Loons are always with me. With its fires, mudslides, and Mediterranean climate, southern California could hardly be more different from northern Wisconsin, but the loons winter here. I see them at Newport Pier, a bustling wharf that juts out into the Pacific and draws scads of Vietnamese anglers…..and me. The chattering fishermen are after pacific mackerel, which feed beneath the wharf in great whirling clouds. I am looking for pelagic birds that might fly by, like red-footed boobies, pomarine jaegers, and common murres. But I always see loons too. In fact, common, pacific, and red-throated loons all occur along the coast of southern California in good numbers.

My first sighting this morning was auspicious; I spotted a fast-flying parasitic jaeger as I reached the end of the pier. Small pods of common dolphins surfaced at intervals as they too pursued mackerel, exciting the gulls and pelicans near them. Great rafts of western and Clark’s grebes stretched out north and south of the pier. Experience told me that these circumstances were likely to produce a rare bird sighting.

As I completed my initial scan of the water adjacent to the pier, I saw a common loon with a buoy near it — at least, the odd dayglow-pink item near the loon registered as a buoy on my first glance at it through my spotting scope. (A photo taken with my phone through the scope appears above.) As I studied the loon and pink item further, I realized it was a bobber connected to one of the legs, because it followed along a foot behind and bobbed up and down rhythmically as the bird swam slowly along the surface. I groaned. Even in winter, apparently, loons face fishing entanglements.

My relaxing birding trip at an end, I watched the loon for an hour to learn how it was coping with the fishing gear. Fortunately, it swam southward during this period, which, bit by bit,  brought it closer to the pier. Despite the cheerful fishermen whose casts and puttering about blocked my view at intervals, the loon was simple to track. Early on, another common loon approached and preened within a few meters. The entangled loon remained alert but showed no other obvious response. Similarly, it ignored a smaller pacific loon that came near while diving. A second common loon came over and showed a hint of social behavior, such as we see in the breeding season. For a third time, the loon with the bobber made no response. The bird did not even react noticeably when a juvenile western gull flew over, settled beside it, and began to pick at the bobber. At all times, the entangled loon sat high in the water; it never dove, preened, or even gave a wing flap.

The lack of social interaction, disinclination to dive or exhibit other normal loon behaviors, and posture of the loon in the water speak volumes about its condition. These signs indicate that it has probably been dragging the unwanted bobber for some days and is severely impacted. Fortunately, bald eagles, the loons’ nemesis during summer, are rare in southern California, so the loon is not likely to succumb to predation. But its inability to dive means it has already begun to lose weight and become weak. It will surely starve if the bobber is not detached soon. I will visit the pier tomorrow to see if I can relocate the bird. If so, and if its status appears unchanged, I will see if I can put together a capture team. With great luck, we might free the doomed bird.

 

In the dream, I am swimming in a tiny lake – a lake so small that two residents on opposite ends of it could converse without raised voices. The lake is completely encircled by cottages. Docks overhang almost every inch of shoreline, looming menacingly over the water and rendering the lake smaller still. The lake, in fact, looks more like a pond hastily dredged by developers for a suburban apartment complex than a pristine aquatic habitat where loons might live. But in the dream a pair of loons swims about the lake with me, investigating future nest sites after having lost their first nest of the year to a predator.

I awoke yesterday with this dystopian scene vividly in mind. The dream reflects, I suppose, my growing unease over the future of loons along the southern fringe of the species’ breeding range. My concern is fueled by an ongoing analysis of the decline in chick survival since 1993.

That analysis has progressed since I first mentioned it. The investigation started as just a hunch — an uneasy feeling that singleton broods were becoming more common. Now, having looked at the data formally in a controlled analysis, I have brought the decrease in brood size more sharply into focus and verified that it is real. There has been a systematic, highly non-random decline in brood size over the past quarter century in Oneida County.

My worst fear took shape in the dream. I fear that growing recreational pressure, shoreline development, and perhaps environmental degradation have conspired to rob breeding pairs of a chick here, a chick there — to the point where the population might be affected. My recent analysis provided a hint about the cause: the decline is far greater on large lakes than small ones. Large lakes, of course, are those most affected by increased human recreation.

