on

I am never prepared for chick loss. As a scientist, I know that the first several weeks of life are fraught with danger for loon chicks. Have they developed normally? Can they thermoregulate properly? Are they able to dodge eagles, muskies, and snapping turtles that can devour them when small? Are their parents aggressive and vigilant enough to keep intruders at bay, which might otherwise kill them with a few well-placed jabs? Is there sufficient food in their natal lake to sustain them and support their rapid growth? And these are merely the natural threats to chick survival.

As hazardous to chicks as natural dangers, or perhaps more so, are threats that humans pose. Sometimes these are direct impacts; humans drive their boats rapidly and often strike chicks, which cannot elude them as deftly as adults. Anglers’ lures and baits, recognized as unnatural and avoided by most adult loons, are sometimes gobbled up uncritically by chicks, which are just learning what they can and cannot eat and must gorge themselves in order to grow. The hooks — and especially lead jigs and sinkers that they ingest at such times — pose a grave risk to the youngsters. A more insidious and dire threat that we have seen recently is the decline in water clarity in northern Wisconsin in the past decade, which makes it difficult for chicks and parents to find food and likely explains much of the reproductive decline we have seen there. (We will soon determine whether water clarity is declining in loon lakes in Minnesota as well.)

Although I am acutely aware of the increasing dangers that loon chicks face, I struggle to adjust to the steady drip drip of chick mortality in Wisconsin and Minnesota. When the Rush-USA Point pair lost their chick, I reasoned, “Well, that territory gets high boat traffic; it is hard to keep a chick alive there.” I justified the loss of the Cross-National Loon Center chick and the two chicks hatched by the Rush-Hen pair in the same way. I was a bit numbed by the time I considered the loss of the two young chicks of the Eagle-East pair.

I find it easier to stomach brood reduction. When broods decrease from two chicks to one, I take solace in the survival of the remaining chick. So it went at Upper Whitefish-Steamboat, Ossie-Island, and Sand this year. Very often brood reduction of this kind comes about because food is limiting; the death of the smaller chick actually gives the larger chick a fighting chance to make it.

What stings the most is loss of chicks that have reached four weeks of age. In the past few days, two chicks that had attained this milestone perished in the Minnesota Study Area. (The NLC is awaiting necropsies on both individuals.) Quick inspection of the Lower Hay-Southeast chick that lost its life and washed ashore earlier this week showed what appeared to be traumatic injury on the back, suggestive of a propeller strike. When you consider that the Lower Hay-SE territory is right next to a major public boat landing, this likely cause makes sense. The second deceased chick, from Clear Lake, was 32% lower in mass than its sibling; thus it was falling far behind in acquiring food from its parents. So this looks like classic brood reduction. Indeed, Kate Marthens, one of our Minnesota field team, reported that this chick was not keeping up with its family on the day that it was found dead, an indication that brood reduction was imminent.

The significant increase in mortality of loon chicks of all ages (i.e. both younger and older than five weeks of age) is a hallmark of the current population decline in Wisconsin. I should be learning to cope with it — preparing myself to face it in Minnesota too, if our growing sample there reveals the same trend. But that is more easily said than done. It still hurts like the devil to lose a chick.

Featured photo — One of our largest chicks in Wisconsin is that on Little Bearskin Lake. It was alive and kicking as of this writing! (Molly Bustos, a Wisconsin intern, holds the bird.)

on

Sometimes on our research project, we observe a rapid series of nasty events that defy explanation and really shake us up.

This happened to my field interns in Wisconsin. They were “roving” outside our normal study lakes, visiting lakes that are either on the fringes of our 110-lake study area or with little past history of supporting loons. On July 8th, Sarah and Claudia found an adult with a fishhook hanging out of its head on the left side, behind and below the ear. Sarah, Claudia, and Chris covered Little Bass Lake on the following day — and found what appeared to be a second loon with the exact same problem.

