Aspects of the ecology and behaviour of the thick-tailed bushbaby Galago crassicaudatus

A Thesis Submitted to the Faculty of Science University of the Witwatersrand, Johannesburg for the Degree of Doctor of Philosophy Johannesburg 1974The extant prosimian primates, with the exception of some lemurs of the Republic of Malagasy, are nocturnal arid secretive in their habits. Several lines of evidence suggest that they have remained similar to the basal orimate stock, but their study under natural conditions has, until recent'y, been largely overlooked. Only eight prosimian species remain on the Continent of Africa. Two relatively slow-moving lorises (Perodicticus potto and Arctocebus calabarensis) and three active galagos, or bushbabies (Euoticus elegantulus; Galago alleni and G. demidovii) are confined to the equatorial forest belt, while three other galagos (Euoticus inustis ; G. crassicaudatus and G. senegalensis) show adaptations for more open environments. A field study of G. crassicaudatus has been carried out in three distinct habitat types in southern Africa by means of direct observation with red light. Aspects of the ecology and behaviour of this species are presented and compared with those of other lorisoids and lemurs, particularly G. senegalensis, which is sympatric in some areas. In the absence of an adequate fossil record a consideration of species typical behaviour patterns and functional morphology leads to inferences concerning the probable behavioural and ecological condition of ancestral species, and conclusions regarding the separation and divergencies of recent forms. The morphological characteristics of G. crassicaudatus conform to the typical Galagine pattern of adaptation for active leaping progression but some features of their benaviour are reminiscent of members of the Lorisinae, with which they show a superficial similarity in their karyotype. It is concluded that the species directly ancestral to G. crassicaudatus were smaller and more active leaping animals which underwent a secondary, behavioural, adaptation towards slower quadrupedal locomotion. It is assumed that this was accompanied by an increase in body weight which facilitated infant transport on the fur leading to closer contact between mother and offspring and a better developed social group structure. On the basis of this interpretation the behavioural similarities with the Lorisinae are seen as the result of convergence and not due to a close phylogenetic relationship

Vocalization Analyses of Nocturnal Arboreal Mammals of the Taita Hills, Kenya

Three poorly known nocturnal mammal species from the montane forests of the Taita Hills in Kenya, were studied via vocalization analysis. Here, their acoustic behaviour is described. The studied animals were the tree hyrax (Dendrohyrax sp.), the small-eared greater galago (Otolemur garnettii), and the dwarf galago (Paragalago sp.). High-quality loud calls were analysed using RAVEN PRO, and compared to calls of presumed closest relatives. Our findings include the first detailed descriptions of tree hyrax songs. Moreover, our results suggest that the tree hyrax of Taita Hills may be a taxon new to science, as it produces a characteristic call, the ‘strangled thwack’, not previously known from other Dendrohyrax populations. Our data confirms that the small-eared greater galago subspecies living in the Taita Hills is Otolemur garnettii lasiotis. The loud calls of the elusive Taita Hills dwarf galago closely resemble those of the Kenya coast dwarf galago (Paragalago cocos). Thus, the population in the Taita Hills probably belongs to this species. The Taita Hills dwarf galagos are geographically isolated from other dwarf galago populations, and live in montane cloud forest, which is an unusual habitat for P. cocos. Intriguingly, two dwarf galago subpopulations living in separate forest patches in the Taita Hills, Ngangao and Mbololo, have clearly different contact calls. The Paragalagos in Mbololo Forest may represent a population of P. cocos with a derived call repertoire, or, alternatively, they may actually be mountain dwarf galagos (P. orinus). Hence, differences in habitat, behaviour, and contact call structure suggest that there may be two different Paragalago species in the montane forests of the Taita Hills

Taita Mountain dwarf galago is extant in the Taita Hills of Kenya

Peer reviewe

Low geographic and subspecific variation in the loud call of the widespread and phenotypically cryptic northern lesser galago (Galago senegalensis) suggests taxonomic uniformity

