A Northwoods Almanac for April 28, 2023

 A Northwoods Almanac for April 28 to May 11, 2023   

Midwest Sandhill Crane Count 

            The annual Midwest sandhill crane count took place on Saturday, April 15, the last day of our week of other-worldly hot, sunny days before we got another foot of snow. Mary and I have paddled a section of the Manitowish River for three decades counting cranes every April, and this had to be the warmest, calmest morning of any crane count we’ve ever experienced – 42° and no wind. Heaven.

            We were on the river by 5:50 a.m. with good friend and ace photographer, Bob Kovar, and from the get-go, we heard a pair of sandhills doing their unison call. If you’ve not heard the unison call, the carrying power and synchronicity of the male and female is remarkable. The male calls first, and instantaneously (in 0.2 seconds), the female follows. The male crane flips his head nearly straight up and produces a single call. The female crane responds by raising her head at a 45 degree angle and emitting 2 to 3 shorter, higher pitched calls. This call reinforces the pair bond, helps to defend a territory, and serves to avoid conflict among other territorial adults. The calls are so loud that they can be heard up to 2.5 miles away.

Mary watching a bald eagle, photo by Bob Kovar

            I must admit, however, that we’re never just out there to count cranes, though that is the initial motivating force. We’re out there to experience the first paddle of the spring while the river is in flood, the waterfowl that have just returned, the beaver and otter and muskrats that are active, and the first crazy songbirds that are either passing through or are here to stay.

            The Manitowish loves to meander, but the annual spring flood allowed us to just paddle across the oxbows, conserving time and energy. But we really didn’t need to conserve either of those, because the current in the floodwater pushed us right along, allowing me to paddle with ease while Bob shot photos in the bow of the canoe.

            Highlights included perhaps a dozen trumpeter swans along the way, nearly all of which gave us close fly-bys; many beavers, a number of which were concealed and startled us by whacking their tails as we cruised by; good numbers of waterfowl, with buffleheads, surprisingly, being the most common of the lot; and an array of early songbirds, the most exciting of which was our first winter wren of the year.

 

Flooding

            The Manitowish remains in very high flood as of this writing (4/21). Thank goodness for our floodplains spreading out and absorbing so much of this water! 

Manitowish River in flood below our house

            I don’t wish to diminish anyone’s personal loss due to floods – catastrophic floods are just that, catastrophic – but we often have a knee-jerk reaction to annual natural floods as disasters, when it’s essential to remember that floods have always existed and actually provide ecological benefits. The difference today is that floods often do more damage than they did historically, and we often have brought the damage on ourselves. When we build on floodplains, drain wetlands, channelize waterways, farm up to the edges of rivers, build dams and determine that one side benefits at the expense of the other, and pave thousands of acres of land with asphalt, the ensuing result is that we see more floods and experience greater destruction.

            What occurs to a river during a flood? A healthy river will usually absorb all but the most catastrophic floods. The riparian plant life holds the shoreline soil in place with its network of roots, while the leaves of shoreline shrubs and trees further protect the groundlayer from the pounding and erosive forces of heavy rainfall. 

            Sometimes a flood scrubs an area clean of vegetation, but most vegetation has adapted to regenerate quickly. For instance, silver maples and willows actually depend on floods, flowering and going to seed immediately in the spring, so the seeds are ready to drop on exposed riverbanks when the floodwaters recede. 

            Floods cleanse older organic materials like dead plants from the floodplain into the river, and replace them with newer materials. The floodwater also scours the long strings of filamentous algae, as well as other plants, off the riverbed. Afterward, plant populations often explode due to the nutrient-rich organic debris fueling a growth spurt all the way up the food chain.  

            Floods transport wood and rock debris that eventually drops out of the river’s flow and provides new structure within the river. Since different fish need different habitat structure for spawning, feeding, and resting, floods are actually key events in shaping and maintaining high-quality fish habitat. Recent studies on rivers have concluded that on average a river needs to “mobilize” (i.e. flood) its channel bed every other year in order to provide ideal spawning habitat. 

            During floods, rivers cut new channels, resculpt older ones, and clean silt out of spawning gravels. Floodplains work simultaneously to soak up the high water and then release it slowly, keeping the river flowing in drier months.  

            Rivers, and the life within them, survive through resilience. A healthy river is self-sustaining and self-healing. Destruction of one life leads to new life in a dynamic ebb, flow, and flood. 

            The Manitowish River where we live floods nearly every spring after snowmelt. The difference is that no one has built on the floodplains. Still, someday we may get a 100-year deluge rain, and the river will rise and flood us. But for now, we gaze on the overbank flows with curiosity, wondering where the ducks and swans are, rather than wondering if we will survive the flood.