We have seen dozens of angling casualties at this point, but we had never seen two weird and very similar hookings in rapid succession. Our puzzlement increased one day later, when Claudia was alone on Dorothy and saw a third loon hooked in this peculiar and painful way. (The featured photos at the top are hers.)

When Claudia contacted me and Linda Grenzer and described what she had seen, we had brief paranoid thoughts, “Oh my god; someone is systematically casting at loon’s heads and hooking them!” (Linda tells me this has actually happened before.) Or, on a deeper rung of paranoia: “Someone is capturing loons, sticking hooks in their heads, and releasing them.”

Repeated visits to the three lakes by our team shed more light. When Linda and her husband, Kevin, attempted to capture the hooked Buffalo bird, they did not find it on the lake on one night. Linda and Kevin also observed what they are confident are two different loons with very similar hookings on Little Bass Lake on two separate nights.

Here is what I conclude. First, these are young birds — probably floaters — but clearly not territorial birds with strong ties to these lakes. They are doing what loons do between ages 2 and 7: they are drifting about but staying in the same general area. If you scrutinize the photos above, it seems apparent that the 1st (Buffalo) and 3rd loons (Dorothy) are the same. Each shows a hook embedded in the loon’s head in the vicinity of the left ear, a fishing snap and swivel hanging off of the hook, and no fishing line attached to the swivel. But the feathers obscure the wound itself. On the other hand, the middle photo from Little Bass shows what appears to be open, inflamed tissue, again with a naked snap and swivel dangling from a hook or lure. Linda and Kevin think that the middle loon is certainly a different bird. I think it might be the same bird, even though the wound looks different. Either way, the loon(s) are dealing well with what appears to be a severe injury, because they are flying from lake to lake and intruding into breeding territories (Dorothy), as they should be.

Speaking of coping well with injury, we had another unpleasant angling event in northern Wisconsin during the past week. A male marked by the DNR eleven years ago on a territory near Three Lakes became incapacitated and was taken for treatment by Wild Instincts in Rhinelander. Their X-ray photo reveals the problem — this bird has a treble hook lodged in its gizzard. The bird has bounced back and been released at this point, but the nasty treble hook and attached line is still inside him. (Removal, of course, would have involved extensive surgery likely to harm the bird further.) We can only hope that the male’s digestive system will grind down and pass these hooks eventually, as we have seen in other loons.

In short, loons have taken some hard punches recently, as we have come to expect at this peak fishing time. If they are lucky enough to avoid the death sentence of a swallowed lead sinker or jig, they can be remarkably resilient.

on

Yesterday, I heard the cheerful, buzzy calls of Japanese White-eyes* flitting about in the trees in my backyard. They are handsome and engaging little birds, but they don’t belong in southern California. They never lived here before humans did. As recently as ten years ago, white-eyes were quite difficult to find in the area.

A few weeks ago my wife, son, daughter, and I visited my ailing mother in Houston. On our first morning there, we were awakened by the incessant cooing of White-winged Doves*. They too are a striking species. The flashy white stripes on their wings and tails set them apart from the more familiar and homely Mourning Doves. Even the ceaseless calling of White-wings is rather pleasant. Don’t trust me on this; the abundant murmurings of this species inspired Stevie Nicks to write an entire song about them. But White-winged Doves have not always lived in the Houston area. I remember scouring trees around the Galveston County Courthouse in vain for this species with my mentor, Fred Collins, on a Christmas bird count a half century ago.**

Of course, while new species colonize new regions; well-established residents also vanish. In the Upper Midwest, the Piping Plover, a cute little shorebird, has recently become severely threatened. Though I have never seen a Piping Plover in all my years in Wisconsin and Minnesota, I do have experience with a second threatened species, the Black Tern. These agile fliers flit about marshy areas, plucking insect larvae and small vertebrates from the water and vegetation. They are appealing birds — with jet-black bodies that contrast tastefully with greyish wings and tail. But it is a longshot to find them in the Upper Midwest nowadays. What seemed a healthy breeding colony fifteen years ago on Wind Pudding Lake in northern Wisconsin — where we have always had a breeding loon pair — has disappeared altogether. It has been so many years since I last saw Black Terns on Wind Pudding that I have stopped looking for them there.