It is early still. I have much investigation yet to do, especially testing specific measures of human activity (like fishing or boating licenses issued in Oneida County) to see if they are tightly correlated with chick losses. But for a worrywart – and a vivid dreamer – these are unsettling times.

Last year I wrote a blog post in which I concluded that late-hatching chicks returned at a rate no different from early-hatching chicks. I found the result surprising, as one would expect early hatchlings to have a head start in learning to feed themselves, honing their flight skills, and preparing for their first migratory journey. The photo and story I got from Linda Grenzer a few days ago has forced me to wonder if I need to collect more data on this question.

The breeding pair on Squaw Lake had an eventful year in 2018. Delayed, like all other pairs, by the late thaw, they initially nested along the shoreline near the boat landing. After a predator snatched both eggs off of the nest, they nested again not far away. This time they were more fortunate; the eggs hatched, but not until about July 22. When we captured the family on August 3rd, we found the chicks almost comically small — two little puffballs that did not approach the size of the many other juveniles we had encountered. Chicks are cute in their first few weeks, and we enjoyed observing them and handling them cautiously while giving the female a new set of bands.

Our delight at seeing the adorable chicks was tempered by the fear that chicks hatched so late would not mature in time to complete the southward migration. The fear is justified; parents must balance the energetic demands of their demanding offspring against their own need to maintain good body condition and prep for their autumn journey. Inevitably, adult loons spend progressively less time on their home lake in September as they forage intensively, molt into drab winter plumage, build up fat levels, and, in late October or early November, head south. This goes for parents and non-parents alike.

So it was not surprising to get a report from Linda that the Squaw adults had left their breeding lake, leaving their late-hatched chicks to fend for themselves. What was alarming was that one chick had chased someone’s jig, managed to hook itself above the base of the bill, and was no longer diving or foraging normally. Further evidence of its desperate condition was that it was not difficult to capture and weighed a mere 1750 grams — roughly 1 kg less than it should have at 9 weeks. Following an X-ray at Raptor Education Group, Inc. in Antigo, the chick was found to have swallowed a second hook from a separate encounter with an angler.

Since we have long since ceased our routine visits to study lakes, we can only speculate about the series of events that put the chick in this bind. Marge Gibson of REGI suspects that, without parents to help it satisfy its foraging needs, the chick was struggling to feed itself. In its desperation, the chick began to attack fishing lures until the hook in its cheek and weakness conspired to incapacitate it.

If Marge is right, and late-hatched chicks are sometimes left with too little feeding capacity to maintain themselves, then this pattern should show up in our data. Specifically, we should see fewer very-late-hatched chicks return as adults to the study area. This plausible scenario will fuel another round of data analysis…when I find time!

To end on a positive note, the angling victim is bouncing back at REGI and feeding voraciously. If you do not believe me, look at this video from the REGI website.

https://www.facebook.com/RaptorEducationGroupInc/videos/470615703434171/

If it continues to thrive, the REGI folks will face another challenge: what to do with a healthy juvenile, but one whose stay in captivity and recovery made flight practice impossible.

 

In my last post, I told only half of the story of the explosion of the Cunard family — the cheerful half. If you read that post, you know that, following the eviction of the Cunard male and abuse or neglect of the chicks by the evicter, one chick made a daring 1/4-mile trek across land to Hasbrook Lake and is now happily ensconced in that loon family.

The other Cunard chick was not so fortunate. In fact, following interviews of campers and the camp steward, we now know that a day or so before the eviction that led to the desperate dash of one chick to Hasbrook, its sibling had swallowed the live bait and hook used by a camper. As he described it to me, the fisherman panicked and did what most do when they have hooked a loon: he cut the line. I discovered the aftermath of this hooking. The thoroughly consumed remains pictured above suggest that the injured chick became weak, took refuge on shore (as seriously injured loons do), and was attacked and killed by an opportunistic mammal or scavenged after death. Its four leg bands confirmed its identity; the threaded line and fishing snap I found confirmed the cause of death. So the eviction that occurred on July 30th and 31st was actually the second unfortunate turn for the Cunard pair during the last three days of July.

