Former Male Breeder on Jersey City Flowage is Back in the Game!


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Good news has been scarce this year. Black flies snuffed out first nesting attempts by virtually all breeding pairs and will reduce chick production by about 40%, compared to last year. One of the few pairs to continue incubating in defiance of the flies hatched chicks, only to lose them to infanticide when a new young male evicted the male breeder. And one of our most consistent chick producers and well-loved birds, the 19 year-old male on Jersey City Flowage, barely survived severe entanglement in fishing line that caused him to lose 20% of his body weight.

A few days ago, we received a bit of good news. The Jersey City Flowage male, after surgery and rehab work done by the folks at REGI and release near his original territory, has not only shown the capacity to feed himself normally, but has re-paired with a female hatched on Fisher Lake in Vilas County in 2010. This May-December pair seems settled at the north end of Jersey City Flowage, according to Linda Grenzer. Now, whatever judgements we are tempted to make about the age disparity in this relationship, it is nice to see the old male get himself back in shape and ready to give life another try.

The Lasting Impact of Black Flies


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black fly impact


Since 2014 marked by far the most intense explosion of black flies in recent memory, I wanted to look at how loons are faring reproductively this year compared to last. It has now been over a month since the peak of “black fly season”, which was miserable for loons but lasted only about a week. Yet the flies were thick enough and their outbreak coincided so closely with the start of incubation for most pairs that about 70% of all loon pairs in our population abandoned their nests.

It seemed certain that the epic abandonment of early nests in 2014 would negatively impact the number of chicks produced by our population. And it has. Based on my analysis of 96 territories covered in 2013 and 2014, I have the following results. Last year, 41 pairs  had hatched chicks by 30 June, while 14 had nests close to hatching, 10 had early nests whose outcome was uncertain, 21 pairs had failed for the year, and 10 pairs had never nested (to our knowledge). In 2014, the numbers were 6 chicks, 30 promising nests, 15 early nests, 21 failed pairs, and 14 pairs without no nest during the season.

The disparity in chicks produced is alarming, of course. This is the most important number. The picture gets a bit rosier when you crunch the numbers and recognize that many pairs currently on nests will eventually hatch chicks. Based on an assumption of 70% hatch rate among pairs in the “likely hatch” group and 40% in the early nest stage — perhaps slightly optimistic — the total estimated chicks produced in 2013 and 2014 are 54.8 and 33.0, respectively. To put it another way, about 57% of all pairs reared chicks in 2013; 34% will in 2014. This is a decline of 40% in the number of territorial pairs producing chicks.

Now, we need to step back here. Loons are long-lived animals, and most pairs that failed to raise chicks, owing in large part to black flies, will try again next year. So, in the big picture, the decrease in rate of chick production is not so awful. In a few more years, we will look back on 2014 as just a worse-than-average year for loon chicks, not a year that threatened to end loon life as we know it. But it is hard to be very upbeat at the moment.

Elation….then Devastation on West Horsehead Lake


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After the black fly debacle in recent weeks, we were all ready for some good news. Indeed, most territorial pairs had shaken off the flies and gotten back to the business of reproduction. Good tidings seemed the order of the day. Yesterday, Al Schwoegler of West Horsehead Lake called with a thrilling and unexpected report: the eggs laid by the pair, which they had left unattended for many long hours on several days because of the torment of black flies, had begun to hatch! At first neither Al nor I could believe that the eggs were viable. As Al described the behavior of the female on the nest – who has reared a whopping 19 chicks to fledging since 1996, when she was first banded – we gradually let ourselves believe that the impossible had occurred.

But our positive feelings were dashed suddenly by the cruel realities of loon territorial behavior. You see, the last few weeks at West Horsehead have been marked by frequent territorial intrusion. At the very time that the pair was trying to recover from the onslaught of biting insects, the male owner was facing repeated challenges for his position. Finally, by yesterday, both Al and Sally Yannuzzi of my team confirmed that male ownership had passed from the 14 year-old male hatched on Alva Lake who had resided on the lake for most of the past decade to a 9 year-old upstart from Harrison Lake in Lincoln County. The new male, confident in his new position, spent much of the morning resting and foraging near the nest, while the female patiently sat on the eggs. Finally, the female slid off of the nest into the water, revealing a newly hatched chick and second egg, which was on the brink of hatching. Alas, the new male behaved as animals typically do when confronted with helpless young that are not their genetic offspring: he quickly pecked the chick to death as its mother looked on helplessly. The celebration of an unexpected hatch gave way to a wake for a young loon doomed by territorial usurpation. Al took this photo of the female, still mildly protective of her nest containing the dead and unhatched chicks. (Shortly after the photo was taken, the female left the nest to forage with her new mate, with whom she might still renest.) IMG_20140616_134217_724Sorry for the unpleasant photo and description. But there is a valuable lesson here. Loons, like lions and langurs and mice and water bugs, behave so as to promote their own reproduction. Despite the ugliness of this episode, we can hardly hold it against the 9 year-old that he is looking to produce his own biological offspring — before a new usurper comes along and shows him the exit.

