I have put off writing those words from some weeks now. The patterns in my data were clear; every measure of breeding success was pointing downwards. If you have been following the blog, you might recall that number of chicks per pair has fallen sharply since I began studying loons in 1993. Although I had not reported it yet, loss of chicks after hatching has also increased significantly since I began my work. That is, many pairs hatch two young but lose one or both of them nowadays. Furthermore, even chicks that survive to five weeks of age are now in poorer condition (as measured by body mass) than in 1998 or 2006 or 2013. In short, breeding pairs in northern Wisconsin now raise fewer and less robust chicks than they did 25 years ago.

It was a combination of scientific caution and denial that caused me to delay describing the implication of these trends — and others that I have detected more recently. As a scientist, I am used to finding one pattern, drawing a tentative conclusion based on that single finding, and then being proven wrong by the next finding. Having had an initial conclusion reversed many times during my career, I was unwilling to sound the alarm without a stronger, more consistent set of findings. But the data I now have are consistent and come from multiple independent analyses. Furthermore, the data are fundamentally simple. My conclusions are not derived from complex models based on measurements of invisible particles detected by finicky high-tech devices. We are just counting and weighing loons here!

Still, you might wonder why my earlier caution has turned so suddenly to alarm. Let me explain. I followed a simple line of reasoning. If loon pairs are producing fewer and weaker chicks, then fewer chicks must be able to migrate to the wintering ground. And if fewer juveniles make it to Florida, then fewer should survive long enough to return to northern Wisconsin (which happens at 2 to 4 years of age) and look for a breeding territory of their own. So, declining chick production should result in a reduced population of nonbreeders (or floaters) in our study area, which are young adults looking to settle on their first territory with a mate. Since we mark chicks and obsessively reobserve them as young adults, we can test the idea that lower chick production has resulted in fewer floaters. The results are stark. After one adjusts for number of observer-hours spent looking for floaters each year, a dramatic pattern

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emerges. The population of floaters has plummeted. Look at the scale of the graph carefully. This is not a small decline. Between 1998 and 2006 the number of floaters seen per observer hour fell from 0.020 to about 0.010. From 2006 to 2015, that number has fallen still further — to about 0.006. In other words, we have seen roughly 1/3 as many floaters from the 2015 year class (which are 4 years old now) as we saw from the 1998 year class. In terms of percentages, we reobserved about 45% of all chicks banded in 1998 and 1999 much later as adults; we see only about 14% of banded chicks as adults these days.

So what? Floaters are nonbreeders. They contribute no offspring to the population. Do they really matter? There are not even enough territories to hold them. They are surplus individuals, in a sense. You might view the presence of any floaters at all as a positive sign that the population is bursting at the seams. Yes….but floaters are also the future. That is, floaters are loons not yet old enough to claim territories but waiting to fill in for dead breeders (or evict them forcefully). Without floaters, a breeding population cannot sustain itself, because, inevitably, breeders die and must be replaced.

Even now that I have a set of strongly suggestive patterns, I cannot be absolutely certain that loons are in trouble in Wisconsin. Perhaps the steep decline in floater survival simply means that the weak floaters now die off long before settlement, leaving the strong ones to replace dead breeders. Perhaps something very odd is happening in the north-central part of the state (more intense human recreational activity?) that is not happening elsewhere. So, let’s keep fingers crossed that this is a fluke of some kind. But I am convinced that we are seeing a worrisome pattern that is unlikely to be confined to my study area.

What does the future look like, if the floater population truly is declining markedly, as I suggest? Despite the strength of the pattern, the short-term effects might be subtle, because loons are long-lived. Imagine that families in your town or city suddenly began to have only 1/2 or 1/3 as many children as in years past. When would you notice a marked change in the community? You might — if you were very sharp — notice fewer large families at local playgrounds. Sometime later, you might notice the closing of a school here or there. But decades would pass before you would discern a loss of occupied homes in your neighborhood (presuming that kids in your town grow up to inhabit local homes).