In short, my years as a bird-watcher have taught me that populations of birds change dramatically over time. Some species magically appear in new places, and other species disappear. I suppose it is my first-hand experience with the dynamics of avian populations that infuses my current research on loon populations in Wisconsin and Minnesota with such urgency. This is why I sweat the black fly season in May and June, worry about boat strikes and lead poisoning, and am in a bit of a panic over the recent loss of water clarity in the region. I have now seen — as I had not in 1993 when my loon work began — that birds can disappear.

* Photos by Natthaphat Chotjuckdikul and Ted Bradford from eBird.

** In fact, the picture is a bit complicated in the case of this species. White-winged doves occurred commonly in the southwestern U.S. 100 years ago, but the population was devastated by the expansion of the citrus industry. However, in the past three decades, the species has begun to nest in citrus trees and has come roaring back.

on

On May 27th, the Little Pine-Dream Island pair was in dire straits. Hounded by black flies, they could not stand to incubate their eggs for more than a few seconds. At the time of our visit, the female foraged a hundred meters north of the nest, having been relieved of incubation duties for the time being. It was the male’s turn to cover the eggs. We watched helplessly as he mounted the nest, settled on the eggs for a few seconds, and then retreated back into the lake, his nape thoroughly inflamed with bites of flies that still savaged him.

Yet even the short dives he made after leaving the nest did not help. Whether it was because the flies’ mouthparts were inserted too securely into his flesh or their six legs grasped too firmly to his feathers, the male failed to dislodge his tormentors as we looked on.

We did not linger on the ill-named Dream Island territory. Although both pair members are exceptionally tame, we did not wish to be an additional distraction to them during their struggles. As soon as we had freed our prop from a stubborn underwater snag, we departed.

Plagued by boat problems and poor weather, it was a full five weeks before we were able to return to the Dream Island territory. Kate and Emily were thrilled to locate the pair with two healthy 10-day-old chicks bobbing about in the light chop of Little Pine. Evidently this sweet pair had the toughness and determination to achieve an outcome that, five weeks ago, seemed a dream indeed.

Video by Katherine Marthens.

on

The beginning of the tale is heart-rending. A gosling is orphaned before hatching. A loon pair fails to hatch chicks of their own and, seeking to fill the void, sits on eggs they find near their nest. When these two desperate parties converge into a single — if nontraditional — family, they produce a heart-warming story*.

To see two species coexist despite 90 million years of evolutionary time spent apart is surprising. To see them not merely tolerate each other but become thoroughly interdependent, as parent and offspring, is truly striking. Such an improbable scenario makes one hopeful. This story suggests that differences between groups — even vast ones such as between geese and loons — can be overcome.

On the other hand, the sight of a gosling nestled comfortably on a loon’s back is also strange. It is a reminder — like exploding black fly populations, loss of water clarity, devastating storms, and the sudden abundance of wake boats — that the loon’s world has changed.

*Thanks to photographer Brad Thompson, who shared his beautiful photo.

.

on

It is often said of field biologists that we resemble our study animals. I guess it is true. No, I am not aquatic. Nor do I subsist on a diet of fish, crustaceans, insect larvae, and the occasional mollusk. I did not even engage in a dangerous battle to secure my mate and territory. But, like loons, I enjoy being alone.

One of the joys of my profession is the time that I spend alone in a canoe, watching loons and taking in the beauty and simplicity of their lives. When your world is distilled down to watching the sky for other loons and bald eagles, chasing fish under water, and preening from time to time to take care of your feathers, life seems pretty straightforward. During those moments when I am with loons, their few concerns are all that matters. At such times, the headaches of keeping a major research project afloat, supporting a young field staff, repairing or replacing broken equipment, publishing scientific papers, and sharing engaging stories, photos, and video via social media vanish.

