The Case Against Misguided Sentiment

THE CASE AGAINST MISGUIDED SENTIMENT 

January/February issue, 2007Wildlife artist Mia Lane e-mailed me early this winter and announced that her family had just increased by 13. When her nephew discovered that flying squirrels had decided to winter in his attic, he contacted his aunt when queries to his friends and neighbours regarding how to rid his attic of the homesteaders brought in unacceptable terminal suggestions including flushing the intruders down the toilet.

“It never ceases to amaze me how little regard some people have for wildlife,” retorted a visibly upset Mia Lane, who took her nephew’s squirrels under her care, keeping them in an outdoor covered run only long enough until they were adjusted to their new surroundings. On their own, they could then locate a hollow tree somewhere on the extensively treed property where they could nestle down and spend the remainder of the winter. Flying squirrels routinely den up together in small numbers, and these nocturnal animals are occasional nighttime visitors to backyard feeding stations.

Homeowners who solve wildlife problems by flushing unwanted guests down the toilet would benefit by spending some time around Canadian nature film makers John and Janet Foster of the Tweed area. Enjoying wildlife at the grassroots level, they devote endless hours to watching and nurturing backyard wildlife, right down to Monarch butterfly larvae, deer mice and chipmunks. As we sat at their backyard picnic table enjoying a barbecue one day last fall, the real treat was having no fewer than a half dozen chipmunks sitting up on their haunches, begging for handouts less than an arm’s length away.

However though, our love and enjoyment of wildlife can be a bit misguided. This turned out to be a fairly good winter for hawks in eastern Ontario. Red-tailed hawks could be seen perching in trees throughout the area, and it wasn’t a bad year either for rough-legged hawks, residents of more northern regions that often migrate to our area in search of better feeding grounds. Of course, with this increase, came an increased presence of certain hawk species at our bird feeders, primarily members of the Accipiter family – the sharp-shinned hawk and Cooper’s hawk, and on occasion, the much larger northern goshawk. All three are known for their fondness of birds in their diets, and become attracted to winter bird feeders due to an increased concentration of small birds.

Our own feeder had a sharp-shinned hawk for a few days which eventually moved on, but last winter, a Cooper’s hawk helped himself to an average of one mourning dove every two days. You could set your watch by him. The question is, should we interfere and become judge and jury about who we want at our feeders and take measures to prevent birds of prey from doing what Nature has dictated they should do? Hawks provide a natural control to bird populations, taking those from our feeding areas that tend to weaker, older, or less wary. Should we interfere by diluting the gene pool of mourning doves that can avoid the attacks of hawks? By madly flailing our arms and rapping the windows whenever we see a Cooper’s hawk, are we really helping the mourning doves in the greater scheme of things?

Well known Toronto birder Ross James asks this same question concerning cowbirds. In an article, published a while back in OFO News, official publication of the Ontario Field Ornithologists, he takes issue with well meaning people who routinely destroy the eggs of cowbirds whenever they come upon them in the nests of more “desirable” species.

All of us are familiar with cowbird habits. They don’t build a nest or raise their own young Instead, they prefer depositing their eggs in the nest of other birds, for them to raise. As most host species are those much smaller than the cowbird, the interloper grows faster, demands more food, and it isn’t long before the rightful occupants either starve, or are crowded out of the nest. Meanwhile, the host birds work diligently at keeping up with the demand of the cowbird’s appetite.

By destroying any foreign eggs we see in the nests of smaller birds, presumably we are giving Nature a helping hand. “But are we helping?” asks Ross James, who gives an example of a song sparrow’s nest he found. The song sparrow constructed its nest in such a fashion as to be obvious to the female cowbird, who quickly deposited her egg. Had Ross removed the egg, and the young song sparrows survived, he says, genetically, all would be probably be like the parents, unable to foil the efforts of cowbirds. Thus the success of the parasitic way of life would be assured and enhanced for another generation. Had Ross removed the foreign egg, he might have helped one pair of song sparrows raise their young successfully, but at the same time, perpetuated the genes of birds that allow the parasitic way of life.

And let’s face it. Exactly how much help are we giving any species by removing cowbird eggs? There is no possible way, except in extremely rare species, that we can find enough nests of any species to make a dent in their reproductive success by routinely removing cowbird eggs. If any species is to overcome the parasitic effects of cowbirds, then they must develop strategies on their own. And over time, many species have done just that. Some birds immediately recognize the strange egg and promptly kick it out of the nest. The yellow warbler abandons the clutch she has laid when she sees the foreign egg in her nest. But rather than go to the trouble of seeking out a new location and struggling with the construction of a whole new nest, she cleverly builds a new floor above the abandoned eggs, and lays another clutch of eggs. I have seen such nests with as many three tiers above the original clutch of eggs. A three time loser perhaps, but at least she has devised a way of coping with the problem rather than raising the cowbird at the expense of her own offspring.

Saving a small pack of flying squirrels from a hideous death makes sense. However, sometimes though our bumbling efforts to offer well meaning assistance does more harm than good in the long run. It’s a good point to remember too the next time a hawk grabs a guest from our feeders. Occasionally, Mother Nature may seem unkind, but she is still the best judge of how to maintain populations.