Impact of weather conditions,seasonality and moonlight on the use of artificial canopy bridges by nocturnal arboreal mammals

Natural and artificial canopy bridges can be used to mitigate the effects of habitat fragmentation. Understanding the ecological factors that influence bridge use is imperative to the effective design and placement of this potential conservation intervention. Moonlight, seasonality and weather may influence the cost and risk of using bridges, potentially reducing their effectiveness. We installed five artificial waterline bridges and, between 2017 and 2019, monitored via camera trapping their use by Javan palm civets Paradoxurus musanga javanicus and Javan slow lorises Nycticebus javanicus. We used a weather station to record microclimate data (temperature and relative humidity) and calculated the illumination percentage of the moon. We tested the influence of moon luminosity, relative humidity, seasonality (Julian day) and temperature on the frequency of bridge use via Generalised Additive Models. Camera traps captured 938 instances of bridge use by civets, which was significantly lower than the reference value at moon luminosity?>?90%, temperatures?>?20 °C, humidity?>?90%, and during the drier period (May–July). Camera traps captured 1036 instances of bridge use by lorises, which was significantly lower than the reference value during the drier period and higher than the reference value at temperatures?>?20 °C. Lorises showed peaks in bridge use close to sunset and sunrise whereas civets showed peaks around 2 h after sunset and 2 h before sunrise. Our study illustrates the utility of simple-to-construct bridges by two sympatric nocturnal mammals facing severe habitat loss, with bridge use differing between those species according to abiotic factors. In particular, less use by both taxa during the drier season could suggest modifying placement of bridges or providing another intervention during that time. Camera traps were an excellent mechanism to record these differences and to validate the importance of the bridges, including during inclement weather and dark nights, when observations would be more difficult for human observers. By understanding the influence that abiotic factors have on the use of artificial bridges, we can improve bridge placement and construction to encourage use by a variety of species, particularly those threatened by habitat fragmentation.

     

Conservation Assessments of Arboreal Mammals in Difficult Terrain: Occupancy Modeling of Pileated Gibbons (Hylobates pileatus)

Long-term monitoring programs, wildlife surveys, and other research involving species population assessment require reliable data on population status. Given the logistically challenging nature of some species’ habitats and cryptic behaviors, collecting these data can prove to be a considerable barrier. We used detection/nondetection data from pileated gibbons (Hylobates pileatus) in the Cardamom Mountains of southwest Cambodia to estimate their population occupancy and detectability. We modeled occupancy using elevation, tree height, tree density, tree diversity, and disturbance covariates. Modeling demonstrated that 83% of the sites are occupied by Hylobates pileatus and that the detectability of the species varies positively with elevation. No clear relationship between habitat quality covariates and occupancy of Hylobates pileatus emerged. Effort analysis based on model estimates demonstrated that at high elevations, less than half the number of site visits is needed to attain the same detectability estimate precision as across all elevations. We suggest that human activities at low elevations, which affect forest composition, are the central factors impacting the detectability and occupancy of Hylobates pileatus. Longer sampling durations and/or a higher number of site visits, especially at lower elevations, increase precision of the occupancy estimator for the least effort. For effective future monitoring and research for this and similar species, using this relatively simple method, applied with repeat site visits, would allow a longitudinal comparison of detection at sites in difficult terrain.     

Observations of mating, birthing and parental behaviour in three subspecies of slender loris (Loris tardigradus and Loris lydekkerianus ) in India and Sri Lanka

Studies of the life history parameters of slender lorises in captivity have led to conflicting results regarding gestation length, birth seasonality, interspecies variation in litter size and the degree of parental care given to offspring. During the course of field studies of Loris lydekkerianus lydekkerianus, L. l. nordicus and L. tardigradus tardigradus, data were collected on these life history variables, as well as on behaviours relating to mating. All 3 taxa displayed courtship behaviour involving the pursuit of a female by multiple males. Mating corresponded closely with captive observations, with a period of prolonged single intromissions lasting 3-11 min. One gestation period of 163 days was calculated for L. l. lydekkerianus. Births for all 3 taxa were distributed throughout the year, and males were seen mating throughout the year. All 3 taxa gave birth to singletons and twins; no subspecific pattern in litter size was evident. Females carried infants for the first 4 weeks of life and were regularly attended by males, which groomed both the mother and her offspring. After infants had been parked, female L. l. lydekkerianus and L. l. nordicus rarely returned before dawn, though males visited and played with infants. Female L. t. tardigradus maintained proximity with their infants, whilst males were not observed in proximity to infants during the night. All 3 taxa slept in social groups. High-energy milk, in combination with male care, may aid in the potentially high reproductive output of 4 infants per year.     

Activity budget and positional behavior of the Mysore slender loris (Loris tardigradus lydekkerianus): implications for slow climbing locomotion.