So it will be with loons. On some lakes, the death of a pair member — especially a male, because males are in short supply — will leave a vacancy that is not filled by a floater. Some lakes that always supported a breeding pair will lose that pair and instead only see loons that come and go to forage. Large lakes with six perennial breeding pairs will, over time, see some territories “wink out”, leaving only three or four. In a few decades perhaps, even those territories will vanish. If I am correct, and unless this long-term pattern in the survival of young loons reverses itself, loons will ultimately disappear altogether from northern Wisconsin.

The Audubon report put me on notice. Loons are not immune from climate change. While I have wondered at times whether their aquatic habitat might somehow buffer them from the warming of the Earth and increased moisture in the atmosphere, this was a false musing. Recent changes in temperature and precipitation have myriad and complex effects on lakes and their inhabitants. Loons will have to confront the changing conditions just like all other organisms must.

I wondered whether my long-term data on loons might show climate-induced changes. I am not a climate scientist — nor even a hard-core ecologist who might routinely measure fish populations, water temperatures, or lake chemistry. But we do weigh all loons that we capture and band. Perhaps masses of adult loons or chicks have fluctuated in response to the changing climate.

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My findings are quite striking. Chicks have decreased in mass consistently since my team began capturing and marking loons. This finding alone is worthy of concern, but it is not the only one. Breeding males (see below) too show a decline in mass during our study. Breeding females, on the other hand, show no steady loss in mass.

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What are we to make of these patterns? Are populations of small fish down in the past few decades such that chicks and their male parents struggle to put on or maintain body mass? Or are lakes changing in ways (e.g. clarity) that might make fish more difficult to catch? Whatever the cause of these decreases in mass, why are female loons not affected similarly? These questions must remain unanswered for the time being. In fact, these results are so new that I must run some more double-checks before I fully trust them. Even if they are real effects, as it appears, it is much too early to attribute them to global warming. My worrying self, though, fears that these significant declines in body condition might be the leading edge of a changing climate’s impacts on Wisconsin loons.

On its face, it seems absurd. Why would loons ever communicate with eagles? Apart from raccoons, bald eagles pose a greater threat to loons than any other species. Eagles are opportunistic feeders, always looking for an easy meal. And they are large and well-armed enough to seize almost anything edible they find. Nesting loons provide a tempting stationary target for eagle attack. We have had two eagle kills of nesting loons during our study. The eggs themselves are vulnerable to eagles, because they do not flee and provide a nourishing snack. Loon chicks, whose diving skills are more limited than adults’, also draw unwanted attention from eagles. According to our own observations and those of others on our study lakes, eagles are a major cause of mortality among loon chicks older than two weeks. No doubt this explains why chicks learn to track the movements of nearby eagles obsessively, like the three Bass Lake chicks in Linda Grenzer’s photo.

Why would loons, which seem to spend most of their waking hours scanning the skies for eagles, ever speak to them? Could it ever be profitable to speak to your arch enemy? According to a number of studies by behavioral ecologists, it could, providing the information you pass along to your enemy increases your likelihood of surviving.

Deer and antelope engage in a behavior termed stotting in the presence of predators. Stotting means jumping upwards (often while flashing the tail upwards) in a way that makes the animal more conspicuous to its predator. But data collection and analysis on the occurrence and timing of stotting by gazelles has shown that they chiefly practice this behavior when they spot the predator at a distance and can easily outrun it. This and subsequent research suggests that prey often signal to predators to inform them of the unprofitability of an attack. That is, a prey species is saying to its predator, “I see you and am faster than you; save us both a lot of time and energy by looking elsewhere for food.” In fact, honest signals between prey and predators are not uncommon in nature. Many animals have evolved bright warning coloration to signal to potential predators that they are poisonous or dangerous to the predator in some other way that makes attacking them a bad idea. Colorful prey are, in effect, doing predators a favor by informing them that they should not attack! (Again, though, the prey are acting in their own best interests, not the predator’s.)

Could the mournful sounding wail that we often hear from loons be a signal to eagles that they have been spotted and that an attack would be fruitless?  If so, wails should: 1) occur often when eagles are passing overhead, but only when they are at a safe distance, and 2) be emitted by loons regardless of the presence or absence of other loons (like mates and chicks). The second prediction is crucial; if loons give wails to eagles only in the presence of their mates and chicks, it would seem as though they are simply warning their family about the eagle and not talking to the eagle itself. Our data clearly show that the wail is a long-distance signal given by loons when eagles are overhead. And loons wail to eagles whether they are alone or with mates and offspring. So loons certainly look as though they are speaking to eagles with their wails.

