chick

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The saying “success breeds success” was not coined with loons in mind. But we humans know from experience that an initial success can increase the likelihood of a second one. Indeed, I relearn the value of accumulated experience each spring during the period when I train field observers. With no background in the technique, new observers are utterly astounded when we locate the first nest of the year. After five more nest discoveries, though, they begin to develop a “search image” for nests. It is a thrill to see them learn quickly over a period of a few days to the point where they begin to point out loon nests to me!

Loons are not complete strangers to the benefits of learning. Males often place nests in poor locations when they first attempt to nest on new territories. After a bit of blundering about and some poor decisions, males typically find a nesting spot that results in a successful hatch. Afterwards, they reuse that good spot again and again, enjoying much greater success than during their first attempts. Thus, nesting success following an initial period of failure leads to further nesting success.

The impact of a loon pair’s nesting success on territory defense is another matter. The loon territorial system differs in a crucial respect from those described in other species. In many birds, most notably colonial seabirds, young adults prospect for good breeding sites by looking to see where other adults have produced chicks. When these young seabirds settle to breed, their settlement has little or no negative impact on adults already breeding at the huge colony. Not so in loons. Young adult loons prospecting for territories use chicks they spot on a specific territory as a badge indicating quality of that territory alone. Young prospectors must battle the current residents for ownership of such high-quality territories. That is, chicks seen in one year induce prospectors to return the next seeking to evict the owner of their sex and claim the territory for themselves. So adults that produce chicks experience the joy of parenthood…..but have also placed their future territory ownership in jeopardy.

The mixed blessing brought about by successful chick-rearing is nowhere more obvious than on the Pelican Lake-Mousseau Bay territory in the Minnesota Study Area. Online observers watching via the live nest cam were treated to a lengthy battle between two adult loons a few days ago. While the battle was shocking in its brutality, it was not surprising. We have long known that the successful rearing of chicks leads to a surge in interest in the territory and, hence, the likelihood of territory loss by one or both breeders. After raising two strapping chicks last summer, the male and female of Mousseau Bay must have braced themselves for a litany of territorial intruders and challenges. Indeed, the banded 2022 male apparently lost his position this spring; last year’s marked female is now paired with an unmarked male.

And yet there is hope. Yesterday, the old female laid an egg. She and her new mate both seem anxious to sit on it. If they can weather the blitz of black flies currently dogging their incubation efforts, they stand a good chance of repeating last year’s success.

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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.)

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It seems ages ago when my team was out on the lakes, finding pairs with chicks, capturing and banding them — then hastily storing our canoes and the Loonmobile for the winter. So much has occurred since early August that those frantic days linger in my brain only as a hazy memory.

But the loons stayed on. While I was vacationing in the East, attending faculty retreats, and lecturing with a mask and fogged glasses so that we could keep classes in-person, loon parents continued to stuff their young with food, chicks matured and learned to fly, and most adults abandoned their territories for the Great Lakes. Even now though, as I brace myself for that peculiar mixture of joy, renewal, and mortification that only Thanksgiving with family can bring, loons remain on many small lakes in the Upper Midwest. Most are juveniles, like the one in Linda Grenzer’s photo, which often postpone migration until the very last second. This strategy probably permits them to maximize their energy reserves for their first long overland journey to Florida.

So hold a good thought for the stragglers. The Brandy Lake chick, which a lake resident told me about in an anxious e-mail today, is among them. Perhaps by the time we are all sitting down for our Thanksgiving meal, that strapping juvenile will have begun winging his way anxiously in a south-south-easterly direction. Though he cannot have a clear picture of his destination, he will cease his migration off of Cedar Key, Panama City, Tampa, Fort Myers, or Apalachicola. For a time he will be that nondescript brownish diving “duck” that some young family from Nebraska watches distractedly while building their sand castle. Let us hope that we see him back up north in a few years — and in more striking attire.

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Although most of our research team is long gone by September, Linda and Kevin Grenzer remain in Wisconsin. At a time of life when most folks widen the dimples in their BarcaLoungers, these two are devoting their time to rescuing injured birds. (Linda, of course, is also one of our field team members and a gifted photographer to boot!)

