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Since the inception of the study, we have known that some adult loons permit a canoeist to approach to within 5 meters without alarm, while others become uneasy and dive at a distance of 30 meters or more. Over the past several years, we have worked hard to quantify such variability in “tameness”. Our efforts are motivated by the belief that — in a region well-known for human recreation — tameness must matter. That is, it seems inconceivable that loons’ survival rate and reproductive success are not impacted by the way they respond to humans.

At first blush, I would expect loons to have higher fitness (i.e. be able to survive and breed more successfully) if their tameness reflects the lake they inhabit. That is, loons that are very tame should fare well on lakes where humans are numerous and often approach loons closely. A skittish loon on a lake with abundant human traffic would spend a great deal of time and energy avoiding humans and might have to spend more time foraging to compensate for the extra energy expenditure. A skittish individual on a busy lake might even become distracted by humans and pay too little attention to eagles, which occasionally attack adult loons and often attack chicks. On the other hand, shyness towards humans should have no impact on fitness if it occurs in a loon that occupies a remote lake.

Tameness is surprisingly vexing to measure. While it is easy to see that loons vary in approachability by canoe, it is another matter to assign a number to the degree of approachability they show. One obstacle to measurement is simply that of measuring distances accurately across water. Another is the problem that we seek to know exactly at what approach distance a loon dives to avoid a canoe; once this critical distance has been reached, the loon has left only its wake on the lake’s surface for us to measure! After numerous trials, however, Seth Yund, a Chapman student, and I have found a technique that seems to work that requires use of a highly accurate laser rangefinder — and a lot of patience. In July we began to collect measurements on each banded loon in our study population, and this work will continue into the fall and in future years. (By the way, the technique requires paddling slowly in a canoe towards a resting loon until it dives, while taking constant measurements. Since the process must only be carried out once or twice per loon, it involves very mild disturbance. We have found that loons quickly resume normal behavior after we take a tameness measurement.)

It will be some months before we begin to see if our quantification of tameness is stable and consistent enough to constitute a useful behavioral measure. At that point, we can begin to test our preliminary hypothesis that a loon’s tameness should be correlated with amount of human usage on its lake. Since we have many parent-offspring pairs in the population and follow individuals throughout their lives, we can envision asking questions about the heritability of tameness and its constancy over time. We hope that tameness will become a rewarding topic of research for us. Perhaps our ability to quantify this behavioral characteristic will permit us to foresee negative impacts that increasing human-loon contact will have on our population and help recommend ways to minimize such impacts.