Identification: The white-tailed deer is a stately, graceful animal distinguished by conspicuous ears, long legs, and narrow, pointed hooves. Adult males have spreading, branching antlers, which are grown anew each year. The most noticeable feature is the tail, which is brown on top and white underneath. When the animal is alarmed, the tail is raised high, revealing a white "flag" as the deer bounds off through the woods.
White-tailed deer vary seasonally in coloration. The summer coat is reddish-brown to tan and is composed of short, thin hairs. The winter coat is grayish-brown to gray, with long, thick hairs. Fawns are reddish-brown with white spots, which they lose when they are three to four months old, usually by the end of August in Connecticut.
Adult deer can stand three to three and a half feet tall at the shoulder and weigh between 90 and 300 pounds. White-tailed deer are ungulate herbivores, browsing on a variety of plants, including leaves, acorns, and twigs. they are most active at dawns and dusk and are known for their keen senses of sight, smell and hearing.
White-tailed deer can live for 10 years in the wild.
A single deer's annual impact on an ecosystem can be significant, especially in areas with high deer populations or where deer are concentrated. Deer browsing can drastically alter plant composition and diversity, impacting the food web and habitat for other species. An average deer consumes about 2 to 8 pounds of food per day, depending on its size and the quality of available food. This intake can vary seasonally, with deer eating more during times of abundant food like late summer and early autumn when mast is plentiful.
Key Impacts:
Plant Communities:
Deer consume a wide variety of plants, including seedlings, saplings, and mature plants. This can reduce the abundance and diversity of certain plant species, particularly those they find palatable. the white-tailed deer’s diet is dominated by browse (46%), followed by forbs (24%), mast (11%), and crops (4%). The remained includes various other food items such as mushrooms and lichen.
Browse consists of the leaves, buds and ends of twigs of woody to semi-woody, broad-leaved plants. Examples are trees, shrubs, briars and most vines.
Forbs are leaves and stems of non-woody (herbaceous), broad-leaved plants. Examples are weeds, some commercial crops (i.e., soybeans), and really anything that is not a browse or a grass.
Mast are hard or soft fruiting bodies. Examples include acorns, nuts, berries, apples, etc.
Grasses include leaves and stems of non-woody (herbaceous), narrow-leaved plants that originate from a single stem during development (browse and forbs emerge from seed with two stems). Examples include warm amd cool- season grasses, sedges and some crops, such as corn. With the exception of annual cereal grains, deer are not really grass eaters. They almost never consume perennial grasses, which are widespread.
Lichen and Fungi are simple, low-growing organisms that form on trees, rocks, and in the soil. examples include "old man's beard," moss, and mushrooms.
Deer tend to be finicky because they’re constantly trying to balance their overall intake of nutrients with changes in seasons, forage abundance, quality, perceived risk, as well as their own life stage and corresponding protein and/or energetic needs. Of course, with changes in growing seasons comes the predictable, annual ebb and flow of plant growth and drying-out and thus nutrient availability, but recent research has shown that forage nutrients change significantly by plant type, too.
Habitat Alteration:
By changing plant composition and reducing the density and diversity of forest undergrowth, deer can negatively affect the habitat structure for other animals, like birds and small mammals, that rely on specific plant communities for food and shelter. A decline in insect populations and nesting sites can lead to declines in bird species that rely on forest undergrowth and insects that depend on specific plants.
In one Pennsylvania study, areas with long-term deer exclusion showed up to 50% higher abundance, richness, and diversity of aboveground insects compared to areas where deer were present.
Ecosystem Disruption:
Changes in plant communities can disrupt nutrient cycling and alter the course of forest succession/regeneration.
Invasive Species:
Overbrowsing by deer can create opportunities for invasive plants to establish and spread, further disrupting the native ecosystem.
Reduced Biodiversity:
The overall impact of deer overpopulation can lead to a decline in biodiversity as species reliant on specific plants or habitats disappear or decline.
Specific Examples:
Forest Regeneration:
Deer can prevent the regeneration of certain tree species by consuming seedlings and saplings, impacting the future forest structure.
Bird Habitat:
Deer browsing can reduce the understory vegetation that provides nesting sites and cover for many bird species.
In England, a country-wide analysis showed that deer population increases over only ten years were related to population declines of five dense-understory bird species. Experiments also showed that the Blackcap, an understory bird in England, preferred sites not browsed by deer, and the birds’ body condition (weight and body fat) was better on plots where deer were excluded.
On islands off the coast of British Columbia, islands that had had introduced Sitka blacktailed deer populations for more than 50 years had bird populations only 30% to 45% as high as populations of deer-free islands. On islands with long-term deer populations the bird species with the highest dependence on understory vegetation were most affected, and their abundance was only 7% of those on deer-free islands. Deer overabundance decreased bird food resources and reduced nest site quality.
In the islands of Puget Sound, black-tailed deer regulated cover and structure of the understory, which, in turn affected bird populations, and deer-free islands supported the most abundant and diverse bird faunas.
In experiments in Pennsylvania, white-tailed deer were maintained at densities of between about 10 and 64 deer per square mile. Deer density had no effect on ground- or upper canopy-nesting bird populations, but midstory-nesting bird numbers declined 37%, and the number of midstory-nesting bird species declined by one-quarter. Effects were seen when deer population densities exceeded about 20 deer per square mile. Negative effects on vegetation became significant at deer impact levels well below those observed in many eastern forests.
On a group of 10 acre sites in Virginia, when white-tailed deer were excluded the density and diversity of understory vegetation increased, and bird numbers increased as well. The number of bird species did not increase, because open-vegetation species such as Chipping Sparrows were replaced by species such as Ovenbirds that preferred forests. Most species responded positively to the increase in vegetation that resulted from deer exclusion; these included Hooded Warbler, Ovenbird, American Redstart, Eastern Towhee, and Wood Thrush. In contrast to these mostly migratory species, several resident birds, such as Tufted Titmouse, Blue Jay, Northern Cardinal, and Carolina Wren, decreased in abundance in response to deer removal.
Because of the significant effects native or introduced deer overabundance can have on bird populations, both threatened bird species and common species alike, American Bird Conservancy recommends and supports humane control of excessive deer populations. This may include non-lethal methods such as reproduction control, deer-proof fencing, or trap/ relocate programs. Management practices specifically undertaken to increase deer populations in areas with overpopulations should be discontinued. Control may also include humanely-administered lethal methods such as increased and controlled hunting (using non-lead ammunition) or reintroduction of deer predators (wolves, mountain lions). Deer populations should be controlled at levels where natural understory and vegetation is maintained, to ensure the health of bird populations and of the entire ecosystem.
Ecosystem Engineers:
Deer, due to their browsing habits, are considered ecosystem engineers, meaning they can significantly modify their environment and influence the structure and function of the ecosystem.
Hidden Costs:
Deer can also have hidden costs, such as damage to gardens and agricultural crops, further highlighting the impact of deer overpopulation.
Declining Biodiversity in Vermont and New Hampshire Forests is a concern, with issues like deer overbrowse, invasive species, and habitat loss contributing to the problem. These forests, while extensive, face threats from climate change, deforestation, and the spread of non-native plants. Addressing these challenges requires collaborative efforts to manage forests sustainably and protect remaining wildlands.
In conclusion, while deer play a role in the ecosystem, high deer densities can lead to significant ecological changes, impacting plant communities, wildlife habitat, and overall ecosystem health.
