You tend to think that creatures living in the wild are in top physical condition. And most of them are – they wouldn’t survive long if they weren’t. But when you handle a lot of, say, birds (and we banded close to 10,000 in 2011), you notice quite a good deal of variability in physical condition. Take “Stumpy”, the name I’ve given, affectionately, to a young (HY) Black-capped Chickadee that we found in a net on November 18th. It was missing the lower part of its right leg and foot. The injury was not a recent one as it had clearly healed. We wrestled with whether or not we should band it but decided to do so in order to track its possible survival. The bird was certainly feisty enough (chickadees have a lot of spunk!) and didn’t seem slowed down by the injury. Since that time we have retrapped it 3 times, the most recent being today. On all 3 days it was in good physical condition and, in fact, weighed more than it did when banded. It will be interesting to see if Stumpy survives the Winter and breeds or attempts to next Spring.
This wasn’t the only bird we’ve found missing a leg. There is also a Downy Woodpecker around without half a leg and foot. [Please note, and be reassured, that these injuries are in no way related to being caught in a net or banded.] And we’ve had others over the years.
We’ve found quite a few birds with “growths”, some as big as 5 mm long (and high) on various parts of their head and body – reminiscent of tumours, although I couldn’t say definitively what they were (some may have been avian pox). The birds carrying them (and this includes both short- and long-distance migrants) didn’t seem affected or weakened by them or to be in pain. (Would they show it? I don’t know.)
Occasionally we see birds with bill deformities, possibly avian keratin disorder. This usually takes two forms: the mandibles are crossed (like a crossbill) or the upper mandible is longer, and hooks over the lower one. We’ve also seen instances where part of a bill is missing due, probably, to an impact of some sort.
Sometimes we see evidence of Mycoplasmal conjunctivitis, especially in House Finches. This disease results in swollen, runny and/or crusty eyes, which, when further developed often results in blindness and then the death of the bird. Death is not directly due to the disease but to starvation, exposure and predation as a consequence of a loss of vision. House Finches were very hard hit by this disease, which first showed up in them in 1993-94 in Virginia and spread out from there resulting in their populations plummeting. As an example, in the Fall of 1999 we banded 279 House Finches; in 2000, just 23; and numbers banded here ever since then have never come close to the 1999 total.
Another “affliction” we see regularly is parasite infestation: feather lice, proboscid flies (flat, blood-sucking flies that burrow under the feathers) and, occasionally, ticks. Sometimes, when handling a bird, you’ll look down and see scads of little mites crawling all over your hands. They don’t pose a threat to the bander but you have to feel sympathy for the poor bird carrying them. (I get itchy just thinking about them…)
So after this somewhat macabre litany of afflictions…..it was nice to see Stumpy again and doing well. [As well, a couple of years ago I banded a House Finch with a very red and swollen right eye – mycoplasmal conjunctivitis. I recaptured this bird about 8 months later. There was no evidence of the disease and the bird was healthy and in good shape – so the disease isn’t always fatal.]
I noticed this morning that there was a big rain system on its way and, since I needed a “fix”, I decided to open the feeder nets anticipating that the birds would be using them heavily before the nasty weather. And they were: in the space of 2 hours I caught 25 birds:
1 Mourning Dove
1 White-breasted Nuthatch
1 Brown-headed Cowbird
13 American Goldfinches
1 Downy Woodpecker
1 Blue Jay
3 Black-capped Chickadees (including “Stumpy”)
4 American Goldfinches
Some of the retraps got me to thinking….we know that the American Tree Sparrows and Dark-eyed Juncos we get here in the Winter breed a long way up north. We also know that some of them return here Winter after Winter. But we don’t know necessarily where the American Goldfinches we catch here breed – they nest throughout the province so who can say (without, perhaps, doing stable isotope investigations on them). Consider these two older (AHY) males: one was banded November 29, 2009 and not encountered again since until today. Another was banded April 17, 2009; retrapped April 2010; and then October 24, 2011 and again today. These birds were never retrapped here in the later Spring or in the breeding season. Could these be birds that spend the Winter here but breed much further north?
I also retrapped a Black-capped Chickadee that is encountered here only in December: banded December 15, 2009; retrapped December 20, 2010; and then again today. What is its story!? So many questions, so little time.