Tuesday, September 23, 2014

Mute Swan - An Invasive Species

Thursday September 18th 

On my recent trip to the Chicago area I was disappointed to have dipped on sighting any wild Mute Swans. On previous visits to the area I had found them on several lakes, but these visits were in late spring or early summer. So I started doing a little research to find if they leave the area following nesting. 
Mute Swan. Photo by Bob Pelkey
What I did find was that in those states and in Canada were they have become established, the wildlife authorities are seeking methods to control or eliminate the species. Seems that these large birds are not always good neighbors and can become quite aggressive during nesting.  We had witnessed such an event several years ago.  Just imagine the aggressiveness of a Northern Mockingbird that weighs twenty pounds. In fact a man in Illinois was drowned in such an attach a couple of years ago.
This aggression can also be directed toward our native and endangered Trumpeter Swans. In Pennsylvania and other states there is a fear that there growing numbers and their disruption in marshes used by nesting Black Terns will harm the terns. So these non-native, invasive and beautiful swans have to go. Its a shame. Planned hunts in several states have been curtailed due to negative public reaction. So I wondered if these Illinois swans had migrated or were they quietly being thinned out. 

Brown Snake in Guam. Photo by John Uzzardo
We all know that non-native invasive or introduced species can cause havoc in an ecosystem. We are watching the Burmese python in the Everglades. But another snake that recently arrived on the island of Guam has decimated the wild bird bird population. My nephew, John, is a biologist working on Guam and is part of the effort to control the snake.  John tells me that the a walk through the forests can be quit eerie due to the lack of sound. The birds are gone. Wiped out by these predators.Several endemic species are now extinct. The Micronesian Kingfisher and the Guam Rail are no longer found on Guam. They are a part of a captive breeding program, The rails have been good breeders but continue to fail when released on Guam, but have a small foothold on other snake free islands. The kingfishers may never be seen in the wild

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