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The Newfoundland pine marten (''Martes americana atrata'') is a genetically distinct subspecies of the American marten (''Martes americana'') found only on the island of Newfoundland in the province of Newfoundland and Labrador, Canada; it is sometimes referred to as the ''American marten (Newfoundland population)'' and is one of only 14 species of land mammals native to the island. The marten is listed as endangered by the COSEWIC in 2001 and has been protected since 1934, however the population still declines.〔 The Newfoundland marten has been geographically and reproductively isolated from the mainland marten population for 7000 years.〔 The Newfoundland pine marten is similar in appearance to its continental cousin, but is slightly larger, with dark brown fur with an orange/yellow patch on the throat.〔 Females are an average weight of 772 grams and males have an average weight of 1275 grams.〔 The Newfoundland subspecies is also observed to inhabit a wider range of forest types than its mainland counterparts. The population characteristics suggest that the Newfoundland marten is a product of unique ecological setting and evolutionary selective factors acting on the isolated island population.〔 The Newfoundland pine marten is omnivorous, feeding on mainly small mammals, along with birds, old carcasses, insects and fruits; it is currently found in suitable pockets of mature forest habitat, on the west coast of Newfoundland and in and around Terra Nova National Park. The Pine Marten Study Area (PMSA) is located in southwestern Newfoundland and is a 2078 km2 wildlife reserve that was created in 1973 to protect the Newfoundland Marten.〔 ==Habitat== The Newfoundland marten range is now condensed into approximately 13,000 square kilometers in the western part of the island, with a large portion of key habitat in the Little Grand Lake area.〔 Due to the unregulated pulpwood harvest during the last century, the forest age-class distribution is skewed to the younger regeneration stage of forest succession, which led to the majority of the island being contiguous blocks of second-growth forest.〔 The behavioral patterns of habitat use by Newfoundland martens are altered by the ecological conditions of low prey biomass and high natural forest fragmentation that occur in Newfoundland.〔 A wide spectrum of habitat types are used throughout the geographic range, however, it has been found the Newfoundland Marten has a strong association with old successional forest.〔 Old-growth forest is defined as unharvested stands that are older than 80 years of age. The stand-scale habitat use includes mature coniferous forest being the dominant cover types used proportionately more than the availability, along with coniferous scrub and insect-defoliated stands used in proportion to the availability, whereas open areas and fire disturbed area are avoided.〔 However, the fire disturbance is minimized because of the lack of prolonged dry periods on the island.〔 Due to infrequent fires, the episodic defoliation by the spruce budworm and hemlock looper are the primary form of natural stand-replacing disturbance.〔 Newfoundland martens have a preference to mature (61–80 years old) and over mature (>80 years old) coniferous stands〔 since it is critical for foraging habitat.〔 More recent studies have found that martens will use forests with a variety of height and canopy closure conditions creating a wider variety of habitat types than previously thought; this variety includes areas that are disturbed by insects, mid-successional forests, precommercially thinned forests, along with the areas of mature and overmature forests.〔 Home range requirements for the Newfoundland Marten are extremely large due to the larger body size.〔 Males hold larger home-ranges (29.54 km2) than females (15.19 km2) which are significantly larger than other species of martens across most of the geographic range.〔 These larger home-ranges reflect the larger body sizes and the lower diversity and abundance of prey.〔 Martens will also adjust their behavior and home-ranges to suit the habitat needs since the average home-range of the marten is typically larger than the average defoliate parch size and therefore will need to adjust for defoliation disturbance.〔 Newfoundland martens are also intrasexually territorial and show home-range fidelity.〔 Home-range size have variation between years for both sexes based on the changes in the food abundance as well as the individual's ability to obtain their prey.〔 Within the year, martens may modify their movements during the winter because it is an additional energetic constraint that they have to respond to the harsher weather conditions and lower resource availability.〔 Newfoundland martens are forest-dependent species because they require overhead canopy for security and avoidance of predation, structurally complexity with abundant coarse woody debris and large diameter trees for winter resting sites, maternal dens, and access to small mammal prey in winter, as well as martens are more successful at catching prey in the older, structurally complex forest which is not necessarily where the prey are abundant.〔 The older coniferous forest is not needed just for escape from predation, prey availability, and den sites but also for thermoregulation.〔 Tree height is important to provide this thermally neutral area from resting sites as well as escape routes from predators. Canopy closer is a critical element of marten habitat, studies have shown that the presence of vertical stem structure and down woody debris is adequate to provide the security needed even if over head cover is absent; though marten still typically avoid the areas that are devoid of trees.〔 Down logs and other woody debris are important to the marten habitat, not just for cover from predators, but also for access to prey and for suitable sites for resting and maternal dens.〔 The determinant of suitable habitat may be forest structure over the species composition or age.〔 The reduced number of larger mammalian predators on the island compared to mainland martens slightly reduces the necessity to have escape cover which releases the selective pressure for Newfoundland martens to expand their habitat into areas that have higher prey densities, but with less secure cover relative to the mainland populations of martens.〔 Essentially the Newfoundland marten needs the jumble of dead and down timber that is provided by the old growth forests, where it allows for access under the snow during winter to small mammals providing the martens the resources needed to survive until spring; resources clearcuts cannot provide.〔 Habitat structure required for a healthy marten population needs decades to develop and have individual home range requirements that are large for the small carnivore.〔 Due to the changes in the stand-level dynamics and landscape-level phenomena shows that serious management is necessary to get the forests of Newfoundland to be prime habitat.〔 However, the conflict between the valuable economic resource of the timber and the preservation of the Newfoundland Marten will continue, suggesting that the system of permanent habitat reserves may not be a stable management strategy.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Newfoundland pine marten」の詳細全文を読む スポンサード リンク
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