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At what inclination does climbing begin? In this paper, we investigate the transition from walking to climbing in two species of parrot (Agapornis roseicollis and Nymphicus hollandicus) that are known to incorporate both their tail and their craniocervical system into the gait cycle during vertical climbing. Locomotor behaviors ranging in inclination were observed at angles between 0° and 90° for A. roseicollis, and 45°–85° degrees for N. hollandicus. Use of the tail in both species was observed at 45° inclination, and was joined at higher inclinations (> 65°) by use of the craniocervical system. Additionally, as inclination approached (but remained below) 90°, locomotor speeds were reduced while gaits were characterized by higher duty factors and lower stride frequency. These gait changes are consistent with those thought to increase stability. At 90°, A. roseicollis significantly increased its stride length, resulting in higher overall locomotor speed. Collectively these data demonstrate that the transition between horizontal walking and vertical climbing is gradual, incrementally altering several components of gait as inclinations increase. Such data underscore the need for further investigation into how exactly "climbing" is defined and the specific locomotor characteristics that differentiate this behavior from level walking. [ABSTRACT FROM AUTHOR]

It is thought arboreal species avoid foraging on the ground due to perceived predation risk, making the study of when and where arboreal species use the ground key in understanding foraging versus safety tradeoffs. We used publicly available, opportunistic, camera-trap observations from surveys across Madagascar to examine whether arboreal lemur ground use was spatially and temporally related to fosa (Cryptoprocta ferox), a native predator, and human presence. We observed 14 species of diurnal lemur (n = 287 individual observations) and six species of nocturnal lemur (n = 105 individual observations). With static two-species occupancy models and kernel density estimation, we found diurnal and nocturnal lemur ground use was spatially and temporally related to fosa presence. Diurnal lemurs used the ground less at camera locations where fosa were present compared to camera locations where they were absent, particularly if those camera locations lacked other native carnivores. Nocturnal lemurs used the ground more at camera locations fosa were observed at within the past 5 days compared with camera locations where fosa were not observed at within the past 5 days. Despite humans and diurnal lemurs being active at the same time 80% of the diel cycle (temporal overlap Δ = 0.80; 95% confidence interval [CI]: 0.75–0.85), diurnal lemur spatial or temporal use of the ground and human presence were unrelated. Diurnal lemur temporal overlap with humans at camera locations where fosa were uncommon was higher (Δ = 0.79; 95% CI: 0.71–0.86) compared with where fosa were common (Δ = 0.57; 95% CI: 0.46–0.66). Future research on how arboreal lemurs navigate ground use in a multipredator landscape should include behavioral observations to better understand animal decision-making. [ABSTRACT FROM AUTHOR]

Disturbance shapes ecological communities. Frequency, predictability, and intensity characterize disturbances, which select for resistant and/or resilient traits of species. Unpredictable and infrequent disturbance events, especially those with no reliable cues, lack selection strength and have less calculable effects on species assemblages and trait-based species sorting. In a flood plain in Northeast Costa Rica, across sites with varying flood frequency and no reliable cues to signal flooding, we used ants as a focal taxon to assess the impact of disturbance on ant activity and species assemblage. We examined activity patterns such as extent of occupancy of baits and nesting guild (i.e. strata used) that might mediate the effects of stochastic flood events. We hypothesized that the ant community in the most frequently flooded site would be dominated by above-ground nesting ants whose nesting traits make them resilient to inundation. The site with the most frequent flooding had the lowest level of ant presence on baits and differed in species assemblage, as demonstrated by the analysis of similarity, compared with the sites with lower flooding frequency. Neither overall species richness nor richness of species in the above-ground nesting guild differed between sites. However, nesting in trees above flood waters may be beneficial to escape frequent and unreliable flooding of habitats, and, as we hypothesized, there was greater activity of above-ground nesting ants compared with ground nesting ants in the most frequently flooded site. These differences in nesting guilds were diminished in the drier sites. [ABSTRACT FROM AUTHOR]

