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He doesn’t look it, but this male from Townline Lake, just outside of Rhinelander, is at least twenty-seven years old. He is among a dwindling few males from among those we banded in the mid 90s. This bird was banded in 1994, at which point he was certainly at least five years old, which means that he was hatched in 1989 or before. Thus, twenty-seven is a minimum estimate for his age.

The age of “Silver over Red, Orange over Green” (as I call him affectionately) is not his only remarkable attribute. What sets this individual apart from most others is his ability to hold onto his territory year after year while fledging healthy chicks. (Below, he relaxes near his mate and two strapping chicks from 2016.) A successful common loon is not only good at locating safe nest sites and defending and feeding young. A breeder that wishes to

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reproduce successfully must confront intruders that land in the territory without warning throughout the breeding period.

Intrusions are especially frequent during the chick-rearing period. A common scenario plays out as follows. Early in the morning, a male is diving for food, while his two chicks track his progress from the surface. Each time he surfaces, the chicks rush over to him, snatch food from his grasp, and nibble relentlessly at his bill, neck and chest, signaling their unquenchable appetites. On one occasion, he surfaces holding a small yellow perch, only to find five adult loons in flight above his lake. He drops the fish, gives a short barking call, and the chicks dive and head to the nearest shore. The male too dives but surfaces near the middle of the lake, drawing the now-descending intruders to himself. Three quarters of an hour later he has driven off the intruders, thanks in part to a lunge and point yodel that caused his five visitors to scatter and tremolo. Shortly afterwards his mate returns, and both parents forage for the chicks. The family suffers no further disruptions until the evening, when another group of three nonbreeders circle and land, causing yet another brief skirmish.

Considering that a large pool of territorial intruders are constantly sizing up the resident male or female of any successful territory for an eviction attempt, it seems remarkable that residents are able to hold on to their territories for even a single year. Yet Silver over Red, Orange over Green has put together a string of 23 years of straight ownership, the only blemishes a half-year in 1996 and another in 2003, when he was briefly deposed. He has fledged 20 chicks during his breeding career with four different mates. This male is not the only resident with an impressive resume. A female on nearby Langley has fledged 17 chicks on that territory since 1995, while the O’Day female has been on territory since at least 1997 and has produced at least 16 full-grown chicks during her breeding career.

But female loons are survivors. Females enjoy a high rate of survival and no detectable senescence well into their twenties. Males, on the other hand, hit the wall abruptly at age 20; almost half of all territorial males of age 20 will perish before the subsequent year. So when we see a male who defies the odds, like this one, it is worth looking closely to see if he possesses an attribute that sets him apart. As a scientist, I am loathe to draw conclusions based on a sample of one. Colleagues in my field would dismiss any such conclusions out of hand. But today Nelson, one of my Chapman research students this year, reported that Silver over Red, Orange over Green is the tamest bird we have ever measured in the study area. So let me invite ridicule by advancing a very preliminary hypothesis. Perhaps the key to lifetime productivity in a habitat rife with human recreation is picking one’s battles carefully. Maybe by ignoring the inquisitive, well-meaning primates in their watercraft, this male has been able to conserve his metabolic resources for provisioning young and driving off pesky intruders.

The goose population has been increasing in northern Wisconsin. Ten years ago, a Canada Goose was an infrequent sight on one of our study lakes. Geese were confined chiefly to a few large lakes and seen overhead only as they migrated northwards. But no more. Now we encounter adult geese and often pairs with goslings on about half of our study lakes.

Apparently the increased availability of waste grain from agriculture, the proliferation of lawns, and increased temperatures have fueled the explosion in goose numbers, which has the potential to impact loon reproductive success. You see, geese and loons both prefer nesting sites safe from mammalian egg predators like raccoons and foxes. Such sites are often on islands and are limited in number. If a small island offers the only available safe nesting on a lake, goose and loon pairs are both likely gravitate to it.

The problem is not merely that loons must now compete with geese for nesting sites; geese actually get “first dibs”. While both loons and geese incubate their clutches for about four weeks, geese initiate their clutches two weeks or so in advance of loons. (The earlier onset of goose nesting is evident right now in our study area, as many goose pairs are rearing their broods of two to six goslings, while the earliest loon nests will not hatch for another week or ten days.) On occasion geese and loons nest within a few meters of each other on islands — as we observed on Oneida Lake a few years ago. Coexistence between the species is possible. But the presence of a sitting goose appears to discourage loons from nesting nearby, which often forces loon pairs to select sub-optimal sites for incubation.

