Time Constraints Limit Group Sizes and Distribution in Red and Black-and-White Colobus Monkeys

Researchers have shown that, in frugivorous primates, a major constraint on group size is intra group feeding competition. The relationship is less obvious in folivorous primates. We investigated whether colobine group sizes are constrained by time limitations as a result of their low energy diet and ruminant-like digestive system. We used climate as an easy to obtain proxy for the productivity of a habitat. Using the relationships between climate, group size, and time budget components for populations of Colobus and Piliocolobus at different research sites, we created 2 taxon-specific models. In both genera, feeding time increased with group size or biomass. The models for Colobus and Piliocolobus correctly predicted the presence or absence of the genera at, respectively, 86% of 148 and 84% of 156 African primate sites. Median predicted group sizes where the respective genera were present are 19 for Colobus and 53 for Piliocolobus. We show that the differences between the 2 genera are due mainly to intrinsic differences in the way each taxon’s digestive physiology interacts with climatic variables to influence resting time requirements. The models may help us explore their responses to climatic change in both the past and the future

Group size, Grooming and Social Cohesion in Primates

Most primates live in social groups in which affiliative bonds exist between individuals. Because these bonds need to be maintained through social interactions (grooming in most primates), sociality will be limited by time constraints. It has previously been shown that the time primates invest in grooming increases with group size. However, when groups become too large, individuals will not have enough time available to service all possible social relationships and group cohesion is expected to decrease. In this study, we used data from previously published studies to determine how large groups compromise on their grooming time and how ecological, phylogenetic and life history variables affect time invested in grooming (across species as well as within taxa). We used path analysis to analyse direct and indirect (via group size) effects on grooming. We showed that not only is grooming time determined by group size, but it is also affected by dispersal patterns and sex ratio. Furthermore, we found that grooming time is asymptotic when group size exceeds 40 individuals, indicating that time constraints resulting from ecological pressure force individuals to compromise on their grooming time. This was true across species, but a similar effect was also found within taxa. Cognitive constraints and predation pressure strongly affect group sizes and thereby have an indirect effect on primate grooming time. Primates that were found to live in groups larger than predicted by their neocortex size usually suffered from greater predation risk. However, most populations in our analysis were placed well within what we define as their eco-cognitive niche. © 2007 The Association for the Study of Animal Behaviour

Time and distribution: a model of ape biogeography

We use data from 20 chimpanzee, bonobo and gorilla study sites to develop an African great ape time budgets model to predict the animals' capacity to survive in a range of habitats across sub-Saharan Africa. The model uses body mass and climatic data to predict the time animals must allocate to key activities (feeding, moving, resting and social interaction), and then uses these to assess the limiting group size that could be sustained in a particular habitat. The model is robust against changes in minimum cut-off values, and predicts the current biogeographic distributions of the two African ape species remarkably well. Predicted group sizes for Pan and Gorilla are close to observed averages. The model also indicates that moving time plays a crucial role for both Pan and Gorilla site presence: i.e. at sites where they are absent it is primarily moving time that is increased as compared to other time budget variables. Finally, the model demonstrates that Pan and Gorilla distributions and group sizes can be accurately modelled by simply modifying the body mass variable, indicating that both share a similar underlying ecological bauplan

Dry season drinking from terrestrial man-made watering holes in arboreal wild Temminck’s red colobus, The Gambia

Like most arboreal primates, redcolobus monkeys obtain most water from plants in their diet, licking their body or drinking occasionally from standing water in tree holes. Terrestrial drinking is not normally reported for arboreal primates. Here we report observations of terrestrial drinking from man-made watering holes by Temminck’s red colobus (Piliocolobus badius temminckii) in Abuko Nature Reserve and Bijilo Forest Park, The Gambia. Colobus drinking behaviour in Abuko has been reported previously by Starin (1991, 2002), mostly involving juveniles or lactating females; water was most commonly obtained by licking water from the body and leaves or obtained from tree holes. Some juveniles were seen drinking from swampy ground and puddles in the dry season, but otherwise the only terrestrial water body available to colobus during the study by Starin contained crocodiles, a known predator of red colobus at the site. Our observations show that shallow man-made watering holes that have since been created and do not harbour predators were used by different age classes. We discuss some of the implications of this behaviour for this endangered subspecies and report on the trend of increasing temperatures in The Gambia

Influence of micro-topography and crown characteristics on tree height estimations in tropical forests based on LiDAR canopy height models.

