Islanders will get say on deer problems next week
Representatives from the state Department of Environment Management and the Department of Health are expected to attend.
Amidst the controversy surrounding deer management on Conanicut Island, several local wildlife biologists are concerned that the public is unaware of the basic biological consequences of deer overabundance. As the island becomes more developed and we grow more accustomed to seeing deer in our back yards, it is easy to forget that although the island’s landscape is no longer forested or natural, we are still part of nature and are participants in a delicate ecosystem.
According to Chris Powell, a marine fisheries scientist at the state Department of Environmental Management’s Division of Fish and Wildlife, all ecosystems are based on predator-prey relationships. Without human intervention, the predator-prey dynamic will shift until the system is unbalanced.
Consider the historical relationship between deer and wolves on Conanicut Island. As a prey species, deer are biologically designed to have many off-spring in order to maintain their population. In fact, at as young as one year, females will have one fawn, and every following year the does will give birth to twins, despite ill health or food scarcity. Wolves, however, are able to adjust their own population size depending on environmental conditions. If deer are abundant, the wolves will have larger litters and the predator population will grow, keeping the deer population in check. As food sources diminish, the wolf population will decline as well. When humans enter into the equation however, this balance is disrupted and equilibrium is harder to achieve.
Throughout the 17th and 18th centuries wolves were abundant on Conanicut and Aquidneck Islands. In fact, records show that in 1642 the general court in Newport requested that Roger Williams consult with the Narragansett Indians regarding the control of the wolf population on Aquidneck Island. Wolves were eventually eradicated from the area and today the deer on Conanicut Island face no predators, allowing the deer population to increase exponentially.
Lori Gibson, a deer specialist at the DEM’s Division of Fish and Wildlife, reports that in addition, deer have low mortality rates — 50 percent the first year and 10 percent each following year — long life spans, about 8 years, and an abundance of tasty food from gardens and shrubs. Combine these factors with refuge from hunting and deer populations will grow unbounded.
Automobile collisions, decimated gardens, and a growing number of Lyme disease cases are the most visible effects of deer overpopulation on Conanicut Island. Though less visible, the deer’s effects on the island’s ecosystem are significant and irreversible. The deers’ first adverse effect on the ecosystem is reduced forest health, says Gibson. Deer are often called “browsers,” referring to their eating habits, and generally eat between 4 and 6 pounds of foliage each day. As food sources become strained, the deer will eat everything within their reach, creating a “browse-line,” a level in the forest below which all the trees and plants are stripped bare. Repeated foraging year after year will reduce the forest’s ability to regenerate.
Numi Mitchell, a local wildlife biologist, reports that a browseline is especially obvious on the south side of Route 138 West, just beyond the Jamestown Bridge, heading towards Route 1. Mitchell has observed that forest area that was once impassable to humans because it was so densely thicketed is now open and exposed.
As the forest becomes denuded, many other species lose their habitat. Animals such as foxes, otters, and mink are shy species that like insulated forests, Mitchell says. As the foliage is stripped from the forest understory, these species become more vulnerable to predation, especially from cats and coyotes. Migratory and ground-nesting birds are also particularly susceptible to increased predation and habitat loss when low levels of the forest are exposed.
According to Gibson, bird species in decline include the Canada warbler, yellow breasted chat, wood peewee, eastern phoebe, and wood thrush. In addition, Powell has noticed that there are significantly fewer oven birds and black and white warblers nesting at the north end of Conanicut Island.
Animals are not the only ones impacted. Gibson explains that deer not only browse on several rare plant species, but even find them especially palatable. Orchids and lilies are some of the deer’s favorites, and once the deer have plucked off the flowers the plants have no way to spread their seeds and repopulate. At a conference on the impact of deer on the biodiversity of Pennsylvania in 2004, it was reported that deer were believed to have eliminated bearberry from the state, reduced the number of hoary puccoon (a little plant found in the Great Lakes region) by 60 percent, and were often found browsing several of the state’s endangered plant species, including lady-slippers and Philadelphia lilies. The impact does not stop there, however. As the indigenous species disappear, invasive species readily take over.
It is ironic that in a day of constant fear of loss of species and biodiversity we are faced with problems caused by overabundance of one important part of our ecosystem. The truth is, however, that we are responsible for disrupting the predator-prey equilibrium and have been inattentive to the biological facts of our island’s ecosystem.
As Gibson concludes,“Even inaction is a course of action and the public must be prepared to face the consequences of doing nothing.” An ever-increasing deer population will not only leave us frustrated as our string beans and peppers are gobbled up, but will result in loss of biological diversity and environmental balance.