lead poisoning

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Sometimes on our research project, we observe a rapid series of nasty events that defy explanation and really shake us up.

This happened to my field interns in Wisconsin. They were “roving” outside our normal study lakes, visiting lakes that are either on the fringes of our 110-lake study area or with little past history of supporting loons. On July 8th, Sarah and Claudia found an adult with a fishhook hanging out of its head on the left side, behind and below the ear. Sarah, Claudia, and Chris covered Little Bass Lake on the following day — and found what appeared to be a second loon with the exact same problem.

We have seen dozens of angling casualties at this point, but we had never seen two weird and very similar hookings in rapid succession. Our puzzlement increased one day later, when Claudia was alone on Dorothy and saw a third loon hooked in this peculiar and painful way. (The featured photos at the top are hers.)

When Claudia contacted me and Linda Grenzer and described what she had seen, we had brief paranoid thoughts, “Oh my god; someone is systematically casting at loon’s heads and hooking them!” (Linda tells me this has actually happened before.) Or, on a deeper rung of paranoia: “Someone is capturing loons, sticking hooks in their heads, and releasing them.”

Repeated visits to the three lakes by our team shed more light. When Linda and her husband, Kevin, attempted to capture the hooked Buffalo bird, they did not find it on the lake on one night. Linda and Kevin also observed what they are confident are two different loons with very similar hookings on Little Bass Lake on two separate nights.

Here is what I conclude. First, these are young birds — probably floaters — but clearly not territorial birds with strong ties to these lakes. They are doing what loons do between ages 2 and 7: they are drifting about but staying in the same general area. If you scrutinize the photos above, it seems apparent that the 1st (Buffalo) and 3rd loons (Dorothy) are the same. Each shows a hook embedded in the loon’s head in the vicinity of the left ear, a fishing snap and swivel hanging off of the hook, and no fishing line attached to the swivel. But the feathers obscure the wound itself. On the other hand, the middle photo from Little Bass shows what appears to be open, inflamed tissue, again with a naked snap and swivel dangling from a hook or lure. Linda and Kevin think that the middle loon is certainly a different bird. I think it might be the same bird, even though the wound looks different. Either way, the loon(s) are dealing well with what appears to be a severe injury, because they are flying from lake to lake and intruding into breeding territories (Dorothy), as they should be.

Speaking of coping well with injury, we had another unpleasant angling event in northern Wisconsin during the past week. A male marked by the DNR eleven years ago on a territory near Three Lakes became incapacitated and was taken for treatment by Wild Instincts in Rhinelander. Their X-ray photo reveals the problem — this bird has a treble hook lodged in its gizzard. The bird has bounced back and been released at this point, but the nasty treble hook and attached line is still inside him. (Removal, of course, would have involved extensive surgery likely to harm the bird further.) We can only hope that the male’s digestive system will grind down and pass these hooks eventually, as we have seen in other loons.

In short, loons have taken some hard punches recently, as we have come to expect at this peak fishing time. If they are lucky enough to avoid the death sentence of a swallowed lead sinker or jig, they can be remarkably resilient.

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We have had a good week on the Loon Project. A few days ago, the November 2020 issue of Condor: Ornithological Applications came out that contains our article on the declining loon population in northern Wisconsin. Our article was selected as an “Editor’s Choice” for the issue! Linda’s photo graces the cover, and it

features Linda’s “own” loons in a touching embrace. Of course, there is brutal irony here. The article documents the fact that there are fewer and fewer two-chick broods in the Northwoods these days. Linda’s picture, therefore, displays an exception to the trend of reduced breeding success in the past quarter century.

  • Condor’s list of the articles most often read by visitors to the journal website.

Speaking of our article, as of today it is the one most frequently read by visitors to the journal’s website. I take heart to see this; maybe that means that we are getting the word out that Wisconsin’s loon population should not be taken for granted. During my optimistic moments, I hope that attention focused on the fragility of our population and its current downward trend might help us take the first easy and obvious step to help loons. What is this step? First, we must get rid of lead sinkers and jigs, which kill many Wisconsin loons each year painfully and needlessly. This requires simply having the sense of responsibility to replace all of the sinkers and jigs in our tackle boxes with lead replacements that work just as well but do not kill loons and other wildlife. If we take this simple step and — here’s the hard part — have the chutzpah to ask our friends and relatives and neighbors to do the same, we can start a wave and get it done. Are you willing to step up and do this for Wisconsin’s loons?