Tree or canopy height is an important attribute for carbon stock estimation, forest management and habitat quality assessment. Airborne Laser Scanning (ALS) based on Light Detection and Ranging (LiDAR) has advantages over other remote sensing techniques for describing the structure of forests. However, sloped terrain can be challenging for accurate estimation of tree locations and heights based on a Canopy Height Model (CHM) generated from ALS data; a CHM is a height-normalised Digital Surface Model (DSM) obtained by subtracting a Digital Terrain Model (DTM) from a DSM. On sloped terrain, points at the same elevation on a tree crown appear to increase in height in the downhill direction, based on the ground elevations at these points. A point will be incorrectly identified as the treetop by individual tree crown (ITC) recognition algorithms if its height is greater than that of the actual treetop in the CHM, which will be recorded as the tree height. In this study, the influence of terrain slope and crown characteristics on the detection of treetops and estimation of tree heights is assessed using ALS data in a tropical forest with complex terrain (i.e. micro-topography) and tree crown characteristics. Locations and heights of 11,442 trees based on a DSM are compared with those based on a CHM. The horizontal (DH) and vertical displacements (DV) increase with terrain slope (r: 0.47 and r: 0.54 respectively, p < 0.001). The overestimations in tree height are up to 16.6 m on slopes greater than 50° in our study area in Sumatra. The errors in locations (DH) and tree heights (DV) are modelled for trees with conical and spherical tree crowns. For a spherical tree crown, DH can be modelled as R sin θ, and DV as R (sec θ – 1). In this study, a model is developed for an idealised conical tree crown, DV = R (tan θ – tan ψ), where R is the crown radius, and θ and ψ are terrain and crown angles respectively. It is shown that errors occur only when terrain angle exceeds the crown angle, with the horizontal displacement equal to the crown radius. Errors in location are seen to be greater for spherical than conical trees on slopes where crown angles of conical trees are less than the terrain angle. The results are especially relevant for biomass and carbon stock estimations in tropical forests where there are trees with large crown radii on slopes

Applying Knowledge of Species-Typical Scavenging Behavior to the Search and Recovery of Mammalian Skeletal Remains.

Forensic investigations involving animal scavenging of human remains require a physical search of the scene and surrounding areas. However, there is currently no standard procedure in the U.K. for physical searches of scavenged human remains. The Winthrop and grid search methods used by police specialist searchers for scavenged remains were examined through the use of mock red fox (Vulpes vulpes) scatter scenes. Forty-two police specialist searchers from two different regions within the U.K. were divided between those briefed and not briefed with fox-typical scavenging information. Briefing searchers with scavenging information significantly affected the recovery of scattered bones (χ(2) = 11.45, df = 1, p = 0.001). Searchers briefed with scavenging information were 2.05 times more likely to recover bones. Adaptions to search methods used by searchers were evident on a regional level, such that searchers more accustom to a peri-urban to rural region recovered a higher percentage of scattered bones (58.33%, n = 84)

An Investigation of Red Fox (Vulpes vulpes) and Eurasian Badger (Meles meles) Scavenging, Scattering, and Removal of Deer Remains: Forensic Implications and Applications

Within northwest Europe, especially the United Kingdom, the red fox (Vulpes vulpes) and the Eurasian Badger (Meles meles) are the largest wild scavengers capable of modifying a set of remains through scavenging. Knowledge of region-specific and species-typical scavenging behaviors of scavengers within the crime scene area and surroundings can aid in more efficient and accurate interpretations. The scavenging behaviors of captive and wild foxes and badgers were recorded and compared through actualistic methods and direct observation. The scavenging by wild foxes and badgers of surface-deposited baits and whole deer (Cervus nippon; Capreolus capreolus) in a woodland was observed and analyzed. Wild foxes were found to scavenge deer more frequently than badgers. The scavenging of deer remains by foxes was also compared with forensic cases. The scavenging pattern and recovery distances of deer and human remains scavenged by foxes were similar but were potentially affected by the condition and deposition of a body, and the presence of clothing

Structural attributes of individual trees for identifying homogeneouspatches in a tropical rainforest

Mapping and monitoring tropical rainforests and quantifying their carbon stocks are important, bothfor devising strategies for their conservation and mitigating the effects of climate change. AirborneLaser Scanning (ALS) has advantages over other remote sensing techniques for describing the three-dimensional structure of forests. This study identifies forest patches using ALS-based structural attributesin a tropical rainforest in Sumatra, Indonesia. A method to group trees with similar attributes into forestpatches based on Thiessen polygons and k-medoids clustering is developed, combining the advantagesof both raster and individual tree–based methods. The structural composition of the patches could be anindicator of habitat type and quality. The patches could also be a basis for developing allometric modelsfor more accurate estimation of carbon stock than is currently possible with generalised models

Measuring and modelling microclimatic air temperature in a historically degraded tropical forest

Climate change is predicted to cause widespread disruptions to global biodiversity. Most climate models are at the macroscale, operating at a ~1 km resolution and predicting future temperatures at 1.5–2 m above ground level, making them unable to predict microclimates at the scale that many organisms experience temperature. We studied the efects of forest structure and vertical position on microclimatic air temperature within forest canopy in a historically degraded tropical forest in Sikundur, Northern Sumatra, Indonesia. We collected temperature measurements in ffteen plots over 20 months, alongside vegetation structure data from the same ffteen 25×25 m plots. We also performed airborne surveys using an unmanned aerial vehicle (UAV) to record canopy structure remotely, both over the plot locations and a wider area. We hypothesised that old-growth forest structure would moderate microclimatic air temperature. Our data showed that Sikundur is a thermally dynamic envi ronment, with simultaneously recorded temperatures at diferent locations within the canopy varying by up to~15 °C. Our models (R2=0.90 to 0.95) showed that temperature diferences between data loggers at diferent sites were largely determined by variation in recording height and the amount of solar radiation reaching the topmost part of the canopy, although strong interactions between these abiotic factors and canopy structure shaped microclimate air temperature variation. The impacts of forest degradation have smaller relative influence on models of microclimatic air temperature than abiotic factors, but the loss of canopy density increases temperature. This may render areas of degraded tropical forests unsuitable for some forest dwelling species with the advent of future climate chang