Bird Calendars
Misplaced or Out-of-Place Species
By Clem Klaphake
Alien or invasive species. Sounds pretty sinister. What is really meant is that a species—plant, animal, virus or bacteria—is not where we think it should be, and thus terrible things will result from this misplacement.
How a species gets misplaced can be a result of nature, as happened 3.5 million years ago when a mollusk species of the North Pacific Ocean invaded the North Atlantic. Before this time, the Arctic Ocean had created a barrier of nutrient-poor water under ice. But then a period of global warming made the Arctic more open and "friendly" to foreign mollusks and mussels. Did the Atlantic Ocean become less diverse in terms of mussel species? No, it increased in diversity due to an increase in hybridization.
The Arctic Ocean appears to be warming again—probably for reasons related to human activity this time. Some computer projections now show that the Arctic Ocean will be ice-free part of the year by 2050 (that is less than two generations from now). So does this mean that we will see a repeat of what happened 3.5 million years ago? Some say yes (Dr. Peter Roopnarine of the California Academy of Sciences and Dr. Geerat Vermeij of the Univ. of California, Davis) and some say no (Dr. Anthony Ricciardi of McGill Univ, Montreal).
Dr. Vermeij argues that the current biological invasions are very different from those of the past. He states, "What's happening now is a major form of global change. Invasions and extinctions have always been around, but under human influence, species are being transported faster than ever before and to remote areas they could never reach previously. You couldn't get 35 European mammals into new Zealand by natural mechanisms. They couldn't jump from one end of the world to another by themselves."
It is estimated that humans are moving 7,000 species a day. As a result, species are being moved or introduced to places never before seen. We tend to think of these invasive species as trees, grasses, birds (House Sparrow and European Starling) or other well-known species. But invasive species can also be microscopic or unnoticed.
Let me illustrate this last point with two examples. First, botulism is killing tens of thousands of birds around the Great Lakes every year. It now appears that this outbreak is triggered by two invasive species. The quagga mussel, introduced from the Ukraine, makes water clearer. More sunlight can then penetrate the lake, which in turn allows more algae to bloom. Finally, more dead algae increases the amount of oxygen-consuming bacteria. With lower oxygen levels, botulism-causing bacteria multiply. The mussels take up the bacteria and are in turn eaten by an invasive fish species which is eaten by birds. The birds become infected and die.
Secondly is the case of West Nile Virus, which first showed up in the United States in 1999. It has had a dramatic impact on a number of bird species—especially the corvids. Recently it was reported that the Yellow-billed Magpie has been hit hard by this virus.
This bird species only occurs in central California and therefore does not exist in large numbers nor in a variety of geographic locations. The West Nile Virus became widespread in California in 2004. According to an article in The Auk, from 2004 to 2006, 12,211 Yellow-billed Magpie carcasses were reported to the California Department of Health Services. Of the 1,007 carcasses tested, 78 percent tested positive for West Nile Virus. The total population of Black-billed Magpies is about 180,000. The results of these tests indicate that this population may have been reduced by 49 percent in just two years. BBS and CBC data show dramatic declines in Yellow-billed Magpies also. In retrospect, I'm glad I was able to see this species for the first time in the summer of 2007.
Most of you have heard of the zebra mussel that has caused so much trouble in numerous waterways, lakes and rivers. It is now right here in the metro area. It was first identified in April 2006 in the Base Lake in Sarpy County. The Air Force has now begun treatment of the lake with copper sulfate. Two applications will be made between now and the spring of 2009. Each application will cost $100,000. Remember this is a small lake!
In the future, you will continue to hear much more about alien, out-of-place, invasive or misplaced species from the Audubon Society of Omaha, politicians, conservationists, farmers, biologists, epidemiologists, backyard gardeners, pet owners, hunters, fishermen/women and others.
09/26/08