Consider the plight of the Clear Lake loon pair. The safest, most desirable nest location on Clear Lake is a small shrubby island off of the public boat landing. Loons have shown a strong preference to nest on this island during most years. This year, the geese got their first, and the loons had to settle for a new nesting location on a long peninsula about two kilometers south. They may hatch chicks off of this peninsula, but the site is not offshore, like the shrubby island, so it is clearly vulnerable to mammalian egg predators.

I am optimistic that this spunky loon pair will be able to pull off a hatch. As can be seen from our shaky video, the male (on the right in the video) is still working on improving the surrounding nesting area, and the pair has a well-constructed nest with two eggs (visible to the left of the female, after the camera pans left). Still, this well-constructed nest will not protect them from a scavenging raccoon that ambles by.

 

 

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I have been back in California for some months now, my research in Wisconsin a distant memory. A stroll to the end of the pier at Newport Beach changed that. Several of my study species — unbanded animals that probably belong to breeding populations from Alaska, British Columbia, or Alberta — were foraging contentedly off the pier’s end, as fishermen cast their lines all about them. The fishermen appeared to avoid casting near loons, so I was not alarmed by what I saw. Loons are usually adept at avoiding fishing lines (though not always). Furthermore, an ecologist would not be surprised to see loons sharing a fishing hole with anglers, since they are competitors for the same small fish — mostly smelt and mackerel.

Common loons were not the only species diving and pursuing small fishes among the sea lions and occasional pod of common dolphins. It was a treat to find this juvenile red-throated loon out in the waves as well.

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Back home in Irvine I am crunching data, as I do habitually in the off-season. I feel some urgency at the moment, as I am about a week away from having to give a talk on my findings at the Winter Animal Behavior Conference in Colorado.  I will be more positive in a week or so, but I have already confirmed senescence in two different respects. First territorial common loons older than 20 abruptly begin to show much higher year-to-year mortality (roughly 20% annual mortality from 20 on; only 6% mortality up to 20 years). Second, territory holders 20 and older also stand a much greater chance of losing their territory through eviction (again a 20% rate of loss) than do those younger than 20 (12% rate of loss). In the coming days I will explore whether the sexes differ in these respects and whether old territory holders make any behavioral adjustments to this apparent decline in health and fighting ability.

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It is human to overgeneralize based on the chance co-occurrence of rare events.  As a scientist, I know this. I spend a good deal of my research time sorting through quantitative patterns in data, fending off the tendency to infer a meaningful biological pattern where only chance trends are present.

And yet, the events at Alva Lake last night shocked me. The Toussaints, dear friends who live on the lake and kept me alive during my first year of loon research in 1993, had informed me before my team attempted capture of the breeding pair and their month-old chick that the male had been holding his leg strangely, as if injured. My crew had reported no abnormal behavior of the pair; indeed, I had seen only normal territorial and parental behavior when I had scouted the lake for capture at noon. Still, the Toussaints are careful observers of loons, so their statement gave me concern. I told them as we cast off from the dock that we would try harder than usual to catch the male, just in case.

Capture was swift and uneventful. Both pair members sat protectively on the lake’s surface as we approached slowly and scooped them into our net. After catching the chick as well, we headed back to the dock feeling good about ourselves. Not until we inspected the female’s legs on shore did we detect anything amiss. As the photo shows, the female’s left leg was encircled tightly just above the foot by Dacron fishing line (used commonly in Wisconsin for muskie fishing), and a 5cm-long thick snarl dragged behind. The line had become tight enough to bite into the leg and cause a painful wound. Taking great care not to worsen the wound, we cut through the super-strong line and removed it. Fortunately, the entanglement appears to be recent, the wound superficial. The female should recover fully within a week.

Surrounded by three generations of Toussaints and still jittery from seeing the female’s leg, we were ill-prepared for the sight of another, more severe injury on the male. In this case, monofilament line had become wrapped around the leg just below the ankle joint. Again the line was constricted tightly around the leg, but this entanglement had occurred many months ago and the skin and keratinized scales of the loon’s legs had overgrown and surrounded the monofilament strands, leaving the circle of line protruding to the outside via two holes in the skin, like an earring. Though absorbed and surrounded by leg tissue, the line had caused local inflammation, as revealed by the irregular swelling in the adjacent portion of the leg. After an emergency consult with Mark Naniot of Wild Instincts, we resolved to pull out the line if we could do so without doing further harm to the bird. Fortunately, once cut, the line slid easily out of the holes, revealing infection but an injury from which the bird should recover.

