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Recently, Eric, a second-year team member who is experienced at reading colored leg bands, ran across our oldest loon. This male, evicted in 2007 from Little Bearskin Lake, has been cooling his heels in Bearskin Lake since his displacement and shows no indication of regaining a territory. “Blue over Silver, Yellow only” produced 14 fledglings during his breeding career, 7 of which also bred in the study area. That level of chick production places him among an elite few in our study population.

Blue over Silver, Yellow only’s age sets him apart from all others. He is at least 28 years old, because he was banded as an adult breeder, which means he was at least 4 in 1991. He may be in his 30s. But a number of other loons that we have marked during the study approach this male in age — and three exceed him in productivity. The female on Upper Kaubashine (“Silver over Yellow, Red over Green”), for example, is 27 years old at a minimum. (Females first breed at no younger than 5 years of age, so her estimated minimum age is one year older than if she were a male.) She can boast having bred with four different partners on four different lakes, spanning two counties. The 25+ year-old Townline male, “Silver over Red, Orange over Green”, is unrivaled in terms of stick-to-itiveness, as he has held the Townline territory since at least 1994 — and still owns it. He has reared 16 chicks to fledging during his tenure, if we throw in the two from this year. Only two loons have raised more young: the current Oneida-West female (19 fledglings and counting on Oneida-East and Oneida-West) and the former Hancock male (17 fledglings from 1993 to 2009).

Although it is fun to gawk at the age and breeding success of certain star individuals, my quick analysis of the study’s oldest loons reinforces another point that I have made before — and one with substantial scientific importance: females are the ones that generally live to a ripe old age in loons. The reason(s) for this gender disparity are becoming clear. Males seem doomed to die young because of their participation in dangerous battles, and perhaps also their unfortunate proclivity for attacking fishing lures and baits. Inspection of the table above certainly makes one wonder whether males should rethink their high-risk approach to both territory acquisition and foraging. Then again, maybe there are compensating benefits that offset the costs.

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image1Chris checked in on the Flannery-Velvet chick today. The chick, whom lake residents call “Houdini” because of his ability to escape certain death, continues to inhabit this odd world where it is necessary to hide under piers and avoid adults — rather than fraternize with two parents who feed him to satiation. When his mom is not bonding with a new male up on Flannery so that she can prepare herself for future breeding attempts, she spends time with him down on Velvet. Today Houdini begged from his mom repeatedly, but he also foraged for himself during a considerable period.

The photo above, generously supplied by Hugh Jones who lives on Velvet, is notable for two features. First, it shows a chick that is in full adult-like feather. That is, it has outgrown its chicklike, downy plumage and assumed adult attire. This fact, of course, is comforting, as it shows that the chick is getting the nutrients it requires to mature and prep itself for independence and migration to the wintering ground. Second, however, the chick continues its retiring ways. It has learned to avoid adults, because of the occasional beatings it had received from its stepdad. So it seeks protection, using whatever piers and pontoon boats will give it cover.

We have never witnessed a situation like this one. In all other cases, chicks that lost their fathers were either: 1) several weeks old and recipients of abundant feedings from their mothers, or 2) summarily ignored by their stepfathers and permitted to grow and mature without interference. Since we are in uncharted waters, we can only be cautiously optimistic. All we can say is that Houdini — whom LP personnel know attactionately as “white over white, pink over silver”, from his leg bands — continues to pass developmental milestones despite daunting obstacles.

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“Wow”, Lainey said, “that band number is right next to the female we caught last night on Sherry”. She was right; the adult male from Skunk, which we had just netted and whose band number I was reading aloud to Lainey for data entry during banding, had a number imprinted on his aluminum USGS band that followed immediately after that of the Sherry female from the previous night. The reason for consecutive bands is that the Sherry female is the mother of the Skunk male and was caught and banded with him a decade ago (less two days) on Sherry Lake. I remember July 31st, 2005 on Sherry vividly, because I was equipped with a video recorder on top of a helmet with which we recorded the capture process for research presentations. But the recapture of mother and son on back to back nights ten years after we had first marked them has also caused me to reflect upon several key features of loon biology that have become familiar to me through my work.

First, loons live a long time. In this twenty-third year of my work, I still encounter birds in the study area that were on territory, as adults, when I first started covering them. Females, in particular, are survivors. While males have rather high mortality –partly owing to their proclivity for battling dangerously — females linger. When their mate dies, females find another; when a female is evicted unceremoniously from her territory, she stoically moves to a new lake nearby and awaits a chance to re-insert herself back into the breeding population. So it goes with the Sherry female whose worn-out band from 2005 is pictured on the bottom in the photo. She was “widowed” suddenly in 2009 (a possible eagle kill) but hung onto her territory and was joined by a new male in short order, who has been her mate since.