The Downside of Dual Incubation and a Ray of Hope


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To be sure, 2014 is shaping up to be a dismal breeding season. Ice-out occurred weeks later than usual, owing to thick ice and cool weather in March and April, and delayed breeding for all loon pairs. The ensuing warmup in May caused the black fly population to explode to higher levels that we had ever seen. Pairs that had just laid eggs were blanketed by the relentless bloodsuckers and incubating males and females driven off their nests at rates never seen before. In short, almost all loons abandoned their first nests.

Although it is counterintuitive, loons are probably more vulnerable to nest abandonment than many other birds because males and females incubate the eggs equally. Consider the plight of loons trying to incubate their eggs to hatching for 27 days in the presence of black flies. Each pair member must incubate for stretches of several hours before being relieved by its mate. The rotation system must be efficient enough that eggs are incubated over 99% of the time. When not sitting on eggs, a breeder rests, preens and forages to replenish its energy reserves. If either pair member fails to incubate, the nest is doomed to failure, because its mate cannot compensate for missing incubation by remaining on the eggs at all times without long breaks for foraging. So we have a case where the weakest link breaks the chain. Even a tough, determined male incubator is destined to lose a clutch if his mate is less determined than he is and refuses to sit on the eggs and tolerate the torment of biting insects.

We have learned about the necessity of dual incubation from past observations. Nest abandonment commonly occurs following territorial eviction of a pair member during incubation. If its mate is evicted by an intruder, the remaining pair member usually continues to sit on the eggs for a time. With rare exceptions, though, its new mate (the usurper) does not incubate — why should it sit on eggs containing young to which it is unrelated? — the cycle of shared incubation duties breaks down, and the nest fails within a day. (If it is early enough in the season, such pairs will lay a new set of eggs that both will incubate.) A rarer cause of nest failure during incubation is death of a pair member. In 2005, the female on Alva Lake was killed by an eagle while sitting on the eggs. The male valiantly sat on the eggs, taking breaks to forage from time to time, even as female floaters competed in front of him to fill the breeding vacancy. Despite being within a week of hatching, this male could not complete incubation on his own, and the nest was lost.

Enough talk of failure! I will end on an up note by showing you the sweet photo that Linda Grenzer took of a breeding male sitting on a nest. This bird and his mate both tolerated the record outbreak of blackflies earlier in the season and were rewarded with a little fuzz-ball – a much-needed reminder that all is not lost this year. Let’s cross our fingers that other pairs, many of which are incubating a new clutch of eggs after abandoning the first, will be able to duplicate this effort.



So Far, So Good!


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Sorry for the posts on back to back days, but I wanted to report on the status of the Jersey City Flowage male, released four days ago. He is looking healthy and diving normally, it seems, as this photo by Linda Grenzer suggests. Thanks, Linda, for tracking him down!LMG_0964

He has moved about a mile in the large lake where he was released, and has skirted the territory of a pair that nests in the lake. So, while it is far too early to pronounce him out of the woods, things are looking promising. It is remarkable to observe the severe injuries from which loons can recover. Let us hope that this bird — who has both the brightest bands in the study area and the calmest disposition — can add to the short list of loons that have flirted with death following fishing entanglement, been captured and disentangled, and recovered to become territory owners again.


Another Territorial Male Victimized by Fishing Tackle


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Now…I am a long-time fisherman. Since I was a young boy, I have enjoyed throwing a line in the water and imagining the lunkers waiting to strike my lure. (I think it started with McElligot’s Pool, the fantastic Dr. Seuss book that my parents read to me and my sibs.) I have spent many fruitless hours fishing — and enjoyed every minute of it. But my lifelong love of fishing has taken some bruises lately, as it has become increasingly clear that many loons in northern Wisconsin die horribly each year after entanglement in fishing line. I discussed some such incidents last year, but we have already had a recurrence of the problem this summer.

The most recent casualty is the territorial male on Jersey City Flowage. We had become rather fond of this bird, whom we banded as a chick on Swamp Lake in 1995. Year after year he and his mates have reared chicks on the Flowage, taking advantage of the abundant marshy habitat and network of islands there. He is tame, permitting us to approach closely and identify him whenever we care to. I vividly recall an occasion in 2005, when I found him foraging with his big strapping chicks. Neither he nor his juveniles cared a whit when my canoe approached them. They all foraged peacefully, oblivious to me. Here is a photo — a rather poor one — that I took Image

of the foraging family on that day.

