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Deer overpopulation troubles municipalities / Efforts to restrict symbol of tourism prove difficult

Deer overpopulation troubles municipalities / Efforts to restrict symbol of tourism prove difficult, The Japan News, Feb 22, 2017 Municipalities that have been protecting deer populations as a tourism resource or natural asset are now increasingly struggling with how to manage overpopulation of the animals. The deer population in Nara Park in the city of Nara has increased to 1,200 from about 500 in 1957, when they were designated as a national natural asset.

Since the population surge, damage to local crops caused by deer feeding has escalated. At the UNESCO World Heritage site Kasugayama Primeval Forest, located near Nara Park, deer eat the buds of young trees, preventing their growth into adult trees.To address the situation, the Nara prefectural government decided to divide the city into four areas and create an area where deer hunting will be allowed from April.

U-M biologists support Ann Arbor deer cull

U-M biologists support Ann Arbor deer cull
Michigan News, Jan 14, 2016

A University of Michigan evolutionary biologist says he and many of his U-M colleagues support the city of Ann Arbor’s plans to kill up to 100 deer this winter, calling the cull “a positive step toward ecological sustainability.”

U-M botanists have long noted declines in native plants that deer favor, Dick said. In a 2015 study, an ecological team surveyed browsing impacts in Ann Arbor’s Bird Hills Nature Area and found browsing damage in 80 percent of the tree saplings.

Habitat-population density relationships for white-tailed deer in Illinois


Habitat-population density relationships for white-tailed deer in Illinois

John L. Roseberry and Alan Woolf, Wildlife Society Bulletin, 2008

White-tailed deer have reached population densities in the agricultural Midwest that would not have been predicted 20-30 years ago. To help explain this phenomenon, we inventoried and analyzed potential deer habitat in Illinois, using classified satellite imagery and a proximity-based habitat model. Statewide prehunt deer densities (ca 1992) were estimated at 4-5 deer per km2 of total area and 30-37 deer per km2 of forest based on population reconstruction and modeling. Habitat suitability indices explained 81% of the variation in deer population densities at the county level. The amount and distribution of deer habitat in Illinois was primarily dependent on intensity of agricultural land use, which in turn was dictated by soil productivity and terrain. We found no evidence that relative use of available habitat at the county level was adversely affected either by habitat fragmentation or human presence on the landscape.

THE EFFECTS OF HIGH DEER DENSITY ON FOREST REGENERATION AND CARBON SEQUESTRATION

THE EFFECTS OF HIGH DEER DENSITY ON FOREST REGENERATION AND CARBON SEQUESTRATION
Environmental Research Journal, 2013

The effects of trampling and browsing pressure at high densities can negatively affect seedling recruitment, which is a critical component of forest regeneration and community structure. If the frequency of seedling disturbances is too high, forest regeneration and succession will be negatively affected. This may, in turn, introduce broader impacts beyond forest ecosystems, concerning stand biomass and the rate of carbon sequestration. As forests constitute major sinks for atmospheric CO2, the sizes of terrestrial carbon pools are of particular interest to ecologists, managers, and policy makers in relation to quantifying the amount of carbon sequestration rate.

Deer density and disease prevalence influence transmission of chronic wasting disease in white-tailed deer

Deer density and disease prevalence influence transmission of chronic wasting disease in white-tailed deer
Ecosphere, Jan 2013

We evaluated the influence of deer density, landscape features, and soil clay content on transmission of chronic wasting disease (CWD) in young white-tailed deer in south-central Wisconsin, USA. We evaluated how frequency-dependent, density-dependent, and intermediate transmission models predicted CWD incidence rates in harvested yearling deer. An intermediate transmission model, incorporating both disease prevalence and density of infected deer, performed better than simple density- and frequency-dependent models. Our results indicate a combination of social structure, non-linear relationships between infectious contact and deer density, and distribution of disease among groups are important factors driving CWD infection in young deer.

The Effects of Population Density on Juvenile Growth Rate in White-Tailed Deer

The Effects of Population Density on Juvenile Growth Rate in White-Tailed Deer
Environmental Management, 2014

Animal body size is driven by habitat quality,food availability, and nutrition. Adult size can relate to birth weight, to length of the ontogenetic growth period, and/or to the rate of growth.

… with the positive correlation between average adult body mass and population-level ontogenetic growth rate established, growth rate can be used to evaluate habitat quality and the efficacy of herd management decisions, and aspects of growth andbody size can better be studied on a population by population basis for purposes of serving quality deer management, sustainable harvest, and/or other management goals.  Deer have relatively long reproductive spans and vegetation may take time to recover from intense herbivory (Horsley 2003).

Our experience suggests that though sport hunters desire greater numbers of deer that are easier to find and harvest, when provided with biological evidence that supports management at lower population densities, they are not only interested but also supportive.

Long-Term Regional Shifts in Plant Community Composition Are Largely Explained by Local Deer Impact Experiments

Long-Term Regional Shifts in Plant Community Composition Are Largely Explained by Local Deer Impact Experiments
PlosOne, Dec 31, 2014

The fact that herbivores and predators exert top-down effects to alter community composition and dynamics at lower trophic levels is no longer controversial, yet we still lack evidence of the full nature, extent, and longer-term effects of these impacts. Here, we use results from a set of replicated experiments on the local impacts of white-tailed deer to evaluate the extent to which such impacts could account for half-century shifts in forest plant communities across the upper Midwest, USA. We measured species’ responses to deer at four sites using 10–20 year-old deer exclosures. Among common species, eight were more abundant outside the exclosures, seven were commoner inside, and 16 had similar abundances in- and outside. Deer herbivory greatly increased the abundance of ferns and graminoids and doubled the abundance of exotic plants. In contrast, deer greatly reduced tree regeneration, shrub cover (100–200 fold in two species), plant height, plant reproduction, and the abundance of forbs. None of 36 focal species increased in reproduction or grew taller in the presence of deer, contrary to expectations. We compared these results to data on 50-year regional shifts in species abundances across 62 sites. The effects of herbivory by white-tailed deer accurately account for many of the long-term regional shifts observed in species’ abundances (R2 = 0.41). These results support the conjecture that deer impacts have driven many of the regional shifts in forest understory cover and composition observed in recent decades.

Deer density and plant palatability predict shrub cover, richness, diversity and aboriginal food value in a North American archipelago

Deer density and plant palatability predict shrub cover, richness, diversity and aboriginal food value in a North American archipelago,
Diversity and Distribution, Sept 2014

[Abstract],
We provide comparative examples of endangered plant communities to demonstrate that, contrary to the intermediate disturbance hypothesis, any positive effect of deer on plant diversity on islands in the Pacific north-west of North America occurs at densities < 0.08 ha−1, if at all. This detailed example of trophic downgrading highlights the need and provides the methods to identify herbivore densities compatible with the persistence of all native species in conserved landscapes.

Excessive Deer Populations Hurt Native Plant Biodiversity, Pitt-Led Study Says

Excessive Deer Populations Hurt Native Plant Biodiversity, Pitt-Led Study Says
University of Pittsburgh News, March 10, 2014

The study, initiated in 2003 at the Trillium Trail Nature Reserve in Fox Chapel, Pa., concludes that an overpopulation of deer (density of deer in the United States is about four to 10 times what it was prior to European settlement of North America) is the primary reason garlic mustard is crowding out native plants, such as trillium, which are preferred food for wild deer.