Strange to think that telling your arch-enemy anything could ever be a good idea!

I will admit it: I am flabbergasted. When the Bass Lake pair hatched three chicks in the first week of July, I never gave them a chance. I suppose my pessimism was, in part, an attempt to protect myself from further disappointment. This year, as I have mentioned, has been a forgettable year in our study area. The dust has not yet settled completely, but 2019 will certainly go down as the worst year for chick productivity since I began the study in 1993. And we have had some dreadful breeding years!

The Bass Lake Miracle — hatching and rearing of three vigorous chicks on a tiny lake — is so far a welcome exception to the dreary pattern. As I noted in my previous post, however, the Bass Lake pair are fighting more than the negative tide of 2019. Lakes that you could throw a baseball across — well, lakes that Trevor Bauer could throw a baseball across — generally do not contain enough food to allow two chicks to reach fledging size, let alone three. Fawn Lake is a case in point. Slightly larger than Bass, Fawn hatched two chicks, which weighed 2.1 and 1.2 kilograms at capture ten days ago. So the smaller chick is just over half the weight of its sibling, and its survival prospects appear grim. Moreover, Evelyn reported that the beta chick was begging fruitlessly for feedings from the male today, while its fat and sassy sibling rested nearby. Such is the normal state of affairs for families that try to raise more than one chick on small lakes.

But don’t tell all of this to the over-sized Bass Lake family. As Linda’s recent photo shows, the trio of chicks there are beating the odds so far. During my visit to the lake today, the three-week-old chicks swam along in a tight group, tracking their foraging parents and getting fed constantly. The food items brought up by the parents were not tiny minnows and leeches, such as one often sees on smaller, food-stressed lakes, but crappies and yellow perch large enough that the chicks had to work a bit to swallow them. There was no desperate begging, no pecking of the small chick by its larger siblings. Most important, the size disparity among the chicks, quite evident a week ago, is less so now, which suggests that all chicks are receiving ample feedings.

I retain some healthy pessimism about the loon family on Bass. I have seen too many starved chicks on small lakes to feel otherwise. But if a pair of loons can adopt a mallard duckling, raise the duckling on fish they catch and feed to it, and teach it to dive as they do, I suppose anything is possible.

We are feeling snakebit this year on the Loon Project. Late July in most years is a time of celebration — a time when we winnow the list of covered lakes to those with one or two chicks and stop visiting those that have failed to produce young. In most years, this narrowing process gives the entire team an emotional boost. Instead of surveying pairs that have lost two nesting attempts, have had a pair member evicted, or — worst of all — are sitting for the seventh week on a clutch of eggs that we know to be infertile, we focus on the positive.

Dropping failed pairs from our circuits gives us a pleasantly warped view of loon breeding success.  We smile while watching chicks ride on parents’ backs. We chuckle at the determined efforts of youngsters to dive like their parents, and at parents’ concerned peering underwater as they monitor those efforts. And we marvel at the rapid and well-choreographed diving responses of entire families to flying intruders, which no doubt succeed at hiding chicks from intruders and thus protect the territorial ownership of both pair members.

This year has been different. Owing to a late ice-out, a lengthy period of black fly abundance — and perhaps other factors we have not yet detected — 2019 has been a dismal year for loon breeding in northern Wisconsin. When I asked Elaina a few days ago to help assign each field observer to a circuit of lakes, this fact became undeniable. She scoffed. “We have just been to these lakes!”, she replied. She was right. Whereas an observer would normally visit each lake with chicks every three to four days, we are now visiting chick lakes about every other day. The reason is simple; only about a quarter of our lakes have produced young in 2019; last year, it was over half. I have begun to view the few pairs with chicks as the chosen ones.

The loon team is searching for a silver lining, but it is difficult. The list of failed lakes is a “Who’s Who” of traditional chick-producers. Blue Lake yielded only one chick in 2019 despite the efforts of two highly successful pairs. East and West Horsehead both failed to raise young. Neither pair on Two Sisters Lake reared a chick; one has to go back to 2010 to see the last time that happened. And on and on.

