It is usually no fun to be wrong, but maybe this is an exception. In my blog post yesterday, I surmised that the sudden appearance in flight of the male from Little Bearskin meant that he and his mate had failed in their second nesting attempt. This seemed a safe presumption; I knew from many years of experience that males do not often leave females alone with small chicks. Yet I was mistaken. A lake resident (thanks, Nancy!) corrected me by pointing out that at least one chick had hatched on Little Bearskin this year, and Martha found two chicks on the lake during her early-morning visit today.

As we have explained in an earlier publication, there are three reasons why males tend not to leave their breeding lakes when their chicks are in their first two weeks of life. First, females cannot yodel, and therefore they are unable to discourage intruders from landing in the lake and approaching chicks by means of this aggressive vocal signal. Second, by virtue of their greater size, males are better equipped to intimidate and drive away intruders that do approach chicks. Third, having two parents guarding chicks when they are small permits breeding pairs to cover two bases — they can send one parent out to engage intruders and leave the other to protect the chicks, in case an intruder should come close.

In fact, years ago on Langley Lake we witnessed the danger that parents face if one of them ventures off territory when their chicks are small. In this case, two intruders landed when the male was off the lake, forcing the female to choose between: 1) staying beside its week-old chick, and 2) leaving its chick to interact with the intruders. She chose the latter course, but that strategy backfired when the intruders dove and split up. At this most inopportune moment, the chick happened to give an alarm call that one of the intruders heard. The intruder quickly found the calling chick and, with no parent nearby to intervene, killed the chick in a matter of seconds.

With that horrid incident seared into my brain (and a good deal of quantitative data on chick attendance to back it up), I was fairly confident that the appearance of a breeding male on a lake not his own meant that he had failed in his breeding attempt at home. In fact, I am still scratching my head over the Little Bearskin male’s decision to leave his mate, his two helpless chicks, and his home lake with its abundant food supply, in order to visit a neighboring lake that held nothing but failed and displaced conspecifics. I guess I will have to continue my research for a few more years to make sense of that odd bit of behavior.

My new team and I are racing around the study area, still catching up to our banded breeding population. At each lake, we record the bands of the female and male, look quickly for any active or failed nests — only in obvious places — and race to the next lake to repeat the process: (“Ok…the female has a yellow band on right and is red over green on left? Good enough….let’s go!”.) The work is frantic and exhausting, and we are only halfway through. We are all so busy covering lakes that there is little time to reflect on what we have seen. I have trouble remembering what lakes we have even visited at the end of each day, so anxious am I to eat a meal and hit the hay for the next 5am wakeup.

Yet some patterns have emerged from our lake visits that remain lodged in my brain. It has been a dreadful first round of nests for most breeding pairs. Typical pairs in the study area abandoned their first nesting attempt three to four weeks ago because of the clouds of flies that descended upon them and have only just begun to renest or think about doing so. Based on what we have seen, it appears that 70 to 80% of all pairs could not stand to incubate the first clutch of eggs they laid in early to mid-May, making 2020 even slightly more devastating a black fly year than 2014, the previous worst year on record. Our study population has seen a steady slide in chick production over the past quarter century; 2020 will only strengthen that demoralizing pattern.

So you can imagine how it warmed my heart to hear about Linda’s loon pair (“Clune” and “Honey”), who managed to buck the trend and stick it out through all four weeks of incubation. At a time when the population as a whole is reeling, the assiduous parenting on display in Linda’s video below took my mind off of the population’s struggles for a moment and reminded me that good things can still happen.

Many of you have e-mailed me to ask, “What became of the duckling reared by loons?” It is a reasonable question. Each passing day during the summer revealed startling new behavioral quirks in the peculiar, touching relationship between these inseparable misfits. Having witnessed well over a thousand loon families — and by this I mean those consisting entirely of loons — I found each of my visits to the Long Lake pair a revelation. Each time I watched male and female loons feed their precious adoptee a fish or warn it about a passing eagle, I involuntarily shook my head. How could two species separated by 70 millions of years of evolution come together into such a tight and successful makeshift family? Every day the family remained together seemed to defy logic.