In tropical forests, epiphytes increase habitat complexity and provision services rare to canopy environments, such as water retention, nutrient cycling, and microclimate refuge. These services facilitate species diversity and coexistence in terrestrial ecosystems, and while their utility in forest ecosystems is appreciated for the Bromeliaceae of the Neotropics, fewer studies have examined the role of Paleotropic epiphytes in ecological niche theory. Here, we compare herpetofaunal presence, abundance, and diversity of in bird's nest fern (Asplenium nidus complex; BNF) to other microhabitats in Madagascar and the Philippines. We measure BNF fern microclimates, examine temporal use of canopy microhabitats, and test models of fern characteristics hypothesized to predict herpetofaunal use. In both countries, one in five BNFs were occupied by herpetofauna, mostly amphibians, and species using BNFs were highly dissimilar from those in other microhabitats. Herpetofaunal presence and abundance were greater in BNFs than in other canopy microhabitats and were most commonly used during the day when fern temperatures were highly buffered. Finally, BNF area was the best predictor of herpetofaunal presence and abundance, compared to canopy cover and BNF height. Importantly, these patterns remained consistent despite the distinct phylogenetic histories of our two communities (Asian versus African). Our results suggests that BNFs and their microclimate services play a critical role in the ecology of two Paleotropic forests, and facilitate the use of canopy habitats by climate-sensitive species. However, future studies are needed to assess the consistency of BNFs' utility as a microclimate refuge across their large range. [ABSTRACT FROM AUTHOR]

Climbing is integral to scansorial and arboreal lifestyles as it enables access to and vertical ranging within the arboreal strata. As early eutherian mammals exhibit osteological correlates for arboreality, it is important to assess the behavioral mechanisms that are related to competent vertical climbing. In this context, we examined climbing gaits in one of the smallest extant rodents, the Eurasian harvest mouse. For these purposes, we filmed six adult Micromys minutus at 240 fps moving on four different substrate sizes (2 mm, 5 mm, 10 mm, 25 mm), during both vertical ascents and descents. All climbing cycles were lateral sequence slow gaits. Upward climbing was characterized by a higher contribution of the hind limbs, longer swing phases, and a significant involvement of stride frequency in velocity modulation. On the other hand, downward climbing was promoted by employing gaits of even lower diagonality, an increased contact with the substrate, enhanced role of the forelimbs, and a subtler modulation of velocity by stride frequency. Eurasian harvest mice effectively negotiate the finest substrates, but their effectiveness decreased significantly on the largest ones. The morphofunctional similarities of M. minutus to Juramaia sinensis and Eomaia scansoria imply analogous behaviors in early eutherians, which apparently contributed to the successful access and exploitation of the fine-branch arboreal milieu. In this way, extant small arboreal mammals can constitute good models for elucidating and comprehending the adaptive significance of behavioral mechanisms that are related to the evolution of arboreality in early mammals. [ABSTRACT FROM AUTHOR]

A new fossil amniote from the Fossil Forest of Chemnitz (Sakmarian-Artinskian transition, Germany) is described as Ascendonanus nestleri gen. et sp. nov., based on five articulated skeletons with integumentary preservation. The slender animals exhibit a generalistic, lizard-like morphology. However, their synapsid temporal fenestration, ventrally ridged centra and enlarged iliac blades indicate a pelycosaur-grade affiliation. Using a renewed data set for certain early amniotes with a similar typology found Ascendonanus to be a basal varanopid synapsid. This is the first evidence of a varanopid from Saxony and the third from Central Europe, as well as the smallest varanopid at all. Its greatly elongated trunk, enlarged autopodia and strongly curved unguals, along with taphonomical observations, imply an arboreal lifestyle in a dense forest habitat until the whole ecosystem was buried under volcanic deposits. Ascendonanus greatly increases the knowledge on rare basal varanopids; it also reveals a so far unexpected ecotype of early synapsids. Its integumentary structures present the first detailed and soft tissue skin preservation of any Paleozoic synapsid. Further systematic results suggest a varanodontine position for Mycterosaurus, the monophyly of South African varanopids including Anningia and the distinction of a skeletal aggregation previously assigned to Heleosaurus, now renamed as Microvaranops parentis gen. et sp. nov. [ABSTRACT FROM AUTHOR]

