The effects of landscape modifications on the long-term persistence of animal populations

Background: The effects of landscape modifications on the long-term persistence of wild animal populations is of crucial importance to wildlife managers and conservation biologists, but obtaining experimental evidence using real landscapes is usually impossible. To circumvent this problem we used individual-based models (IBMs) of interacting animals in experimental modifications of a real Danish landscape. The models incorporate as much as possible of the behaviour and ecology of four species with contrasting life-history characteristics: skylark (Alauda arvensis), vole (Microtus agrestis), a ground beetle (Bembidion lampros) and a linyphiid spider (Erigone atra). This allows us to quantify the population implications of experimental modifications of landscape configuration and composition. Methodology/Principal Findings: Starting with a real agricultural landscape, we progressively reduced landscape complexity by (i) homogenizing habitat patch shapes, (ii) randomizing the locations of the patches, and (iii) randomizing the size of the patches. The first two steps increased landscape fragmentation. We assessed the effects of these manipulations on the long-term persistence of animal populations by measuring equilibrium population sizes and time to recovery after disturbance. Patch rearrangement and the presence of corridors had a large effect on the population dynamics of species whose local success depends on the surrounding terrain. Landscape modifications that reduced population sizes increased recovery times in the short-dispersing species, making small populations vulnerable to increasing disturbance. The species that were most strongly affected by large disturbances fluctuated little in population sizes in years when no perturbations took place. Significance: Traditional approaches to the management and conservation of populations use either classical methods of population analysis, which fail to adequately account for the spatial configurations of landscapes, or landscape ecology, which accounts for landscape structure but has difficulty predicting the dynamics of populations living in them. Here we show how realistic and replicable individual-based models can bridge the gap between non-spatial population theory and non-dynamic landscape ecology. A major strength of the approach is its ability to identify population vulnerabilities not detected by standard population viability analyses

Foraging behaviour and fuel accumulation of capital breeders during spring migration as derived from a combination of satellite- and ground-based observations

The work was supported by Aarhus Univ., Denmark, the Norwegian Research Council (project MIGRAPOP, granted to I. Tombre) and the Schure-Beijerinck-Popping Fund (granted to BAN).The migration strategy of many capital breeders is to garner body stores along the flyway at distinct stopover sites. The rate at which they can fuel is likely to be strongly influenced by a range of factors, such as physiology, food availability, time available for foraging and perceived predation. We analysed the foraging behaviour and fuel accumulation of pink-footed geese, an Arctic capital breeder, at their mid-flyway spring stopover site and evaluated to what extent their behaviour and fuelling were related to physiological and external factors and how it differed from other stopovers along the flyway. We found that fuel accumulation rates of geese at the mid-flyway site were limited by habitat availability rather than by digestive constraints. However, as the time available for foraging increased over the stopover season, geese were able to keep constant fuelling rate. Putting this in perspective, geese increased their daily net energy intake along the flyway corresponding to the increase in time available for foraging. The net energy intake per hour of foraging remained the same. Geese showed differences in their reaction to predators/disturbance between the sites, taking higher risks particularly at the final stopover site. Hence, perceived predation along the flyway may force birds to postpone the final fuel accumulation to the last stopover along the flyway. Flexibility in behaviour appears to be an important trait to ensure fitness in this capital breeder. Our findings are based on a new, improved method for estimating fuel accumulation of animals foraging in heterogeneous landscapes based on data obtained from satellite telemetry and habitat specific intake rates.Publisher PDFPeer reviewe

Characteristics and propagation of airgun pulses in shallow water with implications for effects on small marine mammals

Airguns used in seismic surveys are among the most prevalent and powerful anthropogenic noise sources in marine habitats. They are designed to produce most energy below 100 Hz, but the pulses have also been reported to contain medium-to-high frequency components with the potential to affect small marine mammals, which have their best hearing sensitivity at higher frequencies. In shallow water environments, inhabited by many of such species, the impact of airgun noise may be particularly challenging to assess due to complex propagation conditions. To alleviate the current lack of knowledge on the characteristics and propagation of airgun pulses in shallow water with implications for effects on small marine mammals, we recorded pulses from a single airgun with three operating volumes (10 in3, 25 in3 and 40 in3) at six ranges (6, 120, 200, 400, 800 and 1300 m) in a uniform shallow water habitat using two calibrated Reson 4014 hydrophones and four DSG-Ocean acoustic data recorders. We show that airgun pulses in this shallow habitat propagated out to 1300 meters in a way that can be approximated by a 18log(r) geometric transmission loss model, but with a high pass filter effect from the shallow water depth. Source levels were back-calculated to 192 dB re µPa2s (sound exposure level) and 200 dB re 1 µPa dB Leq-fast (rms over 125 ms duration), and the pulses contained substantial energy up to 10 kHz, even at the furthest recording station at 1300 meters. We conclude that the risk of causing hearing damage when using single airguns in shallow waters is small for both pinnipeds and porpoises. However, there is substantial potential for significant behavioral responses out to several km from the airgun, well beyond the commonly used shut-down zone of 500 meters

Using habitat selection theories to predict the spatiotemporal distribution of migratory birds during stopover - a case study of pink-footed geese Anser brachyrhynchus