We have discovered several such hookings during our study, despite the fact that anglers do not trumpet them. Perhaps we should take a moment to describe what to do when a loon takes your hook. The best outcome is removal of the hook by the fisherman. Removal of the hook gives the loon a good chance to survive the encounter. Cutting the line, on the other hand, frees the angler but leaves the hooked loon with a death sentence. A hooked loon (or other animal) on the end of a cut fishing line has to contend with a hook or lure that it probably cannot dislodge on its own. Its feeding impaired or prevented altogether, a hooked bird will probably succumb to starvation or predation resulting from its weakened condition. The second best outcome is to cut the line and immediately inform a local wildlife official of what has happened so that he or she can get help for the bird. In many cases, a hooked bird can be captured and de-hooked by me or someone else trained to do so. In other words, if you cut, don’t cut and run. Those of us who study and love loons will do our best to save one that is in trouble.

The Cunard chick’s death is a case in point. Had we known about the hooking, we would have had little difficulty re-capturing the chick and likely removing the hook as well. In that case, Hasbrook Lake might have ended up with four chicks rather than settling for three!

If you have been following the goings-on at East and West Horsehead lakes, you know that the picture was bleak a few weeks ago. After Iceberg, the female on East Horsehead, was hooked on a fishing line on Memorial Day weekend, she ceased interacting with her mate, YellowBlue, and seemed headed for a rapid, unpleasant demise. Reacting to the loss of a viable mate, YellowBlue searched nearby territories for a new mate, and he gained one after evicting CopperGreen, the male on neighboring West Horsehead Lake. Meanwhile, CopperGreen, after losing his territory, appeared a shadow of his former self, and was reduced to skulking about on the fringe of his former territory to avoid raising the ire of YellowBlue. His mate, WhiteYellow, was left with eggs to incubate and no mate able to help her do so. Thus, the hooking not only threatened the life of an adult loon, it also also compromised the breeding effort of the neighboring pair.

What a difference a few days makes! After a final skirmish with YellowBlue at dusk on the 6th of June, CopperGreen flew off his territory for good to lick his wounds, giving up the fight for ownership of West Horsehead. Fortunately for him, many lakes in the north support no territorial loon pair and yet are full of fish. These lakes are natural soft landing spots for loons displaced from their breeding lakes. One such lake is Birch, where we spotted CopperGreen five days later. But he did not give up his territorial aspirations and settle for a life of ease. In fact, Al Schwoegler reports that CopperGreen has just settled with afflicted female Iceberg on East Horsehead, “across the street” from his former territory. While still bothered by the small jig embedded in her throat (!), Iceberg’s behavior is otherwise normal, and she now interacts extensively with her new mate. So it is possible that CopperGreen has bounced back from his eviction to claim a good territory with a recovering mate.

Meanwhile, back on West Horsehead, things got complicated for WhiteYellow, CopperGreen’s former mate. Having enjoyed an uninterrupted 23-year run as female owner of the West Horsehead territory, during which she produced a whopping 19 fledged chicks, WhiteYellow is a spectacularly productive individual. We cannot impugn her breeding prowess. But in the aftermath of her mate’s eviction, she elected to continue incubating the eggs they had produced. You cannot blame her for trying to hatch these eggs; according to our records, they were within a few days of hatching when her mate met his match. Her decision, however, was fateful. In effect, WhiteYellow was gambling that: 1) she could hatch the chicks as sole incubator and despite spotty incubation owing to black fly infestation, and 2) her new mate would accept and raise the chicks sired by his predecessor.

WhiteYellow has faced such difficult decisions before. Twelve years ago her mate was booted off of the territory late in incubation, yet the evicting male helped her complete incubation of the eggs and rear the chicks. Four years ago, WhiteYellow again completed incubation during a period of male territorial rancor, only to see an evicting male kill the newly-hatched chick. So she knows the ups and downs of continued breeding during territorial instability.

