A Northwoods Almanac for April 14 – 27, 2017
Over 30,000 adult loons reside in the U.S., half of which nest in MN, WI and MI. Wisconsin alone has an estimated summer population of about 4,000 adults. Of those, the Lakeland region is home to the second largest loon population in the Midwest, and they’re returning now. Up to ice-out, “our” loon pairs content themselves with overflights of their territories to look for open water. In the meantime, they wait (mostly along the Wisconsin River) the lakes to open-up, though a lake may be only partially open and the loons will still land.
Since 1991, researchers have banded over 3,600 adult loons and chicks in northern Wisconsin, providing a wealth of information on when loons leave for their autumn migration, where their migratory routes take them, where they spend their winters, and much, much more. A far smaller number have had satellite radio transmitters surgically implanted in them, allowing biologists to track their daily movements.
This extensive banding and observation of marked loons has shown that over-wintering adult survivorship is high and more than half of chicks born here return to the area as adults. Loons first return to their breeding grounds at age 2 to 4 years of age, with males tending to return nearer to their natal (birthplace) territory than females.
Both sexes tend to wander as “floaters” and use many different lakes for 2 to 3 years before either founding or acquiring a territory. Males and females both show a striking age-dependent pattern in the means they use to gain a territory: when 4-5 years old, they usually try to settle in a vacant territory with a mate and thus create a new territory. But finding a vacant territory these days is quite uncommon unless the adult pair on a lake fail to return from their winter on the Gulf.
Thus, nearly all desirable territories are already spoken for, and most younger loons have no choice but to acquire their territories by force. If the loons have not created a new territory by 6 to 8 years of age, they usually attempt to seize a territory from an established owner after a violent territorial battle. Among males, about one-third of these battles result in the death of the displaced male owner. Displaced females are more likely to leave the battle before being killed, but then typically will still need to fight to acquire a new territory. These territorial evictions are about equally frequent in males and females.
During these battles, the response of the other member of the breeding pair is stand aside. Walter Piper, who has studied loons in our area for 25 years, has observed many of these battles and has learned that females, which are about 20% smaller than males, can’t help their mate avoid eviction – they’re too small to make a difference in the battle. Their size, though, ensures they are protected. Piper notes, however, that males might be expected to help their female mate drive off a would-be usurper, yet Piper and his crew have never observed a male teaming up with his mate to drive off a potential usurper. Why not help out? Well, while loons are monogamous, they are married more to their territory than their mate. As Piper notes, “Perhaps males are better off with a mate that fights strongly (such as a proven usurper), since having a vigorous mate ensures future years of eviction-free breeding. It is a bit sad and selfish to say it, but if your mate is vulnerable to eviction, it is probably best to let her fend for herself than to intercede and save her.” Obviously, the same would also hold true for females not jumping in to help their male counterparts.
Peepers, Wood Frogs, and Chorus Frogs Singing
It’s frog time, and as soon as we have warm nights in the high 30s and the ground thaws, spring peepers, wood frogs, and chorus frogs will emerge from their woodland hibernation and begin their breeding clamor. Fishless temporary wetlands (called vernal pools or ephemeral wetlands) are ideal for breeding – the water warms quickly and the frogs can lay their eggs in relative safety from predators.
Spring peepers inflate their throat pouch to nearly the size of their body and use it to push air over their vocal cords, making a sound when they both inhale and exhale. Each call rises in a crescendo until collectively there is total tumult in the pond. The frogs engage in duets, trios, quartets, what one naturalist describes as “nature’s choir fortissimo.”
Peepers can be heard from as far as a mile to two away depending on the number of peepers in the chorus. And when you hear them, you can bank on spring being here, at least “spring” as defined very loosely in the Northwoods.
Mating Strategies – Don’t These Birds Have Any Morals?
For birds, mating isn’t about sex, it’s about leaving behind a maximum number of offspring and contributing to the gene pool. So, morals don’t play into the equation. However, most bird species mate monogamously, which would appear to meet the family values test of humans. In fact, monogamy occurs in more than 90 percent of avian species. Sounds good on the surface! The problem is biologists have discovered from blood tests that chicks are often of mixed parentage, and that most species of songbirds participate in “extra-pair copulations (EPCs).” Paired males commonly copulate with other females, but females also initiate EPCs by flying into another male’s territory. So, there’s lots of hanky-panky going on, but under the appearance of a monogamous relationship. Think of various soap operas – “Days of Our Lives,” “Dallas,” etc.