Both predator defense and feeding ecology models have been proposed to explain the relatively slow climbing locomotion of the Lorisinae. During a study of the socioecology of the Mysore slender loris (Loris tardigradus lydekkerianus) in Tamil Nadu, India, six categories of behavior and eleven different postures were recorded to estimate a general activity budget for the slender loris, and are examined here particularly in relation to slow climbing locomotor strategies. Reactions to potential predators are also described. The main study population was composed of 15 animals. Activity budgets were compiled in three ways: all instantaneous point samples collected over 1,173 h pooled (n = 13,717), the means of individual lorises (n = 15) and behavior at the moment of first contact (n = 357). No significant difference was found between these three data sets. Approximately 45% of the activity budget was spent in inactive behaviors including sitting vigilant, resting and sleeping. Foraging and traveling comprised nearly half the activity budget, with the rest of the time spent grooming. The most common postures assumed by lorises were sitting and quadrupedal walking. Individual lorises were relatively gregarious and spent up to half their activity budget with other animals. Unlike pottos and angwantibos, lorises did not freeze, head butt or drop from branches in reaction to potential predators, but either ignored them, fled or made loud calls. Cryptic and slow climbing locomotion were used before traveling on open ground between discontinuous substrates, thereby supporting hypotheses relating to predator pressure, and also before capturing fast moving insect prey, supporting hypotheses relating to diet. It is proposed that a divergence in foraging strategies between bushbabies and lorisines may be the best adaptive explanation for their behavioral and morphological differences, including predator defense mechanisms.     

Hiding in the dark: Local ecological knowledge about slow loris in Sarawak sheds light on relationships between human populations and wild animals

Local ecological knowledge (LEK) increases understanding of certain species and the threats they face, especially little-studied taxa for which data on distribution and conservation are often lacking. We conducted 111 semi-structured interviews in Sarawak, Malaysia, to collect local knowledge about the behavior and distribution of the Philippine slow loris (Nycticebus menagensis) from two ethnic groups, the Iban and the Penan. Our study revealed that male Penan respondents, generally hunters, who frequently go into the forest were better at identifying animals from pictures. Overall, the Penan have a more detailed knowledge of slow loris behaviors, habitat, and distribution than the Iban. The two ethnic groups have different attitudes towards slow loris as the Penan hunt, eat, or keep them as pets while the Iban consider them sacred and signifiers of good luck. We advocate the use of LEK for providing complementary information to scientific methods in the study of cryptic animals.     

Coexistence between Javan Slow Lorises (<Emphasis Type="Italic">Nycticebus javanicus</Emphasis>) and Humans in a Dynamic Agroforestry Landscape in West Java,Indonesia

In a world increasingly dominated by human demand for agricultural products, we need to understand wildlife’s ability to survive in agricultural environments. We studied the interaction between humans and Javan slow lorises (Nycticebus javanicus) in Cipaganti, Java, Indonesia. After its introduction in 2013, chayote (Sechium edule), a gourd grown on bamboo lattice frames, became an important cash crop. To evaluate people’s use of this crop and to measure the effect of this increase on slow loris behavior, home ranges, and sleep sites, we conducted interviews with local farmers and analysed the above variables in relation to chayote expansion between 2011 and 2015. Interviews with farmers in 2011, 2013, and 2015 confirm the importance of chayote and of bamboo and slow lorises in their agricultural practices. In 2015 chayote frames covered 12% of land in Cipaganti, occupying 4% of slow loris home ranges, which marginally yet insignificantly increased in size with the increase in chayote. Slow lorises are arboreal and the bamboo frames increased connectivity within their ranges. Of the sleep sites we monitored from 2013 to 2016, 24 had disappeared, and 201 continued to be used by the slow lorises and processed by local people. The fast growth rate of bamboo, and the recognition of the value of bamboo by farmers, allow persistence of slow loris sleep sites. Overall introduction of chayote did not result in conflict between farmers and slow lorises, and once constructed the chayote bamboo frames proved to be beneficial for slow lorises.     

Interactions between a wild Bornean orang-utan and a Philippine slow loris in a peat-swamp forest

All documented orang-utan–loris interactions have been from Sumatra, where lorises were opportunistically preyed upon by orang-utans. In this paper, we describe two accounts of the Bornean orang-utan (Pongo pygmaeus wurmbii) interacting with the Philippine slow loris (Nycticebus menagensis). The interactions were by two adolescent female orang-utans. No attempts to catch the loris were observed on either occasion. Neither interaction was hostile. During the second observation, which was more detailed, we considered the behaviour to be play rather than aggression or attempted predation. Based upon the lack of interest from the adult females during these rare encounters, we propose that the behaviour represents play or non-aggressive exploration rather than predation.     

Extreme primates: Ecology and evolution of Asian lorises

Asia's slow and slender lorises (Nycticebus and Loris) are among nature's most extreme primates. Until recently, it was not understood why lorises have such huge forward‐facing eyes, strange steady climbing locomotion, tiny dependent babies, and a bite that potentially can kill a human! Indeed, early studies described them as slow, solitary, and boring. Twenty years of field research now indicate that lorises are among the most intriguing mammal species.