Differences in habitat requirements and the spatial distribution of habitat for native and introduced species can determine outcomes of biological invasions. Introduced eastern gray squirrels (Sciurus carolinensis) have displaced native red squirrels (S. vulgaris) in Europe and have been implicated as a contributing factor to the decline of western gray squirrels (S. griseus) in North America. Eastern and western gray squirrels are associated with oak (Quercus spp.), but little is known about how these species interact. From April 2007 to April 2012, we radio‐tracked sympatric eastern and western gray squirrels in western Washington to compare habitat use and evaluate competitive interactions. We developed resource utilization functions for each species and evaluated distribution of habitat on Joint Base Lewis‐McChord, Washington, USA. Both species shared affinity for closed canopy forests and oaks; however, important differences in relationships with riparian areas and shrub cover resulted in low overlap in habitat distribution, which likely limited potential competitive interactions. Eastern gray squirrels appeared restricted to areas around wetlands likely because they supported the deciduous tree species that comprise habitat for this species in its native range. Use by western gray squirrels, but not eastern gray squirrels, significantly decreased with increasing shrub cover. Forestry practices that promote mixed oak‐conifer with little shrub cover in uplands can benefit western gray squirrels and minimize interactions with eastern gray squirrels. © 2020 The Wildlife Society.

中文翻译：

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本地和引进的灰松鼠的资源差异利用

生境和外来物种的栖息地要求和栖息地空间分布的差异可以决定生物入侵的结果。引入的东部灰松鼠（Scuulus carolinensis）已取代了欧洲的本地红松鼠（S. vulgaris），并被认为是导致北美西部灰松鼠（S. griseus）数量下降的原因。东部和西部的灰松鼠与橡树（Quercusspp。），但对这些物种之间的相互作用知之甚少。从2007年4月到2012年4月，我们在华盛顿西部对同伴的东部和西部灰松鼠进行了无线电跟踪，以比较栖息地的使用情况并评估竞争性相互作用。我们开发了每种物种的资源利用功能，并评估了美国华盛顿路易斯·麦克乔德联合基地的栖息地分布。两种物种都对封闭的冠层森林和橡树有亲和力。但是，与河岸地区和灌木覆盖关系的重要差异导致栖息地分布重叠率低，这可能会限制潜在的竞争相互作用。东部灰松鼠似乎仅限于湿地附近，因为它们支持落叶树种，而该落叶树种构成了其本地栖息地的栖息地。由西方灰松鼠使用 但东部灰松鼠则没有，但随着灌木覆盖的增加而显着下降。在高地上推广灌木丛很少的混交针叶林的林业实践可以使西部灰松鼠受益，并减少与东部灰松鼠的互动。©2020野生动物协会。