Living on the edge: Space use of Eurasian red squirrels in marginal high-elevation habitat.

In marginal habitats located at the edge of a species\u2019 range, environmental conditions are frequently extreme and individuals may be subject to different selective pressures compared to central populations. These so-called edge or marginal populations tend to have lower densities and reproductive rates than populations located in more suitable habitats, but little is known about local adaptations in spacing behavior. We studied space use and social organization in a population of Eurasian red squirrels (Sciurus vulgaris) in a high-elevation marginal habitat of dwarf mountain pine (Pinus mugo) and compared it with spacing patterns in high-quality Scots pine (Pinus sylvestris) forest at lower-elevation. Home ranges and core areas were larger in the marginal habitat. In both habitats, males used larger home ranges than females, but sex differences in core area size were significant only in the edge population. Patterns of core area overlap were similar in both habitats with intra-sexual territoriality among adult females and higher degrees of inter-sexual overlap, typical for the species throughout its range. However, low densities in the edge population resulted in higher female by males overlap in spring-summer, suggesting males increased home ranges and core areas during mating season to augment access to estrus females. Thus, in the marginal habitat, with low food abundance and low population densities, linked with extreme winter conditions, squirrels, especially males, used large home ranges. Finally, squirrels responded more strongly to variation in food availability (inverse relation between home range size and seed abundance), and even to fluctuations in density (inverse relation between core area size and density of animals of the same sex), in the marginal than in the high-quality habitat, suggesting high behavioral plasticity to respond to the ecological constraints in marginal habitats

Cervical spine injuries: A whole-body musculoskeletal model for the analysis of spinal loading

This is the final version of the article. Available from Public Library of Science via the DOI in this record.Cervical spine trauma from sport or traffic collisions can have devastating consequences for individuals and a high societal cost. The precise mechanisms of such injuries are still unknown as investigation is hampered by the difficulty in experimentally replicating the conditions under which these injuries occur. We harness the benefits of computer simulation to report on the creation and validation of i) a generic musculoskeletal model (MASI) for the analyses of cervical spine loading in healthy subjects, and ii) a population-specific version of the model (Rugby Model), for investigating cervical spine injury mechanisms during rugby activities. The musculoskeletal models were created in OpenSim, and validated against in vivo data of a healthy subject and a rugby player performing neck and upper limb movements. The novel aspects of the Rugby Model comprise i) population-specific inertial properties and muscle parameters representing rugby forward players, and ii) a custom scapula-clavicular joint that allows the application of multiple external loads. We confirm the utility of the developed generic and population-specific models via verification steps and validation of kinematics, joint moments and neuromuscular activations during rugby scrummaging and neck functional movements, which achieve results comparable with in vivoand in vitrodata. The Rugby Model was validated and used for the first time to provide insight into anatomical loading and cervical spine injury mechanisms related to rugby, whilst the MASI introduces a new computational tool to allow investigation of spinal injuries arising from other sporting activities, transport, and ergonomic applications. The models used in this study are freely available at simtk.org and allow to integrate in silico analyses with experimental approaches in injury prevention.Funding: This project is funded by the Rugby Football Union (RFU) Injured Players Foundation. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Nutcrackers become choosy seed harvesters in a mast-crop year.

As an efficient seed-disperser, Eurasian nutcrackers (Nucifraga caryocatactes) generally consume and hoard mature, edible pine seeds for future use. In 2009, when the Arolla pine, Pinus. cembra, produced a mast-crop, we investigated cones discarded by nutcrackers. Most cones were only partly eaten and some mature seeds remained in the distal part. This was in contrast to years of lower seed production when nearly all seeds were harvested from the majority of cones. To determine whether nutcracker cone-discarding behaviour maximised intake rate, seed kernels and the aborted seeds rate were measured from the different cone parts. In 2009, seeds from cone-tops were on average 17% lighter than in the base and middle sections, and the proportion of aborted seeds in the top part was 81% higher than in the other sections. There was no difference in seed mass and proportion of aborted seeds in cone-tops of intact cones and cones handled by nutcrackers. Regarding each cone as a patch, cone discarding behaviour can be considered as an optimal cone-leaving rule, maximising rate of energy-intake, supporting the Marginal Value Theorem. Hence, we suggest that increased food abundance leads to more selective seed harvesting in nutcrackers

Analysis of cervical spine loading in rugby scrummaging: a computer simulation approach

Musculoskeletal modelling is widely used in biomechanics for the analysis and simulation of human motion. A modelling approach allows estimates of the internal load on specific anatomical structures, and the individual muscle forces that govern movement execution. Within the analysis of impact events in rugby union, modelling can help the understanding of the mechanisms of acute and chronic cervical spine injuries, starting from experimental measures of external load on the player, and progressing to the estimation of stresses acting on the internal cervical structures. During this part of the applied session, we will use a novel musculoskeletal model and previously collected experimental data (forces and kinematics) to analyse the cervical spine loading experienced during a rugby scrum. An open-source biomechanical software (OpenSim 3.2) will be used to set up and run inverse and forward dynamics pipelines to calculate joint moments and joint reaction forces, and to analyse “what if…” scenarios

Measuring impacts and informing modelling processes

Primarily using rugby union situations as case study examples for the practical demonstration, the initial part of the session will discuss both familiar and emerging techniques to measure the biomechanics of sport impact situations. We will cover some of the issues that need to be accounted for to acquire robust data in such complex environments, and we will discuss how experimental measures can be either used in their own right to develop knowledge of impact biomechanics or can provide data to input a modelling pipeline and for model validation purposes

Estimating offspring production using capture-mark-recapture and genetic methods in red squirrels.

