Now showing 1 - 3 of 3
  • Publication
    Large-scale movements in European badgers: has the tail of the movement kernel been underestimated?
    1. Characterising patterns of animal movement is a major aim in population ecology, and yet doing so at an appropriate spatial-scale remains a majorchallenge. Estimating the frequency and distances of movements are of particularimportance when species are implicated in the transmission of zoonotic diseases. 2. European badgers (Meles meles) are classically viewed as exhibiting limited dispersal, and yet their movements bring them into conflict with farmers due to their potential to spread bovine tuberculosis in parts of their range. Considerable uncertainty surrounds the movement potential of badgers, and this may be related to the spatial-scale of previous empirical studies. We conducted a large-scale mark-recapture study (755km231 ; 2008-2012; 1,935 capture-events; 963 badgers) to investigate movement patterns in badgers, and undertook a comparative meta analysis using published data from 15 European populations. 3. The dispersal movement (>1km) kernel followed an inverse power-law function, with a substantial 'tail' indicating the occurrence of rare long-distance dispersal attempts during the study period. The mean recorded distance from this distribution was 2.6km., the upper 95%ile was 7.3km and the longest recorded was 22.1km. Dispersal frequency distributions were significantly different between genders; males dispersed more frequently than females but females made proportionally more long-distance dispersal attempts than males. 4. We used a subsampling approach to demonstrate that the appropriate minimum spatial-scale to characterise badger movements in our study population was 80km243 , substantially larger than many previous badger studies. Furthermore, the meta-analysis indicated a significant association between maximum movement distance and study area size, while controlling for population density. Maximum long-distance movements were often only recorded by chance beyond the boundaries of study areas. 5. These findings suggest that the tail of the badger movement distribution is currently underestimated. The implications of this for understanding the spatial ecology of badger populations and for the design of disease intervention strategies are potentially significant.
      515Scopus© Citations 39
  • Publication
    Population estimation and trappability of the European badger (Meles meles): implications for tuberculosis management
    Estimates of population size and trappability inform vaccine efficacy modelling and are required for adaptive management during prolonged wildlife vaccination campaigns. We present an analysis of mark-recapture data from a badger vaccine (Bacille Calmette-Guérin) study in Ireland. This study is the largest scale (755 km²) mark-recapture study ever undertaken with this species. The study area was divided into three approximately equal-sized zones, each with similar survey and capture effort. A mean badger population size of 671 (SD: 76) was estimated using a closed-subpopulation model (CSpM) based on data from capturing sessions of the entire area and was consistent with a separate multiplicative model. Minimum number alive estimates calculated from the same data were on average 49-51% smaller than the CSpM estimates, but these are considered severely negatively biased when trappability is low. Population densities derived from the CSpM estimates were 0.82-1.06 badgers kmˉ², and broadly consistent with previous reports for an adjacent area. Mean trappability was estimated to be 34-35% per session across the population. By the fifth capture session, 79% of the adult badgers caught had been marked previously. Multivariable modelling suggested significant differences in badger trappability depending on zone, season and age-class. There were more putatively trap-wary badgers identified in the population than trap-happy badgers, but wariness was not related to individual's sex, zone or season of capture. Live-trapping efficacy can vary significantly amongst sites, seasons, age, or personality, hence monitoring of trappability is recommended as part of an adaptive management regime during large-scale wildlife vaccination programs to counter biases and to improve efficiencies.
    Scopus© Citations 38  341
  • Publication
    Survival and dispersal of a defined cohort of Irish cattle
    (Springer (Biomed Central Ltd.), 2009) ; ; ;
    An understanding of livestock movement is critical to effective disease prevention, control and prediction. However, livestock movement in Ireland has not yet been quantified. This study has sought to define the survival and dispersal of a defined cohort of cattle born in Co. Kerry during 2000. The cohort was observed for a maximum of four years, from January 1, 2000 to December 31, 2004. Beef and dairy animals moved an average 1.31 and 0.83 times, respectively. At study end, 18.8% of the beef animals remained alive on Irish farms, including 6.7% at the farm-of-birth, compared with 48.6% and 27.7% for dairy animals respectively. Beef animals werae dispersed to all Irish counties, but mainly to Cork, Limerick, Tipperary and Galway. Dairy animals mainly moved to Cork, Limerick, and Tipperary, with less animals going to Galway, Meath and Kilkenny. The four-year survival probability was 0.07 (male beef animals), 0.25 (male dairy), 0.38 (female beef), and 0.72 (female dairy). Although there was considerable dispersal, the number of moves per animal was less than expected.
    Scopus© Citations 19  383