When a forest is fragmented, this increases the amount of forest edge relative to the interior. Edge effects can lead to loss of animal and plant species and decreased plant biomass near forest edges. We examined the influence of an anthropogenic forest edge comprising cattle pasture, coconut plantations, and human settlement on the mantled howler (Alouatta palliata), white-faced capuchin (Cebus capucinus), Central American spider monkey (Ateles geoffroyi), and plant populations at La Suerte Biological Research Station (LSBRS), Costa Rica. We predicted that there would be lower monkey encounter rate, mean tree species richness, and diameter at breast height (DBH) in forest edge versus interior, and that monkeys would show species-specific responses to edge based on diet, body size, and canopy height preferences. Specifically, we predicted that howler monkeys would show positive or neutral edge effects due to their flexible folivorous diet, large body size, and preference for high canopy, capuchins would show positive edge effects due to their diverse diet, small body size, and preference for low to middle canopy, and spider monkeys would show negative edge effects due their reliance on ripe fruit, large body size, and preference for high upper canopy. We conducted population and vegetation surveys along edge and interior transects at LSBRS. Contrary to predictions, total monkey encounter rate did not vary between the forest edge and forest interior. Furthermore, all three species showed neutral edge effects with no significant differences in encounter rate between forest edge and interior. Interior transects had significantly higher mean tree species richness than edge transects, and interior trees had greater DBH than edge trees, although this difference was not significant. These results suggest that forest edges negatively impact plant populations at La Suerte but that the monkeys are able to withstand these differences in vegetation.

Maderas Rainforest Conservancy (MRC) was incorporated as a conservation nonprofit organization in 2008, and manages two sites where biological field courses have been offered since the 1990s: La Suerte Biological Research Station in Costa Rica, and Ometepe Biological Research Station in Nicaragua. MRC employs a One Health approach to conservation education, and can serve as a model for other biological field sites. The Nicaraguan Molina family, who owns the sites, partnered with primatologist Paul Garber in 1994 to develop a primate field course aimed at introducing university students to field research. Through using their land to further conservation education and research, the Molina family has preserved the forest and engaged the local communities near their sites. Eight graduate theses and 46 refereed publications have been completed since 2010 based on research undertaken at MRC sites. While primate field courses have been offered at least once annually since 1994 and remain popular, a range of other ecological courses are now additionally offered. MRC operates from a One Health perspective, engaging in forest restoration and ecological monitoring projects, and has gradually expanded community outreach initiatives. MRC now conducts regular medical and veterinary missions in the communities surrounding the research stations which provide health care to local people and limit the population growth of domestic animals, thereby increasing the survival of wild animals. MRC is also active in ESL‐teaching and conservation education, and funds Proyecto Jade, which empowers local women to make and sell organic jewelry. Through these programs, MRC works to help the local communities live more sustainably with the environment around them. MRC's support of research, commitment to education, medical and veterinary missions, and outreach initiatives to the local community all work together for the well‐being of both the people and the environment, thus exemplifying the One Health perspective.

The ring‐tailed lemur (Lemur catta) is a group‐living strepsirhine primate endemic to Madagascar that has a complex vocal repertoire including affiliative moan and hmm calls. Past research has suggested that both vocalisations may be contact calls, and we assessed their usage in addition to examining the effect of individual differences and social factors on male calling behaviour. We tested three hypotheses: the group cohesion, preferred companion and individual differences hypotheses. From March to July 2010, 565 h of focal animal data were collected on 31 males aged ≥1 year at the Beza Mahafaly Special Reserve, Madagascar. Focal males were observed for 30 min, with vocalisations, allogrooming and agonistic interactions noted using one‐zero sampling, and general behaviour, nearest neighbour identity and distance noted using instantaneous point sampling, all at 2.5 min intervals. We found support for the group cohesion hypothesis for both vocalisations, and support for the preferred companion and individual differences hypotheses for the hmm but not the moan vocalisation. Moan and hmm calls maintained the distance between a male and his nearest neighbour, and were made at higher rates during behaviours which may lead to separation from conspecifics, such as travel and vigilance. Males made hmm calls at higher rates when they were low‐ranking, and/or when the nearest neighbour of a male or a preferred companion of either sex. Low‐ranking males may hmm call to maintain proximity to specific individuals within social groups who will show them increased tolerance, with the hmm signalling peaceful intent. Ring‐tailed lemurs are one of the best living models of gregarious primate ancestors, and gaining a better knowledge of the function and range of usage of their contact calls informs our understanding of the evolution of primate cognition.

The function of long calling is a subject of interest across animal behaviour study, particularly within primatology. Many primate species have male‐specific long‐distance calls, including platyrrhines like the folivorous howler monkey (Alouatta spp.). Howler monkeys may howl to defend resources such as feeding trees or areas of rich vegetation from other monkey groups. This study tests the ecological resource defence hypothesis for howling behaviour in the mantled howler monkey (Alouatta palliata) and investigates how anthropogenic forest fragmentation may influence howling behaviour. More specifically, this study examines how howling bout rate, duration, precursors and tree species richness, DBH, and canopy cover vary in 100 m anthropogenic edge and interior forest zones at La Suerte Biological Research Station (LSBRS), a fragmented tropical rainforest in Costa Rica. Results show that tree species richness and canopy cover are higher in forest interior at this site, suggesting that monkeys should howl at greater rates in the interior to defend access to these higher‐quality vegetation resources. Overall, our results supported the ecological resource defence hypothesis. The main howl precursor was howling from neighbouring groups. Although howling rate did not differ between forest zones, howling bouts from forest interior were longer, had a greater number of howls per bout and were preceded by different precursors than howls from anthropogenic edge zones, including more howls from neighbouring groups. Our findings provide some of the first evidence for behavioural edge effects in primate vocal communication behaviour.