Like other nocturnal primates, many species of galago (Galagidae) are phenotypically cryptic, making their taxonomic status difficult to resolve. Recent taxonomic work has disentangled some of the confusion. This has resulted in an increase in the number of recognised galago species. The most widespread galago species, and indeed the most widespread nocturnal primate, is the northern lesser galago (Galago senegalensis) whose geographic range stretches >7,000 km across Africa. Based on morphology, 4 subspecies are currently recognised: G. s. senegalensis, G. s. braccatus, G. s. sotikae and G. s. dunni. We explore geographic and subspecific acoustic variation in G. senegalensis, testing three hypotheses: isolation by distance, genetic basis, and isolation by barrier. There is statistical support for isolation by distance for 2 of 4 call parameters (fundamental frequency and unit length). Geographic distance explains a moderate amount of the acoustic variation. Discriminant function analysis provides some degree of separation of geographic regions and subspecies, but the percentage of misdesignation is high. Despite having (putative) parapatric geographic ranges, the most pronounced acoustic differences are between G. s. senegalensis and G. s. dunni. The findings suggest that the Eastern Rift Valley and Niger River are significant barriers for G. senegalensis. The acoustic structures of the loud calls of 121 individuals from 28 widespread sites are not significantly different. Although this makes it unlikely that additional unrecognised species occur within G. senegalensis at the sites sampled, vast areas of the geographic range remain unsampled. We show that wide-ranging species do not necessarily exhibit large amounts of variation in their vocal repertoire. This pattern may also be present in nocturnal primates with smaller geographic ranges

Species identity and behavior of cave-dwelling tree hyraxes of the Kenyan coast

We surveyed tree hyrax populations living in forests, limestone rocky formations, and caves in coastal Kenya to identify the species and estimate the threat-level populations are in. Tree hyrax vocalizations were recorded in three different habitats with passive acoustic monitoring (PAM) for a total of 84 h in January and February 2022. We also observed tree hyrax behavior with thermal imaging camera and photographed individuals. Tree hyraxes in coastal Kenya are vocally active throughout the night, with most calls emitted between 23.00 and 04.00. We identified four different calls: snort, hac, hac ping-pong, and wheeze. Their calling range is between 220 and 15,000 Hz. Calls of tree hyraxes from the coast of Kenya were compared with calls stored by the Oxford Brookes University's Nocturnal Primate Research Group and identified as eastern tree hyrax, previously recorded from Tanzania. Here, we present what are, to our knowledge, the first photographs of live D. validus from Kenya. These tree hyraxes live in social groups. Due to strong pressure from humans, conservation measures are necessary to prevent the extinction of these isolated D. validus populations in Kenya.Peer reviewe

Habitat preferences, estimated abundance and behavior of tree hyrax (Dendrohyrax sp.) in fragmented montane forests of Taita Hills, Kenya

We studied a previously almost unknown nocturnal mammal, an apparently undescribed species of tree hyrax (Dendrohyrax sp.) in the moist montane forests of Taita Hills, Kenya. We used thermal imaging to locate tree hyraxes, observe their behavior, and to identify woody plants most frequently visited by the selective browsers. We also documented acoustic behavior in forest fragments of different sizes. Data on calling type and frequency were analyzed together with lidar data to estimate population densities and to identify forest stand characteristics associated with large populations. Viable populations were found only in the largest forest fragments (> 90 ha), where tree hyraxes preferred most pristine forest stands with high, multilayered canopies. The estimated population sizes in smaller forest fragments were very limited, and hyraxes were heard to call only during late night and early morning hours, presumably in order to avoid detection. While we frequently recorded tree hyrax songs in the largest forest fragments, we almost never heard songs in the small ones. All remaining subpopulations of the Taita tree hyrax are under threat of human disturbance and further habitat deterioration. Conservation efforts should include protection of all remaining habitat patches, but also reforestation of former habitat is urgently needed.Peer reviewe

Variation in grouping patterns, mating systems and social structure: what socio-ecological models attempt to explain

Socio-ecological models aim to predict the variation in social systems based on a limited number of ecological parameters. Since the 1960s, the original model has taken two paths: one relating to grouping patterns and mating systems and one relating to grouping patterns and female social structure. Here, we review the basic ideas specifically with regard to non-human primates, present new results and point to open questions. While most primates live in permanent groups and exhibit female defence polygyny, recent studies indicate more flexibility with cooperative male resource defence occurring repeatedly in all radiations. In contrast to other animals, the potential link between ecology and these mating systems remains, however, largely unexplored. The model of the ecology of female social structure has often been deemed successful, but has recently been criticized. We show that the predicted association of agonistic rates and despotism (directional consistency of relationships) was not supported in a comparative test. The overall variation in despotism is probably due to phylogenetic grade shifts. At the same time, it varies within clades more or less in the direction predicted by the model. This suggests that the model's utility may lie in predicting social variation within but not across clades

