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.
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.
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.
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.
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.
Two nights ago we completed our last night of loon capture and marking for the 2013 season. It was a banner year, as we banded 87 chicks, 26 unbanded adults, and made 56 recaptures of adults banded previously. (We broke our 2005 record for chicks banded by 20!) Of the recaps, 10 males and 3 females were birds we (or Mike Meyer of the Wisconsin DNR, in the case of 2 of the females) had marked as chicks but never caught as adults. Weighing of these birds contributes vital data to our analysis of changes in body condition that occur with age among young adults and have provided further evidence that loons — at least males — do improve in body condition from ages 4 to 10 years. This is an important finding, as it runs parallel to the clear behavioral finding that young adults improve in competitive ability during this phase of life. That is to say, young adults are in better condition (measured by body mass) at ages 7-10, when they usually usurp territories from established breeders, than ages 4-6, at which time they choose to found new territories in vacant lakes (without having to fight for them). This is a neat and intuitive result that I am currently writing up for publication.
The abundance of chicks banded this year will allow us to enlarge upon our investigation of natal site matching (based on our recent paper) that we began last fall. Kristin and Gabby from this year’s team will spend this fall tracking the chicks as they mature, begin to fly and disperse to lakes nearby their natal one. Our goal here is to determine whether young loons “imprint” on lakes similar to their natal lakes in the first few months of life. If so, chicks hatched and reared on small lakes — which, as we have recently shown, tend to settle to breed on small lakes — might choose to visit small lakes when flight allows them to do so to feed, while chicks from large lakes should select other large lakes for foraging. Stay tuned for the outcome of this autumn investigation!
After last night’s work, we had banded 54 loon chicks and 16 new adults and had recaptured 37 adults that had been banded previously. (Recaptures permit us to replace lost or faded bands and weigh individuals to assess their body condition.) Since we are only about two-thirds of the way through our banding for the year and have already surpassed last year’s totals, this is turning out to be a big year for loon capture.
There are a couple of different reasons for our success at banding this summer. First, more breeding pairs than average produced chicks, the lack of blackfly abandonments more than offsetting the slight negative impact of a very late spring. Second, the field crew — Kristin, Gabby, Mari and Jacki — have done a great job of finding new breeding pairs on outlying lakes that have chicks. We can only capture adults reliably when they have chicks, because we rely upon adults’ protectiveness of chicks to approach them with spotlights at night. So when we find new pairs with chicks, we can: 1) band the adults and add new territories to the study area, and 2) band the chicks and have a 50% chance of seeing them again, as adults, in 3-6 years, as they search for breeding territories and mates.
We are excited to have banded so many loons this year. Kudos to the 2013 loon crew for their hard work, which has ensured productive behavioral research in the study area in 2014 and beyond!
1991 was the first year that marking of loons occurred in our study area. In that year, Dave Evers and his crew captured and banded seven adult loons, five males and two females. It was not until two years later that I began my behavioral study of the population.
Of those seven marked adults, two survived for at least 15 years, but none had been observed for the past two years. I had given up hope that any of the “Magnificent Seven” was still alive.
All of that changed recently, when Kristin nailed the bands on the male that had been caught on Little Bearskin Lake in 1991, produced 14 fledged chicks between that year and 2005, and was finally evicted by a younger male in 2006. (He tried to breed on Heiress Lake in 2008, but his nest failed.) Last spotted in 2010, this old fellow is at least 26 years old. Here is how we know this: He was first spotted as an adult in 1991, and no adult has ever nested at an age younger than 4 years; so he must have hatched no later than 1987.
So….kudos to Kristin for IDing this old guy and especially to the old guy himself, the only remaining member of the Magnificent Seven.
Although we were sad eight days ago, when we lost the male to an eagle on Tomahawk-Sunflower Bay, his sudden demise gave us an opportunity to observe what happens when an established breeder disappears. In this case, the unbanded mate of the dead male was on her own for a day or so and then was joined by a banded male that we know well. He is blue over orange (right leg), blue over silver (left leg) or “B/O,B/S”. B/O,B/S is the former breeder on Mud Lake, just next door. In late May of 2011, B/O,B/S picked up an orange fishing bobber on his right leg that slowed him down a little and affected his diving. We were very worried about him, as we thought that the bobber and associated monofilament line might cut off his circulation and cause him to lose his leg. We visited the territory often to check on him. He lost the Mud territory that year but remained in good health, it seemed. He was sometimes spotted on Bird Lake, just next door, so clearly he was able to fly. Now he has come full circle, as he has lost the bobber on his leg, recovered from that injury, and established himself again on a breeding territory. By the way, B/O,B/S is a male ABJ (Adult loon that was Banded as a Juvenile) that has a special place in my heart, because he is a “third-generation” loon to our study. He is the son of a female ABJ from Shallow Lake that was hatched and banded in 1993, my first year of research on loons. (This female is still around. After many years as the breeder on Fawn Lake, she is now a pair member on Lumen Lake.)