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.

 

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.

I am still deciding how to feel about recent events. On the one hand, one of our marked females lost her mate and territory, beached herself on a lake shoreline, tolerated a lengthy car ride, survived a difficult surgery, and now faces an uncertain path to recovery. On the other hand, a crew from the Loon Project and veterinary staff from Raptor Education Group, Inc. rescued this bird from near death, transported her safely to the REGI facility, expended countless hours conducting major surgery, and is diligently nursing her back to health. These heroic efforts – especially those of the REGI staff and veterinarians — have transformed certain death into the prospect of full recovery.

As I struggle to process this troubling series of recent events, one image lingers. It is the x-ray below (provided by REGI) of the female’s gut seemingly stuffed with fishing tackle.

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Foremost among the questions swirling around my brain is this one: Is ingestion of fishing tackle a common occurrence? That is, do many adult loons in northern Wisconsin have to contend with fishing gear they have swallowed while foraging?

Our understanding of lead poisoning, scrutiny of our field notes, and inspection of the fishing gear recovered from the female’s gut (in the photo from REGI) help in answering this question. Lead is a potent toxin in birds and mammals, causing severe impacts to nervous and digestive systems. Lead toxicosis, moreover, occurs shortly after loons ingest lead — a day or a few days later — not weeks or months after ingestion. Linda Grenzer reported the Mable female intruding on her lake on 20 June. So the female was flying normally three days before she became utterly helpless on Mable (23 June). Furthermore, the fishing tackle in the photo seems to represent that found on the end of one person’s line. So the Mable female apparently swallowed someone’s fishing line on about the 20th or 21st of June and quickly began to deteriorate. Viewed from a population perspective, this is good news, because it suggests that loons in our study area do not ingest lead sinkers very often. If they did, we would face the ghastly prospect of helpless, neurologically-impaired loons constantly casting themselves ashore on our lakes.

Having concluded that the plight of the Lake Mable female is the exception, not the rule, I have begun to breathe more easily. Loons face considerable hurdles in coping with fishing tackle in northern Wisconsin, but lead poisoning — as far as we can tell — seems to be somewhat less of a threat in the Upper Midwest than it is in other populations. So I will end this post on that cheerful note and with Linda’s cheerful photo of the 2019 Loon Project team, which has worked tirelessly to watch over our study population this summer.

2019 loon team at REGI w MAble female

“Wow, loon chicks and ducklings sure look alike!” Evelyn remarked upon returning from Long Lake two weeks ago. Elaina, a veteran assistant who has seen a lot of both, thought this statement a bit odd, but was not terribly surprised. The chicks of loons do look somewhat like ducklings. Both are duck-shaped and downy, quite unlike adults of their respective species. And after all, Evelyn had never laid eyes on a loon chick before.

Ten days passed, and it was Elaina‘s turn to visit Long Lake. She was stunned to find the female slowly swimming about with a young mallard duckling on its back, and she took these cool photos to document her observations. The female, Elaina noted, acted as loon parents always do: she nervously guarded her small passenger, scanning the skies for bald eagles and peering underneath the water at intervals for large snapping turtles and muskies. The nearby male too behaved normally. Like his mate, he was vigilant, but he also caught tiny fish, carried them to the duckling on his mate’s back, and attempted to feed it, just as he had his own chick last year. His efforts were in vain; the duckling refused all food.

Many questions leap to mind here. First, how on earth did a loon pair meet up with a single mallard duckling? Second, why on earth would they adopt the duckling rather than raising their own chick or chicks? Third, why does the duckling participate in this charade? Fourth, will loons, which provide their chicks with a large fraction of their food, be able to rear a mallard duckling, which normally finds all of its own (very different) food?

The first question is the easiest. Loons and mallards are both common on our study lakes. They encounter each other all the time. But the usual result of such encounters is starkly different from what Evelyn and Elaina observed. For their part, mallard ducklings swim about with their many siblings in a large, tight, comical flotilla behind their mother. Loons often stalk these flotillas, causing the mallard female to rush her offspring to the nearest shoreline. Loons occasionally attack and kill ducklings, but do not eat them (to our knowledge). The usual nature of loon and mallard interactions, in other words, is a far cry from what Evelyn and Elaina observed.

