Tree and forest characteristics influence sleeping site choice by golden lion tamarins

Effect of landscape attributes on the occurrence of the endangered golden-headed lion tamarin in southern Bahia, Brazil

The golden-headed lion tamarin (Leontopithecus chrysomelas) is an endangered primate that occurs exclusively in the Atlantic Forest of southern Bahia, Brazil. Its geographic range has been severely reduced by deforestation and its populations are restricted to a human-modified landscape consisting primarily of Atlantic forest fragments and shade cacao (Theobroma cacao) agroforestry, locally known as cabrucas. In the last 30 years, there has been a 42% reduction in the geographic range and a 60% reduction in the population size of L. chrysomelas, with only 8% of its habitat represented by protected areas. Thus, we investigated the occurrence of L. chrysomelas in forest fragments and cabrucas based on interviews and using playback census, and evaluated the influence of landscape attributes on its occurrence. The occurrence was measured using a Generalized Linear Model using a set of 12 predictor variables, including fragment size and elevation. L. chrysomelas inhabited 186 (38%) of the 495 forest fragments and cabrucas. Most inhabited habitat patches (n = 169, 91%) are in the eastern portion (ca. 70 km wide region from the Atlantic coast to inland) of its geographic range. The remaining (n = 17, 9%) are in the western portion of the distribution, between 70 and 150 km from the Atlantic coast. Our models indicate a higher occurrence of L. chrysomelas in the eastern portion of its geographic range, where the landscape exhibits lower land cover diversity, greater functional connectivity, lower altitudes (<400 m), and is primarily composed of forest fragments and cabrucas with a higher core percentage. In contrast, we observed a lower occurrence of L. chrysomelas in the western portion, where the landscape is more diverse and heterogeneous due to anthropogenic activities, such as agriculture and livestock. We urge the establishment of ecological corridors via reforestation of degraded areas in the western portion of the range. This increase in habitat availability and suitability in the west together with the protection of the forests and cabrucas in the east would increase our chances of saving L. chrysomelas from extinction.

Yellow fever in Brazil threatens successful recovery of endangered golden lion tamarins

The golden lion tamarin is an endangered primate endemic to Brazil's Atlantic Forest. Centuries of deforestation reduced numbers to a few hundred individuals in isolated forest fragments 80 km from Rio de Janeiro city. Intensive conservation action including reintroduction of zoo-born tamarins into forest fragments 1984-2000, increased numbers to about 3,700 in 2014. Beginning in November 2016, southeastern Brazil experienced the most severe yellow fever epidemic/epizootic in the country in 80 years. In May 2018, we documented the first death of a golden lion tamarin due to yellow fever. We re-evaluated population sizes and compared them to results of a census completed in 2014. Tamarin numbers declined 32%, with ca. 2,516 individuals remaining in situ. Tamarin losses were significantly greater in forest fragments that were larger, had less forest edge and had better forest connectivity, factors that may favor the mosquito vectors of yellow fever. The future of golden lion tamarins depends on the extent of additional mortality, whether some tamarins survive the disease and acquire immunity, and the potential development of a vaccine to protect the species against yellow fever.

Spatial Response to Linear Infrastructures by the Endangered Golden Lion Tamarin

Linear infrastructures are a primary driver of economic development. However, they also can negatively affect wildlife by mortality and the barrier effect. In this paper, we address how paved and unpaved roads, high-tension power lines, and gas/oil pipelines affect home range size, core areas, and movement in an endangered primate, the golden lion tamarin (GLT). Location data were recorded using radio telemetry on 16 groups in two protected areas and in privately owned forest fragments. The GLT’s home range, not core area, increased in size for the groups that occupied locations far from linear infrastructures; home range was also significantly influenced by available forest size. None of the home ranges contained a road, but home ranges did contain power lines. GLTs used the surrounding landscape near all types of infrastructure. Movement analysis showed that most of the step lengths (distances between subsequent locations) were less than 100 m between two consecutive locations, but step length was longer for roads and longer for groups in fully forested habitats. Tamarins avoided paved roads when in close proximity to this type of infrastructure; this behavior increased in areas without adequate adjacent forest habitat. Our results show that linear infrastructures differ in their level of impact: roads can act as a barrier, whereas other types of infrastructure have minimal effect on movement and home range. We discuss these differences in impact in terms of structure, maintenance schedules, and edge effects of infrastructure.