Elaina, back for her second year on the study, feels the blow harder than most. Last night, as we drove between our first and second capture lakes of the year, she and Tarryn grasped at a silver lining. “At least we will not have to carry the motorboat in at Buck and Greenbass”, they agreed. (The carry-in for canoes at both lakes is lengthy; to carry in a motorboat for capture, as we do most years, looks like masochism.)

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It is not all gallows humor and rueful comments this year. Linda Grenzer’s two striking photos show one of the few bright spots. In an apparent effort to compensate for the poor productivity of other lakes, the Bass Lake pair hatched not two, but three chicks! Two chicks is already a crowd for loon parents; Gabby Jukkala’s paper showed that male loons yodel three times as often while defending two-chick broods than with singleton chicks. Imagine the stress faced by the Bass Lake parents! But since Tarryn texted me excitedly almost two weeks ago to announce the spectacle, the parents have tended their over-sized family assiduously. Despite obvious size disparities between alpha, beta, and gamma chicks, all three are staying together and receiving regular feedings. Linda’s hilarious “loon pyramid” photo suggests that there are even brief moments of reluctant alloparenting.

I will be honest; I am on pins and needles. Bass Lake is a 40-acre lake. Only once in eighteen years of hatches — way back in 1995 — has the Bass Lake pair even fledged two chicks. Never has any pair in our study area raised three chicks to fledging age. (Washburn Lake did hatch three in 1997; they fledged only one.) So my scientist’s sense tells me that the gamma chick is doomed, and the beta chick’s survival is highly uncertain. But I am trying to stay upbeat about the family of five on Bass. I need something to cling to this year.

 

 

 

The loon pair and mallard duckling remain a close-knit family, if a non-traditional one. This fact became clear on Linda’s recent visit to Long Lake, as the pair remained fiercely protective of their charge (as her photo shows), and the male permitted it to preen while standing on his back. But Linda’s observations also suggested that the duckling is not helping its foster parents’ in their efforts to safeguard their territory ownership.

Let me provide some context. During July and August, loons that do not have territories  look hard for them. Why? Well, because (with apologies to Jane Austen), “….it is a truth universally acknowledged that a single loon in good physical condition, must be in want of a territory.” Indeed, single loons search ceaselessly, and at times desperately, for territories and mates. They do not search blindly but instead heed a signal. The presence of chicks with a breeding loon pair is a shining beacon to unpaired loons that announces, “This is a good breeding territory; remember this lake, return to it next year, and claim it for your own!”

In order to counter the prying eyes and evil intentions of such nonbreeders, loon pairs play hide-and-seek with their chicks. This is not the kind of light-hearted hide-and-seek that we humans play with our offspring. Instead, loon pairs with chicks play a high‑stakes hide-and-seek game to keep nonbreeding loons from spotting their young.  And if pairs (or their young) play the game poorly, they place their future territory ownership at risk.

Hiding of loon chicks by parents often seems a difficult task. Loon chicks are chocolate brown in color and can hide near shore among rocks and logs — if they wish to do so. Nonbreeders, for their part, do not call ahead to warn of their visits. Instead, nonbreeders appear suddenly over a lake, flying at 70 miles an hour, and scan the lake’s surface for loon chicks. Often they land in the lake as well. Under these circumstances, it is a daunting task to keep chicks out of sight. Yet, if pairs with chicks are fortunate enough to spot flying intruders early and to be in a part of a lake from which their chicks can easily swim to shore, they sometimes hide their chicks successfully by means of an odd “dive and scatter” strategy.

Hiding of a fostered duckling from snooping intruders has turned out to be an even greater challenge, Linda reports. While keeping a fostered duckling well fed is easy, preventing intruders from spotting the duckling is comically difficult. Picture the scene from a few days ago. An intruder suddenly appeared overhead, emerging out of the early morning fog while the loon pair and duckling were resting. Both adults immediately dove and swam underwater towards the center of the lake to engage the intruder. Instead of diving itself and racing underwater to hide near shore, as a loon chick would have, the duckling freaked. When it spotted its foster parents far away and next to nonbreeders that had landed, the duckling raced towards middle of the lake, while peeping loudly, making itself very obvious. Needless to say, efforts by the loon parents to hide their youngster were at an end.

