Bird Conservation - Living on the Edges -
[Cached Version]
Published on: 10/31/2003
Last Visited: 10/31/2003
Leaning against an ironwood tree a few feet from the stream, Christopher Moorman isn't surprised.A wildlife ecologist at North Carolina State University, he carefully notes the species and location of each bird that sings or wings within a 50-foot radius."Clearly, Black Creek is an oasis for birds," he whispers.But Black Creek flows through a tidy neighborhood in Cary, North Carolina, one of the nation's fastest growing towns.The paved greenway trail beside the creek is beloved by hikers, bikers, dog walkers, families on picnics, and children on Rollerblades.Backyards crowd the woods."The problem," Moorman says, "is that it's an oasis for humans, as well."
Greenways and parks have long been attractive to humans seeking respite from the pressures of city and suburb.Now Moorman and his collaborators are trying to learn if the Black Creek greenway is a healthy place for birds, and if there are ways to make it better.
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Such wooded corridors are frequently touted for providing much-needed wildlife habitat in developed landscapes, Moorman says, "but we don't know if it's good habitat, because we don't know what's happening to the birds that use it."
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Moorman and his collaborators, including a landscape ecologist, an urban planner, and a parks and recreation expert, are studying how songbirds fare in small fragments of land cover surrounded by neighborhoods, shopping centers, and industrial areas.
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When a natural landscape is carved into smaller, more isolated patches, some species gain a competitive advantage, says Christopher Moorman, a wildlife ecologist at North Carolina State University.Other species are dealt a competitive blow.
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"These strips of woodlands are all the birds have left in many of these urbanizing environments,"Moorman says."We can suggest better ways for developers and urban planners to boost their value for birds."
Recreational trail design is one instance in which there are lessons to be gleaned.Moorman says the team's most important finding was that wide, maintained paths and landscaped areas within the greenways "are bad news for birds."Break up a 1,000-foot-wide greenway with a 30-foot-wide walking trail and mowed shoulder, and you don't have a 1,000-foot-wide greenway any longer.You have two greenways that are not quite 500 feet wide."This is something greenway planners can easily prevent," he insists, "and with public education, it's something greenway users should support."Also, since greenways less than 150 feet wide proved to be a wasteland for some deep-woods-nesting neotropical migrants, that could be considered a minimum size.
Developers also have the opportunity to craft more bird-friendly spaces.Many residential areas are designed with straight lines of grassy lawns and hedges-often planted in nonnative species-along the border between neighborhoods and natural areas.These abrupt edges leave a meager transition zone for birds to use as escape cover from predators such as hawks and cats.Adding insult to injury, Moorman explains, is that many greenway areas are shorn of shrubs and small trees."That leaves big trees and turf, with no intermediate vegetation, and that's not much good for birds no matter how wide a greenway may be," he says.Replicating natural cover as closely as possible, with shrubs and trees of varying heights, increases nesting and foraging habitats.