,” it’s really starving and trying to stay warm, even on a warm day with food. Please take the time to clean your feeders with soapy water and then with a solution of one part bleach to nine parts water.
Birds can also become sick from leftover seeds and hulls that begin to ferment. Rake up excess seed or hulls from under the feeder, bag them, and put them in the trash.
Mary Madsen in Presque Isle sent me a photo of a bald eagle that she captured in March on Twin Island Lake and took to the Raptor Education Group in Antigo. The eagle was suffering from lead poisoning. Mary noted, “Sadly, it did die. It was a l7-year-old eagle, banded in the U.P.”
Lead has no business being used for hunting and fishing. The Raptor Education Group’s website in Antigo says this: “Lead poisoning this time of the year usually comes from a bird eating from a discarded animal that was shot with lead ammunition and was either placed in the woods for predators to eat or died in the woods of its injury. Often those that want to feed animals with carcasses have no idea that they contain lead, or how lethal it is. Lead the size of a grain of sand causes lead poisoning in a human child. We hope all hunters make the switch to copper jacketed bullets when hunting. It is safer for wildlife, not to mention their own family.”
|eagle with lead poisoning - photo by Mary Madsen|
Sightings: First-of-the-year (FOY)
Mid-March: Patrick Kessenich sent an excellent photo of a bobcat seen in his yard on Clear Lake in Manitowish Waters.
|bobcat - photo by Lori Kessenich|
3/27: Sarah Krembs sent excellent photos of a red crossbill that stunned itself by smacking into one of her windows.
|red crossbill - photo by Sarah Krembs|
3/29: Mary and I spotted our FOY turkey vultures in Minocqua, and a FOY northern harrier in Manitowish.
3/30: FOY song sparrows, fox sparrows, purple finches, and phoebes all in Manitowish.
3/31 - Carne Andrews observed 6 males and 1 female wood ducks foraging in the grass on the bank of the Manitowish River.
4/3 – Carne also spotted a FOY male yellow-bellied sapsucker.
4/6: FOY: Sue DeFrancisco observed a hooded merganser hen entering her wood duck box.
4/7: Pat Schmidt reported the FOY common loon for our area on Silver Lake west of Hazelhurst. Silver Lake, just 40 acres in size, is one of Walter Piper’s study lakes (see www.loonproject.org), and has had a breeding pair of loons for many years.
4/8: With our eight inches of snow this day, the birds were frantic around our feeders. A woodcock appeared under the feeder late in the day and spent many minutes probing through the snow for food. It was there the next day as well. Given that invertebrates constitute 80% of a woodcock’s diet, and they only occasionally eat seeds, I think this woodcock was very hungry.
|woodcock probing for food through 8 inches of new snow - photo by John Bates through a window|
4/10: John Randolph reported a FOY osprey on a telephone pole nest near McNaughton.
According to 40 years of ice-out data collected by Woody Hagge, the average ice-out date for Foster Lake, a relatively deep, 39-acre seepage lake in Hazelhurst, is April 17. I expect this average date to hold true for many lakes in our area.
Look on 4/17 for Jupiter about two degrees above the waxing gibbous moon.
The “Grass Appearing,” “Awakening,” “Maple Sugar,” full moon occurs on 4/22. Unfortunately, the peak Lyrid meteor shower also occurs this night and will be washed out by the brilliance of the moon. This will be the most distant and thus smallest full moon of the year, some 14% smaller and 30% dimmer than the closest full moon for this year, which will occur on November 14.
We’re up to 14 hours of daylight as of 4/23!
Look in the pre-dawn on 4/25 for Saturn and Mars to be just below the waning gibbous moon.
Please share your outdoor sightings and thoughts: call me at 715-476-2828, drop me an e-mail at firstname.lastname@example.org, or snail-mail me at 4245N Hwy. 47, Mercer, WI.