I know what you are thinking — the loon pair lost nothing from the conspicuous behavior of the duckling. The intruder might have been confused by the duckling’s presence, but it probably would not have confused the duckling with a loon chick, taken it as a sign of breeding success, and planned to challenge the pair for territory ownership next year. That is probably true, unless, of course, nonbreeders cue in not only on loon chicks themselves but also on protective and aggressive behavior exhibited by loon parents. Let’s hope the duckling’s misbehavior had no long-term impacts. It would be a shame if the loon pair suffered doubly — by rearing a youngster of the wrong species and losing their territory the following year.

You might think that the month-old Long Lake duckling would have been satisfied with its lot. Facing certain death after it became separated from its mother and siblings four weeks ago, this youngster somehow crossed paths with a loon pair that was grieving for its own lost chick. Though they look somewhat alike on the water, loons and mallards are not closely related among birds. Loons’ closest relatives are penguins and pelicans; ducks’ are chickens and grouse. But dire need trumped phylogeny, in this case, and the loon pair and duckling became a family. The loons are attentive parents, as Linda Grenzer’s photo shows.

The difference in diet between loons and mallards proved no obstacle; the duckling greedily consumed fish captured and offered to it by its adopted parents. As I mentioned in an earlier post, Elaina and Linda also found that the duckling foraged on its own, taking invertebrates and possibly also plant material from the shore and passing vegetation, as a normal mallard duckling would.

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Recently, though, the duckling has shown itself to be a far more versatile forager than any normal mallard. You see, it also dives. Linda verified this behavior with numerous video recordings. The duckling, moreover, does not dive for an instant and then pop immediately back up to the surface. It submerges itself for several seconds, reaching the bottom of the lake — which is more than a meter away — and returns to the surface. (Linda’s photo captured one of these plunges, just as the duckling’s tail was about to disappear beneath the water.) We know that the duckling dives deeply, because it sometimes grabs a prey item from the bottom, brings it up to the surface, and consumes the item next to its foster parents. While Linda watched, for example, the duckling captured and ate a snail.

To appreciate the shock I felt upon learning of the novel diving behavior of this mallard, one needs to understand a bit of duck taxonomy. Mallards are “dabbling ducks”, so named because their aquatic foraging consists of upending themselves — dunking their heads in the water and sticking their tails straight up in the air — while picking up small animal prey and plant matter from shorelines. They never become fully submerged, like loons do. As dabblers, mallards are allied with gadwall and teal, which feed similarly, and differ starkly from other group of ducks, like scaup and bufflehead, which are “diving ducks”. So by mimicking the diving behavior shown by its foster parents, this little duckling is thumbing his bill at a well-known scheme of avian taxonomy.

I would give a lot to get inside the duckling’s head and learn how and why it began to dive. Was it pure learning picked up from the loon pair, which dive constantly and might have served as role models? Or did the youngster attempt to dabble, find itself in water too deep for dabbling, and simply “extend” its dabbling efforts to reach the lake bottom, where food awaited? Either way, the duckling has shown incredible flexibility in acquiring food.

I never wanted to fall in love with this duckling. I thought that Daffy and Donald had ruined ducks for me forever. But this little guy’s plucky adaptability might just turn me around.

 

This is a frantic time of year for wildlife and wildlife rehabbers. Why? Because while you are ditching Weird Aunt Beatrice at your family reunion, loon pairs and their chicks must dodge your crazy nephew Lucas on his Jetski. Needless to say, loons have considerably more on the line.

The tranquility of May did not prepare the Tomahawk-Kemp pair — or me — for the life and death struggle they would face in July. On May 11th I ran across the super tame male and female from Tomahawk-Kemp when they were preparing to nest in the long channel between Minocqua and Tomahawk. On that visit, they seemed almost to welcome my presence, and it was a simple matter to scribble down all of their colored leg bands as they rested and made short dives near my canoe. I experienced one of those moments when you are alone with nature and feel a sudden, ineffable connection with a wild animal. I wondered: “Does the male remember me from 17 years ago, when I first encountered him as a settler on South Two Lake?”