Our team noted a month ago that the male had not returned to his territory in 2014. We were disappointed at the loss of cherished individual, but accepted that he had died over the winter or on migration or, perhaps, been evicted by another male this spring. Such are the perils faced by loons. But Marge Gibson of Raptor Education Group, Inc. notified us last week that her group had picked up a badly injured and emaciated male from a lake near Tomahawk, Wisconsin which turned out to be this male. He had swallowed two lead sinkers and, as you see, had become irrevocably entangled in the attached monofilament line.  Image

Although this bird had lost 25% of his body weight (down to 3400 g from his normal 4500 g) and was in desperate shape, Marge reports that the REGI staff were able to disentangle him, remove the lead sinkers, and get his weight back up to 3800 g with vigorous feedings. They were also able to repair his bisected tongue and restore blood flow to it. Recently, he was released near his old territory. Although it is always tricky to rehab a bird in such a weakened condition, we are allowing ourselves to hope that he will recover and will let you know what we learn of his health and territorial status. (He has lost his territory, and the new male there and his mate are nesting, according to Linda Grenzer, our tireless citizen scientist. So it will be a long road back for the injured male, even if he does return to health.)

I think that I will always enjoy the unique mixture of natural beauty, solitude, and occasional surge of adrenaline that I have enjoyed while fishing. But I will never again use lead tackle, especially now that there are many appealing alternatives. Help me spread the word about them!

The Scourge of Blackflies


As this searing photo by Linda Grenzer demonstrates, blackflies are making incubation miserable for loon pairs this spring. Actually, this guy — a 16 year-old male from Muskellunge Lake — is hanging tough despite dozens of the remorseless bloodsuckers. Where blackflies infestations are worse still, such as the hundreds we have seen swarming around nests on Bobcat and Upper Kaubashine lakes, loons abandon their nesting attempts altogether. Based on visits to dozens of lakes this spring, it seems that about 70% of all loon pairs that have started



nesting have been unable to incubate owing to blackflies. This is much the highest rate of blackfly-induced abandonment that I have seen in 22 years of loon study. (32% was the worst rate before this year.) These dipterans are such a nuisance that they even cause loons to change their daily activities. Normal adults spend lots of time oiling their features, preening and resting, but those terrorized by the tiny flying demons spend virtually the entire day diving, surfacing to take a breath and shake their head free of blackflies, then diving again. Luckily, most pairs that abandoned their nests due to blackflies did so within the first week of incubation. Thus, they still have plenty of time to renest, which most will do soon.

While loons are no doubt the most serious victims of blackflies, the tireless arthropods impact field observers as well. You see, preening and resting are the two activities of loons that make it easiest to ID individuals. Since loons have reduced or eliminated preening and resting from their activities and, instead, begun to dive incessantly to avoid flies, we have a devil of a time getting close enough to individuals to identify them from their colored leg bands. (Loons have even shortened the resting time between dives to reduce their exposure to blackflies.) So, we too look forward to the end of a brutal year of blackflies.

Loons are Nesting…and Young Male Gets Slammed


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A lot can happen in a short time, it seems. I have spent only three days in the study area so far, but already we — Joel, Eric Andrews and I, and our incredible citizen scientists Linda Grenzer and Al Schwoegler — have found 8 active nests. Considering the territories we have visited recently and those we have not, I estimate that about 15-20% of all pairs in the study area are already incubating. Clearly the pairs have shortened the window between ice-out and egg-laying in order to compensate for the very late spring this year. I suspect this is possible, in part, because females were able to recoup much of the energy consumed during spring migration by foraging for weeks along rivers in the study area, before their breeding lakes opened up. That is, the extra foraging time near their territorial home apparently compensated for the foraging time that would normally occur on their territory.

Territorial turnovers have been common this spring; many marked pair members from 2013 either failed to return in the spring or did return but were evicted from their territories. The evicted birds include a young “ABJ” (“adult banded as a juvenile”; meaning a loon we banded as a chick) male from Schlect Lake. This ABJ male, hatched on Fox Lake in 2005, produced two chicks, of which one fledged, in 2012. But in early 2013, the Fox ABJ had been replaced by another ABJ male, this one also hatched in 2005, but on McNutt Lake. In late 2013, the Fox ABJ was able to retake his territory (possibly after the McNutt ABJ left it) and lived there the rest of the summer. However, two days ago, Eric and I witnessed a nasty battle between the Fox and McNutt ABJs (now both 9 years old) that culminated in the exhausted and defeated Fox male taking refuge on shore to avoid further attack from the McNutt male. Quite a grim spectacle! It remains to be seen whether the Fox ABJ can recover, drag himself off of this tiny 25-acre lake and get on with his life.

While our problems pale in comparison to the desperate life-and-death struggle that the Fox ABJ is facing, this latest contest is troubling to us as well. You see, we have hypothesized that dangerous contests of this kind likely occur when very old males (with very little reproductive fitness to lose) roll the dice by battling to win a few more years on their territory rather than accepting displacement by a younger, stronger male. (This is termed the “terminal investment hypothesis”.) Naturally, we must use statistical tests on a large body of data before drawing any conclusions. Still, it was unsettling to see a vigorous young male — and one that doubtless would have many potential future years of reproduction ahead of him — suffer a life-threatening encounter that flies in the face of our pet hypothesis.

The Loons Are Back!


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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

New Findings: Eviction Breeds Eviction!



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.


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