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.
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.)
Yesterday, we received a report of an adult female on the Turtle-Flambeau Flowage who swallowed a fishing lure with multiple hooks on it. The bird was severely wounded, was captured, and has been taken by a wildlife rehabber to see if it can be saved surgically. However, this is a longshot. Although this female was apparently not a territorial bird, her sad situation reminds me of the many territorial adults — important chick producers which help support the population — who die fishing-related deaths each year. Loons are rather poor colonizers of lakes. That is, a pair develops a strong bond with a territory and often produces many chicks there. If the pair dies, especially the male, who is in charge of nest placement for each breeding attempt, a territory can fall into disuse or be settled by a new male that is a klutz in nesting and is not able to find safe nesting sites. So loss of a successful breeder can have a serious negative impact on local chick production. This is why I mourn each loss of a territorial breeder to an avoidable death from a fishing lure or lead sinker. Recent deaths that have hurt chick production in the study area have occurred on Squash, Hildebrand and Carrol Lakes.
Now, I am a fisherman myself. I have always enjoyed throwing a lure in the water. Angling will always be a rich and important part of recreational life in Wisconsin. But, like me, please: 1) try to be careful not to fish when loons are nearby, and 2) replace your lead sinkers with alternatives like tin, steel, tungsten or granite (yes….granite!).
This morning Kristin found the banded male on Tomahawk – Sunflower Bay freshly killed and being consumed by eagles. This is a sad discovery for us, because he was a sweet, tame bird with a rich history of rearing chicks — on two separate territories. We cannot be certain that an eagle killed the male, but he was healthy on our last visit, and the pair had recently nested. So we strongly suspect our national bird!
This is a reminder that, while they usually seem to be merely a nuisance, eagles DO have the potential to kill adult loons. Our best-documented example of an adult kill was a female attacked and dispatched by an eagle on a nest on Alva Lake back in 2005. Of course, eagles are a constant threat to chicks.
Funny, but I have struggled to love our national symbol recently. I hope that does not sound unpatriotic!