Loons would seem to gain even more than I do from avoiding crowds, especially at this moment. As a migratory species that winters along oceanic coasts, summers on northern lakes, and uses a variety of lakes and rivers in between, common loons appear at great risk from the current outbreak of highly pathogenic avian influenza. After all, waterfowl like ducks and geese, which share these waterbodies with loons, are known to be important hosts for the virus. Yet to date, loons seem to have avoided the epidemic of HPAI that has decimated other aquatic birds in the United Kingdom and eastern North America. How have loons dodged this juggernaut? Mostly by breeding solitarily, instead of gathering in dense breeding colonies on oceanic islands, where the virus spreads quickly via saliva, respiratory droplets, and feces.

Loons’ ability to avoid massive mortality events from HPAI is welcome news. After all, they already have had to contend this year with a late ice-out that has delayed their reproductive efforts and a higher-than-usual population of Simulium annulus, the black fly that singlehandedly makes May a miserable month. Yet some pairs have remained steadfast. At long last this week, several breeding pairs in Minnesota and Wisconsin Study Areas have hatched chicks, like the ones in the photo above from Ossawinnamakee Lake (photo by Keith Kellen). Maybe things are beginning to turn around!

on

I’ll just admit it: I have started to root for the elderly. While I used to support one contestant or the other based solely on geography, I now rejoice when an old individual surprises us by winning a battle against a younger opponent. Recently, for example, I have found myself more than normally excited that Justin Verlander, who at 39 is far older than most Major Leaguers, is still a dominant fireballer for my Houston Astros. Despite my lingering dislike for the Patriots, at times I catch myself admiring Tom Brady, who has continued to be an effective NFL quarterback at 44, defying the usual bounds of age.

Among loons, it is females that normally show the ability to perform well at advanced ages. The most impressive old female, without question, is Red/Green of Upper Kaubashine. After raising chicks with at least three different partners on three different lakes, Red/Green produced two chicks with a fourth male on a lake that had not seen chicks before. A few years later, she survived a bloody and violent battle that cost her the Upper Kaubashine territory, but not her life. (She is pictured above in Linda Grenzer’s photo, a few days after that battle.) The current Little Bearskin female, White/Yellow, is another example of steadfastness by a thirty-something bird. After producing 18 fledglings during a 23-year breeding career on West Horsehead Lake, she was severely injured by a fishing line last summer during her first year on Little Bearskin. White/Yellow has bounced back and is now the mother of one of our first chicks of 2022. Banded as an adult in 1996, she is at least 33 years old.

Attuned as I am to learning of female loons’ age-defying exploits, I was blind-sided by Sarah Slayton’s report from Pickerel a few days back. Upon her arrival, Sarah witnessed a nasty battle between two adults on the Pickerel-North territory. She nailed bands on the participants and was able to ascertain that this contest was between males. The contestants, she told me, were Green/Mint-Right and Blue/Red-Left. Blue/Red-Left, I thought???. Blue/Red-Left is the ancient male from Pickerel-West who was evicted from his own territory last July by a young male from Pickerel-South. That defeat was especially painful; Blue/Red and his mate were rearing two chicks at the time which were certainly killed by the new male as he solidified his hold on the territory. Lacking the strength to re-engage with the 8-year-old opponent that had recently bested him, Blue/Red evidently set his sights on a more achievable prospect — evicting the 17-year-old male a short distance up the lake whose territory has been a consistent chick producer.

We have limited information on territorial contests between old loons. Quite frankly, male contests usually involve a very predictable pair of opponents: a male (15 or older) that is past his prime and a young male (5 to 8 years of age) that has suddenly realized he is capable of defeating an older male and seizing his territory. I have to confess that I have begun to give up on old, defeated males. A few of these washed-up individuals are able to recover from eviction by settling peacefully on a vacant lake near their original territory. Some have even bounced back and reared multiple chicks on their new stomping grounds. But most males that are evicted after age 15 disappear from the study area quickly and quietly, as if stoically bowing out to make way for the younger generation.

