Niche partitioning and environmental factors affecting abundance of strepsirrhines in Angola

Abstract

The African nocturnal primates (galagos, pottos, and angwantibos: suborder Strepsirrhini) are the result of the first major primate radiation event in Africa, and are found in different primate communities spread across the entire sub-Saharan Africa. Thus, they represent an interesting group of taxa to investigate community strategies to avoid interspecific competition. Here, we present the result of the first study on nocturnal primate communities in western Angola. We aimed to identify habitat factors influencing strepsirrhine abundance, collect evidence of spatial niche segregation, and discuss possible indications of competitive exclusion in this region. We conducted nocturnal surveys at four study sites: Kumbira, Bimbe, Northern Scarp, and Calandula. At each encounter we recorded species, group size, height of animals above ground, and GPS location. We sampled vegetation using the point-centered quarter method and collected data on canopy cover, disturbance, and undergrowth density. We observed a total of five strepsirrhine species with varying community structures. We did not encounter Galagoides thomasi but we recorded a new species Galagoides sp. nov. 4. Levels of disturbance, canopy cover and undergrowth density were the habitat factors that most influenced variation in abundance of Galagoides demidovii and Perodicticus edwardsi, the latter also preferring the habitat with higher tree density. Vertical separation between sympatric strepsirrhines was strongest in Northern Scarp, where overall relative abundance was also highest. Competitive exclusion between G. thomasi and G. sp. nov. 4 may explain why the former was not present within the Angolan Escarpment sites. We observed coexistence between mainly allopatric Otolemur crassicaudatus and P. edwardsi in Kumbira, and of Galago moholi and G. demidovii in Calandula. Both unusual combinations showed some levels of spatial segregation. Habitat characteristics of the Escarpment region are likely to allow for unique nocturnal primate species assemblages. We urge immediate conservation interventions in the Angolan Escarpment.

A giant among dwarfs: a new species of galago (Primates: Galagidae) from Angola

“…The facial morphology and vocal behavior identified the new species as a western dwarf galago, Galagoides sp., but in terms of general appearance, size and mass it was more similar to a lesser galago, Galago spp. The new species was observed to use mid to high strata, with a median height of 12 m ( n = 36) and ranging between 2 and 32 m (see more details in Bersacola et al, ). It was observed leaping and climbing on branches of all sizes, but it was never observed on the ground.…”

“…Observed in moist, tall forest, primary, and secondary (Kumbira and Northern Scarp Forest) and semiarid baobab savannah‐woodland in areas where tree‐lined water courses allowed access (Bimbe; Table ). Encounter rate was higher in moist forest (2.60–2.67 individuals/km) compared to savannah‐woodland (0.17 individuals/km, see Bersacola et al, for more information and statistical analyses).…”

“…MS Svensson, E Bersacola, MSL Mills and SK Bearder conducted nocturnal surveys in Angola between 5 and 19 September 2013. The surveys lasted for 39 h, walking on small roads and established paths and recording the habitat use and height in the canopy for each animal observed (for a more detailed description of the survey method see Bersacola et al, ). Nocturnal animals were photographed with a Canon EOS 600D camera, with Canon 70‐200 mm EF Zoom lens and Canon Speedlight 430EX II flash.…”

“…thomasi , Kingdon () was of the opinion that distinct populations, possibly even a new subspecies or species, occurred on the Angolan Escarpment and in the Katanga Province of the Democratic Republic of Congo (DRC). In contrast, neither Groves (), based on studies of museum specimens, nor Bersacola et al (), based on field surveys, found evidence of Gd. thomasi in Angola.…”

“…demidovii phasma , whereas the occurrence of a fourth species, Gd. thomasi in the country is based solely on museum specimens (Bersacola, Svensson, & Bearder, ; Nekaris, ). Machado () reported Gd.…”