Shaken as I am by seeing back to back angling-related wounds, I chalk up the discovery of two such similar injuries within a mated pair mostly to chance. That is, there is no reason to suppose a sudden, devastating impact of fishing line on the health of common loons. After all, we have captured dozens of other loons this summer that showed no ill effects from having lived in waters plied constantly by all manner of fishing lines, lures, baits, bobbers, and sinkers and riddled with tangles of line left behind by grouchy anglers. All but a few loons we have seen have thrived for many years in Wisconsin waters, despite this piscatory onslaught.

So what can we learn from the events of last night on Alva Lake? Two lessons, I think. First, loons are tough. Designed for maximum strength and minimum thickness, fishing lines bite deeply into animal tissue when forced against it. The Alva pair, no doubt, experienced severe discomfort and some loss of circulation. Yet they completed two months of incubation, chick-rearing, and territorial defense and stand to survive their brushes with fishing line without permanent damage. Second, angling exacts a steady toll on loons and other wildlife. Loon populations are stable or perhaps even increasing slightly in northern Wisconsin. It is becoming obvious, though, that sustaining loon populations in areas where anglers are more abundant every year will require concerted efforts of those who love loons.

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Two days ago, Mark Naniot of Wild Instincts got a report that a loon on Two Sisters Lake had been hooked by a fisherman in the leg and was trailing 50 feet of monofilament line and a bobber. Mark learned also that a well-intentioned kayaker had approached the loon and cut much of the line, including the bobber, but leaving the hook and several yards of fishing line trailing. Having captured and unhooked a loon several weeks before on the same lake, we were disappointed to hear of another angling incident. Could the same bird have become entangled again?

Seth happened to be collecting data on Two Sisters Lake yesterday. He found the impacted loon, which was not the Two Sisters-West male that we had rescued in June but the female from Two Sisters-East. (The lake has east and west halves, each with a successful loon pair.) Seth reported that the female was using her right leg sparingly, trailing fishing line, and had tried but failed to take off and fly on several occasions. She was not with her mate and two young chicks. Clearly the bird was in trouble.

After digesting Mark and Seth’s reports, I turned my attention to the prospect of catching the impacted loon. I viewed the challenge with mixed feelings. On the one hand, this female, hatched on Crab Lake in Vilas County in 2004, was well-known to us as a rather tame individual, making capture more feasible. On the other hand, we had captured her four nights earlier, which raised the possibility that she would recall that event and be more difficult to approach a second time. The most crucial card we held was that the female had chicks to protect.

Several major research programs that focus on common loons in the northern U.S. and Canada rely, more than any other factor, on the ability to approach adult loons closely at night and net them when they have chicks. If researchers could not approach adults closely during this reproductive window, we would not be able to mark them and study their behavior, health or survival. We would therefore be unable to generate models to determine whether loon populations are increasing or decreasing. In short, loon research would grind to a halt without the presence of chicks to freeze adults on the surface and permit us to catch and mark them.

Last night’s adventure served as a vivid reminder of the value of chicks to adult capture. We began searching for the hooked female shortly after nine p.m. and located her quickly along the southwest corner of the lake’s eastern half. Her behavior was odd; she seemed to restrict her movements to one small portion of the lake and was not anywhere near her mate or two large chicks. She held her hooked leg out of the water when resting on the surface. Before full darkness, we spotlighted and approached her to attempt capture, but she repeatedly dove before we could get within a net’s reach. Although frustrating, this cheered us a bit, because it showed that she was still relatively healthy despite the hook. At the same time, we were vexed to see that a loon that was in dire need of human assistance and which we had scooped out of the water with ease four nights before was resisting capture. We made several more passes by the female, until it became clear that the distance at which she dove was increasing rather than decreasing. We had a loon in need of help, a huge staff from Wild Instincts on shore waiting to assist it, and no obvious means of catching the bird. The critical ingredient missing was her chicks, which were nowhere nearby and which, we felt, might have held her on the surface and permitted us to net her.

