Variation in monthly sizes of home‐ranges of Hooded Vultures Necrosyrtes monachus in western, eastern and southern Africa

Abstract

Tracking studies are often used to inform conservation plans and actions. However, species have frequently only been tracked in one or a few localities, whereas space use can be remarkably flexible, especially in long‐lived species with advanced learning abilities. We assessed variability in space use in the Critically Endangered Hooded Vulture Necrosyrtes monachus by pooling movement data from three populations across the species’ sub‐Saharan range (in South Africa, Botswana, Ethiopia, Kenya, The Gambia and Mozambique). We estimated minimum convex polygons and kernel density estimators (KDEs) and compared monthly home‐range sizes between breeding and non‐breeding seasons, age‐classes and subspecies, accounting for uneven sampling within groups. Mean (± sd) monthly home‐range sizes (95% KDEs) for adult Hooded Vultures from southern (12 453 ± 21 188 km2, n = 82) and eastern Africa (3735 ± 3652 km2, n = 24) were 103 and 31 times larger than those of conspecifics from western Africa (121 ± 98 km2, n = 48). This may relate partly to subspecific differences, and individuals with small home‐ranges in western Africa and Ethiopia were trapped in urban environments. Regional variation in space use by Hooded Vultures may be linked to flexibility in feeding behaviour (degree of commensalism) which may arise in response to resource availability and persecution in different areas. Age‐class also affected monthly home‐range sizes, with immature birds generally having larger monthly home‐range size estimates than adults. Our results highlight the flexibility of Hooded Vultures in terms of their home‐range sizes and suggest that home‐range sizes differ between populations and individuals, depending on the extent of human commensalism. Our results also reaffirm the importance of international co‐operation in conservation efforts aimed at protecting this wide‐ranging, non‐migratory species.

Further observations and implications of Oil Palm Elaesis guineensis fruit consumption by Hooded Vultures Necrosyrtes monachus in coastal Gambia.

“…Highly commensal West African birds differ considerably in feeding behaviour and in general ecology from their East and southern African conspecifics, although more research is needed in this area (Barlow et al 2020). There are also huge variations in home ranges between regional populations as proven by satellite tracking studies (Reading et al 2019, Thompson et al 2020. Most other countries in West Africa are reporting serious declines, for example in Senegal (Mullié et al 2017) and Nigeria (Nosazeogie et al 2018).…”

Size cline not subspeciation in the Hooded Vulture

“…Their Figure 2 drawn from the "combined matrix" of using all five taxonomic groups, fairly well follows High and Low Africa. Nevertheless my regions do not strictly follow theirs; but this difference could be expected from a wide-ranging vulture (Thompson et al 2020).…”

“…It has previously been noted (Mundy et al 1992: p. 136) that Burchell in 1824 did not in fact describe a Hooded Vulture but something much larger, and the first proper description of the bird in southern Africa is by Smith (1829), who named it carunculatus. This taxonomy has remained to the present day (Brown & Amadon 1968, Stresemann & Amadon 1979, Cramp & Simmons 1980, Brown, Urban & Newman 1982, Kemp 1994, Ferguson-Lees & Christie 2001, del Hoyo & Collar 2014 through to Thompson et al 2020).…”

Homogeneity in cranial biometrics and bill morphology is verified by measurements from The Gambia, Botswana and Kenya in the case of the putative sub-species of the highly commensal Hooded Vulture Necrosyrtes monachus monachus and non-commensal Necrosyrte

“…The studies will include where there are current strongholds (e.g., The Gambia: Jallow et al 2016, Barlow & Fulford 2013); and Guinea-Bissau: (Henriques et al 2017(Henriques et al , 2018 and where declines are occurring e.g. Dakar, Senegal: Mullié et al 2017;Nigeria: Nosazeogie et al 2018;and Botswana: Reading et al 2019) and throughout their range (Pomeroy et al 2015, Thompson et al 2020.…”

“…The highly commensal West African birds differ considerably in feeding behaviour and in general ecology from their east & southern African counterparts (Thompson et al 2020, Jallow et al 2016, Mundy et al 1992, although more research is needed in this area. There are vast differences in their home ranges as proven by satellite tagging studies (Reading et al 2019;Thompson et al 2020). As there is no plumage variation between the putative subspecies, we hypothesized that differences in the feeding ecology in the commensal and non-commensal populations may have led to adaptation in bill morphology.…”