Nuttall’s cottontail (nuttallii subspecies) COSEWIC assessment and status report: chapter 8
Limiting Factors and Threats
S. n. nuttallii is at the northern limits of its range in Canada where it inhabits a restricted area in the Okanagan Basin. Biological factors that determine its limited range are not clear, but its distributional area in Canada coincides with the limits of low elevation shrub steppe habitats. Following its appearance in 1939, S. n. nuttallii reached its current range within 15-20 years. Although, shrub-steppe grassland habitat exists in the Nicola, Thompson, and Fraser River valleys, these valleys are separated from the Similkameen and Okanagan valleys by extensive tracts of forest. Limited suitable habitat is probably the main constraint on the distribution of S. n. nuttallii in Canada.
This subspecies is not at risk in the United States. In Canada its distribution is in an area undergoing rapid development and habitat change. The only imminent threat is ongoing habitat loss from urban and agricultural development. From 1939 to 2001, urban areas in the southern Okanagan-Similkameen region increased from 368 ha to 3,567 ha, and cultivated areas increased from 11,482 ha to 19,057 ha with a corresponding loss of shrub-steppe habitat (Table 2). Most habitat loss occurred before 1995, but more S. n. nuttallii habitat is expected to be lost. The total human population for the Okanagan-Similkameen Regional District was estimated to be 81,967 in 2004 (BC Stats 2005). It is projected to reach 112,000 (27% increase) in this region by 2021 with a projected loss of 4,000 ha of grassland, 4,000 ha of riparian habitat, and 250 ha of dry forest (Ministry of Environment, Lands and Parks 1998).
The growth of the wine industry with the recent expansion of vineyards has also impacted habitat. Vineyards in British Columbia now total about 2,210 ha with most in the Okanagan Valley. Since 1999, 517 ha of land has been converted to vineyards; another 242 ha of new vineyards is projected for 2005-2006. The amount of Nuttall’s Cottontail habitat that was on these lands converted to vineyards is unknown. Habitat has been lost in the southern Okanagan valley. For example, some of the bench lands with extensive shrub-steppe habitat on the east side of Osoyoos Lake in the Osoyoos Indian Reserve, an area known to support Nuttall’s Cottontail since the early 1950s (Guiguet 1952), have been converted to vineyards. Additional habitat on the Osoyoos Indian Reserve lands could be lost with future development.
Potential threats are few. Carter et al. (1993) speculated that livestock grazing reduces population densities presumably because of the loss of forage. Nonetheless, no research has been done on the impacts of grazing on S. n. nuttallii populations in British Columbia. Although poison baits were used 25-30 years ago to control S. n. nuttallii feeding on young fruit trees, it is no longer considered a pest and this practice has been abandoned (Sullivan 1983). Pesticides applied in fruit orchards potentially could have an impact, but this rabbit is uncommon in cultivated agricultural lands.
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