So it was thrilling to see Blue/Red, who at 24+ years of age is well into his dotage, put himself in harm’s way, challenge the 17-year-old Pickerel-North male for his territory…and actually win the contest. To be clear, this was a battle between one of the handful of really old males in our Wisconsin Study Area and a male, Green/Mint, that is not ancient but certainly well past his prime.

What now? According to Sarah, who heroically paddled up and down the main bay of 581-acre Pickerel Lake to get the skinny on all loons on the lake, the evicted Green/Mint is now living alone on the former Pickerel-South territory, where he lived from 2010 to 2013 and fledged three chicks. With luck, he will re-pair with a new female there and possibly even nest again this year.

The burning question on Pickerel Lake is this. What happens to the Pickerel-North nesting attempt, which is within a week of hatching? Blue/Red, the ancient male that has just won this territory in battle, might decide to join the female, Copper/Yellow, and incubate the eggs as if they were his own. (We have seen evicting males do this four times in the past.) It is more likely that he will make the evolutionarily-sound decision to ignore the nest until Copper/Yellow finally abandons it. Fortunately, there is still plenty of time to nest. So we hope that Blue/Red will do what he has done in 8 previous years on the lake during an 18-year breeding career: find a good nest site, incubate the eggs patiently for 28 days with his mate, and raise two big, fat, sassy chicks. If he does so, he will have completed a rare and improbable comeback by a very old male.

on

Each spring I feel my adrenaline level rise as we carry out the annual census of returning loons. This practice seems mundane, at first glance. During the census, we simply visit all loon territories and identify each territorial loon we find from its colored leg bands. But since I have gotten to know many of my study animals quite well, I wait with bated breath to learn whether Clune (the famously tame male on Linda Grenzer’s lake, whom I have known since he was a chick) comes back. I feel almost as strongly about Clune’s son, who settled 6 km away, on tiny Virgin Lake. I even have a soft spot for the comically skittish female on Silverbass Lake. She routinely appears down at one end of this long skinny lake, seems to wait for us to paddle in her direction from the other end, and then races by us underwater and reappears at the end of the lake we just vacated. She is so notoriously hard to approach that her very skittishness has become a useful identifying trait. In Minnesota, I was anxious to see whether the young male of unknown identity on Lower Whitefish — who nested rather recklessly on a water-logged artificial nesting platform exposed to the powerful west wind and waves — would return from the winter and try that move again or learn from his mistake and seek a more protected location. (I am happy to report that all four of these loons are back this year.)

Apart from the relief or dejection we feel when we spot our familiar study animals — or don’t — loons’ tendency to return provides critical scientific information. A tally of the proportion of all adult breeders that returned from the wintering grounds in the spring tells us about survival between late summer of the previous year and early spring of the current one. Of course, territorial eviction muddies the water. That is, a loon can either fail to return to its previous territory because it is dead or because a competitor has driven it off of its territory and forced it to move elsewhere. So we must be cautious in interpreting return rates. Still, they provide us with a crude metric of survival.

Let’s look at return rates throughout the study. What is clear from a quick inspection of the graph below is that loons in the Wisconsin Study Area have fluctuated in their tendency to return, coming back at a rate of over 90% in great years and just above 70% in dismal ones. (Minnesota study loons returning in 2022 also fell within this window, as the graph shows.)

Perhaps the most striking pattern is the lack of concordance between return rates of each sex. In other words, knowing that it is a bad year for male survival tells us nothing about female survival. True, there are some years in which male and female survival seem to go hand in hand — look at 2005-2009, for example. But male and female rates seem to run in opposite directions between 2010 and 2017. Overall, there is no statistical tendency for male survival to be correlated with female survival.

We can draw an important — though tentative — conclusion from the fact that male and female survival do not vary in concert. Major loon mortality events outside of the breeding season do not seem to drive annual loon survival strongly. If major die-offs during the non-breeding period (i.e. winter and migration) were a major cause of loon mortality, then male and female numbers should be correlated, because the sexes use similar migratory routes and winter quarters and should suffer in parallel each year.