The link between laterality in humans and other primates is still hotly debated. Hylobatids have been rather neglected in this research area, yet they can provide important insights because: (1) they share with humans a complex vocal repertoire, which in humans is thought to be associated with brain hemispheric specialization and lateralized behaviors; (2) their adaptation to arboreality has produced unique postural constraints; (3) the little that is known about laterality in gibbons is contradictory (captive studies have provided conflicting results, while a field study on siamangs reported a population-level left-hand preference). To clarify this, we investigated hand preference in captive hylobatids [ n = 42; 22 siamangs ( Symphalangus syndactylus) and 20 gibbons ( Hylobates sp., Nomascus leucogenys)] in nine Japanese facilities. We had a large sample size, controlled for possible confounds (posture, enclosure limitations) and used a well-established testing protocol (tube task). Handedness indices calculated from raw frequencies and bouts were highly correlated and showed a significant left-hand skew, which is consistent with data from wild siamangs. Major differences between captive and wild siamangs were a larger number of ambiguously handed individuals, and no significant age-related variation in captivity. The use of the index finger elicited a much more strongly lateralized response than the thumb. These results confirmed a left-hand preference in siamangs, but were equivocal in other hylobatids, and suggest selective pressures that may have acted on the highly arboreal hylobatids to favor handedness. Our study also indicates factors that might explain the discrepancy in the literature between handedness studies on captive and wild primate populations. [ABSTRACT FROM AUTHOR]

Although investigations of forelimb characteristics are central to therian evolutionary studies, the functional origins of forearm pronation are neglected. However, recent research based on bipedal manipulations strongly suggests that proximal radioulnar joint mobility is highly conserved in tetrapods. This new information calls for a replication of previously published physical simulations of forearm bone movements, to investigate whether active therian pronation/supination evolved from the plesiomorphic mechanism via which locomotor-induced torsion is passively alleviated during forelimb retraction. Preliminary results using representative extant and extinct tetrapod forelimb elements are supportive, and also offer insight into why another overlooked forearm trait, osteological full pronation (mechanically aligned elbow and wrist/finger joints), evolved only in therians and chameleons. During forelimb retraction in tetrapods with unfused radii/ulnae, the radius unexpectedly remains fixed in place as a functional complex with the firmly planted manus/carpus, which the ulnar complex (ulna/humerus) displaces relative to. Therefore, the highly conserved functional morphology of the tetrapod forearm indicates that enhanced therian manual dexterity, which emphasizes isolated radial movements bipedally, was preceded by the locomotor evolution of ulnar supination relative to the radius quadrupedally. This counterintuitive information indicates that the traditional hypothesis, that therian pronation/supination evolved arboreally to amplify radial mobility, requires modification. The authors propose that proximal long-axis rotations of the therian ulnar complex co-evolved with osteological full pronation during a period of arboreal, chameleon-like locomotion, to continue allowing torsion at a reinforced proximal radioulnar joint. These adaptations were later or simultaneously co-opted for object manipulation using active radioulnar pronation/supination. [ABSTRACT FROM AUTHOR]

Vertical stratification of the arboreal habitat allows the coexistence of several species in a given area, because the complex arboreal strata can be used in different ways by arboreal and scansorial mammals. The present report experimentally investigated the gait metrics on different arboreal substrates, of three sympatric rodents living in a deciduous forest in Poznań, Poland. Arboreal locomotion was compared between the burrowing striped field mouse, Apodemus agrarius , the scansorial bank vole, Myodes glareolus , and the more arboreal yellow-necked mouse, Apodemus flavicollis . We filmed two wild-caught individuals from each species walking on four different substrate diameters (2 mm, 5 mm, 10 mm, 25 mm) and three different inclinations (45° descending, horizontal, 45° ascending) at 240 fps and collected a set of gait parameters from a total of 273 complete cycles. Our results did not demonstrate clear relationships between arboreal locomotion and the ecology of the three species. Only A. flavicollis exhibited locomotor features partly associated with arboreal competence, including lower velocity and diagonality on narrow substrates and asymmetrical gaits on wider ones. On the other hand, the two Apodemus species, despite their different ecologies, shared a few locomotor similarities, such as velocity regulation primarily by stride frequency, and similar effects of substrate size and inclination on diagonality, duty factor, and duty factor index indicating the possibility of a phylogenetic signal. Because the selected gait parameters provided limited insight into the ability of small mammals to move competently through an arboreal habitat, these findings indicate that the relationship between behaviour and ecology is complex. [ABSTRACT FROM AUTHOR]

