The range, abundance and habitat of Hinde’s Babbler Turdoides hindei: fine-scale changes in abundance during 2000–2011 reflect temporal variation in scrub cover

Abstract

SummaryIn developing countries 'land sparing' may be more effective than 'land sharing' in partially mitigating the impacts of farming on bird species diversity. We examined the pattern of change in the global and local distribution of Hinde's Babbler Turdoides hindei, a 'Vulnerable' Kenyan endemic whose local abundance is dependent on a passive form of land sharing, in which farmland is left fallow or abandoned, enabling Lantana scrub to colonise. In 2011 we assessed the species' global range and resurveyed three IBAs, surveyed previously in 2000-01, to determine whether fine-scale changes in abundance reflected temporal changes in habitat quality. Although the babbler's known range increased between 1900-70 and 1991-2011, we suggest that this apparent expansion largely reflects an improved knowledge base, and that several recently discovered sites are likely to have been overlooked in the past. In combination, the three IBAs surveyed in 2000-01 and 2011 showed little net change in the number of individuals (+1.3%) or groups (-3.8%) encountered, despite a 68% decline in the number individuals recorded at one site. Within 1-km transect sections there was a positive correlation between change in Hinde's Babbler abundance and change in the amount of scrub cover available, such that a reduction in scrub cover of 22 and 6 percentage points, respectively, was associated with the loss of one group or one individual. The availability of scrub cover was dependent mainly on the amount land left uncultivated, perhaps in response to changes in the value of coffee and other crops. Since the babbler's abundance thus currently depends mainly on land sharing by default, rather than by design, we suggest that a more proactive approach, involving land purchase or payments for land set aside, might help to secure its future.

Movement ecology of Afrotropical birds: Functional traits provide complementary insights to species identity

“…Previous studies have shown that habitat or diet generalists use a broader variety of habitats and resources than specialists do and, thus, may adapt more readily to environmental changes (Devictor et al., ; Gray, Baldauf, Mayhew & Hill, ). Conversely, bird species specialized on dense habitats typically have high site fidelity and remain within their favored habitat patches (Shaw & Musina, ; Shaw, Njoroge, Otieno & Mlamba, ), as long as sufficient resources are available (Wiktander, Olsson & Nilsson, ). However, increasing habitat degradation and fragmentation might cause increased overall home‐range size in both generalist and specialist bird species (Carey et al., ; Hansbauer et al., ).…”

Comparison between telemetry and spot-mapping to determine space use of the Kenyan endemic Hinde's babbler

“…The probability that locations are displayed outside a riparian thicket due to high inaccuracy of triangulation (while in reality T. hindei is inside dense thicket, see Shaw et al . 2014) is very likely. In contrast, data from spot-mapping underline restricted movement and long-term roosting in dense thickets.…”

“…The species is a cooperative breeder and thus exists in distinct family groups differing in size (ranging between two to 10 individuals) (Shaw et al . 2014). In this study we observed four identical family groups, using spot-mapping and telemetry.…”

“…These contradictory results may arise from two non-exclusive coherences: The fine-grained mosaic of riparian thicket patches (mean patch size: 1.28 ± 0.25 ha) and agricultural land (mean patch size: 0.75 ± 0.11 ha), in combination with the inaccuracy of location estimates based on VHF triangulation (here, the inaccuracy of positioning was about 44 m). The probability that locations are displayed outside a riparian thicket due to high inaccuracy of triangulation (while in reality T. hindei is inside dense thicket, see Shaw et al 2014) is very likely. In contrast, data from spot-mapping underline restricted movement and long-term roosting in dense thickets.…”