Second, young males do not disperse far from their natal lakes to breed. The Skunk male, from whom we removed the top band in the photo last night, moved about 15 miles from his natal haunt, Sherry. That dispersal is, actually, a bit longer than average for males, many of whom settle to breed on a lake adjacent to where they hatched years earlier. Short-distance male dispersal is essential to my work; without it, I would not have a large marked cohort of 2 to 5 year-olds of known age and natal origin in the study area at all times whose territory settlement strategies could be investigated. (At last count, we had seen 295 adult loons in the study area that were marked originally as chicks.)

Third, loons vary tremendously in their behavior towards humans. My assistants and I dread the Sherry female, because she is the most skittish individual we know. She cannot be approached easily within 100 meters on the water; she tremolos (i.e. alarm calls) incessantly when a chick is present and a canoe appears on the water. In fact, my assistants tell me that she begins to tremolo in anticipation of a canoe being placed on the water and that they have begun a strategy of hiding behind bushes and trees along the shoreline in order to make observations of her when she is with the chick. (Fortunately, Sherry Lake is tiny, so this observation strategy is workable.) I joked that we should wear camouflaged clothing when visiting Sherry; my assistants did not find this funny. Oddly, the Sherry female’s mate is among the tamest loons we study and never tremolos at us when we collect data there.

The great variety in loon tameness is a topic of great interest to us, as I have mentioned. It amazes me that an adult such as the Sherry female could react so strongly (and, it would seem, maladaptively) to humans, which she encounters constantly. Doesn’t she waste energy with her fruitless calls? Shouldn’t skittish birds like her leave fewer offspring and live shorter lives than other adults who tolerate humans without constant complaint? If so, she is not a good example of the pattern, as she has behaved this way for the ten years we have known her while cranking out chicks. Indeed, the Sherry female and the Oneida-East male, another vociferous but fecund individual with whom my staff has to cope, make me wonder if I have got it backwards. Maybe loud-mouthed loons warn humans away, lessening the likelihood of injury to themselves and their brood, and are rewarded with high evolutionary fitness.

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For the past several years, we have covered Blue Lake, which contains two loon territories: Blue-West and Blue-Southeast. Blue-Southeast is the more productive territory. In fact, it has produced chicks for the past 3 years. A few nights ago, we captured and banded the two chicks and female from Blue-Southeast. We thought nothing amiss in finding the chicks with only one parent; it is common during both day and night for either male or female to watch over the chicks while its mate wanders off to feed on its own.

What was odd that night was that, on our trip to return the Blue-Southeast female and chicks to their territory, we blundered upon a banded loon pair where none should have been in an area that might be called “Blue-Central”. We captured one of this new pair (a six year-old female hatched on Franklin Lake, some 40 miles east). The other pair member, it seems, was the male from Blue-Southeast! While it is tempting to make some tawdry comment here about the skirt-chasing tendencies of males, this was not a case of the Blue-Southeast male cavorting with another female while his mate cared for the chicks. In fact, the new Blue-Central male had been evicted from Blue-Southeast several days before, which forced him to leave his chicks in the care of his mate and the male that had evicted him. Moreover, reports of a banded and injured bird on Blue in the few days prior to our visit lead us to believe that the vanquished male had been seriously injured in the battle that cost him his territory and separated him from his mate and chicks. (Clearly he had recovered from his wounds by the time of our visit.)

The current situation on Blue-Southeast is a bit worrisome and quite similar to that on Flannery Lake. There too, the territorial male was lost during chick-rearing, forcing the female to care for the chicks alone, while seeking to re-pair with a new male. On Flannery, a new territorial male killed one of small chicks — though the other is alive and now 6 weeks old. On Blue-Southeast, the chicks were far older at the time of eviction, but a recent visit by Seth revealed that the new male (sadly, an unbanded bird) is paired with the female and is pecking at the large, healthy chicks and not feeding them. Based on past observations, we hope and expect that these chicks are old and strong enough to mature and fledge despite their step-dad’s hostility, providing their mother continues to feed them. However, the awkwardness of a mother-stepfather pair with chicks seems to have consequences. The Flannery chick, captured and weighed a few nights ago, has far lower body mass than he should for his age. Let’s keep fingers crossed that the Blue-Southeast chicks, which are strapping youngsters at present and live on a large lake with a strong record of fledging chicks, can weather this parental storm.

