NWA 2/5/16

A Northwoods Almanac for 2/5 – 18, 2016 

Chickadee Winter Survival

            Chickadees employ numerous adaptations and strategies for surviving a northern winter, from utilizing a controlled hypothermia at night, to being a master at caching seeds, to utilizing tree cavities or birdhouses at night and then huddling with their compatriots to reduce their heat loss.             

But I hadn’t known that they also have exceptional eyesight. In his book The Forest Unseen, David George Haskell writes that “the retinas at the back of the chickadees’ eyes are lined with receptors that are two times more densely packed than are mine. The birds therefore have high visual acuity . . . Where I see a smooth twig, birds see a fractured, flaking contortion, pregnant with the possibility of hidden food. Many insects pass the winter ensconced inside tiny cracks on tree bark, and the chickadees’ discerning eyes uncover these insect hideaways.”

            Haskell also notes that “chickadees have an extra color receptor that detects ultraviolet light. This gives chickadees four primary colors [humans see three primary colors] and eleven main combinations, expanding the range of color vision beyond what humans can experience or even imagine . . . Chickadees live in a hyperreality of color that is inaccessible to our dull eyes.”
            Combined with their acrobatic capabilities of hanging upside down to look into bark crevices, chickadees are thus masters at finding wintering insects that have spent an evolutionary eternity trying to outwit their predators.

            Still, as skilled and adapted as they are, only about half of the chickadees that began the winter will see the spring. Natural selection ensures that only the hardiest chickadees will live to potentially pass on their genes to a clutch of chicks. That’s the way of it. Whether through winter starvation, disease, predation, or other natural causes, all animals that survive to breed this spring will have been profoundly challenged by the cumulative stressors of five months of winter. Through this fire, they will be the ones selected as the most fit for continued life in the Northwoods.

Michipicoten Island Wolves and Caribou

Over the last year I’ve written several times about the highly controversial decision that must be made by the National Park Service on whether to reintroduce wolves onto Isle Royale. Remarkably, while the declining wolves on Isle Royale are down to three closely related individuals, another unique predator-prey relationship has begun on Michipicoten Island, roughly 180 miles across the lake from Isle Royale, where two years ago, three mainland wolves crossed the ice to the island.

The three wolves have since colonized the forests of the 71-square-mile island (about 90,000 acres), the third-largest island on Lake Superior. The wolves left briefly last winter, but then returned and likely have bred. In February of 2015, all three wolves were GPS-collared for study.

The unique aspect to this story is that woodland caribou were reintroduced to Michipicoten in the 1980s, where they have been doing well, with an estimated very dense population of 250 to 300. These caribou, however, are “predator-naive” – they’ve had no experience with wolves.

To add to the intrigue here, there have been almost no humans present on the island since 1900, making the island pristine for wildlife.

Michipicoten is similar to Isle Royale in that both are protected islands in Lake Superior with a single ungulate prey and a single large predator. And both islands have three wolves at last count. But the similarity ends there given that the wolves on Isle Royale are expected to die out due to inbreeding in the next few years, while the wolves on Michipicoten are headed on a very different trajectory.

Preliminary findings since the discovery of the wolves on Michipicoten show that while they do kill caribou, they also take a fair number of the abundant native beaver, much like mainland wolves do.

Questions abound regarding the future for both the wolves and caribou. Will the limited genetic diversity of the wolves bring about the same long term decline that’s been seen on Isle Royale? And while caribou are formidable prey that can defend themselves reasonably well (woodland caribou are smaller than moose but bigger than deer), will the wolves still dramatically reduce the caribou population? Will beaver numbers impact how all of this transpires? And finally, what will occur that no one has really considered, since nature always bats last and is a notorious spray hitter?

Feeling Cold?

            It was cold in mid-January when our first “polar express” came through, but was it really cold?

No, not really.

Really cold for our area is -30 to -40 degrees or lower. That’s the criteria for being defined as Zone 3 in plant-hardiness as determined by the USDA. This area was considered Zone 3 until the latest iteration by the USDA in 2012, when this area was upgraded (downgraded?) to Zone 4.

The zones are based on the average annual minimum winter temperature, divided into 10-degree Fahrenheit zones. While we hit -20 at our house on 1/11, that is still only the dividing line between Zone 4 and 5.

So, like all things, cold is relative. It would have been cold for Iowa, but not for here.

Sightings

Finches are still hard to come by this winter. Jim and Marge Sauer are entertaining many pines siskins and purple finches at their feeders in Tomahawk, but the rest of us are seeing very few of them.
On 1/21, Kurt Justice observed a robin behind Kurt’s Sport Shop in Minocqua. A harbinger of spring to come? I sure hope not. We need winter to stay around, despite its long term effects on our psyches. Otherwise, we may as well live in Iowa, and I, for one, don’t want to have to live through the Iowa caucuses every four years.

Great Horned Owls Breeding and Nesting in February

The deep resonating notes of dueting great horned owls often punctuate cold winter nights in the Northwoods. Arthur Bent described their territorial song in his classic 1938 book Life Histories of North American Birds of Prey: Part 2 as being different from a barred owl: “It is on a lower key, deeper bass, and softer, but has great carrying power. I have likened it in my notes to the sound of a distant foghorn, the far-away whistle of a locomotive, or the barking of a large dog in the distance. At times, when near, it has seemed more like the cooing of a dove than the hooting of an owl. The ordinary note, when the owl is not excited, is a prolonged, soft, somewhat tremulous, and subdued hoot, with little or no accent.”

It’s possible to distinguish the female from the male by their calls – the females have a higher pitch because of their smaller syrinx, and they typically add an extra note at the beginning of their call.

In Wisconsin, territorial hooting ends generally by mid-February in keeping with the timing of first eggs being laid anywhere from late January in the southern counties to mid-March in the North Country.

 Great horned owls don’t build their own nests, but rather occupy a wider range of nest sites than any other bird in North America. They most commonly use tree nests of species like red-tailed hawks and other hawks, as well as nests of crows, ravens, herons, and squirrels in whatever tree is available.

They don’t maintain the nests – poor renters these. Often a tree nest deteriorates during a season’s use, and thus few are used more than one time. Still, a well-constructed nest in a firm tree crotch can last for two to ten years before it falls apart. We watched a great horned owl’s nest in a large aspen along Hwy. 182 for many years, but it has long since disappeared.

Celestial Events

            On 2/6, look for Venus 4 degrees south of the waning crescent moon.

            If you haven’t noticed, we’re receiving lots more daylight now. On 2/10, we’ll hit 10 hours of daylight, and on 2/17, 10½ hours. Recall that on winter solstice, we were down to 8 hours and 39 minutes.

            Pre-dawn in February gives us an opportunity to view a rare parade of five planets, at least until mid-February. Look for brilliant Venus low in the southeast, Mercury even lower (and to the left of Venus) in the southeast, Saturn in the south-southeast, Mars in the south, and Jupiter in the southwest. On 2/13, look in the early morning for Mercury and Venus to be within 4 degrees of one another, the closest they will be all month.

            How can you measure degree distances in the night sky? Hold one of your arms straight out in front of you with your index finger, middle finger, and ring finger extended – this equals about 5 degrees. Your little finger held up alone is about 1 degree, while your fist held up is about 10 degrees.

Photography Contest at Northwoods Wildlife Center

            The Northwoods Wildlife Center is sponsoring its annual amateur photography contest. Entries must be received by 2/12, so get a move on! For more information, see www.northwoodswildlifecenter.org