This time, I think, WhiteYellow has erred. Though she continues to incubate sporadically, the eggs are a now a full week overdue for hatching. And WhiteYellow’s hopeful incubation has prevented her from getting on with her life  — bonding reproductively with the evicting male, YellowBlue, so that the two of them might produce a new clutch of eggs and rear some late-hatching chicks.

Apart from the West Horsehead/East Horsehead saga, the news from our study area is mixed. Seventeen of 120 pairs survived the black fly onslaught and have hatched chicks from their first nesting attempt. Another 54 pairs are incubating eggs — nearly all from renesting attempts after abandoned first attempts. A few more pairs will yet try to nest. There is a chance that the newly-formed West and East Horsehead pairs could be among this last group. For the time being, though, they are just hoping for a return to normalcy.

I am still shaken by the recent spate of fishing entanglements. Perhaps my sadness and vexation over these troubling events prevented me from looking clearly ahead. I thought: “Well, the hooked female at East Horsehead will die slowly from the ingested lure, and that will be miserable, but another female will settle on the lake and replace her.” I gained some measure of relief from anticipating the orderly progression of events that would unfold on the lake. As expected, the afflicted female, “Iceberg”, has declined, although she is still not yet weak enough to catch. Her mate, “YellowBlue”, has not stuck to the script, however. Far from waiting passively for another female to settle with him, YellowBlue is proactively seeking a new territory. And that is the problem.

It should have been obvious to me when Nelson reported, last Wednesday, that he saw YellowBlue intrude onto nearby Alva Lake. Females leave their breeding lakes occasionally to intrude onto the neighboring territory; males do so rarely in the height of the breeding season. So YellowBlue’s intrusion was a sign that something was afoot. But I dismissed his visit as an anomaly — the distracted antics of a male whose mate was unwilling to initiate a nest. As it turned out, YellowBlue was probing neighboring lakes for a weak spot, a territory whose owner he could defeat in battle and whose territory he could seize. Based on the aggression and chasing that occurred when YellowBlue visited Alva, the Alva male was not on board with this plan.

But YellowBlue’s search continued. In the next few days, he found a vulnerable male on a different neighboring territory: West Horsehead. We were not present to observe the entire sequence of events, but Al Schwoegler reported yesterday that CopperGreen, the West Horsehead male, was skulking about and hunkering down at the northern end of the lake, far from the nest that he had built with his mate (a 28+ year-old female, “WhiteYellow”, who is among our oldest birds). A quick look at the middle of the lake explained CopperGreen’s diffidence. YellowBlue was foraging and resting there, acting like he owned the place. (Melanie confirmed that this state of affairs continued today.) Now loon behavior in many ways is unsubtle, and territorial behavior is a good example. When a loon is in the middle of a lake, acting like he owns it, he owns it! So YellowBlue had clearly battled CopperGreen, defeated him, and forced him to lay low along the lake’s periphery to escape further attacks. We have seen this sequence of events scores of times. If events proceed normally, WhiteYellow will ultimately cease her efforts to incubate the eggs alone, and the nest will be abandoned. Perhaps WhiteYellow and YellowBlue will renest again this year, but that is doubtful. (CopperGreen, if he is healthy enough, will fly to a nearby undefended lake, like Bearskin, where he can lick his wounds.)

What is troubling about this latest turn of events is the central role played by humans. That is, an angler — a careless or perhaps just an unlucky one — hooked Iceberg on East Horsehead and fled the scene. Iceberg immediately ceased breeding behavior and began a struggle to survive. This turnabout forced her mate, YellowBlue, to go with Plan B, leaving his lake to find another nearby with a healthy female on it. In leaving his own territory and evicting a male on West Horsehead that was sitting on eggs, YellowBlue likely doomed both East and West Horsehead to breeding failure in 2017. So a single fishing casualty affecting a single adult loon has precipitated the loss of breeding opportunities on two of our most productive lakes.

While we are concerned for the impacted loons, this latest eviction has some scientific value. YellowBlue is quite a phenomenon — the youngest male ever observed to evict an established male from his territory. Hatched on Little Bearskin Lake, YellowBlue is only four years old. Perhaps it was his good fortune that CopperGreen was himself only six years old (a product of Oneida Lake). So the YellowBlue-CopperGreen contest featured the youngest combatants ever. I hope that the novelty of this latest encounter takes away a bit of the sting from the event that set it in motion.

