New Findings: Eviction Breeds Eviction!

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As most of you know, most loons acquire their territories by force. That is, a non-breeding adult intrudes into a territory defended by a breeding pair, challenges the pair member of its sex, battles with that pair member and, if lucky, evicts that owner. (An evicted owner is sometimes killed in battle, especially if it a male, but more often simply leaves its former territory after a defeat and looks elsewhere to settle.) By the way, evictions (also called takeovers or usurpations) are about equally frequent in males and females.

We have now observed or inferred 226 territorial takeovers, and we are at a point where we can begin to look for other patterns in these data. I have been analyzing the data to learn whether one eviction leads to another. For example, if the territorial male on a lake gets evicted, does that place his mate at risk for losing her position as breeder as well? Based on 2207 breeder-years of data, the answer is a resounding “Yes!”. When a male is evicted from his lake, his mate is at substantial risk for losing her position. Female eviction also exposes male breeders to an increased threat of eviction, although the pattern is not as strong.

What can we make of this pattern? It is early, and many analyses remain to be completed, but here is an early read on this finding. Breeders are largely stuck with the danger of eviction and with the problem that their mate’s eviction threatens their own position. Females, which are about 20% smaller than males, are really in a bind, as their size probably prevents them from helping their mate avoid eviction — thus protecting themselves indirectly. On the other hand, males might be expected to chip in and help their mate drive off a would-be usurper, if doing so protected their ownership as well. Yet we have never observed a male teaming up with his besieged mate to drive off a potential usurper. If this happens, it must be rare. Indeed, males appear to be dispassionate observers of female battles for territorial ownership, despite the risk it poses to them. Why? Perhaps males are better off with a mate that fights strongly (such as a proven usurper), since having a vigorous mate ensures future years of eviction-free breeding. It is a bit sad and selfish to say it, but if your mate is vulnerable to eviction, it is probably best to let her fend for herself than to intercede and save her.

The Upside of Loon Recoveries

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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.

What I am working on…and some photos

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Well, the loons are gone from the study area. I know we all miss them. Each year I mourn after the loons migrate south and we all have hunkered down for the winter.

But research goes on. I am in the midst of an analysis to learn whether loons that have settled on one lake and bred there — either successfully or not — choose a second breeding lake that is similar to the first. What I am asking here, in effect, is whether a loon learns what constitutes a good breeding lake through its reproductive efforts and applies what it has learned in subsequent reproductive attempts. For example, a loon might first settle on a very clear lake, adapt to foraging on that lake, and then look for a second lake that is also clear. We have preliminary data to suggest such a pattern. If loons do learn what features of lakes are helpful to breeding, and fine tune their lake choices on the basis of their first territory settlements, this would be an interesting and important advance in the study of habitat selection. It would also add to our recent finding that loons initially choose to settle on breeding lakes that match the lakes on which they were reared.

I will let you know what I find out about territory settlement as the work progresses. Meanwhile, enjoy these nice photos from Linda Grenzer, who tracked the breeding female from her lake onto Bridge Lake this fall and caught her molting.

LMG_9523 Molting Loon LMG_9464 Molting Loon2

Disheartening Loss of the Mildred Male

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One of the many triumphs of the 2013 research season was the capture and banding of the male from Mildred Lake. Although unmarked, the Mildred male was unique behaviorally. Since he took over in 2009, he was an aggressive presence in his territory. While most males get lackadaisical — or perhaps fearful — about approaching and engaging intruders, the Mildred male always did so without hesitation. He was a big, intimidating bird. Once, in 2009, he even took to the air to express himself; I will never forget him giving a ringing rendition of the territorial yodel while chasing 9 intruders in the sky far above my canoe. (This is the only time that I have ever witnessed a loon yodeling in flight.) In 2013, when, after years of fruitless incubation, he and his mate finally hatched chicks, they both tirelessly defended and fed their young until they were full grown. So he had just had a big year.