Th is study was part of MC ’ s PhD project funded by Aarhus University. Th e fi eldwork was supported by the Norwegian Research Council project MIGRAPOP.Understanding how animals select for habitat and foraging resources therein is a crucial component of basic and applied ecology. The selection process is typically influenced by a variety of environmental conditions including the spatial and temporal variation in the quantity and quality of food resources, predation or disturbance risks, and inter-and intraspecific competition. Indeed, some of the most commonly employed ecological theories used to describe how animals choose foraging sites are: nutrient intake maximisation, density-dependent habitat selection, central-place foraging, and predation risk effects. Even though these theories are not mutually exclusive, rarely are multiple theoretical models considered concomitantly to assess which theory, or combination thereof, best predicts observed changes in habitat selection over space and time. Here, we tested which of the above theories best-predicted habitat selection of Svalbard-breeding pink-footed geese at their main spring migration stopover site in mid-Norway by computing a series of resource selection functions (RSFs) and their predictive ability (k-fold cross validation scores). At this stopover site geese fuel intensively as a preparation for breeding and further migration. We found that the predation risk model and a combination of the density-dependent and central-place foraging models best-predicted habitat selection during stopover as geese selected for larger fields where predation risk is typically lower and selection for foraging sites changed as a function of both distance to the roost site (i.e. central-place) and changes in local density. In contrast to many other studies, the nutritional value of the available food resources did not appear to be a major limiting factor as geese used different food resources proportional to their availability. Our study shows that in an agricultural landscape where nutritional value of food resources is homogeneously high and resource availability changes rapidly; foraging behaviour of geese is largely a tradeoff between fast refuelling and disturbance/predator avoidance.Publisher PDFPeer reviewe

Health promotion in primary and secondary schools in Denmark:time trends and associations with schools' and students' characteristics

BACKGROUND: Schools are important arenas for interventions among children as health promoting initiatives in childhood is expected to have substantial influence on health and well-being in adulthood. In countries with compulsory school attention, all children could potentially benefit from health promotion at the school level regardless of socioeconomic status or other background factors. The first aim was to elucidate time trends in the number and types of school health promoting activities by describing the number and type of health promoting activities in primary and secondary schools in Denmark. The second aim was to investigate which characteristics of schools and students that are associated with participation in many (≥3) versus few (0–2) health promoting activities during the preceding 2–3 years. METHODS: We used cross-sectional data from the 2006- and 2010-survey of the Health Behaviour in School-aged Children study. The headmasters answered questions about the school’s participation in health promoting activities and about school size, proportion of ethnic minorities, school facilities available for health promoting activities, competing problems and resources at the school and in the neighborhood. Students provided information about their health-related behavior and exposure to bullying which was aggregated to the school level. A total of 74 schools were available for analyses in 2006 and 69 in 2010. We used chi-square test, t-test, and binary logistic regression to analyze time trends and differences between schools engaging in many versus few health promoting activities. RESULTS: The percentage of schools participating in ≥3 health promoting activities was 63% in 2006 and 61% in 2010. Also the mean number of health promoting activities was similar (3.14 vs. 3.07). The activities most frequently targeted physical activity (73% and 85%) and bullying (78% and 67%). Schools’ participation in anti-smoking activities was significantly higher in 2006 compared with 2010 (46% vs. 29%). None of the investigated variables were associated with schools’ participation in health promoting activities. CONCLUSION: In a Danish context, schools’ participation in health promotion was rather stable from 2006 to 2010 and unrelated to the measured characteristics of the schools and their students

Does the Association between Workplace Bullying and Post-Traumatic Stress Symptoms differ across Educational Groups?

The aim of this study was to investigate whether the level of reported post-traumatic stress (PTSD) symptoms among targets of workplace bullying differ depending on their educational level. Exposure to workplace bullying was assessed by the behavioural experience method and the self-labelling method among 563 Danish employees. PTSD symptoms were assessed by the Impact of Event Scale – Revised. Educational level was measured as years of education. The results showed that workplace bullying was significantly associated with the reporting of PTSD symptoms. However, PTSD symptoms were not reported differently among those with experience of work-place bullying. Implementing bullying policies is an important step in promoting a healthy psychosocial working environment. All targets of workplace bullying would benefit from interventions aiming to reduce progression of PTSD symptoms

Den danske grænsekontrol fra et tysk perspektiv: En sproglig analyse af, hvordan grænsekontrolsagen blev vinklet i den tyske avis Die Welt

Anne Grethe Julius Pedersen and Dorthe Nabe Nielsen Den danske grænsekontrol fra et tysk perspektiv En sproglig analyse af, hvordan grænsekontrolsagen blev vinklet i den tyske avis Die Welt (Danish border control from a German perspective A linguistic analysis of how the case of border control was journalistically angled in the German newspaper Die Welt). I 2011 the then Danish government had introduced border control at the border to Germany. This article analyses how the case was treated in four copies of the German newspaper Die Welt. The aim of the article is to uncover how the case and its consequences were journalistically treated from a German perspective, and it asks and seeks to answer three questions about which aspects of the case got prominence, what arguments against the border control were stated and how was the relationship between Germany, Denmark and Schleswig-Holstein depicted. The article employs a textual and linguistic interpretative approach