337,718 research outputs found
Living on the edge : Roe deer (Capreolus capreolus) density in the margins of Its geographical range
No full textOver the last decades roe deer (Capreolus capreolus) populations have increased in number and distribution throughout Europe. Such increases have profound impacts on ecosystems, both positive and negative. Therefore monitoring roe deer populations is essential for the appropriate management of this species, in order to achieve a balance between conservation and mitigation of the negative impacts. Despite being required for an effective management plan, the study of roe deer ecology in Portugal is at an early stage, and hence there is still a complete lack of knowledge of roe deer density within its known range. Distance sampling of pellet groups coupled with production and decay rates for pellet groups provided density estimates for roe deer in northeastern Portugal (Lombada National Hunting Area - LNHA, Serra de Montesinho – SM and Serra da Nogueira – SN; LNHA and SM located in Montesinho Natural Park). The estimated roe deer density using a stratified detection function was 1.23/100 ha for LNHA, 4.87/100 ha for SM and 4.25/100 ha in SN, with 95% confidence intervals (CI) of 0.68 to 2.21, 3.08 to 7.71 and 2.25 to 8.03, respectively. For the entire area, the estimated density was about 3.51/100 ha (95% CI - 2.26–5.45). This method can provide estimates of roe deer density, which will ultimately support management decisions. However, effective monitoring should be based on long-term studies that are able to detect population fluctuations. This study represents the initial phase of roe deer monitoring at the edge of its European range and intends to fill the gap in this species ecology, as the gathering of similar data over a number of years will provide the basis for stronger inferences. Monitoring should be continued, although the study area should be increased to evaluate the accuracy of estimates and assess the impact of management actions.Peer reviewe
Habitat Selection and Risk of Predation: Re-colonization by Lynx had Limited Impact on Habitat Selection by Roe Deer
No full textRisk of predation is an evolutionary force that affects behaviors of virtually all animals. In this study, we examined how habitat selection by roe deer was affected by risk of predation by Eurasian lynx - the main predator of roe deer in Scandinavia. Specifically, we compared how habitat selection by roe deer varied (1) before and after lynx re-established in the study area and (2) in relation to habitat-specific risk of predation by lynx. All analyses were conducted at the spatial and temporal scales of home ranges and seasons. We did not find any evidence that roe deer avoided habitats in which the risk of predation by lynx was greatest and information-theoretic model selection showed that re-colonization by lynx had limited impact on habitat selection by roe deer despite lynx predation causing 65% of known mortalities after lynx re-colonized the area. Instead we found that habitat selection decreased when habitat availability increased for 2 of 5 habitat types (a pattern referred to as functional response in habitat selection). Limited impact of re-colonization by lynx on habitat selection by roe deer in this study differs from elk in North America altering both daily and seasonal patterns in habitat selection at the spatial scales of habitat patches and home ranges when wolves were reintroduced to Yellowstone National Park. Our study thus provides further evidence of the complexity by which animals respond to risk of predation and suggest that it may vary between ecosystems and predator-prey constellations
The performance of farm animal assessment
No full textThis paper argues that the current drive towards greater use of animal-based measures for welfare assessment raises important issues for how farm visits by welfare assessors are performed. As social scientists, we employ a number of contemporary social science ideas to offer a new approach to examining the practice and performance of farm animal assessment. We identify key findings from a recent study of contemporary farm assessment and speculate upon what some of the challenges of introducing animal-based measures may be. We conclude by arguing for a greater awareness of how sets of knowledge are made, circulated, practiced and become an integral component of the procedures, practices and discourses around farm animal welfare assessment in farm assuranc
Partial migration in roe deer
No full textWe studied partial migrations in the European roe deer (Capreolus capreolus), a species particularly suited for such a study, due to a wide distribution range and a high level of ecological plasticity and adaptation to human-induced environmental changes. We undertook a comparative analysis of a set of representative and contrasting European ecosystems (boreal, boreo-nemoral, alpine, central European and sub-Mediterranean), using a dataset of about 100 individuals tracked for at least 1 year, using GPS collars. One of the main finding was the relevance of intermediate migratory behaviour, i.e. many animals performed numerous trips back and forth between winter and summer areas before taking a final decision and stabilize their range. The migration process resulted highly inter- and intra-individually variable, where the “classic” partial migration alternatives (residents and sharp migrants) were only the extremes of a highly complex behavioural gradient. The probability of adopting a migratory strategy, and sharp migrations in particular, depended on modulation by external factors, and in particular by the presence of snow, and on costs of displacement. The behavioural migratory gradient seemed therefore an expression of ecological plasticity and quick adaptation to climatic variation. However, migration patterns differed a lot between males and females, providing evidence that sex-specific adaptations also play a role in shaping the movement tactics of roe dee