Linda and Kevin have gotten more proficient at rescue in recent years. Four years ago, they often found themselves hours from home on some false alarm — an eagle that was heat-stressed but recovered; a loon that seemed wounded but was merely preening. These days they insist on seeing photos or getting vivid descriptions of injured birds from experienced observers before setting out to save them.

After Ken and Joanne Lubich sent us the photo at the top of the page, it was clear that a bird was in trouble. The Lubiches keep a close eye on the two loon pairs on eyeglass-shaped Two Sisters Lake. On a routine patrol around the lake on September 13th, they were horrified to see that one of the two strapping chicks on the east lake had a huge muskie lure attached to its left leg and was swimming erratically.

It might seem difficult to find the positive here, but, in fact, this chick was fortunate. The Lubiches keep a close eye on the loons on Two Sisters and have a network of contacts who live on the lake. Thus, the distressed chick was found only a day or so after being hooked. Furthermore, Joanne and Ken know Linda and Kevin and immediately reported the hooked bird to folks who could help it.

Once they made it to Two Sisters yesterday, Linda and Kevin were able to capture the distressed chick, when it ventured close to shore. A quick inspection told them that at least two of the hooks on the lure had punctured the chick’s foot tissue and become infected. They decided to transport the bird to REGI for treatment.

As is evident from the photo below, we had captured and banded this chick. On the night of capture, July 13th, the bird weighed 2460 grams. Yesterday, the chick weighed 2470 grams, which means that it was only 10 grams heavier yesterday than it had been two months before. This tells us that the bird has lost a great deal of weight — perhaps 500 to 600 g — owing to the hooking. Needless to say, loons go downhill quickly when they are prevented from feeding themselves. This bird probably fed little or not at all for six days.

The world is looking brighter for this chick. Multiple hooks were removed from its foot. One hook was too close to a bone to remove and had to be left in the bird. (REGI staff hope that swelling in the foot will push the hook out in time.) If its injured left leg recovers, and it becomes fully mobile again, the bird will be released in a few days back on Two Sisters. Meanwhile, this loon is taking full advantage of the favorable fishing conditions provided in its temporary home!

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The phenomenon is absurd on its face. A loon chick wholly dependent upon its parents for food and protection abruptly abandons them, swims to the shoreline, and sets off through the woods. Hopelessly adapted to an aquatic propulsion because of the posterior attachment of its legs, the chick skootches itself along the ground, resting on its belly at intervals. What could possibly induce a chick to leave its familiar home and loved ones and commence such an awkward and dangerous journey?

If seen only once, a loon chick taking an ill-advised jaunt through the woods would seem like an anomaly — the behavior of a mutant and doomed animal. Indeed, when compared with typical chick behavior, such a reckless journey by a single chick seems to underscore how faithfully most chicks stick with their parents and territory.

But we have witnessed desperate overland treks of chicks many times now, beginning in 1999. On July 15th of that year, I sat on 27-acre Benedict Lake and watched a two-week-old chick get pecked mercilessly by its older sibling. Three days later the abused chick was spotted several hundred yards from the nearest shoreline of Benedict on Witches Lake Road. On July 19th I spotted the youngster again — but on Bug Lake, close to a kilometer’s distance from Benedict. Clearly the youngster had dragged itself out of its home lake, through dense woods, along a country road, and had finally come to rest on a neighboring lake.

As it happened, Bug Lake, though only 21 acres in size, also supported a loon pair. But the Benedict youngster was not well-received there. You see, the loon pair on Bug had also hatched a chick, and that chick was already six weeks old when the tiny refugee from Benedict came calling. As I watched helplessly from the shore, both the male parent on Bug and the giant Bug chick pecked at the Benedict chick, which responded by keeping its head submerged most of the time. Four days later, the Benedict chick was gone.

Followers of the blog may recall another occasion when a chick faced adversity at home, abandoned its natal lake, and bushwhacked its way to a neighboring lake. In this case too, the refugee found a loon pair that had hatched chicks. This time, though, the displaced chick, a six-week-old from Cunard Lake, had better luck. The two chicks already being cared for on the neighboring lake, Hasbrook, were scarcely a month old. Apparently the larger size of the Cunard chick helped it overcome the home-court advantage of its smaller step-siblings. It quickly joined the family and was fed and treated well by both foster parents (see Laura Unfried’s photo at the top of the page.)

