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.