Sleeping site and tree selection by Sichuan snub-nosed monkeys (Rhinopithecus roxellana) in Baihe Nature Reserve, Sichuan, China

For non-human primates to optimize their survival chances, sleeping site selection is crucial as they spend much of their time sleeping. We studied sleeping site and tree selection by a group of wild Sichuan snub-nosed monkeys (Rhinopithecus roxellana) in the temperate forests of Baihe Nature Reserve, Sichuan, China, to assess if certain site and tree characteristics were selected. We identified a total of 39 sleeping sites and 111 sleeping trees over a period of 1 year. We compared nine sleeping site and six sleeping tree variables related to the environment, habitat, and vegetation structure. We found that certain characteristics of sleeping sites and sleeping trees predicted their selection by R. roxellana. On a larger spatial scale, sleeping sites were selected based mainly on four factors: canopy height, slope direction, slope gradient, and vegetation type. They also selected sites with trees that were taller and larger, had larger crown diameters and higher bole branches. On a smaller spatial scale, they selected larger trees with larger crown diameters. The selection of these characteristics could be explained in terms of predator avoidance and thermoregulation efficiency, although it was difficult to delineate which was more important. This could be due to some characteristics of R. roxellana, that is, large groups living in temperate climates, which required a balanced strategy for sleeping site and tree selection in order to optimize their survival chances.

Sleeping site preferences in Sapajus cay Illiger 1815 (Primates: Cebidae) in a disturbed fragment of the Upper Paraná Atlantic Forest, Rancho Laguna Blanca, Eastern Paraguay

Wild primates can spend up to half of their lives sleeping, during which time they are subjected to many of the same selective pressures that they face when awake. Choosing an appropriate sleeping site can thus have important fitness consequences. We examined the sleeping site preferences of wild hooded capuchins (Sapajus cay) in a small degraded fragment of the Upper Paraná Atlantic Forest at Rancho Laguna Blanca (RLB) in eastern Paraguay. Sleeping trees and sites were identified during 5 months of field observations and their physical characteristics were compared to those of non-sleeping trees and sites. Capuchins preferred larger emergent trees with more main and forked branches, no lianas and denser undergrowth directly below. These were found in sites of more mature forest with fewer small trees, less liana coverage and denser undergrowth but more fruiting trees. The species composition of the sleeping sites differed from that of the non-sleeping sites and was dominated by Albizia niopoides (Mimosaceae) as well as Peltophorum dubium (Fabaceae) and Anadenanthera colubrina (Fabaceae). The capuchins were found to sleep most often in these three tree species: 69.23% in Albizia niopoides (Mimosaceae), 11.54% in Peltophorum dubium (Fabaceae) and 11.54% in Anadenanthera colubrina (Fabaceae). We found evidence for the predator avoidance, thermoregulatory, social contact and feeding site proximity hypotheses. We found no support for parasite avoidance, given the reuse of sites, although the small size of the forest fragment may have restricted this. Their preference for older-growth forest suggests that selective logging impacts hooded capuchins. However, their persistence in a disturbed fragment shows they are highly adaptable, providing support for the value of conservation and reforestation of even small fragments of the Paraguayan Upper Paraná Atlantic Forest.

Characterization of the Tree Holes Used by Lepilemur ruficaudatus in the Dry, Deciduous Forest of Kirindy Mitea National Park

Knowledge of the key resources for a species is critical for developing an effective conservation strategy. Kirindy Mitea National Park is an important refuge for the red-tailed sportive lemur (Lepilemur ruficaudatus), a nocturnal folivorous lemur endemic to the dry deciduous forest of western Madagascar. Because L. ruficaudatus sleeps in tree holes during the day, sleeping trees may be an important resource for this species. Our goal was to characterize the sleeping sites used by L. ruficaudatus at the Ankoatsifaka Research Station in Kirindy Mitea National Park. In July and August 2012, tree characteristics were recorded for 60 L. ruficaudatus sleeping sites. Intact and alive trees, particularly Strychnos madagascariensis, were preferred by L. ruficaudatus. Sleeping holes were generally located in taller trees (median hole height = 4 m) and in trees with large girths (median = 20.5 cm). Greater protection from predators and thermal shifts may be provided by intact trees and concealed tree holes. Because tree characteristics can influence the presence and abundance of forest-living primates, the availability and characteristics of particular trees as potential sleeping shelters in a habitat must be taken into account in conservation strategies for L. ruficaudatus.

