COLUMBUS DISPATCH (Ohio) 04 November 08 A real slug (salamander and snake) fest - As Ohio plans to reduce deer populations, a study suggests the results could affect ecosystems (Spencer Hunt)
By 1904, after decades of unlimited hunting, the white-tailed deer was wiped out in Ohio.
What a difference a century makes.
State wildlife officials say Ohio has at least 700,000 deer. That estimate doesn't include thousands living in metro parks, suburban areas and city fringes. For example, more than 200 deer live in Sharon Woods, Blacklick, Blendon and Highbanks parks in central Ohio.
Officials say that many deer in Ohio damage crops, slow new forest growth and cause auto accidents.
So the state now drafts plans to winnow Ohio's deer population through hunting. This year, a record 250,000 deer are expected to be killed.
Despite this annual thinning, the total remains steady year to year.
Some groups, including the Ohio Farm Bureau Federation , want the state to significantly reduce the number of deer in Ohio -- perhaps by 450,000.
But a new study suggests there is more at stake than the number of deer.
Researchers at Ohio State University and the National Park Service found that a large number of deer might be beneficial to some amphibians, reptiles and mollusks.
The results surprised Katherine Greenwald, an OSU doctoral student and conservation biologist, who found more redback salamanders, garter snakes and slugs in areas left open to grazing at Cuyahoga Valley National Park than in areas fenced off to deer.
"I would have said there would be more salamanders in the fenced-off areas," Greenwald said.
She and study co-author Lisa Petit, the park's science and resource management chief, say that state officials need to weigh the potential effects on these animals when they plot deer-reduction strategies.
"We want this kind of research to come into play," Petit said. "We want these kinds of results to be considered."
State wildlife officials aren't convinced.
"I think there is more study needed," said Mike Tonkovich, the state's deer biologist.
His main complaints are the size of the study and that researchers don't know whether the number of deer is linked in any way to the size of the other animal populations.
Tonkovich said a follow-up study should allow a reduced number of deer into areas to see what effect that would have on amphibians, mollusks and reptiles.
"One would expect that the density of salamanders and snakes would go down," he said.
Dave Risley, director of wildlife management and research for the Ohio Department of Natural Resources, said thinning the deer population still has "more pluses than minuses" for people and the environment.
Greenwald and Petit said the effects that reducing deer populations would have on the intricate web of plants, insects and animals aren't fully understood.
Petit said the study shows there might be more ecological consequences to hunting than people think.
"None of these relationships are ever so obvious that deer always mean bad things," Petit said. "What we want to do is make sure we have the appropriate balance of deer in the ecosystem."
Tonkovich and Petit said deer coexist well with nature when there are 15 to 20 per square mile of habitat.
Petit said that when deer exceed that population density, they begin to overgraze, killing out wildflowers and tree seedlings.
That leaves fewer habitats for other animals, including ground- and shrub-nesting birds such as hooded warblers, wood thrush and Acadian flycatchers. It also affects a forest's ability to replace older, dying trees with new growth, Tonkovich said.
The Ohio Department of Natural Resources estimates that deer exceed 25 per square mile in 23 Ohio counties, primarily in the east and southeast.
Cuyahoga Valley National Park has 45 to 50 deer per square mile.
When deer leave the forest and get into farm fields, they eat crops. A 1996 Ohio State University study put statewide crop damage by deer at $25 million a year.
According to the Ohio Department of Public Safety, 26,304 deer-vehicle collisions were reported in 2007. There were 10 deaths and 1,022 injuries.
"We think only about half (of all crashes) are reported," Risley said.
Greenwald said the effects of deer reductions on reptiles, amphibians and other wildlife have not been extensively studied.
"They are difficult to find, and they are often overlooked," Greenwald said of snakes and salamanders.
And besides, "They're not fuzzy or charismatic."
To conduct their study, Greenwald and Petit set aside 12 research plots in the national park and studied them from 2004 through 2005.
Each plot included a fenced area 33 feet long by 33 feet wide and an unfenced area the same size. Greenwald put five 1-square-foot boards on the ground in each of the fenced and unfenced areas.
The boards served as artificial shelters for ground-dwelling amphibians, reptiles and other animals. Petit and Greenwald counted the critters they found living under and near boards about once a month from May to December in 2004 and from May to September in 2005.
Greenwald found 84 redback salamanders living beneath the boards in areas left open to deer, compared with 30 of the same species in the fenced areas.
The study also found 33 garter snakes, which eat salamanders, in the grazing areas, compared with six in the enclosures. There were 1,233 slugs found living under the boards in grazed areas, compared with 760 in the fenced areas.
One explanation for the study's findings is that deer droppings create a more nutrient-rich environment that favors slugs and salamanders, which attract snakes that eat salamanders.
Petit said it's possible that the boards created a refuge from deer hooves in the grazed areas. Salamanders, slugs and snakes that lived within the fences might not have been as motivated to live beneath the boards.
Another issue is the kinds of animals that were found. Redback salamanders and garter snakes better adapt to damaged or altered habitats than other species.
"I didn't find any other salamander species" besides redback, Greenwald said. "Two-line salamanders, dusky salamanders -- they are more associated with undisturbed habitats."
State officials say they aren't likely to wait for answers to these questions. Risley said the state is committed to thinning the deer herd.
"If we could knock the population below 600,000, that would be good," he said.
The Ohio Farm Bureau Federation wants it reduced to 250,000.
"It's a top concern for our organization," said Keith Stimpert, the federation's senior vice president for public policy. "None of the steps to date have had a significant impact on the (deer) population."
Stimpert said the federation regularly hears complaints about crop damage caused by deer. The Department of Natural Resources logged 1,677 complaints from farmers last year. In 2000, there were 879.
Michael Walton, a Cleveland State University biology professor who studies forest-floor food webs, said there are more questions than answers about deer and population studies.
"There is not a lot known about how the effects of deer cascade down through a forest ecosystem," Walton said.
A 1994 study of red deer in the Scottish Highlands found nearly four times more moth and butterfly larvae, three times more ants and twice as many beetles, spiders, flies and midges in areas that kept deer out.
Another question is the type of animals that Greenwald and Petit found living in areas with deer.
Walton said a large number of slugs isn't necessarily a good thing. "Many (species of) slugs are invasive," he said. "They are an indication of an unhealthy, disturbed forest floor."
However, Greenwald said that the effects of deer reductions on amphibians and snakes should not be discounted.
"Salamanders are an important part of the food web," she said. "It's really hard to predict how other things will change if you change one thing. Everything is so interconnected."
A real slug (salamander and snake) fest