A few weeks ago, a singleton chick from Bass Lake set off on a desperate journey from its home lake. No lake in either our Wisconsin or Minnesota study area is more isolated than Bass; it is at least 4 kilometers from the nearest lake inhabited by loons. Indeed, the Bass Lake chick was found wandering along a road and not near any lake. A similar event occurred when the youngest from a rare three-chick brood on Virgin Lake abandoned its home lake in early October 2019 and ended up next to a highway. Sadly, the Bass chick was too emaciated to recover despite being fed by a rehabber. The Virgin chick was fattened up and released on a large lake in the area. Although October is a bad time for a chick to be starving and try to regain its health — and migrate — there is a chance that the Virgin chick survived and made the flight southwards.

How are we to understand the decisions of chicks — ranging from two to thirteen weeks of age — to jump ship and head out across the land? I think the pattern has become clear from the four examples described here and several other cases reported by rehabbers like REGI. Food shortages on small lakes have dire consequences for loon families. Loon chicks are entirely dependent upon food in their natal lake, until they are able to fly off of it. So if food runs short (or an aggressive older sibling prevents them from getting any), chicks can either leave the lake or starve. Striking out across the land is a longshot bid by a defenseless chick at any age. It is far more likely to be eaten by a coyote or a fisher — or simply die of starvation — than to find a foster family willing to take it in. But when staying at home means certain death, even a longshot journey becomes an acceptable option.

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Yes, it has come to this. Chick production of breeding pairs in northern Wisconsin has declined steadily during the past quarter-century. Black fly outbreaks have made hatching success even worse in the past five years. So we are searching desperately for a positive outcome that we can greet with a sigh of relief. And we have one: breeding success has ticked slightly upwards in 2021.

I wish I could report that breeding success has rebounded with a vengeance. After a dreadful 2020, I felt that a strong rebound might be in order. But the recovery has been modest. Looking at the numbers, only three breeding pairs in our study area had chicks as of this date in 2020. That laughably low number resulted from 97% abandonment rate of May 2020 nesting attempts owing to black flies. Meanwhile 59 pairs were incubating eggs on this date in 2020. As of August of last year, 36 pairs were rearing chicks. This amounts to about 33% chick production in 2020 (36 of 110 breeding pairs). At present, we have 24 pairs in Wisconsin raising chicks and 41 other pairs still sitting on eggs. If we use the 2020 nesting outcomes to project 2021 success, we should end up this year with roughly 46 of 110 pairs with chicks in northern Wisconsin. A 42% breeding success rate is nothing to crow about. But since I am a positive person, I will choose to focus instead on the 28% increase in chick production between last and this year!

What about Minnesota? We have only just arrived in Minnesota and have no data from 2020. So we are not able to provide a very calibrated picture of breeding success in the Crosslake area, where we are located. Furthermore, Crow Wing County, where we work, is running about a week behind Wisconsin, so our data are even more preliminary in Minnesota than in Wisconsin. Still, we can already say that 2021 was a light black fly year in north-central Minnesota, as it was in northern Wisconsin. And that is a good thing. Out of 104 territorial pairs we are currently following in the Crosslake area, Jordana and Katy reported a few days ago that 13 have chicks and 42 are on nests. We estimate that the total pairs with chicks will number about 40, by the time August rolls around. But we are still scouting many of our Minnesota lakes, so that number could grow to 50.

Scouting new lakes is a tricky business, by the way. Going onto a new lake with no information on previous loon usage or breeding success forces you to read the behavior of loons on the lake to infer if those you see are: 1) an established pair that has is not currently incubating eggs, 2) a pair that hangs out together but never breeds, 3) an unpaired young floater, or 4) the “off-nest” member of a pair, whose mate is on a nest on the lake. Katy and Jordana’s daily sleuthing has been effective so far. But sometimes you misread the signs, which, in fact, can be thrilling. No doubt a few lakes where K and J found no loon or only a skittish loner on their first visit will offer a view like that in Linda’s photo on their second.