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The second question — what the loons are doing adopting a duckling – is the most vexing. Yet we have insights that permit us to reconstruct some parts of the story. The shape, size, and number of eggshell fragments in a loon nest tells us the fate of a nesting attempt. When I visited Long on 13 May, the pair had just started nesting, so we expected a hatch on 10 or 11 June. Indeed, Evelyn noted many small fragments on Long on June 14th—- a clear sign of a successful hatch. So we know that the Long pair did hatch an egg —- a loon egg — about two weeks ago. Loon pairs provide extensive parental care for their young, of course, and are hormonally primed to do so. Without question, then, the Long pair had high levels of prolactin in their blood in mid-June, as they began to care for their own chick. The rest of what occurred to bring about this most unlikely association is open to speculation. Perhaps a tiny duckling, the last to hatch in its brood, was left behind by its mother and siblings. Maybe the duckling became separated from its mother and siblings following an eagle attack. In any event, the tiny waif was likely discovered by the loon pair just after they had lost their chick and were predisposed to find and care for anything that even remotely resembled a newly-hatched loon.

Classical studies of animal behavior help us answer the question of how the duckling would accept loons as its parents. Ducks (like chickens and many other precocial birds) have a well-known capacity to imprint on the first large, moving, animal-like object they encounter after hatching. This instinct makes sense, because that object is almost always their mother or father. Imprinting helps them fixate and remain near their protector at all times. But a duckling hatching after its sibs had left would not have had a chance to imprint on any object. So it is conceivable that such a duckling might see and latch onto a loon pair. If ducklings accept humans as parents, they should easily accept loons.

Can a loon pair provide enough nourishment and feeding opportunities to allow a duckling to survive to fledging? We shall see. Loons have adopted ducklings before. A published study from the late 70s reported adoption of five eider ducklings by a pair of Arctic loons, and I reported a few years back on a pair of common loons in British Columbia that adopted a common goldeneye duckling. In both cases, the ducklings were known to have survived for many weeks in the care of their foster parents. But a mallard is a dabbling duck, not a diving duck, like an eider and a goldeneye. Mallard ducklings normally feed themselves on a variety of invertebrates and plant matter found on shorelines and in shallow water — not fishes provided by a parent bird. Despite the seeming disconnect between loons and mallards in diet and mode of feeding, Elaina’s photos show an alert, healthy-looking young mallard. Since we know the loons have been parenting the duckling for at least ten days, we must conclude that the youngster is receiving substantial nourishment by some means. So perhaps loons can keep a mallard duckling alive.

In short, we know bits and pieces of the story of how a pair of loons came to care for a mallard duckling. Much regarding this series of unlikely events remains shrouded in mystery. Even in our considerable ignorance, though, it is impossible not to marvel at this charming spectacle.

“Bring me the broomstick of the Wicked Witch of the West”, the Wizard of Oz booms. It is an iconic phrase in one of the most-watched movies of all time. The phrase is also both poignant and baffling. Of course, Dorothy and her companions are crestfallen to hear this “very small task” the Wizard has in mind for them. “If we do that”, the Tin Man stammers, “we would have to kill her.”

It is impossible not to side with Dorothy and the Tin Man here. The Wizard’s task – which requires that the four floundering protagonists gain entry into a well-fortified castle and kill a powerful witch who is bent on vengeance — seems disproportionate to the companions’ requests of the Wizard. In addition, three of the four requests our heroes make — a brain, a heart, and courage – are arguably possessions needed before the task, not afterwards. The task seems all the more unfair because it is arbitrary. Plucking a broomstick from the clutches of a dead witch and presenting it to the Wizard in no way helps him provide the companions with a heart, a brain, courage, or a trip to Kansas.

