While roadside restoration is touted as a way to provide more habitat for native species, living along roads can do more harm than good. Florida scrub-jays that nest along a highway die in greater numbers than they reproduce, according to new research in the April issue of Conservation Biology.

"Roadsides are death traps," says Ron Mumme of the Department of Biology at Allegheny College in Meadville, Pennsylvania, who co-authored this paper. "I think everyone recognizes that the number of animals killed by vehicles around the world is mind-numbingly large."

Figuring out how road kills affect a population is difficult for most species but can be measured precisely in Florida scrub-jays. Because the jays are easy to catch and band, researchers can reliably identify each individual in a population. And because jays are territorial and don't migrate, researchers can safely assume that adults that disappear are dead.

From 1986 to 1995, Mumme and his colleagues studied a color- banded population of Florida scrub-jays, a threatened species found only in the state's peninsular oak-scrub habitat. The researchers monitored the survival and reproductive success of jays nesting along Old State Road 8, a two-lane highway at Archbold Biological Station in Highlands County. Over the nine years of the study, 434 jays bred on 55 territories and had 527 young that fledged.

The researchers found that 15% more breeding adult jays died on roadside territories than on non-road territories (38% versus 23% per year). Moreover, on roadsides the number of adults that died was much larger than the number of young that survived, which means that the roadside population would have decreased by nearly a third each year if new jays had not immigrated there. In contrast, on non-road territories the number of yearlings that survived was 19% higher than the number of breeding adults that died.

The roadside death rate was particularly high for
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Contact: Ron Mumme
011-506-645-6106
Society for Conservation Biology
12-Apr-2000