A Northwoods Almanac for 2/1 – 2/14, 2019 

Why Extreme Cold Is Good

            January came in like a lamb, but certainly went out like a lion. While our recent spate of very cold temperatures is painful on our bodies, our car batteries, and our heating bills, these temperatures are nothing out of the ordinary for our area, and more importantly, are actually a very good thing. 

Yes, I said very good. Have I lost my mind? Well, that’s long been debatable, but, yes, cold is good! Why? Because extreme cold has the potential to beat back some of the invasive insects that are threatening northern tree and plant species.

For instance: The hemlock woolly adelgid (pronounced a-DEL-jid), a native of Asia, is only 1/32 inch long – perhaps the size of a period in one of these sentences – but has created an Armageddon for Eastern hemlocks. The adelgids feed on the sap at the base of hemlock needles, disrupting the nutrient flow and causing the needles to fall off. Without needles, the tree starves to death, usually within three to five years of the initial attack. White, woolly masses, which resemble tiny cotton balls at the bases of hemlock needles, indicate an infested tree.    

         

Without any native predators to keep it in check, this tiny aphid-like insect spreads at an average rate of 15 to 20 miles per year, blown by winds, carried by birds and other wildlife, and transported by infested nursery stock. As of 2018, it had killed or caused extensive declines in millions of hemlocks in eighteen states from Georgia to Maine, and has edged its way west into Ohio. This tiny, aphid-like insect now threatens more than 150 million hemlock trees in Michigan forests, and will eventually work its way into Wisconsin. 

But here’s the key. These insects are unique because they feed throughout the winter. If temperatures get cold enough, a high proportion of the insects can be killed. Adelgids use a process called supercooling, equivalent to antifreeze in a radiator, to survive the winter. But their antifreeze begins to fail at -5°F, and then they start to die. 

Researchers say that only the most northern stands of hemlock and those at the higher elevations in its northern distribution may ultimately escape the adelgids. That’s northern Wisconsin, but our hemlocks will only survive if we maintain extremes of cold.

Likewise, emerald ash borer (EAB), an Asian insect first identified in 2002, has become the most destructive forest insect to ever invade the U.S. As of 2018, populations of emerald ash borer have been found in 31 states, along with Ontario and Quebec, and the insect continues its march westward. Across Wisconsin, 48 counties are now under quarantine. 

            The best deterrent to EAB currently is severe cold. The larvae can supercool, but they die if they freeze. A 2010 study in Minnesota showed that 5% of the insects die at 0°F, 34% at -10°F, 79% at -20°F, and 98% at -30°F. That’s great news, but the larvae spend the winter under the bark of trees where they may be insulated by the bark itself – temperatures under the bark can be 2 to 7°F warmer than the air temperature. However, prolonged cold well below zero minimizes the insulating effect of bark.

Many other insect species have expanded their range northward in recent years. In the Pinelands in southern New Jersey, state foresters are battling the southern pine beetle. The beetle can tunnel through a tree’s bark, eating a layer of tissue that supplies the tree with critical nutrients – it’s killed millions of acres of pines in southern forests. Until recently, the beetles, which are native to the southern United States, did not survive north of Delaware, because of the cold. But that has changed as winters have turned milder. Efforts are underway to quell a large outbreak in Long Island's pine barrens and monitoring traps have caught beetles as far north as New England. The insect could reach Nova Scotia by 2020 and eventually infect forests from the upper Midwest to Maine.

There are a host of other ecological reasons to celebrate extreme cold temperatures, but the bottom line is that these cold temperatures are what make the North the North. Please understand that I, along with nearly all you, don’t enjoy this level of cold – I like it warmer, too! On these below zero days, we all spend inordinate amounts of time close to our wood stoves. But the North Country needs these extremes of cold. Be grateful, however much shivering you may be doing. The extreme cold typically only lasts a few weeks, but it can make all the difference.