Celebrating 50 years of the Primate Society of Great Britain

The Primate Society of Great Britain was established in 1967 by John Napier and colleagues for the scientific study of everything related to primates. It is credit to Napier’s foresight that the Society’s 400+ members represent fields as diverse as anatomy, behaviour, cognition, conservation, ecology, evolution, physiology, neuro- and veterinary sciences and captive welfare. The 50th anniversary conference was held at the Royal Geographical Society, London, on 28th – 29th November 2017. What more prestigious way to start a 50th celebration than with a letter of congratulations from the Queen, HRH Elizabeth II? This was read out as part of the President’s opening address by Simon Bearder to the 400 delegates gathered to celebrate past achievements and look forward to the next 50 years of primatology research in the UK

Hiding from the Moonlight: Luminosity and Temperature Affect Activity of Asian Nocturnal Primates in a Highly Seasonal Forest

The effect of moonlight and temperature on activity of slow lorises was previously little known and this knowledge might be useful for understanding many aspects of their behavioural ecology, and developing strategies to monitor and protect populations. In this study we aimed to determine if the activity of the pygmy loris (Nycticebus pygmaeus) is affected by ambient temperature and/or moonlight in a mixed deciduous forest. We radio-collared five females and five males in the Seima Protection Forest, Cambodia, in February to May, 2008 and January to March, 2009 and recorded their behaviour at 5 minutes intervals, totalling 2736 observations. We classified each observation as either inactive (sleeping or alert) or active behaviour (travel, feeding, grooming, or others). Moon luminosity (bright/dark) and ambient temperature were recorded for each observation. The response variable, activity, was binary (active or inactive), and a logit link function was used. Ambient temperature alone did not significantly affect mean activity. Although mean activity was significantly affected by moonlight, the interaction between moonlight and temperature was also significant: on bright nights, studied animals were increasingly more active with higher temperature; and on dark nights they were consistently active regardless of temperature. The most plausible explanation is that on bright cold nights the combined risk of being seen and attacked by predators and heat loss outweigh the benefit of active behaviours

Sleep patterns, daytime predation, and the evolution of diurnal sleep site selection in lorisiforms.

Synthesize information on sleep patterns, sleep site use, and daytime predation at sleep sites in lorisiforms of Asia and Africa (10 genera, 36 species), and infer patterns of evolution of sleep site selection. We conducted fieldwork in 12 African and six Asian countries, collecting data on sleep sites, timing of sleep and predation during daytime. We obtained additional information from literature and through correspondence. Using a phylogenetic approach, we established ancestral states of sleep site selection in lorisiforms and traced their evolution. The ancestral lorisiform was a fur-clinger and used dense tangles and branches/forks as sleep sites. Use of tree holes and nests as sleep sites emerged ∼22 Mya (range 17-26 Mya) in Africa, and use of bamboo emerged ∼11 (7-14) Mya in Asia and later in Africa. Fur clinging and some sleep sites (e.g., tree holes, nests, but not bamboo or dense tangles) show strong phylogenetic signal. Nests are used by Galagoides, Paragalago, Galago and Otolemur; tree holes by Galago, Paragalago, Sciurocheirus and Perodicticus; tangles by Nycticebus, Loris, Galagoides, Galago, Euoticus, Otolemur, Perodicticus and Arctocebus; all but Sciurocheirus and Otolemur additionally sleep on branches/forks. Daytime predation may affect sleep site selection and sleep patterns in some species of Nycticebus, Galago, Galagoides, Otolemur and Perodicticus. Most lorisiforms enter their sleep sites around sunrise and leave around sunset; several are active during twilight or, briefly, during daytime. Variations in sleep behavior, sleep patterns and vulnerability to daytime predation provide a window into the variation that was present in sleep in early primates. Overall, lorisiforms use the daytime for sleeping and no species can be classified as cathemeral or polycyclic