Conserving the smallest mammals on the tallest peaks

Tanzania has some of the most well-known, charismatic wildlife in the world. It’s the home, for example, of Jane Goodall’s famous chimpanzees in Gombe Stream National Park. Tanzania also contains one of the most charismatic landscapes in the world: Mt. Kilimanjaro, Africa’s tallest mountain. Kilimanjaro, however, is home to some of the world’s least known, less charismatic critters.

Most studies of mammals in Tanzania have focused on larger animals, while the smaller mammals – rodents and shrews – living on the slopes of the nearly 6,000 meter tall Kilimanjaro have largely been ignored. “The lack of detailed biotic vertebrate surveys,” writes Field Museum researcher William T. Stanley, “such as those of small mammals, hampers efforts to monitor ecological change over time on the mountain.” Researchers have recently asserted that climate change is altering the habitat and ecology of the volcano. In one sense, that’s undeniable: climate change is altering just about everything. However, without a baseline for the distribution and ecology of plants and animals on the mountain, it would be fairly difficult to pinpoint just what it is that’s changing. That’s why Stanley, together with Field Museum researcher Mary Anne Rogers, University of Dar es Salaam zoologist Philip M. Kihaule, and Maiko J. Munissi of the Southern Highlands Conservation Programme decided that they needed to head out to Mt. Kilimanjaro.

For roughly six weeks in July and August of 2002, they trapped, assessed, and released the small mammals (shrews and rodents) at five elevations ranging from 2,000 to 4,000 meters, along the southeastern slope of the mountain. In all they sampled 319 shrews of six species, and 293 rodents representing ten species. None of them were introduced or invasive; all had been previously recorded on the mountain.

One of the species, Myosorex zinki, is the only mammal known to be endemic to Mt. Kilimanjaro and was previously only known by a scant few specimens. The data collected by Stanley and his colleagues now suggests that the species is more widely distributed than once thought, since they found it at all but the lowest of the sites they sampled. It is, they say, “one of the most widespread species of small mammal along the gradient.” Further, the researchers write the trap success at 3,500 meters was “notably low” for all species. Why? One possibility, they say, is the higher amount of human activity lower on the mountain. While more research is necessary, not just at lower altitudes but also at higher ones (there has been no systematic sampling of small mammals higher than 4,000 meters), the correlation between trap success and human behavior on the lower parts of the mountain underscores the importance of conserving Kilimanjaro’s forest habitat. – Jason G. Goldman | 14 November 2014

Source: Stanley, W.T., M.A. Rogers, P.M. Kihaule, & M.J. Munissi (2014). Elevational Distribution and Ecology of Small Mammals on Africa’s Highest Mountain. PLOS ONE 9(11), e109904. DOI: 10.1371/journal.pone.0109904

Header image: Grammomys dolichurus in the montane habitats of Mt. Kilimanjaro, Tanzania. Photo by William Stanley.