All is not lost among loons this year. In fact, one advantage I have, as someone who tracks breeding behavior on 120 lakes, is the capacity to shift my attention away from those where things have gone south to lakes that where all loons are healthy and productive. So let me end with a beautiful photo of Linda’s from Muskellunge Lake that will remind us that there are lakes where loons are free of hooks, where they defend their territories successfully, and where the next generation thrives.

LMG5508 Clune Yodeling Tight with Family2-2

 

To most people, Memorial Day weekend is both a sacred and joyous occasion. It is a time to remember those who have given their lives for our country. And it is a holiday that lets us gather around the barbecue with friends or enjoy an extra day of rest followed by a short work week. In the northwoods of Wisconsin, Memorial Day often brings a hint of summer’s warmth at a time when we are not quite free of the clutches of winter. Memorial Day convinces us that summer will return to the north.

Since 1993, when I first starting studying loons in northern Wisconsin, I have dreaded Memorial Day. On this holiday weekend, throngs of anglers bolt from their southerly homes for the northwoods to throw a hook in the water. Meanwhile, loon pairs that have managed to fight off black flies, eagles, and raccoons are well into the four-week incubation period. Memorial Day is the time when hopeful loon parents and hopeful human anglers collide.

I used to gird myself for the disturbance to nesting loons that humans caused each Memorial Day weekend. Fishermen and boaters commonly disregard or do not see loon nests and venture close to them, driving loons off of nests for a time. But such incursions now seem innocuous. They seldom cause great problems for loons, who sometimes complain but dutifully jump back on their nests after boats have moved off.

Now that we have better connections to the local community, I see that the substantial danger posed by humans to loons on big fishing weekends is not from flushing off of nests but from fishhooks and monofilament line. On Memorial Day weekend, the loon pictured in Linda’s photo, a female that reared a chick on Nokomis Lake in 2010, was hooked in or near its throat while it foraged on Nokomis. As ugly as it is to look at the silver hook buried in its throat and the local swelling that resulted, the Nokomis female might recover. She appears to be hooked externally, and Linda reports that she dives strongly.

A second female fell prey to an angler’s lure this Memorial Day. This bird, the mother of many recent chicks on East Horsehead Lake, apparently swallowed a lure or bait used by a fisherman. Initially Linda found that this female was severely impacted, often trying to jump onto the shoreline, as loons do when seriously injured. Nelson and I raced up to East Horsehead to help Linda and her husband, Kevin, try and capture this bird and transport her to a wildlife rehabber for treatment. But our efforts were in vain. The bird had bounced back and begun to dive normally, despite the fishing line protruding from its bill. Having ingested a lure, this bird’s long-term prospects are rather dim. She will certainly die if she swallowed a lead sinker.

These two cases illustrate a vexing paradox often faced by those of us trying to protect wildlife: animals commonly become injured in a way likely to kill them eventually but not so catastrophically that immediate capture is possible. So we must wait and monitor them until creeping hunger or infection reduces their mobility sufficiently for us to grab them and see to their injuries. These are most unpleasant and heart-wrenching vigils. Moreover, these occasions often end badly, if the animal becomes compromised beyond the point of recovery before it can be captured and treated. Still, knowing that a grave injury of this kind has occurred gives us a chance.

An encounter with fishing tackle ended quite badly for the East Horsehead male last year. Although it was not reported to us until a few days ago, last year’s East Horsehead male — the long-time mate of the female who swallowed a lure a week ago — became hopelessly ensnarled in monofilament line last August. Based on our records, we surmise that he succumbed to this entanglement sometime after August 10th, as we observed the female alone caring for the chicks on our two visits after that date. (Since the chicks were 11 weeks old by late August, they likely survived to migrate south. That, at least, is a relief!)

