Individual study: Habitat Management for the Endangered Stephens' Kangaroo Rat: The Effect of Mowing and Grazing
Kelt D.A., Konno E.S. & Wilson J.A. (2005) Habitat Management for the Endangered Stephens' Kangaroo Rat: The Effect of Mowing and Grazing. The Journal of Wildlife Management, 69, 424-429
This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.
Manage vegetation using livestock grazing
A replicated, controlled, before-and-after study in 1998–2000 in five grassland sites in California, USA (Kelt et al. 2005) found that using livestock grazing to manage vegetation had mixed effects on the abundance of Stephens’ kangaroo rat Dipodomys stephensi. One year after grazing started, there was no difference in the density of Stephens’ kangaroo rat (9 animals/ha) compared to before grazing started (9 animals/ha). However, after two years, their density had increased to 22 animals/ha. Areas that were grazed had a lower density of kangaroo rats both before grazing started and after one year when compared to ungrazed areas (9 animals/ha vs 28 animals/ha), but after two years there was no longer a significant difference (22 animals/ha vs 28 animals/ha). In 1998 and 1999, two sites were grazed by sheep for between four hours and three days, and two sites were not grazed in either year. An unspecified number of Sherman live traps were placed in each site. In 1996–2000, at unspecified times of year, trapping was conducted over three consecutive nights. Traps were opened in the evening and checked at midnight and at dawn and animals caught were individually marked.
(Summarised by Phil Martin)
Other biodiversity: Use grazers to manage vegetation
A replicated, randomized, controlled before-and-after study in 1996–2000 in grasslands in southern California, USA, found that Stephen’s kangaroo rat Dipodomys stephensi increased in numbers on sheep-grazed plots, but not on ungrazed plots. Monthly survival was lower on grazed plots. Mammals: Similar numbers of kangaroo rats were found in grazed and ungrazed plots after two grazing sessions (13–38 individuals/ha), but fewer were found after one grazing session and in six of eight surveys before grazing (1–19 vs 21–39). Similar numbers were found in plots that were mown and then grazed, compared to ungrazed plots, after grazing (18–38), but fewer were found before grazing, in 14 of 15 surveys (3–14 vs 21–38). Monthly survival was lower on grazed plots, compared to ungrazed plots (data not provided). Methods: Eight 80 x 80 m plots were established in December 1996. Three were grazed in June 1998 (1,500 sheep for four hours) and 1999 (200 sheep for three days), three were mown in 1998 and grazed in 1999, and two were neither mown nor grazed. Kangaroo rats were trapped in 24 periods of three nights each.
Remove vegetation by hand/machine
A replicated, controlled, before-and-after study in 1996–2000 of a grassland area in California, USA (Kelt et al. 2005) found that after vegetation mowing commenced, Stephens’ kangaroo rat Dipodomys stephensi abundance increased. More animals were estimated to be in mown plots two years after mowing began (mown: 21; before mowing 18) and in plots that were both mown and grazed (mown: 15; before mowing: 8). Plots that were neither grazed nor mown contained more animals than mown or mown and grazed plots, although the number after management of other plots commenced did not differ from that before management (28 vs 28 kangaroo rats). Seven plots (80 × 80 m) were surveyed. Two were mown in 1998 and 1999, three were mown in 1998 and grazed by sheep in 1999 and two were not grazed or mowed. Mowing cut vegetation as short as the mower allowed. Cut vegetation was left on site. Grazing removed all available forage. Kangaroo rats were surveyed using grids of Sherman live traps, over three consecutive nights, bimonthly, from November 1996 to October 2000.
(Summarised by Phil Martin)