Andrew D. Ramsey

A Hypothetico-Deductive Approach to Assessing the Social Function of Chemical Signalling in a Non-Territorial Solitary Carnivore

The function of chemical signalling in non-territorial solitary carnivores is still relatively unclear. Studies on territorial solitary and social carnivores have highlighted odour capability and utility, however the social function of chemical signalling in wild carnivore populations operating dominance hierarchy social systems has received little attention. We monitored scent marking and investigatory behaviour of wild brown bears Ursus arctos, to test multiple hypotheses relating to the social function of chemical signalling. Camera traps were stationed facing bear ‘marking trees’ to document behaviour by different age sex classes in different seasons. We found evidence to support the hypothesis that adult males utilise chemical signalling to communicate dominance to other males throughout the non-denning period. Adult females did not appear to utilise marking trees to advertise oestrous state during the breeding season. The function of marking by subadult bears is somewhat unclear, but may be related to the behaviour of adult males. Subadults investigated trees more often than they scent marked during the breeding season, which could be a result of an increased risk from adult males. Females with young showed an increase in marking and investigation of trees outside of the breeding season. We propose the hypothesis that females engage their dependent young with marking trees from a young age, at a relatively ‘safe’ time of year. Memory, experience, and learning at a young age, may all contribute towards odour capabilities in adult bears.

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 least-cost 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 least-cost approach to mapping ecological networks.

Scent-marking investment and motor patterns are affected by the age and sex of wild brown bears

Members of the Carnivora employ a wide range of postures and 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 that different age and sex classes spend at scent-marking trees and the behaviours involved at different times of year could provide further insight into the function of marking. We used camera traps stationed at scent-marking trees to investigate scent-marking behaviour by wild brown bears, Ursus arctos. Through image-based data, we found evidence to support the hypothesis that time investment and scent-marking motor patterns are dictated by the age and sex of the bear. Adult males spent more time scent marking and displayed a more complex behavioural sequence of marking than adult females and juveniles. Adult male behaviour at marking trees was consistent throughout the year, indicating a continued benefit of chemical signalling outside of the breeding season. Juvenile bear behaviour at marking trees changed with age. Young dependent cubs were more likely to imitate their mothers behaviour, whereas older dependent cubs were more likely to engage in marking behaviour independently. The marking motor patterns of independent subadults were more simplistic than those of younger dependent cubs, suggesting a change in behaviour with independence. We suggest that these findings further support the hypothesis that scent-marking behaviour by brown bears functions in intrasexual competition between adult males. Cub behaviour at marking trees suggests an influence of social learning.

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.

Assessing Grey Squirrel Dispersal Patterns within the Landscape Using Sequence Variation

Abstract The grey squirrel Sciurus carolinensis is thought to have contributed to the decline of red squirrel S. vulgaris populations in the UK through resource competition and disease spread. This study used mtDNA sequencing to assess patterns of grey squirrel dispersal in the UK. Patterns of genetic variation within the dloop sequence were characterised for seven grey squirrel populations. Infiltration directions and potential barriers to dispersal are identified and discussed, with a focus on Cumbria, a county at the forefront of grey squirrel expansion. Understanding the dynamics of grey squirrel dispersal will aid their management at a landscape scale and enhance the conservation of red squirrels.

Ontogeny of juvenile freshwater pearl mussels, Margaritifera margaritifera (Bivalvia: Margaritiferidae).