We were disappointed to hear only now about the unpleasant entanglement and death of the East Horsehead male. Unlike the two females, this male was probably immediately compromised enough by the fishing line that we could have captured him and cut him loose in good condition and with no harm to his survival prospects. Indeed, we were able to save a female on Perch Lake from a similar predicament in 2010. Since the East Horsehead male’s plight was never communicated to us, he had no chance.

So, now, a plea. Please let folks know that angling casualties happen. We are anglers ourselves and understand this. But anglers who cut the line and flee the scene after accidentally hooking a loon — or observe a loon in distress and fail to report it — are turning a dangerous situation into a catastrophic one. As so often occurs, it is the cover-up, not the crime, that causes real damage. (I am happy to take reports of loons in distress at wpiper@chapman.edu.) Let’s try and have summer holidays in the northwoods bring to mind the events they were meant to commemorate, not the toll they exact on loons.

 

 

2016-07-31 01.32.29

Loon capture is a blur. We set out from our house at 8:45 pm, launch our small motorboat on the first lake, wait for nearly complete darkness, and catch any loon chicks and parents that we can net easily. By the time we have repeated the process four more times, we are rubbing our eyes, our weariness justified somehow by the presence of the sun lurking just below the horizon.

As an essentially negative person, what I often recall after a night of capture and banding are the physical demands of the process and my complete exhaustion. But there are dimensions of the work that are exciting and rewarding. Each loon is unique, and one never knows whether an individual will permit itself to be approached closely and netted or will be wary and elude us. So we experience many disappointments, but they are tempered by the occasional thrill of capturing an individual that, at first glance, appeared too skittish to catch.

The fruits of loon capture are obvious. By marking individuals and resighting them year after year, we learn about survival rates of adults and juveniles, territory fidelity, natal dispersal, and habitat preference. We glean a good deal of important information from these data. For example, survival rates of young and adults allow us to learn whether the  local population is increasing, decreasing, or remaining stable. And tracking of young loons from egg to first territory has revealed that loons develop strong preferences for breeding lakes that closely resemble their natal lake. Finally, capture is essential as a means to disentangle loons that have been run afoul of angler’s lines or lures.

This year’s capture exposed another distinctive pattern in loon ecology: the presence of ecological traps. An ecological trap is a breeding habitat that appears at first glance to be a good one but ends up being poor for reproduction. For example, a field might experience a burst of insect activity during early spring, enticing songbirds to settle there for breeding, but a crash in insect levels after eggs hatch might occur that suppresses the number of young birds produced. Two nights ago, we captured two chicks from two different lakes back to back. The first territory was a shallow 11-hectare portion of Wind Pudding Lake (my favorite lake name). The chick captured there was a five-week-old that weighed a scant 0.92 kg — less than half what we would expect from a chick of that age. Our daytime observations show that the chick’s parents are no slouches; they respond to its constant begging by making frequent dives and retrieving what food they can to feed it. Moreover, the chick itself dives often to forage. But this shallow lake, covered almost entirely by lily pads (which impair loon foraging), offers scant sustenance. I am afraid that the emaciated Wind Pudding chick will ultimately starve to death, as did the chick on nearby Liege Lake, another shallow lake choked by vegetation. Loon parents on small, acidic lakes struggle to rear even a single chick, whereas those on large lakes of neutral pH often raise two. This stark contrast was highlighted for us, as the lake we visited following Wind Pudding was 1373-hectare Lake Tomahawk. To be sure, loon parents on Tomahawk must steer their chicks through countless jet skis, water-skiers, anglers, and speed boats at all times of day. But vigilant parents are rewarded with abundant food for themselves and their chicks. The Tomahawk-Sunflower Bay chick held by Mina in the photo weighed 3.02 kg, yet it was only a few days older than the chick on Wind Pudding. Clearly the strapping youngster in the photo is heading for a healthy future and likely fledging.

Why on Earth would loons settle to breed on lakes that often provide too little food for their chicks? The answer might relate to the disconnect between nesting and foraging requirements. Alas, large lakes that contain many fish for loons often lack the islands, emergent marshy bays, and bogs that allow loons to avoid egg predators like raccoons. So loons looking to breed seem to be lured onto small, marshy lakes that yield successful hatches but doom their offspring to starvation.

