Invasive species
The New York State Invasive Species Task Force has just issued a draft report. The report defines invasive species as "non-native species that can cause harm to the environment or to human health." The report gives an excellent rundown of invasive species present - or on their way - to New York, including invasive crabs, plants and birds - and offers strategies for their control.
Of particular interest to birdwatchers, the report notes that at Iona Island in Bear Mountain State Park, common reed or phragmites "has expanded to almost sixty per cent of what had been a rich emergent ecosystem." As a result, although the number of birds on the island has remained constant, the number of species present has declined by more than half. Even in Central and Prospect parks, efforts are underway to suppress or eliminate phragmites.
Another threat to bird life is posed by invasive zebra and quagga mussels. The bacterium that causes Type E Botulism thrives in beds of Quagga mussels and is passed on through the Round Goby fish to seabirds. As a result, according to the report, "tens of thousands of birds [including loons, ducks, gulls and eagles] have died in recent years." The Round Goby, of course, is itself a non-native species hailing originally from the Black and Caspian Seas. Like many invasive species, it is capable of rapid population growth. According to the above website: "They spawn repeatedly during the summer months, and each time, a female can produce up to 5,000 eggs."
Purple loosestrife - also cited by the report - is an attractive marsh plant. It is highly aggressive and pushes out native aquatic plants. This is believed to have an adverse effect on ducks and other wildlife which lose breeding and foraging habitat.
One invasive species with which even bad birdwatchers are familiar is the starling. These birds nest in cavities or holes in trees - like woodpeckers - but they do not excavate their own nests. Rather, they steal them from woodpeckers - like red-bellied woodpeckers and northern flickers. While populations of red-bellied woodpeckers are increasing, those of flickers are declining. Here's a website that promotes the view that nest competition between starlings and flickers is a cause of the latter bird's decline and which offers some suggestions for helping the flickers to gain the upper hand.
On the other hand, this study found that competition between starlings and Lewis' woodpeckers (a species found in the western United States) was not a factor in that woodpecker's population decline - at least in certain areas. Audubon has included Lewis woodpecker on its Watchlist as a threatened species but notes:
I once witnessed a nest competition between a downy woodpecker and a red-bellied woodpecker in Prospect Park. Although the downy is a much smaller bird, it won and raised a brood in the nest - despite the presence of many starlings in the area. So sometimes the good guys (and gals) win!
Of particular interest to birdwatchers, the report notes that at Iona Island in Bear Mountain State Park, common reed or phragmites "has expanded to almost sixty per cent of what had been a rich emergent ecosystem." As a result, although the number of birds on the island has remained constant, the number of species present has declined by more than half. Even in Central and Prospect parks, efforts are underway to suppress or eliminate phragmites.
Another threat to bird life is posed by invasive zebra and quagga mussels. The bacterium that causes Type E Botulism thrives in beds of Quagga mussels and is passed on through the Round Goby fish to seabirds. As a result, according to the report, "tens of thousands of birds [including loons, ducks, gulls and eagles] have died in recent years." The Round Goby, of course, is itself a non-native species hailing originally from the Black and Caspian Seas. Like many invasive species, it is capable of rapid population growth. According to the above website: "They spawn repeatedly during the summer months, and each time, a female can produce up to 5,000 eggs."
Purple loosestrife - also cited by the report - is an attractive marsh plant. It is highly aggressive and pushes out native aquatic plants. This is believed to have an adverse effect on ducks and other wildlife which lose breeding and foraging habitat.
One invasive species with which even bad birdwatchers are familiar is the starling. These birds nest in cavities or holes in trees - like woodpeckers - but they do not excavate their own nests. Rather, they steal them from woodpeckers - like red-bellied woodpeckers and northern flickers. While populations of red-bellied woodpeckers are increasing, those of flickers are declining. Here's a website that promotes the view that nest competition between starlings and flickers is a cause of the latter bird's decline and which offers some suggestions for helping the flickers to gain the upper hand.
On the other hand, this study found that competition between starlings and Lewis' woodpeckers (a species found in the western United States) was not a factor in that woodpecker's population decline - at least in certain areas. Audubon has included Lewis woodpecker on its Watchlist as a threatened species but notes:
"European Starlings attempt to take over Lewis's nesting cavities, but Lewis's is almost always successful at retaining its cavity. The species is preyed upon by other avian species, particularly raptors. American Kestrels prey heavily
upon young fledglings."
I once witnessed a nest competition between a downy woodpecker and a red-bellied woodpecker in Prospect Park. Although the downy is a much smaller bird, it won and raised a brood in the nest - despite the presence of many starlings in the area. So sometimes the good guys (and gals) win!
posted by Whistling Dixie at 5:13 AM
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