Groundhog Day

Speaking of cold and how organisms deal with cold, groundhogs, or as we know them – woodchucks – are currently in deep hibernation. Waking up a woodchuck in the Northwoods on Groundhog Day would be a very slow process. Their body temperature drops to as low as 35 degrees, their heart rate falls to 4 to10 beats per minute, and their breathing rate falls to one breath every six minutes. These critters are knocked out for the duration of winter in northern Wisconsin, so while some may be awake looking for their shadow in Pennsylvania, there won’t be any wandering around here. 

2018 Deer Harvest Preliminary Numbers

Bow hunters registered 86,805 deer. Gun hunters (nine-day gun, muzzleloader, youth, December antlerless and Holiday Hunt) registered 239,296. Total: 326,101.

Ruffed Grouse and Fast Food

Grouse seldom dilly-dally over their meals – researchers say 20 minutes of foraging on buds will sustain them all day. They eat quickly, store the consumed food in their crop – a wide portion of their esophagus –  and digest it later at their leisure, under cover and away from danger. Grouse have a multi-chambered stomach and with the aid of both gravel to grind-up the buds and microorganisms to break down the cellulose, they enjoy their meal slowly, but not at the original table.

Sightings – Saw-whet and Barred Owl Eating Voles, Ice-up, Lack of Birds

            Debbie and Randy Augustinak in Land O’Lakes sent me this note on 1/16: “We’ve been fishing quite often lately and decided to place a trail cam on the leftovers . . .  The voles have been dining on the fish at night, and the owls have been dining on the voles!” They attached several videos from the trail cam showing a bald eagle eating the fish, and then a barred owl and a saw-whet owl eating the voles. 

I’m particularly pleased to see the video of the saw-whet because it’s always unclear if saw-whets remain the winter up here. Bird banding stations like the one at Whitefish Point Bird Observatory near Paradise, Michigan, record significant numbers of saw-whet’s migrating south. This October they banded 58 saw-whets. At the Thunder Cape Bird Observatory near Thunder Bay Ontario, they regularly band over 300 saw-whets migrating through every fall.

            Some saw-whets, however, winter-over in our area. We hear the males singing almost every spring, but they don’t sing in the winter, and they’re so small and secretive that they are virtually impossible to see. So, how many remain over the winter, and why some do and some don’t is very unclear. 

The Manitowish River below our house completely froze on January 10^th, the latest freeze-up we’ve seen in our 34 years of record keeping here, though our records are incomplete. Average ice-up date is late November.

            Two vehicles went through lake ice in the Mercer area over the last two weeks, demonstrating that temperatures below zero don’t guarantee ice is always safe, particularly where a river current runs through a lake.

            Even with our very cold temperatures in late January, our bird feeders remain very quiet. Usually that’s THE time for birds to appear at feeders – periods of extreme cold. But not this winter. Three pine siskins and four goldfinches showed up briefly at our feeders, but have moved on. 

            Interestingly, this is a pattern throughout much of the state as evidenced by postings on the Wisconsin BirdNet decrying how few backyard birds are being seen. Bev Engstrom, however, did find some bohemian waxwings and pine grosbeaks in the Rhinelander area and sent some exceptional pictures of them. And Greg Bassett in the Hazelhurst area sent along a photo of a pileated and a red-headed woodpecker at his feeder.

bohemian waxwing photo by Bev Engstrom

Celestial Events

            For February planet watching, look after dusk for Mars high in the southwest. Before dawn, look for brilliant Venus low in the southeast, Jupiter in the south-southeast, and Saturn also in the southeast.

            On 2/2, look for Saturn just below the waning crescent moon. February 3 marks the mid-season point between winter solstice and spring equinox. The new moon occurs on 2/4. By 2/7, we’ll be receiving 10 hours of daylight, well up from the 8 hours and 39 minutes we were given on winter solstice.

Thought for the Week

“The human race is challenged more than ever before to demonstrate our mastery not over nature but of ourselves.” – Rachel Carson, written in 1962 and still apropos today.