Jim Casaer

Analysing space use patterns by Thiessen polygon and triangulated irregular network interpolation: a non-parametric method for processing telemetric animal fixes

This paper describes a new non-parametric model to estimate space use. We test the similarity in space use patterns between an artificially generated utilization distribution (Seaman- UD) and the model estimates for five different sample sizes. Three different test statistics (Kappa,gamma,Tc) reveal a high similarity between the estimates and the Seaman-UD. The tests also show that, beyond a certain threshold value, larger sample sizes do not return significantly better results. W e further demonstrate that the Thiessen model delineated areas of intensive use more effectively in a home range than Kernel estimators. UD estimation uses AML (ArcInfo Macro Language), thus facilitating overlay operations with habitat information stored in the same ArcInfo GIS environment.

Successful eradication of a suburban Pallas’s squirrel Callosciurus erythraeus (Pallas 1779) (Rodentia, Sciuridae) population in Flanders (northern Belgium)

Despite a growing catalogue of eradication projects, documented successful vertebrate eradications on the mainland remain scarce. Reporting on successful campaigns is crucial to counter pessimism on ambitious programmes to tackle invasive species and to allow conservation practitioners, wildlife managers and scientist to learn from previous experience. Moreover, there is a need for basic information on the effectiveness of control methods and management strategies that can be used. In this note we report on a successful low-tech eradication campaign of a local population of Pallas’s squirrel Callosciurus erythraeus, a species of tree squirrel with documented ecological and socio-economic impacts in its invasive range. The population was eradicated from a suburban park of about 15xa0ha using baited mesh wire life traps, in five consecutive capture campaigns between October 2005 and January 2011. Using maximum likelihood estimation from catch-effort data we calculated initial densities in the park at 3xa0squirrelsxa0ha−1. Although control started quickly and the extent of the invasion was limited, the campaign took over 5xa0years and required an estimated investment of over €200,000 including 1.5xa0years of post-eradication surveying. We provide basic data on the methods used to eradicate this invasive rodent. Critical success factors and possible improvements with respect to the specific context of this case are discussed. Adding this species to the list of species of EU concern currently under development could provide incentive to minimise impact of this tree squirrel at the continental scale.

CICES going Local : Ecosystem Services Classification Adapted for a Highly Populated Country

Abstract Multiple classification systems for ecosystem services (ES) make comparison and integration between studies and assessments very difficult. With the fast-growing number of ecosystem services assessment and valuation studies, there is a need to identify generally agreed definitions and to design a common base that will enable comparisons between ecosystem services assessments at different places. The recently developed Common International Classification for Ecosystem Services (CICES) is aiming to fill this gap. One advantage of the CICES approach is that it allows adjustment to local conditions. Through an iterative consultation round with Belgian experts from administrations, policy support units, and research centers CICES has been adapted to the needs of a highly populated country, where multifunctional land use is very common. The goal of CICES-Be is to introduce a common reference base for ecosystem services in Belgium, which is locally adapted and compatible with an international standard.

Wildlife comeback in Flanders: tracing the fault lines and dynamics of public debate

Conflicts and debates on wildlife issues often prove “intractable” or resistant to resolution. This paper develops a three-layered methodological approach to identify the fault lines and dynamics, which perpetuate social division and conflict. This approach was applied to the analysis of six publicly debated events that followed the comeback of thexa0red fox and wild boar in Flanders, Belgium. The integrated findings demonstrate that conflict was not merely a manifestation of incompatible goals and views, but was highly determined by the conduct of the debate itself. The debates evolved along a few main fault lines, most notably “belonging/not belonging”, “opportunity/threat” and “control by intervention/nature controls itself”. A number of dynamics were identified along these fault lines, including the convergence and alignment of arguments (in particular, dichotomisation), the linking and scaling up of issues and the stigmatisation of outgroups. These processes were largely driven by the parties’ strategies to gain credibility and support with audiences. At the same time, however, they tended to magnify the problems, polarised positions along the fault lines, and thus hampered resolution. Furthermore, part of the debate served to confirm institutional roles and identities, which, in turn, contributed to the perpetuation of conflict. Contrasting views on “nature” were hardly a topic of discussion. Rather they were locked into dichotomies and classifications expressed by the contending parties. Together, the findings from this paper provide useful clues for transforming the dynamics perpetuating the conflict to different dynamics that allow for more constructive relations between the parties involved.

