Spotted Ground Thrush Survey in Kenyan Coastal Forests, 2003

Study Extent

Sampling

Quality Control

Method steps

1. Surveys were carried out between 16th June and 20th July 2003 within the period when Spotted Ground Thrush is found on the forests of the Kenya coast as a non-breeding visitor. Additional information was collated from an ongoing ringing programme at Arabuko-Sokoke forest, as well as from past literature. In each of the study forests visited (except Shimoni), mist nets were used at sites distributed across the forested area. Choice of site was constrained by the availability of suitable small paths or trails and net lengths used varied. Every site was operated for three or four sessions before nets were moved to another site in the same or different forest. These sessions included one or two mornings (06:00 – 11:00) and one or two evenings (15:30 – 18:30) sessions. All species caught were aged and various biometrics and moulting details taken; in addition, all Spotted Ground Thrushes were colour-ringed. Birds were also sought between 06:00 and 11:00 within random plots, each covering a radius of 30 m and beyond. One or two observers approached each of the plots quietly, and spent 10 minutes in the plot searching for all bird species. Movements by observers were minimized and particular emphasis was placed in looking for the Spotted Ground Thrush on the leaf litter all around the plot. Birds were detected by sight, call or listening to movements. The type of detection (whether by sight or by hearing) during bird searches was recorded for three other ground feeders in the forests: Red-capped Robin chat Cossypha natalensis, Eastern Bearded Scrub Robin Cercotrichas quadrivirgata and Red-tailed Ant Thrush Neocossyphus rufus. Since Spotted Ground Thrush was not detected by hearing its call, the increased probability of detecting other ground feeders from their calls was used to correct the crude density estimate for the Spotted Ground Thrush. Some plot counts (n = 20) done at Gede Ruins were combined with an initial 10-minute play back of song recordings of the race Z. g. guttata (from Southern African Bird Sounds by Guy Gibbon) in an attempt to attract Spotted Ground Thrush. Observers also did targeted birding by walking around the forest making specific searches for the Spotted Ground Thrush, especially at places with habitat features that the bird are more likely to select, i.e., with areas of closed canopy providing deep shade, thick leaf litter and scant or patchy low vegetation (Bennun 1985). This was combined with the help of a knowledgeable local bird guide who was very familiar with the species.