So it seems also with proposals to the National Science Foundation. Getting a proposal funded by NSF requires generating a central scientific question, crafting a clever and engaging thesis, producing a set of testable and bulletproof predictions, and making the case that the research will both engage undergraduate students and edify the public. Don’t misunderstand me here; these are all worthy goals. I am glad that the NSF insists on these strict standards. Yet scientists seeking funds from NSF often feel that, like the Tin Man, they must “prove themselves worthy” of funding by completing a task both disproportionate and disconnected to the scientific work they propose to do.

Like the broomstick challenge faced by Dorothy and her companions, an NSF proposal is a formidable undertaking. While I am sure some of my colleagues come to the task more easily than I do, I estimate that preparing a grant proposal to NSF from scratch takes about as much time as writing two scientific papers. Therefore, it is often not clear whether I should spend my time writing a grant proposal that stands little chance of funding but would permit us to continue our work or publishing two papers. An NSF proposal, as you can imagine, is never published. Bits and pieces of a proposal might find their way into later journal articles, but the proposal itself is a document read only by a panel of colleagues who sit in judgment. Considering the time spent in preparation and the fact that the funding rate has fallen by about half in the past ten years (to 1/6 of all ecology proposals funded over a three-year period, including initial submissions and re-submissions), submitting an NSF proposal has become a high stakes gamble.

Proposal-writing, moreover, is not like doing scientific work. Most scientists work within a certain conceptual framework, to be sure, but their day-to-day efforts to answer scientific questions within this framework force them to follow a tortuous path comprising many steps. Here is the first disconnect between scientific research and a grant proposal. A successful proposal must center around a single, unifying question. Scientific research rarely addresses a single, coherent, all-encompassing question. Instead, most science is particulate, consisting of a long set of meandering steps, each clearly related only to the preceding one.

On the Loon Project, I first learned that loons engage in territorial battles. Thus, I initially aimed to describe territorial contests and their purpose. During that work, I learned that males fight more dangerously than females. This finding led me to examine differences between males and females that might lead to the difference in fighting, which, in turn, led to the discovery that males choose the nest location and have a greater stake in remaining on a familiar territory than females. Even after three logical steps, my journey had taken me far afield — from territoriality to nesting behavior. Discrete steps are essential, by the way, because scientists must publish their findings routinely in scientific journals in order to justify further research, gain tenure, and have a chance to attract extramural funding. So, like most other scientists, I published my work incrementally through short papers focused on narrow topics, not in a book or monograph addressing a broad question. Most importantly, while the logical path I followed makes sense in retrospect, I could not have written a grant proposal that anticipated it.

Another difference between the practice of science and the task of attracting funding for science relates to the role of serendipity and chance discovery. At its best, science is exciting, because the outcome of any experiment or set of observations is not known ahead of time. Some years ago, we expanded our study area to include a larger sample of marked loons for territorial study, chiefly to learn if young adult prebreeders establish “footholds” in certain lakes where they intruded often in order to increase their chance of later competing successfully to settle on those lakes. We did ultimately answer this question — young loons do not use footholds – but while surveying new lakes of various shapes and sizes, we blundered upon an unsuspected pattern. Young loons, we learned, settle to breed on lakes that closely resemble their natal one in size and pH. (The finding stands as a rare case in which an animal seems to learn a preference early in life that is disadvantageous to it later.) If we had not veered from our normal path to describe natal habitat imprinting, we would have been ignoring a crucial finding of great value to other scientists. Yet publishing a paper on natal habitat imprinting cost us precious time and energy that might have been spent solely studying territorial behavior. The new finding took us into the field of habitat selection, a subdiscipline that our proposal had not anticipated. So neither writing a grant proposal nor conducting funded work leaves room for an unexpected discovery that leads to a new line of investigation.

Why am I suddenly so critical of the procedure for acquiring research funding from the National Science Foundation? You guessed it: sour grapes. I just learned that our proposal to NSF, which I spent most of my spring semester working on, was not recommended for funding. Two reviewers loved it, two hated it, and several others were on the fence. While I am in mourning now and shall be for some time, this is not a complete train-wreck; the reviewers were quite specific and helpful in their criticisms. So resubmission of a greatly-revised version of the proposal that addresses reviewers’ concerns might meet with a better outcome. At the moment, though, I am feeling like the Tin Man did after the Wizard’s request!

