As this beautiful photo by Linda Grenzer makes clear, time is passing. Chicks have matured and left their natal lakes, territorial pairs have scattered. Juveniles and adults alike are preparing to head south. Most obvious to loon watchers, adults have shed their striking breeding plumage and donned dowdy winter garb.
Although we might mourn the significant loss of beauty that occurs among loons in the fall, molting is a pragmatic biological pattern. Feathers wear out with time and use, requiring replacement, so seasonal molting of some kind is essential to survival. But why do loons lose the white wing spots, the necklace and chinstrap, and the elegant black head? As usual, the answer is that we cannot be certain without experimental investigation. However, these prominent features of the plumage signal readiness to defend a territory and to breed. Hence, they are inappropriate and possibly costly signals to send during the autumn. An adult that maintained breeding plumage during the fall might attract the attention of others and trigger territorial interactions at a time when it should be feeding vigorously in preparation for migration. Moreover, the contrasting breeding plumage would probably make a loon more conspicuous to predators such as sharks, which could be costly during a long winter on the ocean.
The two loons in Linda’s photo are her breeding male and female — and two of our best-known individuals. They appear often in her photos, such as when 5 intruders came to call and when they refused to abandon their nest, despite merciless black flies. After all they had been through this year, it was a surprise to see the male (Linda calls him “Clune”) and the female (“Honey”) spend a short time together on the brink of fall migration, long after most pairs had dispersed. I find this photo poignant somehow. I suppose it symbolizes to me this pair’s unwavering unified front in the face of all challenges and changes that confront them.
With the first snowfall in the offing and adults and chicks feeding voraciously to steel themselves for migration, an odd and touching event has occurred. We have been able to track the local movements of a pair from their breeding lake to other lakes in the study area. This is not a traditional pair of male and female, but a father and his son who have remained together for an unusual stretch. Hatched on July 1st, the Fawn chick was attended closely by his father from the start. When his mother swallowed a fishing lure and anglers cut the line, leaving her trailing yards of monofilament, she abandoned her mate and offspring for several days to recover. Still his dad remained with the chick and increased his feedings to make up for the absence. (The female survived the ordeal and returned to Fawn Lake afterwards to resume parenting.) Dad continued to feed his son assiduously as he grew, matured and began to take flight. Two weeks ago, however, Fawn Lake was empty of loons. The sharp-eyed residents of Lumen Lake, right next door and almost touching Fawn, reported the sudden appearance of an adult loon and chick that turned out to be the missing father and son from Fawn. The two remained on Lumen for a week or so but then disappeared again. Judith Bloom, who for years has monitored several breeding pairs on huge Lake Tomahawk, e-mailed on Thursday to report that she had found (and ID’d!) an adult and chick feeding in a bay near her home that were not from any territory on Tomahawk (see Judith’s photos). Sure enough, the Fawn father and son had made another appearance in foreign waters.
Now, it does happen that parents continue to feed their chicks at 13+ weeks of age. What is unusual is that a parent-offspring pair has remained together on not just one shift to a foreign lake, but two shifts. Moreover, the second shift was a whopper, as the duo flew about 6 miles together to land on Lake Tomahawk. While it is tempting to view this event as a reflection of the trend that is becoming routine in human society — offspring remaining with their parents well beyond the normal age of independence — it might warrant scientific scrutiny. In fact, such “fawning” behavior by a father towards his son makes sense evolutionarily, providing Dad has improved his son’s chances of surviving migration and its first winter while still maintaining his own health. In three to five years, when this chick stands to reach adulthood, we will see if the father’s tireless investment paid off.
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.) Sorry 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.