Study

Response of northern flying squirrels to supplementary dens

Actions

This study is summarised as evidence for the following.

Action Category

Provide artificial dens or nest boxes on trees

Action Link
Terrestrial Mammal Conservation
  1. Provide artificial dens or nest boxes on trees

    A replicated, randomized, controlled study in 1992–1998 in a forest in Washington, USA (Carey 2002) found that artificial breeding sites were used by northern flying squirrels Glaucomys sabrinus but did not increase their abundance. Average northern flying squirrel abundance in sites with artificial dens (0.51–0.80 squirrels/ha) was not significantly higher than in sites without artificial dens (0.42–0.48 squirrels/ha). During 11 inspections of the 256 dens, a total of 349 northern flying squirrels, 201 Douglas’ squirrels Tamiasciurus douglasii and 16 Townsend's chipmunk Tamias townsendii were detected. By the end of the study 74-80% of next boxes and 34-50% of artificial cavities were used. In 1992, 16 nest boxes (20 × 22 cm across and 22 cm tall, with a 3.8 × 3.8-cm entrance) and 16 artificial cavities (10 ×15 cm across and 18–33 cm tall with a 3.8 × 3.8 cm or 4.5-cm-diameter entrance) were added to eight of 16 Douglas-fir Pseudotsuga menziesii stands. Forest stands were 13 ha and located in four areas (≤4 km apart). Each area had two stands with supplementary dens and two stands without supplementary dens (each ≥ 80 m apart). Supplementary dens were 6 m high and were inspected once in summer and once in winter, from summer 1993 to summer 1998. Flying squirrels were trapped during 49,152 trap nights in 1997–1998, with two Tomahawk live traps at each of 64 samplings stations, in each stand.

    (Summarised by: Ricardo Rocha)

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