Modelling red squirrel population viability under a range of landscape scenarios in a fragmented woodland ecosystem on the Solway Plain, Cumbria, UK.

To assess the viability of the red squirrel Sciurus vulgaris in fragmented woodlands on the Solway Plain we used a combination of Vortex population viability analysis and BEETLE (Biological and Environmental Evaluation Tools for Landscape Ecology). Habitat fragmentation and the expansion of the North American grey squirrel S. carolinensis have had a detrimental effect upon red squirrel populations in the UK; assessing the viability of the remaining populations can guide in conservation management decisions. The initial field work showed red squirrels to use 5 of the 23 woodland fragments on the Solway Plain at a density of 0.65 squirrels ha-1, with a minimum dynamic area of 91 ha of red squirrel woodland habitat being identified using Vortex. Red squirrels may use more than one woodland fragment in its home range as long as fragments are connected functionally with the land cover between fragments producing a low cost for the squirrel. The functional connectivity of these woodland fragments was modeled within BEETLE to create habitat networks. Vortex was then used to identify which habitat networks would hold a viable population. Two areas were identified which could, if the correct landscape management is prescribed, potentially hold viable populations of red squirrels on the Solway Plain. This combination of behavioral, demographic and landscape modeling allows scenario building and has application across a wide range of conservation area design problems

Biscayne aquifer in Dade and Broward Counties, Florida

The Biscayne Aquifer is the principal source of water for the heavily populated area in the vicinity of West Palm Beach and Miami. The publication of this data is timely and will assist in the intelligent development of the water resources of the area.(PDF has 64 pages

Defining Landscape Resistance Values in Least-Cost Connectivity Models for the Invasive Grey Squirrel: A Comparison of Approaches Using Expert-Opinion and Habitat Suitability Modelling

Least-cost models are widely used to study the functional connectivity of habitat within a varied landscape matrix. A critical step in the process is identifying resistance values for each land cover based upon the facilitating or impeding impact on species movement. Ideally resistance values would be parameterised with empirical data, but due to a shortage of such information, expert-opinion is often used. However, the use of expert-opinion is seen as subjective, human-centric and unreliable. This study derived resistance values from grey squirrel habitat suitability models (HSM) in order to compare the utility and validity of this approach with more traditional, expert-led methods. Models were built and tested with MaxEnt, using squirrel presence records and a categorical land cover map for Cumbria, UK. Predictions on the likelihood of squirrel occurrence within each land cover type were inverted, providing resistance values which were used to parameterise a leastcost model. The resulting habitat networks were measured and compared to those derived from a least-cost model built with previously collated information from experts. The expert-derived and HSM-inferred least-cost networks differ in precision. The HSM-informed networks were smaller and more fragmented because of the higher resistance values attributed to most habitats. These results are discussed in relation to the applicability of both approaches for conservation and management objectives, providing guidance to researchers and practitioners attempting to apply and interpret a leastcost approach to mapping ecological networks.This project was funded by the Forestry Commission GB and the National School of Forestry at the University of Cumbria. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Using GPS telemetry to validate least-cost modeling of gray squirrel ( Sciurus carolinensis) movement within a fragmented landscape

In Britain, the population of native red squirrels Sciurus vulgaris has suffered population declines and local extinctions. Interspecific resource competition and disease spread by the invasive gray squirrel Sciurus carolinensis are the main factors behind the decline. Gray squirrels have adapted to the British landscape so efficiently that they are widely distributed. Knowledge on how gray squirrels are using the landscape matrix and being able to predict their movements will aid management. This study is the first to use global positioning system (GPS) collars on wild gray squirrels to accurately record movements and land cover use within the landscape matrix. This data were used to validate Geographical Information System (GIS) least-cost model predictions of movements and provided much needed information on gray squirrel movement pathways and network use. Buffered least-cost paths and least-cost corridors provide predictions of the most probable movements through the landscape and are seen to perform better than the more expansive least-cost networks which include all possible movements. Applying the knowledge and methodologies gained to current gray squirrel expansion areas, such as Scotland and in Italy, will aid in the prediction of potential movement areas and therefore management of the invasive gray squirrel. The methodologies presented in this study could potentially be used in any landscape and on numerous species