EURODEER: a tool for integrating roe deer data at the biogeographic scale
No full textGPS collars represent a powerful tool for roe deer monitoring in terms of quantity and precision of
locations, independence of fixes from operator bias, survey schedule flexibility and continuity. Location data can be joined to environmental or climatic information, thus stimulating advanced analyses at the ecosystem level. This perspective is particularly intriguing when datasets from different regions are put together to investigate variation in roe deer behavioural ecology along
environmental gradients or population responses to specific conditions, such as habitat changes, impact of human activities, different hunting regimes etc. However, there is one drawback, since GPS tracking routinely generates larger data sets than data-management tools commonly used by biologists can presently handle. Similar considerations apply also to other large datasets than GPS
data, e.g. long time series of VHF data or activity data. Spatial data, such as animal locations, were traditionally stored in flat local files, accessible by a single user at a time and analysed by a number of independent applications without any common standards for interoperability. The availability of appropriate software would provide researchers and decision makers with opportunities to take full advantage of the richness of GPS data or long time series of VHF and activity data, allowing to work in a multi-user environment. EURODEER (EUropean ROe DEER Information System) is an
information system with a spatial database at its core and several client applications to help storing, managing, accessing and analysing GPS data from several research groups throughout Europe. In this paper, we exemplify its structure and underline its utility and potentiality to address general questions on biology and ecology of European roe deer at biogeographic scale. In particular, roe deer GPS data from six research groups are being stored in it, obtaining a dataset of several hundred
thousand locations from more than hundred individuals, both females and males, monitored for at least one year. As a pilot study, we analysed seasonal and circadian movement patterns of individuals throughout the study areas, to assess how universal some aspects of spatial behaviour are, including increased activity at twilight or female excursions during the rut
Monitoring roe deer populations in the Alps: the pellet group count with distance sampling approach
No full textRoe deer population size has traditionally represented a difficult task for population ecologists, due to the preference of wood and elusive behaviour of the species. The Alpine habitat, characterised by patchiness and a poorly accessible terrain, may even enhance the difficulties. In this paper, we assessed the feasibility and efficacy of pellet group count with distance sampling as opposed to censusing methods commonly applied in game management (e.g. drives, spot counts, block censuses). The study was conducted in a 9500ha area (Monte Bondone, Trento Province, Italy) where a sample of the roe deer population was tracked by means of GPS-telemetry. Systematic grids of line transects were randomly over imposed to the study area and sampled in 2006, both in spring (winter density) and autumn (summer density), for a total survey length of 43200m and 216 transects. From October 2005 to October 2006, we carried out and experimental assessment of pellet group decay rate, placing fresh samples in different habitats and analysing monthly disappearance rates by logistic regression. In autumn, we carried out thermal imaging distance sampling and mark-resight observations in a portion of the study area. Mean monthly time to decay was mainly influenced by habitat, slope and weather condition at deposition, particularly snow cover in winter months. In spring, pellet group encounter rate was higher than in autumn (0.020 pellet groups/m and 0.009 pellet groups/m, respectively), which led to a lower %CV of pellet group density estimate (13% and 26% respectively). This corresponded to a longer time to decay in spring than in autumn (242.9 days and 57.2 days respectively) and to halved roe deer density values (2.5 deer/100ha and 5.5deer/100ha respectively). However, the disproportion between the decrease of encounter rate and time to decay between the two seasons (2 fold vs 4 fold), is likely due to a high variability of the spring mean times to decay, which may have led to biased spring density values. In autumn, pellet group count density was comparable to thermal imaging distance sampling and mark-resight estimates and consistent with hunting data. Therefore, density estimates proved more robust when pellet groups decayed in a short time, comparable to the length of the sampling period.
