The Current Status of the World's Primates: Mapping Threats to Understand Priorities for Primate Conservation.

Over the past decades, primate populations have been declining. Four years ago, >60% of species were listed as threatened. As the rate of loss accelerates and new IUCN assessments are being published, we used IUCN Red List assessments and peer-reviewed literature published within the last 5 yr to evaluate the status of primates globally, by region and by taxonomic group. We also examined the main factors affecting a species' conservation status to determine if we could predict the status of understudied species. We found that 65% of species are in the top three IUCN Red List categories (Vulnerable, Endangered, Critically Endangered). Globally, the main threats to primates are Biological Resource Use, including Hunting & Logging, and Agriculture. The impact of these threats varied by region and taxon. Our model showed that Malagasy and Asian primates, and those affected by Agriculture, Human Disturbance, and Climate Change were more likely to be considered at risk of extinction. The model's predictive probability, however, was low. Our literature analysis showed that some threats, especially climate change and disease, affected more species than indicated by the IUCN Red List. As we move into the next decade, we must continue tackling hunting and agricultural expansion but also be vigilant about emerging threats. We must also aim to regularly test the effectiveness of mitigation strategies, evaluating their long-term adoption and their impact on primates; as well as to increase communication between researchers and applied conservationists to ensure IUCN assessments include current and emerging threats. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10764-021-00242-2.

Population assessment and habitat associations of the Visayan Hornbill (Penelopides panini) in Northwest Panay, Philippines.

BACKGROUND: Seven out of ten hornbill species in the Philippines are threatened with extinction. Among these is the endangered Visayan Hornbill (Penelopides panini), found on the islands of Panay and Negros. Threatened by habitat loss and hunting, its population size is thought to have declined from 1800 individuals 20 years ago to less than 1000. However, a recent study on Negros estimated 3564 individuals across three core forest blocks. This study aims to quantify the Visayan Hornbill population size in and around the Northwest Panay Peninsula Natural Park (NWPPNP) on Panay, the largest contiguous low-elevation forest landscape remaining across its range, and its broad habitat associations across a gradient of environmental degradation. METHODS: Hornbills were surveyed using 10-min distance sampling point counts (n = 367) along transects (average length 1.1 km). Environmental variables were recorded along transects, while habitat was classified into primary forest, secondary forest, plantation, or open habitat. Distance software was used to estimate population densities stratified by habitat, with the overall population estimate taken as a mean of habitat density estimates weighted by habitat area. Using generalized linear mixed models, hornbill occurrence was modelled using combinations of nine environmental variables as main and two-way fixed effects. RESULTS: Surveys covered 204.4 km2 of the 374.8 km2 Northwest Panay Peninsula. Hornbills were not recorded in plantations or open habitats. Hornbill density was significantly higher in primary forest (17.8 individuals/km2 ± 26.9% CV) than in secondary forest (3.7 individuals/km2 ± 33.2% CV; z = 15.212, P < 0.001). The overall population estimate for the NWPPNP and environs is 2109 individuals, and 2673 individuals for the entire Northwest Panay Peninsula. Hornbill presence was best explained by a model including distance from the Park boundary alongside five interaction effects and transect as a random effect. Distance, and the interaction between distance and medium-sized trees were significant predictors of hornbill presence. CONCLUSIONS: Our study evidences the habitat preference of the Visayan Hornbill, highlights the importance of the NWPPNP for the species' conservation, and provides strong evidence for re-assessing the global population size. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s40657-021-00303-3.

Mother-male bond, but not paternity, influences male-infant affiliation in wild crested macaques.

ABSTRACT: In promiscuous primates, interactions between adult males and infants have rarely been investigated. However, recent evidence suggests that male affiliation towards infants has an influence on several aspects of the infants' life. Furthermore, affiliations may be associated with male reproductive strategy. In this study, we examined which social factors influenced male-infant affiliation initiated by either male or infant, in wild crested macaques (Macaca nigra). We combined behavioral data and genetic paternity analysis from 30 infants living in three wild groups in Tangkoko Reserve, Indonesia. Our results indicate that adult males and infants do not interact at random, but rather form preferential associations. The social factors with the highest influence on infant-initiated interactions were male rank and male association with the infant's mother. While infants initiated affiliations with males more often in the absence of their mothers, adult males initiated more affiliations with infants when their mothers were present. Furthermore, males initiated affiliations more often when they were in the same group at the time the infant was conceived, when they held a high dominance rank, or when they had a close relationship with the mother. Interestingly, paternity did not affect male-infant affiliation despite being highly skewed in this species. Overall, our results suggest that adult males potentially associate with an infant to secure future mating with the mother. Infants are more likely to associate with a male to receive better support, suggesting a strategy to increase the chance of infant survival in a primate society with high infant mortality. SIGNIFICANCE STATEMENT: We explore social relationships between males and infants in a promiscuous primate, the wild crested macaque. Our novel approach addresses the nature of affiliations both from males' and infants' perspectives. The results show that males and infants form preferential associations. Male-female affiliation, but not paternity, was a significant predictor of interactions initiated both by males and infants. Males initiated more interactions towards infants when the mother was in proximity, while infants initiated more interactions in her absence. Finally, high-ranking males were more likely to initiate interactions towards infants. We demonstrated that paternity is not a good predictor of male-infant affiliations, even in a species with a high reproductive skew and a relatively high confidence of paternity. Our paper is one of the first to show that infants are active agents in establishing and maintaining preferential relationships with males.

Social and ecological factors influencing offspring survival in wild macaques.

Premature loss of offspring decreases direct fitness of parents. In gregarious mammals, both ecological and social variables impact offspring survival and may interact with each other in this regard. Although a number of studies have investigated factors influencing offspring loss in mammals, we still know very little on how different factors interact with one another. We therefore investigated fetal and infant mortality in 3 large groups of wild crested macaques (Macaca nigra) over a period of up to 5 years by including potential social causes such as maternal dominance rank, male immigration, between group encounters, and ecological conditions such as rainfall in a multivariate survival analysis using Cox proportional hazards model. Infant but not fetal survival was most impaired after a recent takeover of the alpha-male position by an immigrant male. Furthermore, infant survival probability increased when there was an increase in number of group adult females and rainfall. Fetal survival probability also increased with an increase of these 2 factors, but more in high-ranking than low-ranking females. Fetal survival, unlike that of infants, was also improved by an increase of intergroup encounter rates. Our study thus stresses the importance of survival analyses using a multivariate approach and encompassing more than a single offspring stage to investigate the determinants of female direct fitness. We further provide evidence for fitness costs and benefits of group living, possibly deriving from high pressures of both within- and between-group competition, in a wild primate population.