Yet their familial bond persisted. Following my most recent post on the loon-duckling family, the duckling grew and grew some more. By the end of July (as Linda Grenzer’s photo shows), the duckling was close to adult size, and the only uncertainty was whether or not it would sink its parents by continuing to ride about on their backs. By mid-August, the pair and duckling were spending more time apart. On multiple occasions, we saw the duckling take off and fly around the lake a few times before landing near its anxious guardians. By now fully capable of feeding itself and weeks beyond the normal fledging date for mallards reared by their own species, the duckling seemed to cling to its parents more for their sake than for its own.

By September 4th, the duckling and its loon parents were gone from the lake. We will not ever know where the duckling went or how it lived after leaving Long Lake. Although we could have attempted to mark it in July, as we do loon chicks, I could not bring myself to do so. Even as a scientist fascinated by the behavioral outcome, I was too transfixed by the beauty of the family to capture them and risk disrupting it.

 

Juvenile loons are in a race against time. While their parents seem to relax following the breeding season — wandering from lake to lake as if on a goodwill tour — juveniles, like the three-month-old in Linda Grenzer’s photo, face a ticking clock. After hatching in June or July, juvies must reach near-adult size by ten weeks of age, practice takeoffs and landings, and become strong enough to make flights of hundreds of miles on their southward migration in early November.

They are racing the ice. Temperatures cool in September, become unpleasantly chilly in October, and truly plummet in November — and lake temperatures follow suit. Ice-up can occur anytime between mid-November and mid-December in northern Wisconsin, and ice-up is the end of the line for juveniles. Opportunistic bald eagles await juveniles that are not prepared to migrate and become trapped in the ice. Apparently sensing the desperate task that will confront their offspring in the fall, parents stuff them with fish for eight long weeks in July and August. Chicks grow explosively during mid-summer. But they face their most challenging task in autumn, when parental support wanes and they must learn to feed themselves, improve their body condition, and prepare for their southward journey.

In general, scientists have paid little attention to the juvenile period in birds. Our neglect is natural enough. The breeding season is chock full of interesting behavioral and ecological events: pairing of mates, defense of breeding territories, selection of nest sites, and relentless territorial intrusions by nonbreeding adults seeking to settle. Perhaps ecologists can be forgiven for focusing their attention on breeding behavior and trusting that juveniles will take care of themselves.

But we wondered. If young adults settle on breeding lakes that closely resemble their natal lakes, might juveniles — which must fight for their lives just to become adults — also exhibit clear preferences for certain kinds of lakes over others? Constrained by flightlessness to forage only within the lake where they hatched, we might expect juveniles to become highly specialized to hunt and consume the species of prey found on the natal lake. So once they become capable of flight, we might expect them to visit and forage on other lakes very similar to their natal one. That is, juveniles reared on a diet of bluegill sunfish and used to hunting that species should spend most of the pre-migratory period visiting lakes full of bluegill that they can catch and consume efficiently. And juveniles accustomed to eating snails and leeches should find lakes full of those invertebrates on which they can feast.

Our interest in lake visitation patterns of juveniles during fall inspired us to plot the local movements of youngsters between lakes in the fall of 2012, 2013, and 2014. Kristin, Gabby, and Nathan used their band-spotting skills to locate juvies in September and October of these years. They found close to 200 cases where a juvenile we had marked had flown to forage on a lake other than its own. Using these data, Brian, who joined us this summer, asked, “Do juveniles forage on lakes at random, or do they prefer to forage on lakes like the one that hatched them?”. As the figure below shows, the mean difference in pH between a juvenile’s natal lake and the lake where we spotted it foraging (red vertical line) was far less than the distribution of differences we would have expected, if juvies had foraged randomly (grey bell-shaped curve).

Z_pH_Randomization

Although Brian has a few statistical checks to complete, the pattern seems clear. Juveniles exhibit strong preference for lakes that resemble their natal one in two respects: 1) pH and 2) water clarity (data not shown). Brian’s analysis is ongoing, and he is trying to learn how closely these chemical and physical attributes predict the food available to loons in a lake. But we are betting that the stark preference of three-month-old juveniles for lakes that remind them of home occurs for a simple reason. Juvies try to spend their time hunting prey in familiar conditions to build themselves up for their most dangerous first southward journey.

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.)

IMG_0033

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.

LMG 26875 Baker Lake Loons n Duckling Splash Dive

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.

 

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.