The role of anthropic, ecological, and social factors in sleeping site choice by long-tailed macaques (Macaca fascicularis)

When choosing their sleeping sites, primates make adaptive trade-offs between various biotic and abiotic constraints. In human-modified environments, anthropic factors may play a role. We assessed the influence of ecological (predation), social (intergroup competition), and anthropic (proximity to human settlements) factors in sleeping site choice by long-tailed macaques (Macaca fascicularis) occupying a habitat at the interface of natural forests and human-modified zones in Bali Barat National Park, Indonesia. Over the course of 56 nights, we collected data relating to physical features of sleeping trees, patterns of the use of sleeping sites within the home range, pre-sleep behavior, diurnal ranging patterns and availability of natural and human food. Overall, the macaques used 17 sleeping sites with 37 sleeping trees. When the monkeys slept in forest zones, they selected sleeping trees that had larger trunks but were not significantly taller than surrounding trees. Though the macaques rarely re-used sleeping sites on consecutive nights, they frequently re-used four sites over the study period. The group favored sleeping within the core area of its home range, despite the occurrence of frequent agonistic intergroup encounters there. Macaques preferentially selected sleeping trees located within or near human-modified zones, especially when human food was abundant and natural food was scarce. These results partially support the hypothesis that long-tailed macaques choose their sleeping sites to avoid predation; proximity to human settlements appears to be the primary factor influencing sleeping site choice in this primate species. Our results reflect the strong influence that anthropic factors have on primates, which subsist in increasingly human-dominated landscapes.

Sleeping tree selection of Cao Vit gibbon (Nomascus nasutus) living in degraded karst forest in Bangliang, Jingxi, China

We studied the sleep-related behavior of two Cao Vit gibbon (Nomascus nasutus) groups in Bangliang Nature Reserve in Jingxi County, China between January 2008 and December 2009 to test four hypotheses related to sleeping tree selection (predation avoidance, thermoregulation, food access, and range defense). Gibbons entered sleeping trees 88 ± SD 37 min before sunset before their main potential nocturnal predator become active. They usually moved rapidly and straight to sleeping trees and kept silent once settled. Over the course of the study, gibbon groups used many (87 and 57 per group) sleeping trees and reused them irregularly. They also tended to sleep in relatively tall trees without lianas, choosing small branches close to the treetop. These behaviors would make it difficult for potential terrestrial predators to detect and approach the gibbons. Therefore, these results strongly support the predation avoidance hypothesis. Gibbons tended to sleep closer to ridges than to valley bottoms and they did not sleep at lower elevations in colder months. They thus appeared not to select sleeping trees to minimize thermoregulatory stress. Gibbons very rarely slept in feeding trees, instead generally sleeping more than 100 m away from the last feeding trees of the day or the first feeding tree of the next morning. These patterns led us to reject the food access hypothesis. Lastly, we did not find evidence to support the range defense hypothesis because gibbons did not sleep in overlap areas with neighbors more often than expected based on the proportion of overlap and exclusively used areas.

Characteristics of tree hollows used by Australian arboreal and scansorial mammals

Many species of non-flying mammal depend on tree hollows (cavities or holes) for shelter and survival. I reviewed the published literature on tree hollow use by Australian non-flying arboreal and scansorial mammals to provide a synthesis of tree hollow requirements, to identify gaps in knowledge and to stimulate future research that may improve the management of these species. The use of hollows was described in some detail for 18 of 42 hollow-using species. Most information was for possums and gliding possums, whereas dasyurid marsupials and rodents were largely neglected. The paucity of data for many species must be addressed because it represents an impediment to their conservation. Hollow abundance appears to be the primary determinant of tree preferences. This accounts for the frequent use of standing dead trees by most species. Most hollow-bearing trees used as dens were at least 100 years of age. Further studies that describe the dynamic processes that govern the availability of tree hollows are needed. The few studies that document attrition of hollow-bearing trees suggest that land managers need to improve strategies for the effective retention and long-term replacement of these trees.