Stellar Dynamics at the Galactic Center with an Extremely Large Telescope

We discuss experiments achievable via monitoring of stellar dynamics near the massive black hole at the Galactic center with a next generation, extremely large telescope (ELT). Given the likely observational capabilities of an ELT and current knowledge of the stellar environment at the Galactic center, we synthesize plausible samples of stellar orbits around the black hole. We use the Markov Chain Monte Carlo method to evaluate the constraints that orbital monitoring places on the matter content near the black hole. Results are expressed as functions of the number N of stars with detectable orbital motions and the astrometric precision dtheta and spectroscopic precision dv at which stellar proper motions and radial velocities are monitored. For N = 100, dtheta = 0.5 mas, and dv = 10 km/s -- a conservative estimate of the capabilities of a 30 meter telescope -- the extended matter distribution enclosed by the orbits will produce measurable deviations from Keplerian motion if >1000 Msun is enclosed within 0.01 pc. The black hole mass and distance to the Galactic center will be measured to better than ~0.1%. Lowest-order relativistic effects, such as the prograde precession, will be detectable if dtheta < 0.5 mas. Higher-order effects, including frame dragging due to black hole spin, requires dtheta < 0.05 mas, or the favorable discovery of a compact, highly eccentric orbit. Finally, we calculate the rate at which monitored stars undergo detectable nearby encounters with background stars. Such encounters probe the mass function of stellar remnants that accumulate near the black hole. We find that ~30 encounters will be detected over a 10 yr baseline for dtheta = 0.5 mas.Comment: 14 pages, 5 figures; discussion no longer aperture-specific (TMT -> ELT), matches ApJ versio

Using Markov Chain Analysis to assess stereotyped scent marking behaviour in wild brown bears

Members of the order Carnivora employ a wide range of postures and stereotyped patterns to mark their scent onto objects, and therein communicate with conspecifics. Despite much anecdotal evidence on the marking behaviour of Ursids, empirical data examining marking patterns displayed by wild populations is lacking. Situated on the west coast of British Columbia (2009-2011), we used trail cameras stationed at marking trees to investigate scent marking and investigatory behaviour by wild brown bears Ursus arctos. Transitions between postures were assessed using Markov Chain Analysis. Results showed that scent marking patterns varied by age and sex; adult males exhibited a cyclic pattern of marking behaviour which included ‘core’ and ‘secondary’ postures, whereas adult females failed to exhibit any subset postures. The behaviour of subadults (sexes combined) was a variation and simplification of the patterns displayed by adult males and females. The wider variety of marking postures selected by adult males may convey a more complex signal, relating to the function of scent marking in the species. Females with young were classified separately to assess potential similarities/differences in the behaviour of all members of the family group. Using a simplified ethogram, we found the behaviour of cubs to be dependent on their age and the behaviour of their mother. Younger cubs were more likely to conduct the same behaviour as their mother, whereas older cubs exhibited behaviours independently. This study presents the first detailed description of the development of scent marking behaviour by cubs in the Ursidae

Assessing the scent marking behaviour of wild brown bears: an exploration of time and energy investment, motor patterns and age-related development

Members of the order Carnivora employ a wide range of postures and stereotyped patterns to mark their scent onto objects and thereby communicate with conspecifics. Despite much anecdotal evidence on the marking behaviour of ursids, empirical evidence of scent marking motor patterns displayed by wild populations is lacking. Analysing the time bears spend at marking trees and the behaviours involved, could provide further insight into the function of marking and highlight time and energy investment. Over a three year period, camera traps stationed at marking trees were used to investigate scent marking and investigatory behaviour by wild brown bears Ursus arctos in coastal British Columbia. This work follows on from data presented at the 18th, 19th & 20th IBA conferences

Food availability affects the scent marking frequencies of wild brown bears

For many species, chemical signalling is used to signal the competitive ability of individuals and therefore plays an important role in the breeding system. As breeding generally promotes intrasexual competition, the potential fitness costs associated with competitive behaviour may be mitigated if individuals are able to assess their own ability, and the competitive ability of others, prior to agonistic encounters. Due to their hierarchical social structure and large home-range size, bears (Ursidae) are thought to rely highly on olfactory methods of communication. Through camera traps orientated towards bear ‘rub trees’ over a three-year period, we have begun to establish the function of strategic tree selectivity and the social function of marking behaviour for brown bears Ursus arctos in the Glendale drainage, British Columbia. We hypothesised that marking trees function to signal competitive ability between individuals, with dominant individuals signalling their high competitive ability and receivers detecting these cues and modifying their behaviour accordingly. Here, we provide evidence to further these hypotheses by demonstrating how scent marking frequencies vary in relation to food availability

Naturally occurring diversity helps to reveal genes of adaptive importance in legumes

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