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Levelling the Playing Field - Controlling Purple Martin Competitors
Author: Michael RascoThe greatest challenge for most owners of Purple Martin birdhouses is controlling competitor species. In the now distant past, this would have been much less difficult, as there was a very healthy diversity and balance in North American bird populations. Ranges and dietary preferences, of course, overlapped; sometimes species went extinct, sometimes new ones arose through the processes of natural selection. Overall, the push and pull between all creatures worthy and small was a wondrous, beautiful, and natural thing. This would change somewhat because of the effect of artificially introduced species.
The introduced species with the most profound effect on North American ecology is Homo sapiens. This stems from our high adaptability to our surroundings, and, moreover, from our astounding ability to adapt our surroundings to us.
However, though the sapiens in Homo sapiens means "wise", there are times when that moniker is sorely misplaced. In the mid to late 1800's, house sparrows were introduced into several American locales in an attempt to combat insects that were afflicting crops, cattle, and people. (It may be noted that while most of the insects were natives, the people, cattle, and many of the crops were not.) The sparrows soon spread throughout the continent, invading the habitats and homes of many native cavity-nesting birds like Purple Martins and bluebirds.
An even more egregious example is the story of Eugene Schieffelin, who, in 1890, released a flock of several dozen European starlings in Manhattan's Central Park. By 1940, a scant fifty years later, these aggressive and prolific birds had spread across the entire United States, taking over nesting sites and supplanting native bird species as it traveled. Today, the European starling is a common sight from sea to shining sea.
As the story goes, Mr. Schieffelin wanted to bring to the United States all the birds mentioned in the plays of William Shakespeare. Many ornithologists and birding enthusiasts currently agree that it was a poetic, romantic, and really dumb idea. "What fools these mortals be"
As previously mentioned, house sparrows and European starlings can be a devil of a problem for owners of Purple Martin birdhouses. Advances in birdhouse design have provided quite effective deterrents against starlings. Starling resistant entry holes are of a particular size and shape that hold starlings out, while not giving the martins a problem at all. Many purple martin birdhouses are deeper than they were in years past, and they may have semi-separate nesting chambers in the rear of the cavity or even off to one side. This keeps the martins and young out of the reach of persistent, pesky starlings that might damage them.
House sparrows present a more sensitive and thorny issue for Purple Martin landlords. They are smaller than Purple Martins, so there is no way to design an entrance to exclude them without also excluding the Martins. House sparrows are another very aggressive species; they will not hesitate to enter a Purple Martin's nest and destroy it, along with any eggs or nestlings that are present. It is absolutely imperative for Purple Martin birdhouse owners to perform regular, thorough nest checks to assist ward off these pests. For the average person, though, it is not possible to actively monitor their Purple Martin house all hours of the day. This is the beginning of the debate, because many currently successful Purple Martin landlords profess that the only truly effective way to control house sparrows is by lethal means. They advocate trapping and shooting (or otherwise exterminating) the sparrows. There are many examples of individuals using these measures who support large and prolific colonies of Purple Martins in their birdhouses.
Many individuals would love to give a home to martins, but are unable or unwilling to use lethal tactics, even in defense of a vulnerable new Purple Martin colony. Whether due to personal convictions, familial or social pressures, or local standards and laws, there are often reasons why killing even an unprotected species like the house sparrow is not an option.
Take, for example, the situation of science teachers who have placed Purple Martin birdhouses at their schools. They obviously need a non-lethal solution. Instead of shooting the unwanted birds, they may clip their tails, wings, or both.
Even within this school of thought, there is much room for discussion. Some say that all that is needed is to clip the wings enough to make flying more difficult. The sparrows will have to expend a worthy deal more energy on flight, and therefore, have less energy for their acts of aggression.
Others believe in clipping the wings in a manner to prevent flight altogether. The sparrows then become prey for other animals. Of course, the case could be made that this technique is not exactly "non-lethal".
Tail clipping makes it difficult to fly, and it may cause the bird to appear less attractive to potential mates. In this way, Purple Martin birdhouse owners somewhat diminish their current problem while potentially abating future problems by stemming house sparrow population growth. However, that theory is just that - a theory - and it has not been proven.
Many Purple Martin landlords maintain healthy, steady colonies using non-lethal methods. Though not as abundant as colonies where lethal controls are in place, they certainly prove that individuals who cannot or will not kill house sparrows need not be excluded from the joys of being a Purple Martin landlord.
Whichever method of control a Purple Martin landlord chooses, two things are necessary to remember. First, starlings and house sparrows can certainly be destructive to Purple Martin colonies; but they are neither mean nor evil. They act merely on instinct, and, like all purely instinctive creatures, they have no concept of worthy and evil. They are incapable of sentiments like niceness and meanness.
Secondly, every Purple Martin colony - whether it consists of a dozen Purple Martin birdhouses with a dozen pairs of birds in each, or it is one birdhouse with just two or three pairs - is vital. Each one, as long as its owner exercises some form of pest management, brings us closer to reestablishing Purple Martin populations in North America. That is surely a very worthy thing.
Article Source: http://www.articlesbase.com/nature-articles/levelling-the-playing-field-controlling-purple-martin-competitors-91358.html
About the Author:Michael Rasco is the owner of UtopiaBirdHouses.com, a website committed to providing high quality birding products and wild bird information.
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Keywords:
purple martin sparrows house martins species many starlings birdhouses