 

Winter Severity Index to Date

            Since 1975, the Winter Severity Index (WSI) has been used across Wisconsin to predict the impact of winter on deer herds. WSl is calculated by adding the number of days with a snow depth of at least 18 inches (1 point for each day) to the number of days when the minimum temperatures were 0°F or below (1 point for each day). Days when both conditions occur are scored as 2. These points accumulate throughout the winter from December 1 to April 30. 

            A WSI of 49 or less is considered mild, 50-79 is moderate, 80-99 is severe, and 100 or greater is very severe. Many WSI snow depth readings are taken by WDNR staff biologists and additional snow depth and temperature readings come from National Weather Service stations across the state.

            As of March 31, four counties have exceeded 100 points – Douglas (117), Iron (113), Bayfield (110), and Washburn (108) (see the map). And we still have April to count, which should add more points for snow depth. Note how quickly the points decline as one goes south – Iron County, for instance, has nearly three times as many points as Oneida County. 

            What I find intriguing about this year’s index is that almost all of those points have come from snow depth exceeding 18” in the northernmost counties, and not from temperatures below 0°. We’ve had a very mild winter temperature-wise, but we’ve had a severe winter in terms of snow depth.

            There’s lots of wiggle room in WSI’s very general equation. My question is how do the impacts differ between a high score based predominately on cold winter temperatures compared to a high score based predominately on high snow levels? And how does one take into account the difference between nights that are -5° compared to those that are -35°, both of which score the same 1 point? Extreme cold temperatures require far more energy expenditure for animals to stay warm. Likewise, how does one account for the difference between 20” of snow compared to 40” of snow, the deeper snow requiring far greater effort to wade through?

            I’ll be very interested to see both the deer survival rates and the reproductive rates when our spring finally arrives. 

 

Sightings – Sparrows! Juncos! Evening Grosbeaks! Blackbirds! Oh My!

            Our remarkably warm weather during the week of April 9 to 14 brought in a lot of migrating birds. But that gorgeous weather was immediately followed by a week of snow and sleet and cold rain, which concentrated all those birds at area feeders in a frenzied attempt to survive. We had a small army of dark-eyed juncos, American goldfinches, evening grosbeaks, red-winged blackbirds, common grackles, and black-capped chickadees, among many other species, covering our decks and areas below our feeders. And the sparrows! American tree sparrows, white-throated sparrows, fox sparrows, and chipping sparrows all arrived in large numbers, as did Brewer’s and rusty blackbirds. And that’s not to mention the ever-present red squirrels. All we could do was pour out more and more sunflower seeds and hope the weather would change soon.

            Some first-of-the-years (FYI):

4/7: FYI saw-whet owl calling in Manitowish

4/8: Purple finches returned in large numbers, and FYI brown-headed cowbird 

4/9: FYI northern flicker

4/10: FYI American woodcock

4/11: FYI mourning cloak and Compton tortoiseshell butterflies

4/12: FY ospreys, and FYI dragonflies (species unknown)

4/13: FYI belted kingfisher

4/14: FYI turkey vultures, Wilson’s snipe, ring-necked ducks, greater yellowlegs

4/15: FYI blue-winged teal, winter wren, bufflehead, coot, yellow-bellied sapsucker, horned larks (large flock!), rusty and Brewer’s blackbirds.

rusty blackbird photo by Bev Engstrom

4/16: FYI ruby-crowned kinglet, and 11 white pelicans at Powell Marsh WMA

4/17: FYI chipping sparrows

 

Global Temperatures

            March 2023 will go down in the books as tying for the second warmest March on record. Temperatures globally were several degrees above average in most places.

            March represents the 529th month in a row with temperatures exceeding the 20th-century average. That’s more than 44 years straight without a single comparatively cool month.

            In the United States, March was a mixed bag. The western U.S. experienced temperatures several degrees below average, whereas considerable warmth was present most of the month over the East. Boston, for example, was 2.5 degrees above average while San Francisco was 3.3 degrees below normal.

            Worldwide, March came on the heels of the fourth warmest February on record. 

            In mid-March, average ocean water temperatures surpassed 70 degrees for the first time on record.          

            Since preindustrial times, Earth has warmed 1.9 degrees F.

 

Celestial Events

            For planet-watching in May, look after dusk for brilliant Venus and Mars both high in the southwest. Before dawn, look for Jupiter low in the east-northeast and Saturn in the southeast.

            The full moon (the “Flower” or “Planting” moon) occurs on May 5.

            The peak Eta Aquarid meteor shower is best seen in the predawn of May 6, but bright moonlight will obscure most of the event.

 

Thought for the Week

            One gram of moss from the forest floor, a piece about the size of a muffin, would harbor 150,000 protozoa, 132,000 tardigrades, 3,000 springtails, 800 rotifers, 500 nematodes, 400 mites, and 200 fly larvae. These numbers tell us something about the astounding quantity of life in a handful of moss. – Robin Wall Kimmerer