Alas, while foraging nearby on Crescent Lake, the Mildred male ran afoul of an angler.  On 17 October, the male was found there with a swallowed hook and bait inside him, still attached to a long fishing line and the fishing rod. Apparently someone left their bait and rod unattended, and the male swallowed the bait and could not free himself. As my posts from earlier this year have shown, we have a decent chance of saving a bird — even one that has swallowed a hook — if we learn about the incident quickly and can capture it soon after the event. So it is a real shame that no one was present or had the courage to report this incident and allow us to help the bird.

Our only consolation is that the Mildred male left two big strapping chicks behind, both of which are fending for themselves and not impacted by his demise. We know from genetic tests that one of these chicks is a male and the other is a female. Perhaps we will see one or both of these offspring back in three or four years’ time. That might take some of the sting out of the horrible loss of their father.

Thunder Chick Thriving

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Sue Poskie pic of Thunder chick Oct 2013 Poskie pic of Thunder chick Oct 2013 3rd pic of Thunder ck by Sue Poskie

Check out these beautiful photos taken a few days ago by Sue Ann Poskie near Rhinelander. As you can see, the 4 week-old chick that we banded on Thunder Lake on 20 July is healthy and in good feather. You might recall from my posts on 2 August and 28 August that this chick has had a colorful history. Against all reason, this youngster passed under the bridge separating her natal lake from Boom Lake and blundered into the Boom-Hodag loon pair and their two much larger chicks. When she tried to join this family, she was initially picked on by her hefty step-siblings. However, after a period of following the family at a respectful distance, she eventually gained acceptance and was fed by the adults. Despite the untraditional upbringing, she has matured normally and will soon depart for Florida with the 2013 cohort of juveniles.

“She” you are asking? Why “she”? We know the Thunder chick is a female, because Amy McMillan, a collaborator, has sexed most of the chicks we captured in 2013 from the tiny drops of blood we sent her. Knowing the sex of these juveniles will help us learn from their local movements this fall and also interpret their territory settlement patterns when they return to the breeding ground, in adult plumage, in 2-6 years.

Hooked Chick Released….and Flying!

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In most cases, loons die when they are hooked by fishing lures or snarled in monofilament line. Cases in which birds are able to free themselves and recover — or we catch them, nurse them back to health, and they put their lives back together — are the exceptions. So we are thrilled to report that the 9 week-old chick that was hooked in the leg, captured by our team, and placed on antibiotics by Wild Instincts to rid it of the resulting infection, was released on its natal lake last week and is now behaving normally. Indeed, Gabby saw it circle its lake three times in flight shortly after release.

Juvenile loons have a relatively short window during which they must: 1) learn to capture fish and invertebrates underwater, 2) learn to fly, and 3) develop large enough fat stores to migrate south to Florida for the winter. It seems remarkable that this youngster has bounced back from its dangerous encounter with humans to the point that it might be able to make the journey with its cohort.

Wanderings of Chicks….and Another Chick Unhooked

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We have reached the time in late summer when — following many trial runs, crashes and ugly landings — chicks have begun to fly. But chicks do not always take wing, circle and land in their own lake. They wander. The picture below was taken on September 17th by Bonnie Montgomery of Fifth Lake, east of Rhinelander. She caught the legs on a departing loon well enough that we could identify it (see two bands on right leg pointed out by green arrow) as one of the two chicks raised on Buck Lake, south of town.

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We have a keen interest in the local wandering of chicks like this one. Following our finding that loons settle on breeding lakes that are similar to their natal lakes, we are interested to see how this preference takes shape. Perhaps loons spend their entire lives preferring to live and forage in lakes of a certain size and water chemistry. If so, this lifelong predilection should make itself known early. That is, juveniles that begin to fly and visit lakes near to their natal lake should prefer lakes similar to the one on which they were reared.