In this paper, I describe the food-dropping behavior of western lowland gorillas observed in Moukalaba-Doudou National Park, Gabon. I collected observational data of gorillas eating in trees, and recorded whether any individuals were positioned under the same tree. In 22 of the 24 cases of individuals being present under a tree, I observed the gorilla in a tree dropping food to the individual below. In most cases, the recipient was a silverback or an elder half-sibling of the dropper. The dropper's elder full-sibling was never a recipient. The food-dropping behavior of Moukalaba western lowland gorillas is likely due to a combination of factors: their frugivory, arboreality, large body size, and the scarcity of terrestrial herbs. It is difficult for multiple gorillas to simultaneously feed in the same tree. Under such limitations, younger gorillas face difficulties in defending their feeding patches from older individuals. Nearly 90 % of the recipients were older than the food droppers. Furthermore, food droppers were significantly younger than non-food droppers who simultaneously fed on the same tree, and most-food recipients were significantly older than least-food recipients on the ground. Food dropping may, therefore, be a tactic employed by younger gorillas to defend a feeding site from older individuals. This study suggests that food dropping may reduce feeding contest competition in a gorilla group in Moukalaba. This is a preliminary study that indicates that food dropping may be intentionally used as a way to reduce feeding competition; nevertheless, further studies are needed. [ABSTRACT FROM AUTHOR]

Abstract: Sixteen wood mice Apodemus sylvaticus were radio-tracked in a Mediterranean cork oak agro-forestry-system to describe their spatial distribution and organisation as well as their use of different habitat components. Our study, the first to analyse these features of wood mouse spatial ecology in Mediterranean agro-forestry environments using radio-tracking, showed a high variability in home ranges sizes reaching a mean values of 1.124±0.925ha (mean±sd), with no inter-sexual differences (8 males and 8 females tracked in March and June 2008). The extent to which different habitat components were used by wood mice varied significantly (−N ln λ =22.837, P <0.0001, n =6): while cork oak forests without understory were selected by both sexes equally in core areas (−N ln λ =32.361, P <0.0001, n =6), we also found evidence for a female-driven selection for home ranges to be located in olive groves (−N ln λ =59.949, P <0.0001, n =6), and movements to be set within cork oak forests with understory (−N ln λ =15.091, P <0.05, n =6). This habitat preference appears to result from the need of females to ensure access to sufficient food resources, the need of males to ensure access to females, and the need of both sexes for cover protection from predators. Moreover, we also show that the use of arboreal strata, most probably to access food, may also be an important factor to consider in analysing habitat use by wood mice. Implications of the recent evolution of this agro-silvo-pastoral system to the species ecology are emphasized. [Copyright &y& Elsevier]

Abstract: Although it is broadly accepted that small mammals often climb trees, only few studies explore arboreality in woodland rodents systematically. Here, we investigate the three-dimensional habitat use of wood mice Apodemus sylvaticus and bank voles Myodes glareolus at three different sites in Wytham Woods, Oxfordshire, under varying environmental conditions. A total of 12 trapping sessions was carried out between March and September 2003 and 2004. During each session, 100 Longworth live-traps with shrew escape holes were set in a 25-point-grid for 3 succeeding nights. Each time, 50 traps were placed on the ground, and 50 in surrounding trees at heights of 30–250cm. Wood mice were significantly more arboreal than bank voles, and male wood mice spent significantly more time in trees than did females. Arboreality in bank voles occurred only under high population densities and food shortage, and both species were significantly more arboreal in woodland with dense understorey. Thus we conclude that while arboreality is predominantly a result of inter- and intra-specific competition, of the two species we studied, only wood mice, being more agile, can afford to utilize trees without getting caught by predators, and that sex differences are due to male territoriality. Estimates of population sizes and distribution, as well as studies of inter-specific interactions and socio-spatial behaviour are presumed to be affected by these results, and are currently likely to underestimate rodent numbers considerably. [Copyright &y& Elsevier]