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| The finch being handled |
The seed feeder that I maintain for wild birds in the
backyard is situated far enough from the house that I doubted that the finch
had fled from it—because of a hawk, let’s say—and slammed into the windows. Of course it was a possibility, but I thought
that the likelier explanation was that the finch was intoxicated. Drunkenness in birds occurs more often than
some people might suspect. In the winter
and early spring months, warm days may cause fermentation in the sugary berries
that grow on shrubs and vines. If birds
then consume these potent ethanol capsules in large enough quantities, they may
exhibit symptoms of inebriation: flying erratically or weakly, dropping to the
ground, lurching lethargically, etc. In
rare cases, birds may die from alcohol poisoning.
While I didn’t entertain any real fears that the finch would
die, I was pretty convinced that it was suffering from a mild case of
intoxication, probably from eating too many overripe privet berries. Over the previous few weeks, I had regularly
observed the wintering flock of Purple Finches munching on these blue fruits,
usually in the company of Cedar Waxwings—which, incidentally, seem to be found in
a drunken state more often than most North American birds, if online reports and
articles are any indication. It’s also
possible, although less likely, I think, that the toxin syringin, found in
privet, had poisoned this bird.
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| Purple Finch feeding on privet berries |
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| More finches at the feast |
Since it wasn't practical for us to simply leave the finch on the
patio, my sister and I decided to set it on a large stump near the feeder and
wait for it to recover. The feeder
itself hangs under some very large oak trees and near an expanse of fairly
dense shrubbery—plenty of cover to make the bird feel more secure. We went about our business for a while, and, apparently,
the bird eventually sobered up. Several
of its Purple Finch flockmates were also hanging around the backyard feeder, so,
after a while, I completely lost track of which bird had been ailing. They all seemed alert and healthy. Success!
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| Recovering |
On a not-unrelated note, in Googling a few things for this
blog post, I found yet another item to add to my growing list of concerns about
Chinese privet, the shrub on which the Purple Finches had been feeding. Perhaps unsurprisingly, there has been research indicating that fruit from invasive plants may not be healthy for birds. Specifically, many species invasive to North
America contain more carbohydrates than their native counterparts, which tend
to contain more fats. Unfortunately, this
means that birds often go for the “quick energy,” so to speak, even if it hurts
them farther down the line. Another
problem that I hadn’t considered before is that feeding on invasive plants
might interfere with mate selection in some species of birds. For example, male Northern Cardinals that
feed heavily on the nonnative Amur honeysuckle will have more vibrant plumage
and may therefore be more attractive to female cardinals than males that feed
on native plants, simply because the honeysuckle contains extremely high levels
of carotenoids—i.e., pigments found in plants and certain other groups of organisms. Male cardinals that don’t feed on Amur honeysuckle may well be healthier than their
counterparts, but their plumage won’t reflect that. Finally, I have to wonder if the higher
levels of carbohydrates in many invasive species increase the likelihood that
their fruits will ferment and lead to inebriated birds.
Yes, I realize that I’m probably a bit hypocritical on this
subject: I keep a feeder in the backyard.
It encourages birds to be lazy and to congregate in an area that
normally wouldn’t interest them. On the
other hand, I would guess that the seed mixes they eat from it are healthier than the berries from privet and Japanese honeysuckle, to name only a
couple of common invasives in this region, and at least the feeder isn’t
strangling trees and shading out native vegetation. Chinese privet is a tough weed to
eradicate. The best that most of us amateur
naturalists can do on an individual level to combat its effects is to plant
native shrubs and cut or uproot the privet wherever possible. And, of course, keep alert for birds that might
have had a little too much of this not-so-good thing.
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