Kristin and Gabby this year, Nathan last year, and Joel in 2011 have examined the hypothesis that natal site matching (as we call the preference of a loon to breed on a natal-like lake) is evident even in the local wandering of chicks. It will take a good deal of data to examine this hypothesis, but we are hoping that our crew will collect enough data (especially after this year’s bumper crop of chicks) to make statistical analysis possible.

Speaking of Kristin, Gabby and Joel, they caught another chick tonight that had become hooked in the neck by a lure and snarled in two types of fishing line. Luckily, the hook did not penetrate deeply. The lure was removed by Mark Naniot of Wild Instincts, the line was cut off of the bird, and the juvenile was released, still apparently in good health. 2013 has been a very bad year for loons and fishing!

Loons and Lures Clash Again

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A week ago, a fisherman hooked a juvenile loon in in the leg. We know the juvenile well; it is a chick that hatched 9 weeks ago whose parents and territory we have observed all summer. As a 9 week-old, this chick is close to adult size. At the time of the accident, it was feeding itself for the most part and beginning to practice taking off and flying. The fishing lure changed that. With a hook embedded in its left leg and monofilament line wrapped around the leg, the young loon no longer dove effectively and made painful and pathetic efforts to fly. Fortunately, our team captured the chick last night. A round of antibiotics and feedings, administered by Wild Instincts, might give this youngster a chance to resume its development, regain its health, and ultimately head south with its brethren. We are hoping for the best.

Male Lost on South Two

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We were sad to learn yesterday that one of our long-term resident birds has died. We are not sure what the cause of death is, but the DNR will do a necropsy at some point and share the results. When a vigorous and healthy adult suddenly succumbs to an unknown cause, as happened here, I always fear that a boat-strike or angling casualty might have occurred, but it is too early to know. All we know, thanks to the sleuthing of Georgia Eusebio, is that the male dragged himself onto shore, moribund, on August 23rd and died shortly afterwards at the Northwoods Wildlife Center. This male was a favorite of ours on the study, as he was  tame and relaxed during our behavioral observations, yet fiercely protective of his territory. He was also a long-distance disperser, having hatched in 1994 on Snipe Lake in Vilas County, which is about 5 miles WNW of Eagle River. His passing leaves his mate, who was banded on South Two in 1997, to care for the two strapping chicks, which are just learning to fly. We think they are old enough to survive losing their father. Gabby and Kristin will continue to follow them this fall, so we shall see.

Good News and Bad News: Epilogues from Posts Past

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I have related several stories about the adventures and misadventures about loons in the study area, and I want to update followers on how those loons are faring. As one might expect, some loons that encountered difficulties were not able to recover, while other loons beat the odds and remain healthy and vigorous.

2 August Post

Two chicks strayed from their parents’ territories to other territories on the same big lake, mingling with other families that were already raising larger and older chicks. In one case, the stray chick was apparently lost, as we have not been able to relocate the Pickerel-South chick that joined the Pickerel-West family. But the Thunder chick, which was considerably smaller than the two Boom-Hodag chicks, joined them and has gained full acceptance by the adults and its larger foster sibs, according to Kristin’s recent observations. (Today she reported that the adults are feeding the interloper!) While we do not understand why it left its parents to join another family, the Thunder chick has continued to thrive despite its dubious decision.

25 July Post

The orphan that we placed with the new pair to complete a family of two adults and two chicks has been fully accepted and is growing and being fed by its foster parents. Its acceptance is so complete, in fact, that we are having to use a simple genetic test to determine which is the biological chick and which is the orphan!

9 July Post

The territorial male that became entangled in fishing line in late June has died. We had thought that he would bounce back after Wild Instincts fed him and treated his wounds and we placed him back on his territory. Alas, he was unable to regain the weight he lost, and he did not survive for more than a few days after release. Since we used a similar protocol to treat and release another male in 2012 that survived, we are a bit puzzled by this male’s rapid demise. Obviously, the details of a loon’s injuries and its precise condition when released dictate its chances of recovery. We are sad to lose this male, who was a vigorous defender of his territory and produced three big healthy chicks during his life: two in 2009 and one in 2010.

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