A second piece of good news for the Project this week was the acceptance for publication of our collaborative paper on climatic and land-use impacts hurting the northern Wisconsin loon population. As with the just-published Condor article, this accomplishment is decidedly bittersweet. While it is nice to have your work recognized as important and worthy of publication, it is a shame to see yet more scientific evidence that spells trouble for loons.

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Identifying a loon from its colored leg bands is an incremental process. Once you spot a loon on a lake and approach the bird, you must develop a seat-of-the-pants strategy for recording its bands. The ideal situation is when you observe a preening loon, paddle slowly over to it, and simply wait for the bird to swing its legs up out of the water while distributing preen oil all over its feathers. One generally has at least five minutes to piece together the complete combination of four leg bands of preening birds from a quick view here or there. I talk to myself while getting bands, in hopes that I will remember what I have seen. “Yellow on top, right leg…wait….yellow over mint on right!” If the loon is not preening but foraging, identifications can take hours, and you must hope that, as you remain as close to the forager as possible, it happens to surface right next to your canoe and in good light when you happen to be looking its direction. In such cases, piecing together the bird’s band combination can be an arduous process, because one gets very quick views of bands underwater or for an instant just as the bird plunges beneath the water.

Despite diligent efforts, we often end up with only “partials” on loons’ bands during our hourlong visits to study lakes. However, since most of the loons we see are territorial birds on the lakes where we color-banded them, partials are often good enough to tell us the identity of the bird. Then again, sometimes — especially early in the year — we get surprised by a loon that was not banded on the lake where it is spotted.

Imagine what Linda must have experienced on Halfmoon Lake yesterday. After spotting a lone bird, Linda was expecting that it would be one of the two banded pair members from Halfmoon. She was no doubt pleased to see that the loner was preening, which gave her hope that she could nail its bands before it resumed foraging. Was this bird going to turn out to be “Grandma”, the female originally banded fourteen years ago on Muskellunge Lake, who had earned her name when she intruded onto Crystal Lake in 2015 at the time her son was rearing her grandchild? Or would the preener prove to be the rather skittish male from Halfmoon, which we had finally caught and placed bands on last July? As Linda’s crisp photo shows, the preener was “Yellow over Mint, Silver over Red-stripe” — neither Grandma nor her evasive mate. 

Linda knows this surprise visitor to Halfmoon better than anyone. You see, Yellow over Mint is “Mabel”, the female that has been a regular intruder into Linda’s lake since 2011. Years after Linda and our team had begun reporting Mabel as an intruder on our lakes, we expanded the study area to include Mable Lake and learned that Mabel was not a roving nonbreeder but the breeding female there. Mable is a tiny 25 acre lake near Tomahawk. With food so limited by the size of the lake, Mabel and her unbanded mate have struggled reproductively. Twice in the past three years the pair has hatched a chick but lost it at six to seven weeks of age — just on the brink of fledging.

Mabel’s breeding woes pale in comparison to the nightmare that befell her in 2019. As I described in a post last summer, Mabel swallowed someone’s fishing line on about June 20th of last year, was incapacitated by lead toxicosis, and only survived owing to Raptor Education Group’s heroic emergency surgery and extensive efforts at treatment and rehabilitation. Rescuing Mabel from lead sinkers was only half the battle. Although the REGI team had done what they could to feed her and get her fit for release, it was far from certain that she would be able to recover sufficiently to survive in the wild. In fact, we lost track of her after she was let go last July on Lake Alice. We simply hoped for the best, knowing full well that few loons survive a severe bout of lead poisoning.

Yet there Mabel was yesterday, looking (according to Linda) none the worse for wear. Indeed, having survived two migrations since her debacle, she has clearly returned to form. Mabel is still not back to her former status; she has lost her territory and joined the ranks of the many displaced female breeders who wait — often for years — for breeding vacancies to occur. But just surviving long enough to join that queue is a huge victory for Mabel — and for those of us who dared to hope that she could come back.