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In his routine visit to Two Sisters Lake to check on the status of an incubating pair, Chris was alarmed to find out that the male had a hook lodged in his cheek and fishing line protruding from his bill. This male — captured and marked in 2010 as a breeder on Brown Lake before being evicted two years later — had been a “floater” for the past three years before replacing the absent Two Sisters male this spring. I was thrilled to see this tame bird get his life back together.

When Chris reported the hook in this male’s bill, I wondered if this bird was just snakebit. The entanglement could not have occurred at a worse time. The male and his mate were on the brink of completing four weeks of incubation and hatching of two chicks, which require great care and protection at this stage. Indeed, between yesterday morning and afternoon, the male had finished incubating the second egg and left the nest for good with two head-sized chicks alternately hiding under his wing and riding on his back. Attentive as he was, the hooked male was ill-equipped to defend his brood. As we have learned recently, male loons are especially vital to the defense of a pair’s young chicks, because the male-only yodel discourages landing by intruders (which, on occasion, kill young chicks) and because males are active defenders of chicks towards intruders that approach them in the water. With the hook lodged in his mouth, the male was unable to open his bill, and his protective vocalizations yesterday were so muffled and distorted as to be ineffective.

Upon receiving the report of the hooked male yesterday, we agonized over the decision of how to proceed. Adults with small chicks are the easiest to capture, so we were not worried about catching the male. However, one must take great care when young chicks are present, as they are tiny and are always on, next to, or underneath the wings of the adults. When one is netting the 10 to 12 pound parent and hauling it into the boat, it is conceivable that an unseen chick might be crushed beneath it. Would it be wise to wait for a few days or a week, until the chicks were larger and stronger, before attempting capture? In the end, we decided that the male was impacted enough that we were endangering his life and those of the chicks if we did not act immediately to help him. So last night, Joel, Eric and Seth set out on Two Sisters to try to: 1) gently separate the tiny chicks from the male, and 2) catch the male so that the hook could be safely removed by Mark Naniot of Wild Instincts, who was standing by on shore.

As you can see from Seth’s photo, we caught the male, and Mark expertly removed the hook from his cheek. The chicks were unharmed in the process. The male seemed in good shape, considering his close encounter with an angler’s line. (We suppose that he became hooked only a day or so before we caught him.) Still, we shall be checking today to see that the family is back to normal. While there are many dangers facing loons in the first few weeks after hatching, the team of rehabbers and loon researchers has given them a chance to confront these dangers without human impacts layered on top!

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We have almost completed the first round of visits to study lakes. Our ever-expanding list of lakes makes this no mean task, as our list has grown from 95 territories in 2008 to 123 this year. Kudos to the field staff of Joel, Eric, Chris, and Linda (whose photo appears above), who have worked hard to visit lakes and ID loons from leg bands — and also Al on West Horsehead and Pat on Silver Lake, who have e-mailed with data from their lakes.

Of 162 banded loons on territories as of late 2014, 141 (or 87%) have reclaimed those territories this spring. Among 21 missing territory holders from 2014, 4 have been resighted in 2015, but were apparently evicted from their territories early this year. Thus, the minimum survival rate from 2014 to 2015 for territory holders is about 90%. This figure agrees closely with survival rates calculated from Wisconsin and elsewhere within the breeding range.

Sky-high return and survival rates for our population highlight a simple pattern in the life history of common loons. In ecological terms, loons are “K-selected”. That is, they are long-lived, take several years to reach sexual maturity, produce few offspring during their lives, and invest heavily in parental care for the few offspring they do produce. Loons are not explosive reproducers that “shot-gun” many offspring out into an uncaring environment in hopes that a few survive. Rather, they work hard to maintain ownership of their breeding territory, eke out one or two chicks a year (in a good year!), and defend their chicks vigorously against all comers!

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By any reasonable measure, 2014 has been a dreadful year for loon reproduction. Even if we capture every remaining loon chick that we know of, our total number banded will be almost exactly half of last year’s total. Clearly, the black flies hit the loons’ breeding efforts in the mouth, and they could not recover. Still, it is only one year. As my work has shown me over the past two decades, breeding success is a roller-coaster. In fact, if you combine last year’s bumper crop of chicks with the withered output of this year, the message is that loons are producing enough chicks to sustain the population. So all is not lost.

