A Northwoods Almanac for June 17 – 30, 2011
Loon Aggression
Loon chicks hatch-out around June 15, so you may now be seeing the chicks, who initially are little more than tiny balls of down, riding on the backs of their parents. They take the taxi service for several weeks until they are able to thermoregulate, and then they’re on the water full-time with the adults.
This area of northern central Wisconsin is home to the best common loon research being done in the world. Over the last 15 years, researchers have banded more than 3,000 loons in four counties (Vilas, Oneida, Iron, and Forest), providing a bounty of data that has altered much of what was once accepted as “truth” regarding loons.
The largest myth to be shot down by the research was that loons mate for life. They don’t. Instead, they are “mated” to their territory. Thus, if a new male usurps the male from a long-standing pair on a particular lake, the female remains and mates with him. Likewise, if a new female runs off the female in a pair, the male remains and mates with her.
There are some intriguing differences, however, in how attached a male is to a territory compared to a female. For instance, when a young male returns as an adult to his natal area after two years on Atlantic Ocean or Gulf of Mexico saltwater, he’s faced with the problem of finding a vacant breeding territory, and must take one of three options: he can find a vacant lake and establish a new territory (29% do this), he can assume a territory vacated by a previous resident (26% choose this strategy), or he can aggressively try to take over a territory (45% employ this approach).
When he attempts to oust a resident male from a territory, he usually first flies over the lake and tremelos, whereupon the resident male tremelos back. The “flying tremolo” is considered an acoustic challenge, and it’s thought that if the resident male doesn’t tremolo back with sufficient vigor, the “prospecting” intruder will land and initiate a confrontation. The loons will swim in a circle, splash dive, rise up in a “penguin” posture, and in 26% of the encounters, the action then escalates into overt aggression involving chasing, grabbing the opponent by the bill and beating it with wingbeats, holding the other loon underwater to drown it, and even shooting up from underwater to spear the opponent in the heart with the bill. These male fights are fierce and end up fatal for one of the combatants nearly a third of the time.
On the other hand, when females are confronted by a female intruder, they contest their territories with lots of chasing and some wingbeating, but the loser departs rather than fights to her death. She lives to breed and raise young on another territory another day.
Interestingly, the “spouse” in all the battles simply watches passively, apparently never coming to the aid of his or her mate.
Why do males fight to the death for a territory and the females don’t? Perhaps for a variety of reasons: one, reproductive success goes up the longer a male is on a territory. The male always chooses the nesting site, not the female, based on their success or failure in raising chicks. Breeding success in the first year on a new territory is only 47% for a male, but rises to 66% over a three-year period, whereas, female breeding success appears stable whether on a new territory or not. So, perhaps the male has a great deal invested in a lake he’s been on for a few years.
Another thought is that loons can live to be 20 to 30 years old – perhaps it’s the old guys that are foremost in losing the battles and who might only have a year or two left of breeding potential, and therefore also would have little chance of taking over a new territory.
It may also be that because male loons are very aggressive defenders of their chicks, their aggressiveness spills over into territorial aggressiveness.
Curiously, if a male loon does lose his territory and then in a domino effect takes over another loon’s territory, he will change his yodel call. The yodel, the call most of us think of as the most maniacal, is given only by the male, and apparently only in response to a direct threat. Each male has his own clearly defined yodel, which differs from all other loon yodels in the area. But when a male changes his territory, he drops his characteristic yodel, and sings a new tune. This is very surprising given that most birds learn their songs when they’re young and their songs remain the same throughout their life.
What’s even more remarkable is that the male doesn’t just change his yodel randomly, he makes it as different as possible from that of the previous resident, indicating that the male had studied the resident male before taking over the lake. Is the male trying to proclaim that he’s the new kid on the block and wants everyone to know it by having such a different yodel? It’s unknown.
Yodel calls also increase in length as the aggressiveness of an encounter increases – the longer the yodel, the apparent greater willingness to attack. And the yodels have been found to be longer on territories with artificial nesting platforms, which are much more successful sites for raising chicks than natural sites along shorelines. Thus the best nesting sites apparently engender the most vocal defense.