Polygamy, where a male or female pairs with two or more members of the opposite sex, occurs where birds can monopolize a desirable habitat, or one gender can monopolize a group of the opposite sex. When a male mates with two or more females, it’s called polygyny. Pheasants fit this bill, the male attracting a harem of females to his desirable territory, protecting and fertilizing them, but playing no part in rearing the young. Of North America’s 278 breeding songbirds, only 14 are polygnous - marsh wrens, red-winged blackbirds, indigo buntings, and lark buntings are other examples.
In only a few cases, females pair with more than one male, a practice called polyandry. Spotted sandpipers, phalaropes, and acorn woodpeckers are examples. A spotted sandpiper female is larger and more aggressive than a male. She mates with one male, lays a clutch of eggs, leaves him to incubate and rear them, and then pairs with other males, repeating the process again and again. Because she mates with multiple males, the incubating males often raise chicks that belong to their competitors. Thankfully, birds don’t have custody battles and alimony – think of the legal fees.
Then there are birds that are classified simply as promiscuous. In very good habitat, the female only needs the male for his sperm, so she chooses from a host of males happy to display themselves in the same area. For example, prairie chickens and sharp-tailed grouse mate on leks, which are tiny territories where the males gather, dance and call madly, and often fight, all in hopes they will be selected by a very discerning female. Think wild bar scene. She walks among them, considering, considering, then briefly has a fling, and off she goes to build her nest and carry out all the nesting duties, while the males continue their dancing on the lek. Older males hold territories near the center of the lek, leaving younger males to patrol the periphery and continually challenge the older males for a spot in the choice middle.
Different strokes for different folks - it’s all about taking advantage of habitat conditions and individual reproductive strengths with the goal of advancing the species.
3/28: Robins began their pre-dawn chorusing in Manitowish. Callie and I heard two pairs of sandhill cranes dueting in Powell Marsh.
3/29: FOY (first-of-year) Juncos and tree sparrows arrived in Manitowish.
3/30: FOY fox sparrows and rusty blackbirds returned to our backyard in Manitowish. We also spotted our FOY common and hooded mergansers on the Manitowish River.
3/31: Sarah Krembs heard the FOY American woodcock near her home in Manitowish Waters.
Today, 4/14, we’re now enjoying 13.5 hours of daylight.
On 4/16 and 4/17, look before dawn for Saturn near the waning gibbous moon.
According to Woody Hagge’s 41 years of data, 4/16 also marks the average ice-out date for Foster Lake in Hazelhurst. At 39 acres and a maximum depth of 38 feet, Foster Lake represents a relatively “average” lake in our area. In general, however, larger, deeper lakes will keep their ice longer, while smaller, shallower lakes will lose their ice earlier. Foster Lake now averages 141 days, or 20 weeks, of ice cover.
Around 4/21, the average low temperature for the Lakeland area will hit 32°. Minocqua thus averages 182 days with low temperatures above freezing.
The peak Lyrid meteor shower occurs in the predawn on 4/22 and averages 10 to 20 meteors per hours.
Finally, before dawn on 4/23, look for Venus near the waning crescent moon.
|our daughters, Eowyn and Callie, within the redwoods|
Mary, Callie, and I flew out last week and joined our oldest daughter Eowyn for a visit to the Jedidiah Smith Redwood State Forest near the Oregon border. More on this in a later column, but this trip has likely broken the record for the number of times “WOW” has been said in any given hour. One of the old-growth redwood groves in the park totals 5,000 acres, and includes the world’s largest, though not tallest, coast redwood (Sequoia sempervirens), measuring 20 feet in diameter and 340 feet tall. These are the largest living trees on Earth along with their brethren the sequoias (Sequoia giganteium).
|note the single trillium within the mosses|
John Steinbeck wrote in Travels with Charley, “The redwoods, once seen, leave a mark or create a vision that stays with you always. No one has ever successfully painted or photographed a redwood tree. The feeling they produce is not transferable. From them comes silence and awe. It's not only their unbelievable stature, nor the color which seems to shift and vary under your eyes, no, they are not like any trees we know, they are ambassadors from another time.”
Thought for the Week
“Fueled . . . by a million wings of fire the rocket tore a tunnel through the sky and everybody cheered. Fueled . . . only by a thought from God, the seedling urged its way through the thickness of black and, as it pierced the heavy ceiling of soil and launched itself up into outer space . . . no one even clapped” – Marcie Hans. Let’s remember to clap.
Please share your outdoor sightings and thoughts: call 715-476-2828, e-mail at firstname.lastname@example.org, snail-mail at 4245N Hwy. 47, Mercer, WI, or see my blog at www.manitowishriver.blogspot.com