We shut down the motor and listened. As luck would have it, an adult loon tremoloed far to the northwest, near the small bay where the Two Sisters-East pair had nested. Eric drove us up to the northwest corner, where, after 20 minutes of searching, we located the male and two chicks. Freshly banded from four nights before, the male and two strapping youngsters were nonetheless easy to net and pull into the boat. We set out southwards, where we had left the recalcitrant female, and released all three birds there. After several minutes of silence, the just-released male finally wailed and an answering tremolo came from 400 yards southeast. Again, we were in a bind, because the female had clearly swum a good distance away, where she would not soon encounter the chicks that we had released in hopes of capturing her. So again we netted a chick — leaving one near the male — and motored southeast to where we had heard the female. Having glimpsed the female for an instant before she dove, we gently held the chick in the boat until it vocalized. The injured female was transformed: she immediately sat up in the water, alert, and wailed to call her chick to her. We released the chick, the two reunited, and the female remained alert and protective next to her chick as we slowly approached and netted her.

After all of our efforts, it was rewarding to learn that, while the hook had punched cleanly through the female’s leg a few centimeters above her colored leg bands (see photo, courtesy of Wild Instincts), the prognosis (according to Mark) was excellent for recovery.

Looking back, we spent three hours capturing a family of loons that we had just caught and banded four days earlier. The rescue was a major production, requiring us not merely to locate and capture her but to find and capture her family in a remote location on the lake and transport them to her vicinity in order to restore her parental instincts and permit us to approach and net the impacted loon. This effort threw a wrench in our capture schedule, necessitating that we rush to three more lakes to capture loons there and cancel plans to attempt capture at two more lakes. Still, our team effort with Wild Instincts left us glowing; we had rescued a loon in peril and given her a chance to return to her life as a plucky protector of two young offspring.

LMG_5401 Crystal Lake NestOn its face, the photo is comical. A loon sits on its egg on a swim raft, a meter from an American flag. A garish McMansion is visible on the opposite shore. Few photos of the common loon are more at odds with the image of the species as a symbol of the northern wilderness. Yet Linda Grenzer’s photo of the nest on Crystal Lake is a poignant portrait of the situation faced by most territorial pairs in north-central Wisconsin.

Many popular accounts describe common loon populations as holding on for dear life. To be sure, loons are threatened by shoreline development, which reduces nesting habitat. Recreational fishing and boating kills many adults and chicks prematurely each year. And methylmercury in the food chain, swollen by coal-based power production, likely impacts the loon population as well.

Against all odds, however, loons appear to be holding their own in northern Wisconsin. Despite consistent losses caused by collisions with boats and entanglement in fishing lines, populations have bounced back in recent decades. The surprising resilience of loons seems to result from two facts. First, loons prefer to nest on small islands and on boggy and marshy habitats that humans avoid. Thus, loon pairs continue to produce young on lakes that are virtually encircled by human dwellings. Second, as illustrated in the photo, loons tolerate — and rarely even benefit from — human alterations of aquatic habitats.

The pair on Crystal Lake, whose nest is pictured, were in a real bind. Crystal is a very pleasant lake, but it lacks islands — the nesting spots most favored by loons — and also features neither bog nor marsh. Previous nesting attempts by the male (reared on nearby Muskellunge Lake in 2006) and a parade of 3 or more different females since 2011 ended in abject failure, the eggs an annual donation to local raccoons. Although they crawl onto it with great difficulty and complete loss of dignity, the Crystal pair decided a few weeks ago to place their nest on a low-lying swim raft. The raft is high above lake level and not equipped with any sort of ramp to assist small chicks in re-mounting the raft once they have entered the water, so we are concerned that the chicks will not be able to return to the nest (to be kept warm by a parent in the first few days of life) once they have left it. Still, the likelihood of hatch is good, and Linda and her helpers placed nesting material on the raft to keep the eggs from rolling off. We are hopeful that the loons can cope with the problem of nest height just as they do with a host of other anthropogenic obstacles each day in northern Wisconsin.

I shall keep you informed. If the Crystal pair can hatch and rear their chick to adulthood, they will be a vivid example of the capacity of loons to adapt and thrive in an environment thoroughly dominated by another species.

We were horrified last spring, when one of our best-known territorial males — and a super tame bird to boot — became hopelessly entangled in fishing line. This male, the long-term resident on Jersey City Flowage (“JCF”) had swallowed two lead sinkers, and monofilament line was wrapped tightly about his bill, making it impossible for him to eat. In short, the JCF male was destined to perish quickly from lead poisoning and/or lack of food. However, the folks from REGI freed him and used new technology to pluck both lead sinkers from his gut. Although he lost much of his tongue because of the fishing line, we were heartened when Linda found him in July of last year gorging himself on bullheads near his old territory (see photo below). LMG_1395 Jersey Male n Bullhead

