Bent but Unbroken

The deformity was obvious back on May 17th, when we first saw her. The breeding female on Johnson Lake had part of her bill jutting upwards at a crazy angle. At first, viewing her at a distance, we thought that the dark spike that appeared to emerge from her bill might be a lure of some kind that she had latched onto mistakenly and been unable to dislodge. But, as Elaina’s photo shows, the distal half of her bill is bent upwards at a 45 degree angle. We were alarmed at her situation, which appeared uncomfortable, at least, and deadly, at worst.

But she behaved normally. Since we carefully observe, painstakingly describe, and publish articles about loon behavior, we habitually assess any loon’s comportment that we see according to thousands of others seen before. Her diving and foraging was normal. Far from permitting too-close approach by humans — a common red flag that can indicate severe injury — she was actually rather skittish. She pointedly moved away from us whenever we approached in an effort to look for leg bands.

Anatomically, she is far from normal. Bird’s bills consist of a matrix of bony support, covered by a keratinized epidermal layer (rhamphotheca). In other words, the displaced part of this loon’s bill should comprise not merely soft tissue but bone. Mark Pokras, associate professor emeritus at Tufts School of Veterinary Medicine, assures me that the fact that the bony foundation that should extend to the bill tip is missing means that it “will never grow back normally”. The best we can hope for, he says, is that the bent keratinized tissue — all that remains of the end of her upper mandible — drops off eventually. I was chagrined to hear this news but heartened to learn also that Dr. Pokras has, during his decades of loon anatomical study, seen about 10 cases where large portions of loon bills have been missing. These cases include a male in Maine that had only half of an upper mandible (as this female does) but that fed itself normally, held its territory, and produced offspring in multiple years.

That loons can survive an injury of this kind to a crucial feeding organ and still breed seems remarkable. I suppose their resilience might be explained partly by the  challenges they face routinely across the range of different landscapes they inhabit. That is, an animal that must locate, pursue, and capture a broad spectrum of actively-swimming prey — in water that is sometimes fresh, sometimes salty; sometimes clear, sometimes turbid, must be a flexible and adaptable creature indeed.