The Tomahawk-Kemp pair’s recent experiences with humans have been considerably less pleasant than those in May. We do not know the whole story, but on about June 17th, the pair hatched two chicks. (Judith Bloom, whose June 20th photo appears above, helped us narrow the dates with her routine checks.) Having survived black flies, raccoons, eagles, and curious humans to hatch both eggs, the Kemp pair headed out into the main body of Tomahawk to locate small fish suitable for their ravenous youngsters. There they began the daunting task of diving to catch food for the chicks, while at the same time helping the tiny fuzzballs steer clear of boat traffic. Most boaters adhere to local ordinances with respect to speed, distance from shore, and respect for wildlife; some do not. We suspect that a boater in the latter category ran down – either purposely or not – the Kemp hatchlings on the 1st or 2nd of July. The parents were unscathed; adult loons can dive rapidly and deeply, and those living on Lake Tomahawk have ample experience avoiding motorboats. Young chicks, however, have neither the diving capacity nor the familiarity with speeding watercraft to help them escape collisions.

Both chicks were hit by the boat. Linda Grenzer snapped the photo below of the less severely injured chick; it showed a healed wound towards the tail end, near the base of the left leg.

LMG 26251 Lake Tomahawk Kemp Injured Chick

The second chick looked better externally but had internal damage from the boat strike — a ruptured air sac — which prevented it from floating upright in the water. (Bird’s air sacs are thin membranes that connect to the lungs and are part of the respiratory system.)  So Linda, Elaina, and Kevin decided to catch this listing chick and take it to REGI for treatment. Fortunately, REGI repaired the damage, fed the chick well, and prepared it for successful release three days later. As you can see from Linda’s photos at the release, both pair members quickly accepted their missing youngster.

LMG 26337 Lake Tomahawk Kemp Rehab Chick Release

On the other hand, its sibling had apparently enjoyed being an only and had mixed feelings about the reunion!

LMG 26278 Lake Tomahawk Kemp Rehab Chick Release

According to recent reports, all is now well with all four members of the Kemp family. Life will continue to be a wild ride, because boat traffic will not wane for several more weeks, and the siblings will no doubt bicker over food from time to time. Since chicks rapidly improve their diving skills, though, we can hope that these two have had their last close encounter with fast-moving watercraft.

 

 

At first glance, a mallard duckling raised by loons would seem to be in a pickle. When your parents dive and you do not, you spend many anxious moments waiting on the surface. Furthermore, when you instinctively prefer to spend time in the shallows, and your folks prefer open water, you must tolerate their habitat preference as best you can, while nervously peering under water a bit more than usual.

These minor sources of stress seem tolerable for the Long Lake loon-duckling. As it turns out, there are benefits to having two parents assiduously stuffing food into you instead of one parent merely leading you to foraging areas.

You see, when we first observed that a loon pair had adopted a duckling, we were unsure how the duckling might be getting food. We could see that the duckling was healthy and strong — that it continued to grow and thrive. How, we wondered, was a dabbling duck that evolved to pluck and consume small, squishy invertebrates from the shallows surviving with two parents determined to feed it long, rigid, scaly items captured from the deep?

As we can see from Elaina’s stunning photos, the duckling’s solution has been to accept the proffered scaly items — though only small ones that do not pose a swallowing hazard — and to supplement this steady vertebrate diet with bits of animal and plant material gathered on the fly. To look at the bird, this duel feeding mode provides a favorable balance. The adoptee has matured rapidly from a tiny fuzzball into a strapping individual fast approaching adult (duck) size.

While it is physically healthy, the duckling’s mental state is less clear. This bird is a living, breathing test of nature vs. nurture. If the duckling behaves as genes dictate, it will soon join others of its species in huge foraging groups that congregate on lakes at this time of year. But it is thoroughly imprinted on its loon parents, not on mallards. If it has lived too long as a loon chick, it might attempt to associate with that species. Even in this worst case scenario, all is not lost, I think. Full grown mallards, even those that evince inappropriate affection for loons, know that they must bolt when a loon comes stalking them.