The gills of juvenile freshwater bivalves undergo a complex morphogenesis that may correlate with changes in feeding ecology, but ontogenic studies on juvenile mussels are rare. Scanning electron microscopy was used to examine the ultrastructure and ontogeny of 117 juvenile freshwater pearl mussels (Margaritifera margaritifera) ranging in age from 1–44 months and length from 0.49–8.90 mm. Three stages of gill development are described. In Stage 1 (5–9 inner demibranch filaments), only unreflected inner demibranch filaments were present. In Stage 2 (9–17 inner demibranch filaments), inner demibranch filaments began to reflect when shell length exceeded 1.13 mm, at 13–16 months old. Reflection began in medial filaments and then proceeded anterior and posterior. In Stage 3 (28–94 inner demibranch filaments), outer demibranch filaments began developing at shell length > 3.1 mm and about 34 months of age. The oral groove on the inner demibranch was first observed in 34 month old specimens > 2.66 mm but was never observed on the outer demibranch. Shell length (R2 = 0.99) was a better predictor of developmental stage compared to age (R2 = 0.84). The full suite of gill ciliation was present on filaments in all stages. Interfilamentary distance averaged 31.3 μm and did not change with age (4–44 months) or with size (0.75–8.9 mm). Distance between laterofrontal cirri couplets averaged 1.54 μm and did not change significantly with size or age. Labial palp primordia were present in even the youngest individuals but ciliature became more diverse in more developed individuals. Information presented here is valuable to captive rearing programmes as it provides insight in to when juveniles may be particularly vulnerable to stressors due to specific ontogenic changes. The data are compared with two other recent studies of Margaritifera development.

Designer reefs and coral probiotics: great concepts but are they good practice?

It has been estimated that over 500 million people as well as industries worth billions of dollars (including tourism and fisheries) depend on healthy reef ecosystems (Cesar 2000). As such, the continued decline in coral cover and shifts in community composition which are being observed on a global scale are an extremely worrying trend from economic, social and ecological perspectives. The overarching effects of anthropogenic stresses, including those related to climate change, are unarguably responsible for the recent unprecedented declines. However, understanding how these may interact with natural stresses in regard to their effect on corals is difficult, and in turn makes it difficult to manage and mitigate the declines of these fragile ecosystems. Coral reefs across the world have recently experienced the longest bleaching event on record (from 2014 to 2016) (Cressey 2016) and reports are now starting to highlight that many are experiencing bleaching for a further consecutive year (NOAA Coral Reef Watch 2017). However, with the use of hind cast modelling spatial variation in warming trends, thermal stress events and temperature variability has been mapped back as far as 1985 (Heron et al. 2016). This study suggested that over 97% of the reefs assessed had experienced positive sea surface temperature (SST) trends since 1985, with 60% experiencing significant warming. Furthermore, the frequency of thermal stress exceeding bleaching thresholds has increased threefold between 1985–91 and 2006–12; a trend which climate model predictions suggest will continue (Heron et al. 2016). This has led some to suggest that, as early as 2054, we will likely see annual severe bleaching (ASB) episodes on a large proportion of the world’s reefs. This is assuming emissions follow the Intergovernmental Panel on Climate Change’s representative concentration pathway (RCP) scaling of 4.5, whereby greenhouse gas emissions peak around 2040 and then decline. However, if climate conditions fall under the RCP8.5 scenario (i.e. emissions continue to rise throughout the twenty-first century) ASB conditions are predicted to occur 11 years earlier (i.e. by 2043). It should also be noted that there is likely to be significant spatial heterogeneity in these patterns, with reefs at different locations experiencing variable warming around the overall mean. For example, high-latitude reefs in Australia, Hawaii and India are predicted to have at least 25 years before they experience ASB conditions (under RCP4.5), whilst reefs nearer the equator are predicted to experience these conditions in less than 10 years (Heron et al. 2016). This has led some to propose that the intended nationally determined contributions, which were submitted under the Paris Agreement of April 2016, will do little to aid reefs in adapting or acclimatising prior to the occurrence of ASB events in the majority of locations (Heron et al. 2016). In response to the rapid decline of many marine organisms, particularly those associated with coral reefs, there has been a marked rise in the designation of large-scale marine protected areas (MPAs) (Ban et al. 2017). This has been coupled with an increase in research focussing on adaptability and response of corals to future climate-ocean scenarios (reviewed in Sweet and Brown 2016). However, decisions in locating MPAs are often based on data and requirements at the larger ecosystem scale and not specifically focussed on coral reefs. There is substantial evidence that MPAs can improve the abundance and diversity of organisms in the higher trophic levels, such as fish communities associated with reefs (McClanahan et al. 2006). However, there is significant discussion over the effectiveness of MPAs on the conservation of corals and across the breadth of all reef organisms (Mouillot et al. 2016). In contrast, reef restoration offers a more focussed conservation methodology. This has been used in a wide range of contexts, from areas which have been damaged due to ship groundings and hurricanes, to tourism driven