Tana River Mangabey Use of Nonforest Areas: Functional Connectivity in a Fragmented Landscape in Kenya

Abstract

Habitat loss and fragmentation is a serious threat to biodiversity. Fragment isolation can be reduced if fragments are connected, either structurally through habitat corridors or functionally if the species can move through the surrounding matrix. One-way to evaluate landscape connectivity is to observe natural movements of animals within fragmented landscapes. The Tana River mangabey (Cercocebus galeritus) is an endangered monkey endemic to fragmented forests along the lower Tana River in Kenya, and who has been observed to move through matrix between fragments. One mangabey group moved through 1 km of matrix, while another group moved through two areas of matrix. I collected behavioral and ranging data on the latter group to describe its behavior and time spent in the matrix. Utilizing data from belt transects in the matrix and forest fragments, I characterized the vegetation structure of the matrix and compared it to the forests included in each group's home range. The group spent the majority of their time eating while in the matrix, and spent an average 36.4 min in one matrix area and 100 min in the other. The matrix is generally characterized by the highest measures for a nonforest attribute and the lowest measures for forest attributes. These results suggest that forest fragments are functionally, but not structurally, connected for the mangabey; a landscape approach to conservation, therefore, should be taken for the lower Tana River. Research investigating the limitations of the mangabey's ability to use the matrix is needed.

Conservation planning for primate communities in rapidly transforming landscapes

“…Large body-sized primates, are more sensitive to habitat loss and fragmentation due to their wideranging patterns of space use and large amounts of resources needed to supply their basic needs (10). primates more sensitive to habitat loss and fragmentation (7,11,12). These two processes are associated with a reduction in resource availability and changes in plant diversity and abundance, leading to changes in diet composition and high dietary flexibility (13,14,15,16).…”

“…The priority conservation areas identified in the prioritising process in chapter 5, need to incorporate an expert and stakeholder consultation process to assess the benefits of the priority areas selected. 24 4, 5, 12, 14, 15, 30, 50, 68, 78, 88, 91, 104, 108, 115, 130 9, 10, 15, 36, 39, 79, 92, 110, 128 13, 25 25 13, 25 Distance to nearest town 38 43, 78, 115 Patch shape 123 38 4, 78, 88, 91, 123 110 Forest Cover 123 119 4, 5, 69, 88, 123, 133 110 Edge density 123 123 Mean inter-patch isolation distance 123 123 Number of forest patches 123 4,88,110 Matrix 3,31,54,123 3,5,7,14,26,123,129,6,9,10 58,120 58,120 Appendice C. Additional graphics of all the response variables studied across traits. library (rjags) library (coda) library (snowfall) library ( idx_z <-idx_z + 1…”

“…seems to be determined by their ability to move on the ground (1,2,3,4) and matrix composition (5,3,6,7).…”

“…Home Range Size: Wide-ranging species that require large home range areas to persist have been proposed as more sensitive to habitat loss and fragmentation than species with small home range sizes (7,10).…”

“…Body Size: Body size has been proposed as a determinant of primate species presence and persistence in fragmented habitats (7,8,9). Large body-sized primates, are more sensitive to habitat loss and fragmentation due to their wideranging patterns of space use and large amounts of resources needed to supply their basic needs (10).…”