Roe deer population structure in a highly fragmented landscape

Northern Belgium (Flanders) is one of the most densely populated and urbanized regions in Europe. Many species are therefore likely to suffer from anthropogenic pressure and habitat destruction and fragmentation. Although many large mammals are recolonizing in parts of Europe, including Belgium, due to adaptation, a relaxation of persecution and habitat restoration, we have little actual data concerning the effects of landscape features on their population structure. We analysed the genetic structure of discrete roe deer (Capreolus capreolus) populations in the Eastern part of Flanders, with special emphasis on the impact of habitat fragmentation and anthropogenic barriers. The sampled populations were clearly genetically differentiated. Genetic structure could be explained by purely distance-based landscape modelling, but a simpler model focusing solely on barrier effects of large transportation infrastructure explained nearly as much genetic variance. In contrast, analyses based on least-cost landscape modelling failed to yield a significant effect. Overall, the results suggest considerable landscape-level effects of transportation infrastructure.

First TBEV serological screening in Flemish wild boar.

In the frame of a Flemish wildlife surveillance in 2013, a serological screening was performed on sera from wild boar (Sus scrofa; n=238) in order to detect tick-borne encephalitis virus (TBEV)-specific antibodies. Neutralising antibodies were titrated with a seroneutralisation test (SNT), using two cut-off titres (1/10–1/15). Seven wild boars were found TBEV-seropositive and showed moderate (>1/15) to high (>1/125) SNT-titres; three individuals had borderline results (1/10–1/15). This study demonstrated the presence of TBEV-specific antibodies in wild boar and highlighted potential TBEV-foci in Flanders. Additional surveillance including direct virus testing is now recommended.

Cost-benefit analysis for invasive species control: the case of greater Canada goose Branta canadensis in Flanders (northern Belgium)

Background Sound decisions on control actions for established invasive alien species (IAS) require information on ecological as well as socio-economic impact of the species and of its management. Cost-benefit analysis provides part of this information, yet has received relatively little attention in the scientific literature on IAS. Methods We apply a bio-economic model in a cost-benefit analysis framework to greater Canada goose Branta canadensis, an IAS with documented social, economic and ecological impacts in Flanders (northern Belgium). We compared a business as usual (BAU) scenario which involved non-coordinated hunting and egg destruction with an enhanced scenario based on a continuation of these activities but supplemented with coordinated capture of moulting birds. To assess population growth under the BAU scenario we fitted a logistic growth model to the observed pre-moult capture population. Projected damage costs included water eutrophication and damage to cultivated grasslands and were calculated for all scenarios. Management costs of the moult captures were based on a representative average of the actual cost of planning and executing moult captures. Results Comparing the scenarios with different capture rates, different costs for eutrophication and various discount rates, showed avoided damage costs were in the range of 21.15 M€ to 45.82 M€ under the moult capture scenario. The lowest value for the avoided costs applied to the scenario where we lowered the capture rate by 10%. The highest value occurred in the scenario where we lowered the real discount rate from 4% to 2.5%. Discussion The reduction in damage costs always outweighed the additional management costs of moult captures. Therefore, additional coordinated moult captures could be applied to limit the negative economic impact of greater Canada goose at a regional scale. We further discuss the strengths and weaknesses of our approach and its potential application to other IAS.

Onset of Common Woodpigeon Columba palumbus Breeding Season in Flanders as Based on Gonadal Development

To determine the start of the breeding season of Common Woodpigeon Columba palumbus in Flanders, the gonads of 185 adult Woodpigeons were examined. Analysis of testis size showed that male Woodpigeons became sexually active in March. Follicle size analysis indicated that the first female Woodpigeons became sexually active from the end of February onwards. The observations however indicated an overall start of the breeding season on a population level by late March/early April.