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I have spent my entire academic career making logical deductions about animal behavior. In the early 1990s, I was part of a team of ecologists at Purdue University studying the peculiar cooperative breeding behavior of stripe-backed wrens in central Venezuela. This species could hardly be more different from the common loon. Stripe-backed wrens live in social groups of up to 10 adults, headed by a dominant male and a dominant female, which, we thought, were the only group members to breed. The other group members comprised adult offspring of the dominant male and female that had remained at home as breeding helpers instead of dispersing to breed on their own. When DNA fingerprinting revealed that subordinate males in some groups sired young through matings with dominant females, it surprised us. Seeking to follow up on the striking genetic pattern, I reasoned that the behavior of the wrens should reflect the mixed paternity of the offspring. Specifically, I predicted that: 1) subordinate males were probably actively pursuing matings with dominant females, 2) dominant females were likely seeking out matings with subordinate males, and 3) dominant males were probably not happy about these liaisons and might be expected to attack subordinate males in an effort to deter their amorous proclivities.

My predictions were not rocket science, of course. Though we had no inkling from past behavioral observations that anything but strict monogamy was occurring in wren groups, it stood to reason that we had missed some social behavior that might have clued us in to the mixed parentage pattern we discovered in the lab. Indeed, my behavioral study of the wrens during April and May of 1990 and 1991 revealed all three predicted behavior patterns. During the “fertile period” of the dominant female, the dominant male and various male helpers vied to remain in close proximity and copulate with her when she was receptive. Aggression among competing males was fierce. Dominant females, it seemed, encouraged competition among males wishing to mate by openly advertising their readiness to mate. However, this suite of aggressive and mating behaviors only occurred in “stepmother groups” — those in which a past dominant female that was the mother of all the male helpers had died and been replaced by a “stepmother” from an unrelated outside group. In fact, the death of a dominant female was a crucial event in a wren group, because it turned a staid, monogamous breeding system into all-out warfare between her husband and sons to mate with her successor. Sorry…….I had not meant to go on about my old wren work, but those interested can check out this paper.

Here is my point. As I said, one could hardly hope to find two species more different than common loons and stripe-backed wrens. From the standpoint of a behavioral ecologist, the wrens would seem to offer a cornucopia of research opportunities: helping behavior, living in social groups, deferred breeding by helpers, mating competition. Many questions about the complex wren breeding system remain unanswered. (It does not help that one must travel to an unstable country that generally dislikes Americans and tolerate dreadful living conditions on a ranch overrun by aggressive feral pigs.) But one lesson I have learned is that close scrutiny of any animal’s behavior reveals unsuspected richness and complexity.

The monogamous mating system of loons would seem to offer little to the behavioral ecologist. But the peculiar — possibly unique — system by which young adults seek to learn about breeding territories and established breeders seek to deter their efforts is a gold mine. Consider late-summer social gatherings. The three sets of attendees at these gatherings have recently come into sharp focus, as I describe in a new page I have added to the website. Now that we understand which loons are attending social gatherings and why, we can generate specific predictions about how different attendees should behave that provides a framework for future research.

If members of a territorial pair are trying to safeguard their territorial tenure from floaters, which try to find chicks and use chicks as a badge of quality to target pair members for eviction, pair members should take pains to hide their chicks from floaters during social gatherings like the one shown below.

Thus, we can predict that parents of chicks should lead floaters and other intruders at social gatherings away from the part of the lake where their chicks are hiding and generally discourage exploration of their breeding lake. Furthermore, parents with chicks should behave aggressively towards intruders in cases where a “flotilla” of adult loons approaches the place where the chicks are stowed. How should breeding pairs behave that have failed to produce chicks? They should encourage intruders to explore all parts of their territory, because they want floaters to conclude that there are no chicks present and that the territory is not worth fighting for. For their part, floaters should always try to move about the territory as widely as possible in an effort to spot any chicks present. Finally, how should intruding neighbors behave? Like floaters, intruding neighbors should wander widely in another pair’s territory and induce other intruders to do likewise, in order to maximize the likelihood that floaters spot the chicks of the home pair and return the next year to evict them. In cases where one or two loons appear to “lead” the flotilla about the territory, such as the two left-hand adults in the video, the leaders should tend be floaters or intruding neighbors, not members of the home pair (unless the home pair is without chicks).

Naturally, it will take a lot of work by observers skilled at identifying loons from color bands to test these fine-grained, specific predictions about loon behavior during social gatherings. But now that our long-term probing of loon social behavior has exposed a richly textured system of social information and deception, I relish the challenge.

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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.

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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.