“Wow”, Lainey said, “that band number is right next to the female we caught last night on Sherry”. She was right; the adult male from Skunk, which we had just netted and whose band number I was reading aloud to Lainey for data entry during banding, had a number imprinted on his aluminum USGS band that followed immediately after that of the Sherry female from the previous night. The reason for consecutive bands is that the Sherry female is the mother of the Skunk male and was caught and banded with him a decade ago (less two days) on Sherry Lake. I remember July 31st, 2005 on Sherry vividly, because I was equipped with a video recorder on top of a helmet with which we recorded the capture process for research presentations. But the recapture of mother and son on back to back nights ten years after we had first marked them has also caused me to reflect upon several key features of loon biology that have become familiar to me through my work.
First, loons live a long time. In this twenty-third year of my work, I still encounter birds in the study area that were on territory, as adults, when I first started covering them. Females, in particular, are survivors. While males have rather high mortality –partly owing to their proclivity for battling dangerously — females linger. When their mate dies, females find another; when a female is evicted unceremoniously from her territory, she stoically moves to a new lake nearby and awaits a chance to re-insert herself back into the breeding population. So it goes with the Sherry female whose worn-out band from 2005 is pictured on the bottom in the photo. She was “widowed” suddenly in 2009 (a possible eagle kill) but hung onto her territory and was joined by a new male in short order, who has been her mate since.
Second, young males do not disperse far from their natal lakes to breed. The Skunk male, from whom we removed the top band in the photo last night, moved about 15 miles from his natal haunt, Sherry. That dispersal is, actually, a bit longer than average for males, many of whom settle to breed on a lake adjacent to where they hatched years earlier. Short-distance male dispersal is essential to my work; without it, I would not have a large marked cohort of 2 to 5 year-olds of known age and natal origin in the study area at all times whose territory settlement strategies could be investigated. (At last count, we had seen 295 adult loons in the study area that were marked originally as chicks.)
Third, loons vary tremendously in their behavior towards humans. My assistants and I dread the Sherry female, because she is the most skittish individual we know. She cannot be approached easily within 100 meters on the water; she tremolos (i.e. alarm calls) incessantly when a chick is present and a canoe appears on the water. In fact, my assistants tell me that she begins to tremolo in anticipation of a canoe being placed on the water and that they have begun a strategy of hiding behind bushes and trees along the shoreline in order to make observations of her when she is with the chick. (Fortunately, Sherry Lake is tiny, so this observation strategy is workable.) I joked that we should wear camouflaged clothing when visiting Sherry; my assistants did not find this funny. Oddly, the Sherry female’s mate is among the tamest loons we study and never tremolos at us when we collect data there.
The great variety in loon tameness is a topic of great interest to us, as I have mentioned. It amazes me that an adult such as the Sherry female could react so strongly (and, it would seem, maladaptively) to humans, which she encounters constantly. Doesn’t she waste energy with her fruitless calls? Shouldn’t skittish birds like her leave fewer offspring and live shorter lives than other adults who tolerate humans without constant complaint? If so, she is not a good example of the pattern, as she has behaved this way for the ten years we have known her while cranking out chicks. Indeed, the Sherry female and the Oneida-East male, another vociferous but fecund individual with whom my staff has to cope, make me wonder if I have got it backwards. Maybe loud-mouthed loons warn humans away, lessening the likelihood of injury to themselves and their brood, and are rewarded with high evolutionary fitness.