Multiple components of environmental change drive populations of breeding waders in seminatural grasslands

Environments are rapidly changing due to climate change, land use, intensive agriculture, and the impact of hunting on predator populations. Here, we analyzed longterm data recorded during 1928–2014 on the size of breeding populations of waders at two large nature reserves in Denmark, Vejlerne and Tipperne, to determine the effects of components of environmental change on breeding populations of waders. Environmental variables and counts of waders were temporally autocorrelated, and we used generalized least square (GLS) by incorporating the first-order autoregressive correlation structure in the analyses. We attempted to predict the abundance of waders for short-term trends for two nature reserves (35 years) and for long-term trends for one nature reserve (86 years), using precipitation, temperature, nutrients, abundance of foxes Vulpes vulpes, area grazed, and number of cattle. There was evidence of impacts of nutrients, climate (long-term changes in temperature and precipitation), grazing, mowing, and predation on bird populations. We used standard random effects meta-analyses weighted by (N–3) to quantify these mean effects. There was no significant difference in effect size among species, while mean effect size differed consistently among environmental factors, and the interaction between effect size for species and environmental factors was also significant. Thus, environmental factors affected the different species differently. Mean effect size was the largest at +0.20 for rain, +0.11 for temperature, −0.09 for fox abundance, and −0.03 for number of cattle, while there was no significant mean effect for fertilizer, area grazed, and year. Effect sizes for two short-term time series from Tipperne and Vejlerne were positively correlated as were effect sizes for short-term and long-term time series at Tipperne. This implies that environmental factors had consistent effects across large temporal and spatial scales

Long-term patterns in European brown hare population dynamics in Denmark: effects of agriculture, predation and climate

BACKGROUND: In Denmark and many other European countries, harvest records suggest a marked decline in European brown hare numbers, a decline often attributed to the agricultural practice. In the present study, we analyse the association between agricultural land-use, predator abundance and winter severity on the number of European brown hares harvested in Denmark in the years 1955 through 2000. RESULTS: Winter cereals had a significant negative association with European brown hare numbers. In contrast to this, root crop area was positively related to their numbers. Remaining crop categories were not significantly associated with the European brown hare numbers, though grass out of rotation tended to be positively related. The areas of root crop production and of grass out of rotation have been reduced by approximately 80% and 50%, respectively, while the area of winter cereals has increased markedly (>70%). However, European brown hare numbers were primarily negatively associated with the number of red fox. Finally, we also found a positive association between mild winters and European brown hare numbers. CONCLUSION: The decline of Danish European brown hare populations can mainly be attributed to predation by red fox, but the development in agricultural land-use during the last 45 years have also affected the European brown hare numbers negatively. Additionally, though mild winters were beneficial to European brown hares, the increasing frequency of mild winters during the study period was insufficient to reverse the negative population trend

Quantitative planar and volumetric cardiac measurements using 64 mdct and 3t mri vs. Standard 2d and m-mode echocardiography: does anesthetic protocol matter?

Cross‐sectional imaging of the heart utilizing computed tomography and magnetic resonance imaging (MRI) has been shown to be superior for the evaluation of cardiac morphology and systolic function in humans compared to echocardiography. The purpose of this prospective study was to test the effects of two different anesthetic protocols on cardiac measurements in 10 healthy beagle dogs using 64‐multidetector row computed tomographic angiography (64‐MDCTA), 3T magnetic resonance (MRI) and standard awake echocardiography. Both anesthetic protocols used propofol for induction and isoflourane for anesthetic maintenance. In addition, protocol A used midazolam/fentanyl and protocol B used dexmedetomedine as premedication and constant rate infusion during the procedure. Significant elevations in systolic and mean blood pressure were present when using protocol B. There was overall good agreement between the variables of cardiac size and systolic function generated from the MDCTA and MRI exams and no significant difference was found when comparing the variables acquired using either anesthetic protocol within each modality. Systolic function variables generated using 64‐MDCTA and 3T MRI were only able to predict the left ventricular end diastolic volume as measured during awake echocardiogram when using protocol B and 64‐MDCTA. For all other systolic function variables, prediction of awake echocardiographic results was not possible (P = 1). Planar variables acquired using MDCTA or MRI did not allow prediction of the corresponding measurements generated using echocardiography in the awake patients (P = 1). Future studies are needed to validate this approach in a more varied population and clinically affected dogs