But recovery after a brush with death was just the beginning for this bird. In order to reclaim his previous position, the male needed to regain his strength, migrate successfully to his winter quarters, survive the winter, migrate back north, and then — most challenging of all — regain possession of his former territory, which had been quickly snapped up by another male after the injury. (The new male bred successfully last year and was banded by our team.) Yesterday, Linda confirmed that the old, war-torn JCF male has negotiated all of these hurdles and settled in a breeding pair back on his old territory (see Linda’s photo below). We presume that he is also with his old mate, but she is one of the few wily adults that has managed to elude us, despite several efforts at capture. So she is still unbanded. LMG_3377 JCF Male The resilience of the JCF male is important. He is only the third adult to have been severely injured by fishing tackle, lost his territory, and recovered to reclaim it. Three data points can never be a robust sample, but we also have many cases where entanglement occurred and adult loons did not recover. In fact, we have about 9 well-documented cases of death following entanglement, which, combined with the three success stories, yields an estimate of 25% likelihood of recovery. So while the story of the JCF male’s journey from disaster to full recovery lifts our spirits, it is hard to forget that this is the exception, not the rule.

Since the inception of the study, we have known that some adult loons permit a canoeist to approach to within 5 meters without alarm, while others become uneasy and dive at a distance of 30 meters or more. Over the past several years, we have worked hard to quantify such variability in “tameness”. Our efforts are motivated by the belief that — in a region well-known for human recreation — tameness must matter. That is, it seems inconceivable that loons’ survival rate and reproductive success are not impacted by the way they respond to humans.

At first blush, I would expect loons to have higher fitness (i.e. be able to survive and breed more successfully) if their tameness reflects the lake they inhabit. That is, loons that are very tame should fare well on lakes where humans are numerous and often approach loons closely. A skittish loon on a lake with abundant human traffic would spend a great deal of time and energy avoiding humans and might have to spend more time foraging to compensate for the extra energy expenditure. A skittish individual on a busy lake might even become distracted by humans and pay too little attention to eagles, which occasionally attack adult loons and often attack chicks. On the other hand, shyness towards humans should have no impact on fitness if it occurs in a loon that occupies a remote lake.

Tameness is surprisingly vexing to measure. While it is easy to see that loons vary in approachability by canoe, it is another matter to assign a number to the degree of approachability they show. One obstacle to measurement is simply that of measuring distances accurately across water. Another is the problem that we seek to know exactly at what approach distance a loon dives to avoid a canoe; once this critical distance has been reached, the loon has left only its wake on the lake’s surface for us to measure! After numerous trials, however, Seth Yund, a Chapman student, and I have found a technique that seems to work that requires use of a highly accurate laser rangefinder — and a lot of patience. In July we began to collect measurements on each banded loon in our study population, and this work will continue into the fall and in future years. (By the way, the technique requires paddling slowly in a canoe towards a resting loon until it dives, while taking constant measurements. Since the process must only be carried out once or twice per loon, it involves very mild disturbance. We have found that loons quickly resume normal behavior after we take a tameness measurement.)

It will be some months before we begin to see if our quantification of tameness is stable and consistent enough to constitute a useful behavioral measure. At that point, we can begin to test our preliminary hypothesis that a loon’s tameness should be correlated with amount of human usage on its lake. Since we have many parent-offspring pairs in the population and follow individuals throughout their lives, we can envision asking questions about the heritability of tameness and its constancy over time. We hope that tameness will become a rewarding topic of research for us. Perhaps our ability to quantify this behavioral characteristic will permit us to foresee negative impacts that increasing human-loon contact will have on our population and help recommend ways to minimize such impacts.

Good news has been scarce this year. Black flies snuffed out first nesting attempts by virtually all breeding pairs and will reduce chick production by about 40%, compared to last year. One of the few pairs to continue incubating in defiance of the flies hatched chicks, only to lose them to infanticide when a new young male evicted the male breeder. And one of our most consistent chick producers and well-loved birds, the 19 year-old male on Jersey City Flowage, barely survived severe entanglement in fishing line that caused him to lose 20% of his body weight.

A few days ago, we received a bit of good news. The Jersey City Flowage male, after surgery and rehab work done by the folks at REGI and release near his original territory, has not only shown the capacity to feed himself normally, but has re-paired with a female hatched on Fisher Lake in Vilas County in 2010. This May-December pair seems settled at the north end of Jersey City Flowage, according to Linda Grenzer. Now, whatever judgements we are tempted to make about the age disparity in this relationship, it is nice to see the old male get himself back in shape and ready to give life another try.