The chicks have their own predators to defend themselves against. Nearly 20% of all chicks are lost every year to predators, from eagles to musky to snapping turtles. I’d hate to think about living in a world where my dangling feet in the water could be grabbed at any moment by a predator 50 times my size.
Do loons need counseling for all this stress?
Don’t know, but I’ll still enjoy watching the chicks getting their free rides and revel in the beauty of the adult’s calls, only now with a better ear for what these calls might mean.
Fields of Cottongrass
Cottongrass is in bloom in all the bogs, on occasion their tufted, cottony heads blooming so densely it appears as if snow has fallen. Some eight species of cottongrasses bloom from spring through fall, most forming tussocks – sod-like clumps – in the bogs. These cottongrass tussocks are reputed to survive for a century or more, making cottongrass an “old-growth” species, albeit herbaceous. Look for cottongrass among its many boggy associates which are also flowering: blueberry, bog-rosemary, bog-laurel, Labrador tea, pink lady’s slippers, and many more.
Action Temporarily Down at Bird Feeders
During the month of June it's normal to see a decrease in birdfeeder activity as the birds start families and as natural food sources become more available. Protein-rich insects are the order of the day for feeding chicks thus, during this period you don't have to keep your feeders filled all the time. By the end of the month, we should see increased activity at the feeders as the parents start bringing their fledglings in.
Canadian Tiger Swallowtails
The beautiful yellow and black tiger swallowtail butterflies have returned, and are likely congregated at a puddle near you. This “puddling” behavior, usually by the males, has been likened to the guys gathering at the local pub for two reasons: one, they use the moisture to replenish fluids lost during their emergence. And two, because when the males cluster together, it apparently makes it easier for the females to locate them for mating.
Larry Weber, an excellent naturalist and author in Duluth, says that his ten-year average date for seeing his first swallowtail is May 28. This spring they were certainly later than that in our area.
Turtles Laying Eggs
Painted and snapping turtles are in the midst of their egg-laying. This is parenting at its easiest, though there’s lots of danger merely crossing the roads to get to the sandy sites they prefer for laying their eggs. Large snappers will lay as many as 80 eggs, while smaller ones will produce from 25 to 40 eggs. Painted turtles are less prodigious, laying around ten eggs.
Since predators galore love these eggs, only 5 to 10% of the eggs will survive to hatch, and then only 1 to 3% of the hatchlings will live to become adult turtles. So, while the parenting may be effortless, the success rate is commensurately tiny.
Gray Fox
Bill and Margo Perkins sent me some superb photos of a gray fox and family living under their shed. The coloration on gray foxes is just beautiful – note the reddish brown that typically occurs across the throat, down the side of the neck, and down the legs.
Gray fox are appearing more regularly in northern Wisconsin perhaps due to gradual warming trends.
Whip-poor-wills
Mary Madsen on Twin Island Lake in Presque Isle sent me a note saying she was loudly serenaded for about l0 minutes at dusk on June 5th by a whip-poor-will.
Well, that same night my wife Mary and I conducted one of our three annual frog counts, and we heard at least five different whip-poor-wills at various locations. We have heard a whip-poor-will at Nichols Lake near Boulder Junction for at least a decade, and we weren’t disappointed again this year – it can easily be heard at dusk right at the parking lot for the swimming beach.
Another great site is along Bear Lake Road where a clear-cut took place several years ago. The area looks like hell, but there are whip-poor-wills and nighthawks galore in there. If you can survive the mosquitoes at dusk, it’s a unique sound experience listening to the nighthawks boom and the whip-poor-wills chanting incessantly.
Celestial Events
Summer solstice occurs on June 21, gracing us with 15 hours and 45 minutes of daylight. The down side, and I truly hate to mention it, is that the days start getting shorter on June 22. Seems like we’re just starting to get into summer, and suddenly the days aren’t as long.
On 6/26, look before dawn for Jupiter 5 degrees south of the waning crescent moon. On 6/28, look for Mars about 2 degrees south of the crescent moon.
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