The status and habitat of Karamoja Apalis Apalis karamojae in the Wembere Steppe, Sukumaland, Tanzania

Karamoja Apalis Apalis karamojae is a globally Vulnerable warbler, restricted to north-east Uganda, north-central Tanzania and southern Kenya. Here, we describe its status and habitat in the Wembere Steppe, Sukumaland, Tanzania, an unprotected area of seasonally inundated grassland bordered partly by Acacia scrub. Although its habitat in the steppe was thought likely to span c. 175 km north–south during the 1960s to 1970s, we found the apalis to be patchily distributed over a distance of only 102 km north–south. Distance sampling yielded a density estimate of c. 7–16 birds km−2; equivalent to c. 3–7 pairs km−2, after juveniles (18% of the population) were excluded, and assuming that all adults were paired. The species occupied a very narrow foraging niche, feeding almost exclusively in Whistling Thorn Acacia drepanolobium, which accounted for 66% of woody stems in the study area, but for 95% of stems in the immediate vicinity of apalis sightings. Half of all individuals were encountered in the tallest, densest stands of A. drepanolobium, which covered less than 6% of the study area. Signs of scrub clearance, pruning and browsing were widespread in the steppe, and may have intensified during 1967–2002, when the human population in surrounding districts increased at a mean rate of c. 2–4% per year. Further research is required to determine whether our findings are representative of the species in other seasons and at other sites.