The most interesting and potentially worrisome pattern we could spot in the annual return rate data would be a decline in survival of either males or females. As you can see from the color-coded dotted lines, female return rate has actually shown a slight rise over the past 29 years. On the other hand, male return rate has declined slightly, though not significantly, during this period. Still, since we already know that males are struggling to maintain optimal body mass in the Upper Midwest, it is disconcerting to see male survival decrease in a way that seems consistent with the mass loss.

Of course, while making the rounds of territorial pairs, we also notice if a territory is vacant or occupied by a lone adult after having supported a breeding pair the previous year. And therein lies a bit more troubling news. Ten of 118 Wisconsin territories that were occupied in 2021 are now vacant or inhabited by loners. We have also recorded two new territories in lakes not used for breeding last year, so the net loss in territories is only eight. Still, this was not the picture we wished to see in a population that has been on a downturn. (Though we are only learning about the Minnesota Study Population, it appears that only one territory among seventy or so that we have visited so far fell into disuse this year after having been occupied last year.)

Let’s put aside worrisome population patterns and turn to news of the moment. It is early June in the North. This is a time of great hope for loons. A few breeding pairs in our Minnesota and Wisconsin study areas — like the Lower Hay pair in the photo — were fortunate enough to dodge both black flies and raccoons and are on the brink of hatching young. Many more have rebounded from early setbacks and renested. If we are lucky, we still have the potential for a good crop of chicks in both regions. Lacking any more effectual means of bringing this about, I will keep my fingers crossed.

on

One of the pleasing sights of spring in the Northwoods is that of a territorial pair of loons, foraging side by side. No doubt the myth of lifetime fidelity of loons to their mates arises, at least in part, from the tight association of female and male loons at this time. Their apparent devotion to each other, their compulsion to remain together at all times, the touching plaintive wails that keep them in contact when they chance to become separated for a brief period all recall young human couples with limitless possibilities before them.

During the past three weeks in Minnesota and Wisconsin, I have seen many loon pairs foraging, resting, and preening together. It is truly heart-warming — to a degree. You see, once the territory resettlement period — the first three weeks after ice-out, roughly — has come to a close, loon pairs should be nesting, which means that humans watching out for “their loon pair” should see only one pair member or the other on the water.

Egg-laying marks the start of the nerve-wracking 28-day period of incubation where innumerable things could go wrong. A raccoon could wander by; an eagle could flush the incubating bird and feast on the eggs; a sudden downpour could turn a nest that seemed safely above water level into egg soup, cooling the eggs and killing the embryos. But one single cause of incubation failure has emerged as the single greatest threat to loon breeding success in Wisconsin and Minnesota in the past decade. The agent, a single species of black fly with a peculiar taste for loon blood, has recently surpassed even egg predation by raccoons and their ilk as a cause of nesting failure. When hundreds of black flies surround incubating loons and bite them mercilessly on the head and nape, the agony can become too awful to bear, causing the pair to abandon the nest. In recent years, black fly survival and persistence dictate how productive an entire loon population will be. It is that simple.

Yesterday, five of us — four members of the loon research team and a reporter for Minnesota Public Radio — ventured out onto the Whitefish Chain to mop up the few territorial pairs that we had not yet been able to visit this year. The trip was memorable for more than loons. An unexpectedly stiff west wind turned Middle Whitefish into a seething Lake Superior, forcing us to beach our motorboat prematurely at Boyd Lodge. (It took four Blizzards at DQ in Crosslake to help us move on after that hair-raising experience!)

Despite sketchy conditions, we visited nine new territorial pairs. We were thrilled when Kate spotted an incubating loon in a protected cove of Pig Lake. But that was the only territorial pair we scouted that was sitting on eggs. All others behaved as if the ice had just come off: they preened, rested, and foraged side by side. What would have been a cheerful sight in mid-May causes consternation now. Sixty to seventy percent of all pairs should be incubating eggs at this point in the season. Sadly, the featured image from Sibley-South depicts the situation in many of these lakes at present: two perfect golden-brown eggs — and loons nowhere nearby.