 

The Loon Project is my life’s work. While I greatly enjoy teaching Chapman students, serving on committees with my colleagues, and living in southern California, a part of me resides permanently in the Northwoods with the loons.

I inherited my love of loons. Mom introduced me to them in the 1970s when we made trips to Temagami, a deep, clear, sinuous, 30-mile-long lake in central Ontario. “Listen…..do you hear the loons?” she would ask my brothers and me as we lay beneath thick woolen blankets. As a resident of far-off Houston, I recall feeling awe, and some fear, to hear the mournful wails and maniacal tremolos echo across the huge lake. I wondered what messages loons could be sending each other in the middle of the night.

So I guess I was predisposed to study loons when I re-encountered them in Michigan’s Upper Peninsula in 1992. By the time I had finished listening to Dave Evers (then director of the Whitefish Point Bird Observatory) describe battles for territorial ownership that he and his staff had witnessed during their capture and marking efforts, I was hooked. At first, I implored him to conduct further research. “Your observations suggest a cool territorial system in loons, Dave. There are important questions about behavior and ecology to address here.” But Dave’s interest was not territorial behavior. If anyone was going to follow up those exciting early findings, I, a trained behavioral ecologist, would have to do it.

I began my loon study in 1993 and ran the project on a shoestring back in the mid 1990s. Then a postdoc at Indiana University, I really had no business setting aside my work on parentage analysis by DNA fingerprinting – expertise much sought-after by universities at the time – for a logistically-challenging project that required an enormous investment of time and energy. There was no low hanging fruit here. Several years were required simply to collect enough data to publish my first paper.

It took a decade — until 2003 — to pull together a sufficient cluster of banded loons and early findings to convince reviewers at the National Science Foundation that I was doing productive, cutting-edge research. I was awarded additional funding in 2007 and 2012. But funding rates for ecological proposals are now in the 7 to 9 percent range — roughly a third of where they were 30 years ago.

I love my work and have enjoyed learning about loon behavior, ecology, and population dynamics over the past 27 years. The project is more important now than ever before for loon conservation. With the future of loons in Wisconsin somewhat in doubt, our long-term measurement of breeding success and territory occupancy of marked birds in a large, fixed set of lakes provides us with a vital “early warning system” to detect population decline.

I am excited to invite you to support my efforts to learn about loon behavior and ecology while creating educational opportunities for undergraduates. Here is a link that will take you to our brand new “Donate” page. Thank you in advance for any amount you are able to give — and for your commitment to the loons of the Northwoods!

 

 

One of the challenges of behavioral research is to take notes that adequately describe the totality of what animals are doing. Since I am a behavioral ecologist, I devise a long list of behaviors that both appear important to the evolutionary fitness of loons and are also stereotyped or obvious enough for observers to record confidently on a datasheet. For example, when a loon bows its head so that its bill is pointing downwards instead of horizontally, we can all agree that it is exhibiting a “head bow”. When a territory owner slips quietly underwater, a nearby intruder flees across the water, and the owner resurfaces at the spot vacated by the panicked intruder, we recognize that the owner was “stalking” the intruder. We train field staff also to prioritize the recording of certain critical behaviors, like vocalizations, which reveal the motivational state of an animal and can be linked to particular stimuli occurring just beforehand (e.g. the flight of an intruding loon or eagle overhead). To aid new observers, we include a “cheat sheet”, shown below, that describes behaviors they are to look for and enter with our two-letter codes.

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Naturally, after 27 years of loon observation, we have seen or heard most of what loons can do. Indeed, we have analyzed many of these behaviors statistically to learn why loons carry them out. Yodels are a good example. By playing yodels back from loudspeakers to flying intruders, we were able to show that this call discourages many would-be intruders from landing on a lake and confronting the territorial pair. So a territorial male can employ a yodel as a means of defending his chicks from intruder attacks. Likewise, we have inferred that the mournful wail call must play a role in keeping pairs together and advertising for mates, because loons wail with great frequency: 1) when separated from their mates, and 2) when they lack a mate altogether.