Pellet group count with distance sampling seemed to encompass randomness, replicability and possibility to control a priori the threshold precision/effort. However, if routinely used, a continuous monitoring of decay rate is strongly suggested
Distance Sampling and Thermal Immaging to assess a roe deer population in Northern Appennines: the pros and cons of a fashionable technique.
No full textThe recent development of Oistance Sampling techniques (OS) has provided a promising device to
yield good population estimates with samples of small size (40-80 independent detections) with reasonable
survey costs. On this subject, during the past Roe deer Meeting (Portugal) were presented
interesting results suggesting that OS coupled with thermal imaging (IR) could be a suitable and costeffective
monitoring methodology.
We present the results of a 3-year project devoted to compare density estimates from OS & IR with
more conventional Mark Recapture (MR) estimates of an Appennines roe deer population. We worked
in an open hunting estate, where a long-term study on roe deer ecology includes radio-monitoring
and densities assessment since 1995. We tested the possibility to survey roe deer using a portable
thermo-camera, equipped with a laser rangefinder and an electronic compass, which allows the operator
to record ani mais presence (group size and number of groups) also in completely dark night
and to measure their distance and angle with respect to the observer. We walked 35 transects (total
effort 20.5 km) in 3 nights, from 7:00 PM to 5:00 AM, to survey an area of 523 ha. We made 2 survey
replicates each year (late winter/early spring) to compare the results with estimates of early spring
survey calculated by MR methods.
Night survey is thought to mitigate the problem of g(O) < 1 (which affect daylight ones when animals
f1y away reacting to the presence of an observer) because the use of an IR camera is supposed to
allow the detection of deer before being discovered. However, IR & OS survey design could be
biased because observers are forced to use paths and so transect positioning may not be random
with respect to ani mais distribution. We present an a posteriori evaluation of the survey design and
we compare the 2 survey methods in order to assess the presence of biases in IR & OS
Oral history interview with A. G. Roe
No full textA.G. Roe discusses his life in South Dakota in the early 1900's. Topics include his family and personal background, the Depression, the Farm Bureau, the campaign to make a tuberculosis test for cattle mandatory, campaigning for Sigrund Anderson for South Dakota governor, the Canton Indian Insane Asylum, the ski jump at Canton, South Dakota, and Augustana Academy
Abomasal helmithofauna of roe deer (Capreolus capreolus capreolus) in the Julian Prealps and the anatomopathological aspects associated
No full textRoe deer is a great importance species in relation to wildlife management. Ecoparasitological analyses show that the abomasal parasitic burden and host body condition are closely related, but no information there is on tissue damage induced by abomasal helminthofauna.
Fifty-one roe deer shot during period 2004-2007 and coming from game reserves of Julian Prealps, were investigated for the presence of abomasal nematodes. Each abomasum was opened along the Curvatura major and the content was collected for parasitological exams. After photograph and macroscopic evaluation, abomasal standard samples (n. subjects 47) were collected for anatomopathological analysis. The helminth prevalence (P), mean intensity (MI), abundance (A), relative abundance (RA) of each parasite species were calculated.
Fifteen helminth species (as average 6 species/animal) were recovered in roe deer population: Teledorsagia circumcincta, T. davtiani, Spiculopteragia spiculoptera, S. mathevossiani, Ostertagia lyrata, O. trifurcata, O. leptospicularis, O. kolchida, O. ostertagi, Heamonchus contortus, Tricostrongylus capricola, T. vitrinus, T. colubriformis, T. axei, Nematodirus europeaus. S. spiculoptera (P= 100; A=286; RA=27.3) and O. leptospicularis (P=100; A=273; RA=26), associated to their alternative morphs S. mathevossiani (P=70.6; A=38; RA=3.6) and O. kolchida (P=88.2; A=87; RA=8.3), were the abomasal dominant species. Therefore, species composition was typical of this wild ruminant host in Europe. Between generalist species, H. contortus shows also a high prevalence and abundance (P=74.5; A=294; RA=28).
All the abomasums show histological defensive lesions of variable intensity. Attributing the single identified species to the anatomopathological patterns based on the abomasal multiparassitism in not simple. However the main epidemiological index applied to the different abomasitis forms will be discussed
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