Two days ago we learned that the male on Hilts Lake and the female on the East Central territory on Nokomis Lake have become the latest angling casualties in our study area. The Hilts male swallowed a lure or bait and is dragging line from his bill; the Nokomis-East Central female has line wrapped around her left leg, which she now carried behind her. We are dismayed for the two loons involved, of course. The male on Hilts is among our tamest; since 2007, he and his mate have permitted us to approach them closely without alarm so that we can record an hour of their lives every week or so during the breeding season. Each of us looks forward to visits to Hilts because of the relaxed pair we encounter there. The Nokomis-East Central female too permits us to view her and her mate and young from close by. She contrasts markedly with her mate, who forces us to view from a distance of 50 meters or so to avoid getting an earful of alarm calls. When we spy a lone adult and chick from a distance on Nokomis-East Central, we keep fingers crossed that it is the docile, approachable female, not the male, who happens to be guarding and feeding the chick. (Good news: Seth reports that the Nokomis-EC female leg appeared to be dragging no fishing line yesterday, so perhaps she is out of danger.)

The list of loons ensnared in fishing tackle is longer each year. Observations and reports of this kind have become an unrelenting and disheartening drumbeat. In the early 2000s, close encounters between loons and fishing tackle were anomalies that I wondered about almost dispassionately. Each angling casualty brought sadness and frustration, of course, since one becomes attached to the loons. But such events were so uncommon that I shrugged the losses off as the inevitable consequence of habitat overlap between loons and humans. The steady increase in entanglements in recent years has sensitized me. These days I brace myself for the several – perhaps I should change that to “many” – that will occur during the season and wonder how we can assemble a team to rescue victims without compromising the behavioral and ecological goals of the research. In fact, I have begun to prod Project LoonWatch in hopes of encouraging them to put together a loon rescue squad – a group of 3-5 folks that can remain “on-call” during summers to assist birds injured by human activity.

And I have begun to worry about the loon population. Loons are clearly getting caught on fishing lines more often than before. This makes sense, as fishing activity continues to increase in northern Wisconsin. (It might also be the case that the proportion of inexperienced anglers – those likely to lose lures and fishing line in the water and not make efforts to retrieve and discard tackle that they lose – has increased.) Loons did not evolve in an environment with monofilament line, live bait and lures that mimic small aquatic creatures. Hence, they have developed no system for avoiding these hazards. If the number of loons swallowing and blundering into fishing tackle continues to increase, will so many adults die that the population cannot sustain itself?

A quirk of fishing entanglements makes the situation a bit more severe than it might first appear. As the cases of the Hilts male and Nokomis female illustrate, males and female loons are differentially affected by fishing. For reasons that we do not understand, males appear much more likely than females to ingest lures and baits, as the Hilts male did. We do not understand this difference, although one might speculate that males, having larger bodies to sustain, are less picky in chasing and consuming underwater creatures than are females. In any event, both sexes seem to be equally prone to getting monofilament wrapped around their wings or legs, but males are more threatened by lead-based tackle (sinkers and jigs) — which poisons them and kills them quickly – and by hooks that damage their throats and prevent them from opening their bills and feeding themselves. In short, males are more apt than females to fall victim to fishing tackle and in a way that is likely to kill them.

Why should we care if adult male loons are more vulnerable to anglers? Because, weirdly, males choose the nest site where eggs are to be laid and cleverly reuse nestsites where they have hatched eggs successfully in years past. So males are a reservoir of information about how breeding pairs can best use the nesting habitat within their territories to produce young. When an established, experienced male from a productive territory is replaced by new male (because of death or eviction), the new male does not know where to place the nest and must learn by trial and error. In constrast, when a female is replaced, efficient reproduction can continue uninterrupted, because the identity of the female has no impact on nest placement.

Thus, I grieve for the Hilts male not only because he is a sweet bird who permits us to watch him without complaint but because his demise will cause a new, ignorant male to settle, who must blunder from one failed nestsite to another before he discovers a good one that he will use year after year. And his years of inept breeding will subtract many offspring from the population.