There have been a few bright spots this year. Though we were alarmed in early June when the Jersey City Flowage male ingested a fishing lure and became hopelessly entangled, the folks at REGI were able to save the bird, he was released near his old territory and recovered — except for possession of his territory! The REGI folks were brought an emaciated chick found by a roadside that they fed back to reasonable health and that we were able to foster successfully to a loon family that has raised it as their own. We recently banded both this fostered chick and its sibling, a true biological chick of the pair. Both chicks have become big healthy, strapping young birds, thanks to their parents’ tireless efforts.

In short, life goes on. I am confident that we will long remember 2014 and not wish to repeat the experience. But perhaps we should best remember 2014 as a year that, while dismal for chick production, was balanced out by strong reproductive years surrounding it and did not pass by without a few cheerful tidings.

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We just got a report that a pair of our loons is back, and this is the first pair of the year. Up to now, our pairs have had to content themselves with overflights of their territories to look for open water, which would allow them to land. At other times, they wait (mostly along the Wisconsin River) for their lake to open up. But according to Linda Grenzer, who is super hawk-eyed and on the ball, about 20% of her lake (Muskellunge in Lincoln County) was ice-free by this afternoon, and that was enough to permit the banded pair there to land and begin to defend the territory anew.

The Muskellunge pair that Linda found today is well known to us. The male there is a very tame bird whom we banded on as a chick on Manson Lake in 1998 and who produced chicks with a first female on Deer Lake in 2003 and then bred successfully with her again there in 2004 and 2005. In 2006 and 2007, Deer yielded no chicks. As we have seen with numerous other males, this male then gave up on Deer, evicted the male on Muskellunge (right next door!) in 2008 and paired with a new female there. He has twice produced chicks on Muskellunge and seems firmly ensconced there now. The Muskellunge female is also an interesting individual, as Linda caught her spending some of last summer hanging out with and feeding a chick from Clear Lake (also next door to Muskellunge) when her own chick had shifted to a new lake! Furthermore, Linda photographed this female while she was molting, and I posted the photos on Nov. 28 of last year.) Kudos to Linda for all of the sleuthing. I do not believe her breeding loons do anything interesting without her recording it from her kayak nearby.

Since this post has become mostly a tribute to Linda’s great field work, it is fitting to end up with a photo she sent me a few weeks back. She took this photo on the Wisconsin River near Tomahawk on 14 April. If you look closely, you will notice that one of the colored leg bands has a geolocator tag attached. The tag from this male, who is, by the way, from a territory up in Vilas County, will provide a good deal of information on his past migratory movements and foraging patterns that might help USGS biologists learn about the occurrence of avian botulism, which kills many loons.

 

 

Linda Grenzer photo from April 2014 Wisc River

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It has been awhile since my last post. Sorry about that. With our study animals hunkered down in the Atlantic — mostly off of Florida — there has not been much to write about. But they are molting now, beginning to vocalize, and are readying themselves for a return to Wisconsin. Although the northern weather is not cooperating at the moment, our study animals will soon begin winging their way north.

Even after the summer, though, we accumulate data on our birds. How? By receiving reports of recoveries of our loons during migration and on the wintering grounds. Now, a “recovery” is, in essence, an unpleasant event. The term refers to a report of a bird banded with a U.S Fish & Wildlife Service metal band that has died, been found, and been reported to the Bird Banding Lab in Patuxent, Maryland. I get an e-mail from the BBL each time someone recovers one of the loons we banded. When I see the BBL address pop up on my phone, my pulse races, as I fear that one of our valuable breeding birds may have died. Each time we lose a loon that we have known and studied for 15 years or so, I grieve a bit. This happened two years ago when I learned that the long-time breeding male from Hancock Lake had died. More often than not the news from the BBL is sad but not devastating, as most of the recoveries are of first-year loons — birds we banded as chicks the previous summer that did not survive their first fall migration or winter. We are always sad to lose a bird we banded, but we understand that its first months of life pose a severe test for a loon, as it must complete migration, learn to forage in the ocean, and face a set of dangers to which it is unaccustomed.

Something positive emerges from recoveries. As we accumulate a record of which first-year loons have died and which have survived, we have a chance to confirm a pattern that we detected recently from our summer work. Young hatched on small, acidic lakes return to the breeding grounds at a lower rate than those hatched on large lakes of neutral pH. We do not yet know at what point this difference in mortality occurs. Do juveniles from small, acidic lakes fail to make it off of the breeding grounds? Do they die disproportionately during fall migration? Or do they tend to die in larger numbers after reaching the wintering grounds? Recoveries of these young birds during late summer, fall migration, and winter — as sad as they are — can provide us with the valuable answer.