Reproductive rate is a key demographic parameter of life history and population ecology. In traditional population-ecology studies of small mammals, this and other vital rates are inferred from capture-mark-recapture (CMR) data. However, CMR assumes that immigrants at first capture can be distinguished from unmarked locally born offspring, an assumption not always met. We verified CMR estimates of locally born red squirrel (Sciurus vulgaris) offspring as a measure of reproductive rate, with candidate offspring (CO)\u2013candidate parent (mothers, CPs) assignment by CERVUS, using ten DNA microsatellite loci. Seventytwo of 122 candidate offspring (59%) were assigned to 52 of 125 CPs in six populations. Estimates of mean litter size were 1.5 young (range 1\u20133). The 50 CO (41%) not assigned to a reproducing female in the study site were considered immigrants. Parentage assignment also provided evidence of dispersal between two of our sites. Overall, CMR and CERVUS agreed in 77% of cases. Considering only the 55 juveniles determined as locally born by CMR, 50 (91%) were also assigned as local offspring with CERVUS. The main discrepancy between the two methods was that 22 subadult squirrels classified immigrants by CMR, were assigned by CERVUS to females which had reproduced in our sites. It is concluded that although in our study system agreement between CMR and CERVUS in determining local offspring was high, using genetic parentage assignment helped to correctly classify some subadults, considered immigrants by CMR, as locally born. Hence, in largescale demographic studies, combining CMR with parentage assignment will allow more precise estimates of reproduction and dispersal

Habitat effects on hoarding plasticity in the Eurasian red squirrel (Sciurus vulgaris).

Hoarding patterns can be classified into two general types: scatter-hoarding and larder-hoarding, but there are intermediate types. Various factors affect hoarding patterns. Animals hoarding identical seeds in different habitats may use different hoarding patterns to adapt to habitat variation. We used a sample-plot investigation method to study cache features and recovery rate of seeds of Arolla pine (Pinus cembra) by Eurasian red squirrels (Sciurus vulgaris) in 2009 and 2010 in two subalpine forests with different tree-species composition in the Italian Alps. Hoarding patterns of red squirrels varied among habitats: the typical scatter-hoarding pattern with most caches including 2-6 seeds is found in spruce (Picea abies) dominated forest, while a combination of few large caches (10 seeds) and many small caches (less than 10 seeds) is found in Arolla pine dominated forest. Consequently, average number of seeds/cache was higher in the latter habitat. Among five microhabitats, shrubs, grass, moss, fallen leaves, and stone, Eurasian red squirrels preferred fallen leaves and moss as hoarding substrate. Cache recovery investigation indicated that recovery rate was 62% in spruce forest and only 21% in Arolla pine forest. A lower availability of suitable hoarding microhabitat resulted in changes in hoarding patterns of red squirrels in Pinus cembra dominated forest. We suggest that the main factor influencing differences in recovery rate was a higher cone production per tree in Pinus cembra forest

Evaluation of tackling biomechanics in rugby:video incident analysis and experimental set up

This study consisted of a video incident analysis of rugby tackles leading to spinal injuries, where players’ behaviours and observed loading mechanisms were coded for each incident. The key features of these events were summarised, revealing the role of highspeed impacts, illegal tackles, and poor tackle technique in injury-causing tackles. In addition, lateral bending moments and lateral flexion movements were more prevalent than suggested by previous research. This investigation informed an experimental protocol for the analysis of simulated rugby tackles, with the final goal to obtain measures of cervical spine biomechanics during tackles. Data captured from this protocol could also be input into a full-body musculoskeletal model to provide descriptions of internal cervical spine loading in different tackle event scenarios

Open Source evaluation of kilometric indexes of abundance.

Kilometric Abundance Index (KAI) is a common measure used in wildlife studies because it allows a straightforward comparison of species abundance in different sites or at different times. KAI expresses the ratio of the total number of individuals (or of signs of presence) observed along a transect by the total transect length covered at each site. v.transect.kia is a new tool for GRASS GIS, developed for automating the evaluation of KAI, reducing the risk of manual errors especially when handling large datasets. It can also split the transects according to one environmental variable (typically habitat type) and evaluate true 3D transect length. It calculates KAI using a point map of sightings and saves the results in the attribute table, the output can be displayed in any GIS or used for further statistical analysis. The tool has been tested on field data from Northern Italy for mountain hare (Lepus timidus), allowing a first wide-area estimate