Status and behavioural ecology of Sengis in the Boni-Dodori and Arabuko-Sokoke forests, Kenya, determined by camera traps

Abstract

The biodiversity of northern coastal Kenya, east of the Tana River, is poorly
understood because security problems and poor infrastructure have discouraged access
to the area. However, the wooded areas in the region have great potential for
harbouring endemic and rare species, including sengis or elephant-shrews (order
Macroscelidea), especially giant sengis in the genus Rhynchocyon. Based on extensive
camera-trap surveys of the Boni-Dodori forest, east of the Tana River near the
Somalia border, and the Arabuko-Sokoke forest west of the Tana River, the goldenrumped
sengi Rhynchocyon chrysopygus appears to be limited to the Arabuko-Sokoke
area, while the giant sengi in the Boni-Dodori forest is different. The Boni-Dodori
forest, the largest Kenyan coastal forest, with a potential forest and thicket area of at
least 3000 km² is likely to hold a significant number of Rhynchocyon, making it very
important to sengi conservation. The study generated over 2700 images of giant sengi
and 32 000 camera-trap images of soft-furred sengi in a total surveyed area of
approximately 300 km² providing the first detailed 24-hour behaviour data for the
species. The circadian patterns have confirmed R. chrysopygus and Boni Rhynchocyon
to be strictly diurnal while the soft-furred sengi were mostly nocturnal. Occupancy for
Rhynchocyon was over 80 percent for both the Boni forest thicket and Arabuko-Sokoke Cynometra forest thicket. Occupancy and trapping rates for the soft-furred sengi were significantly higher for the Arabuko-Sokoke forest than the Boni-Dodori forest. It was not possible in the camera trap images to reliably differentiate between the two soft-furred sengi species, four-toed sengi Petrodromus tetradactylus and rufous sengi Elephantulus rufescens, known to occur in the area.

Keywords: Macroscelidea, elephant-shrew, Rhynchocyon, abundance, distribution,
activity pattern