But even two and a half decades of observation and statistical analysis of behavior is not enough to prepare us for everything loons do. This fact was brought home to me a few weeks back on Swamp. Following the death of the breeding female and departure of her former mate to Burrows Lake, an interesting new breeding pair had settled on Swamp. These new breeders fit the mold of many pairs we see: the female is a former breeder on tiny Prairie Lake but was evicted from there in 2015. She is at least fifteen years old and has reared six chicks to fledging. The male is a six-year old hatched on East Horsehead with no previous breeding experience. It is probably safe to say, after watching the video below, that he is still learning. To be clear, copulation in loons, when performed correctly, requires that male and female cloacas (genital openings) make firm and stable contact for several seconds so that sperm transfer can occur.

There are a few points to make here. First, though we might expect copulation, a very simple behavior pattern, to be largely instinctive, there are evidently some motor skills related to copulation (e.g. balancing on the female’s back) that benefit from learning. So males with no previous mating experience apparently fail in some early copulation attempts and must refine the behavior. Second, complex organisms show complex, non-robotic behavior patterns, especially when interacting with others of their species. Call it vertebrate bias if you like, but grasshoppers, crabs, and earthworms show a suite of behaviors that is relatively simple to catalog and describe. Loons, like squirrels and coyotes and turtles, sometimes carry out weird actions that don’t show up in the guidebook. So loon observers need to be ready to drop the two-letter behavior codes on occasion and just write down what the birds did.

Enough about science and field techniques. What I like most about this clip is that we can relate to it. If loons were humans, you could imagine the male saying, “Ok, wait….whoops….oh no…..whoa….oh gosh….umm….ok….nobody saw that, right?”

 

It was jarring two days ago to look at the database we use to track our breeding loons. During most years, the first week in June is the peak of incubation. At this time, breeding pairs that laid eggs early are well into the 28-day period that will carry them to hatching; others have lost an early clutch and replaced it. But steady, determined incubation is the rule at this time of year.

Not so this year. As the screen grab from Evelyn and Tarryn’s data entry shows, 2019 is yet another year of severe black flies. I had a sinking feeling that black flies would be a plague when I was in the study area in May.

As our recent paper shows, cool springs are killers. In years when April and May are cooler than average, black flies live longer than average. From the standpoint of a female fly, cold weather makes flight and dispersal more difficult, so a female in a cold spring is likely to delay her quest for the blood meal she needs to nourish her eggs. Not all females postpone reproductive activity, however, so cold springs reduce synchrony between female flies. The result, from a loon’s perspective, is a longer period when flies are around to harass them on nests. In contrast, warm springs cause a well-synchronized explosion of fly biting activity. During warm years, Simulium annulus blackens the skies for a few days and exacts an awful toll on incubating pairs during that brief period. Many pairs, though, are able to weather the onslaught, maintain viable eggs (no doubt aided by warm temperatures), and incubate the eggs to hatching despite the interruption.

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Elaina’s photo of the nest on Hilts Lake is typical of what we see in a cool spring. Flies are abundant, to be sure. In the photo, you can see many in the air above the nest but also scores hanging onto the arched roof on this platform. There are enough flies around the nest to keep the pair from incubating the eggs, but few enough so that this infestation does not reflect an explosion, such as would occur in a warm year.

Screen Shot 2019-06-10 at 11.07.16 AMNow that I have got you worried — sorry — you must be wondering where 2019 ranks relative to other years. What kind of productivity can we expect? I ran a quick back-of-the-envelope analysis by comparing rate of chick production in each year with the proportion of pairs sitting on nests during the first week of June. Even with the one “outlier” (2013), there is a tight correlation. That is, we can usually tell pretty well how productive a year our loons are going to have by looking at the proportion of all pairs on eggs in early June. If 2019 falls near the line, then the 0.45 proportion of sitting pairs in early June of this year predicts 0.42 chicks per territorial pair. This is not terrible — look at 2011, for some perspective — but not what we had hoped.