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Reindeer Rangifer tarandus tarandus husbandry in Sweden commonly uses the Scandinavian mountain chain as grazing area during the snow-free season and the coniferous forests in the east during winter. Current knowledge of habitat use by reindeer is primarily based on traditional or local knowledge, or on investigations carried out on wild reindeer and caribou in other parts of the world. We identified spatial and temporal habitat use of free-ranging semi-domesticated reindeer by following 48 GPS-equipped reindeer in three summer ranges in the Swedish reindeer herding area. The GPS equipment registered positions every hour or every second hour, during two snow-free seasons. The GPS-collared reindeer were randomly chosen from herds with several thousand animals. Estimated home-range utilisation distributions were used to fit resource utilisation functions (RUFs) including various topographical features, vegetation types, and the vicinity to water and hiking trails. The GPS-equipped reindeer used different parts of the range throughout the snow-free season. Preferred vegetation types were consistently meadows, grass heaths, and other heaths. Avoided vegetation types were all types of forests, sparsely vegetated areas, and bare rocks. The reindeer were seemingly indifferent to hiking trails within their home ranges, which, however, usually coincided with preferred vegetation types, but they avoided areas with houses and holiday huts during early summer. Later in the season, the reindeer preferred higher elevated areas where human constructions were sparse. The home ranges of the GPS-equipped reindeer overlapped considerably during early parts of the season, indicating a dense use of the range by the entire herds. Crowding within the herds appeared to make individual reindeer select non-optimal habitats. However, in our study, we found a non-significant tendency of less predictable individual home ranges when there were large range overlaps. Vegetation types, direction of slopes, time within the season and the possibilities of avoiding insect harassment appear to be key factors for predicting valuable reindeer habitats in novel areas in a land management context.
We studied survival and probable causes of mortality for plains sharp-tailed grouse Tympanuchus phasianellus jamesi chicks up to 30 days of age, and for hens during the reproductive period in Alberta, Canada, during 1999-2001. We used the Kaplan-Meier function for estimating survival for >1 radio-marked chick in the same brood and a bootstrapping technique to calculate standard errors while accounting for censored data. Chick survival was 47% over two years (95% CI: 29-64%) with 81% of mortalities occurring during the first 15 days. Predation accounted for 72% of chick mortalities with mammals taking the largest portion. Chick survival was similar when compared between landscapes with <35% vs ≥35% crop and sparsely covered grassland (8 km2). Hen survival was 53% (95% CI: 44-63%) during the reproductive period over three years. Most hen mortalities were from predation (96%), with mammals accounting for the largest portion followed by raptors. Hen survival was similar in landscapes (8 km2) with <35% crop and sparsely covered grasslands compared with those in areas with ≥35%. Our study helps clarify values of two critical vital rates, i.e. early chick survival and hen survival over the reproductive period.
The quality of released individuals can have a significant impact on the success of reintroduction projects. We tested which of the following release techniques resulted in the highest survival of released grey partridges Perdix perdix in Switzerland : 1) translocation of wild adult birds, 2) release of captive parent-reared adults as family groups, and 3) fostering of captive parent-reared chicks to wild barren pairs. Wild hatched offspring (F1 birds) from our re-established breeding pairs served as the control group. We used a multi-state capture-recapture model to estimate monthly survival rates from the data based on monitoring of radio-tagged individuals and reobservation and recovery of ringed individuals. Survival tended to be highest in wild-hatched partridges of the founder population (mean±SE; 0.90±0.03), followed by that of fostered chicks (0.86±0.03) and translocated adult wild birds (0.82±0.06). While survival of these groups was not statistically different from each other, survival of captive-reared adults was significantly lower (0.70±0.06). We discuss the implication of our results for further partridge reintroduction projects.
The Eurasian woodcock Scolopax rusticola is a popular game bird in much of Europe. However, little is known about its population dynamics. We estimated winter survival of woodcock in a protected area with no hunting in central Italy. We radio-tagged 68 woodcocks with battery-powered radio-transmitters during 2001-2005. Woodcocks were captured in fields at night from November through February and fitted with radios. Birds were classified on capture as juveniles or adults using plumage characteristics. Woodcocks were relocated daily through March of each year or until they died, disappeared from the study area, or until their radio failed. We constructed a set of eight competing models of daily survival for the period 1 December - 28 February. Estimates of survival were obtained using the program SURVIV and Akaike's Information Criteria. The best model suggested daily survival was a constant 0.9985 (95% CI=0.9972-0.9998), corresponding to a survival rate of 0.88 (SE=0.05) for the 90-day winter study period. Our estimate of juvenile survival is higher than previously reported, and may reflect the protected status of the study area. Our estimates of winter survival may be helpful in managing harvested woodcock populations as well as in conserving populations in an increasingly urbanised environment.
Over the last decades, wolf Canis lupus predation in northern Spain has focused on wild ungulates, even though livestock and other prey, such as other carnivores and small mammals, and garbage have been available. During 1994 and 1995, we studied the impact of wolf predation on wild boar Sus scrofa in four study areas in Asturias, Spain. The diet of the wolf was assessed by scat collection and analysis (N = 106, 329, 372 and 649, respectively). The mortality of wild boar was deduced from density estimates and hunting records from the Nature Reserve of Somiedo. Wild boar represented 3-31% of the biomass of food found in the wolf scats in the study areas. We estimated that 75% of wild boars eaten were piglets. The wild boar mortality rate was estimated at 38% (146 dead individuals out of 385). Wolf predation was estimated to cause 12% of the mortality of wild boar and to affect 4.5% of the wild boar population. Hunting had a higher importance as a mortality factor than wolf predation (31 and 12%, respectively). Even though, a two-year study is insufficient to come to a final conclusion, our results suggest that wolf predation may have a low impact on young wild boar and that a hunting pressure of the size we found is unlikely to control the wild boar population.
We explored limits and consequences of male-biased harvesting of polar bears Ursus maritimus using a simulated population based on empirically-derived estimates of age-specific rates of survival and reproduction. The maximum sustainable yield (MSY) was identified as the total kill in which the number of females that could be taken resulted in ≤5% change in females older than 50 years. MSY depended on the proportion of males in the harvest, although the effect of male selection on the post-harvest population was to reduce the mean age and number of males. A practical limit to the increase in MSY possible from male-selective harvesting was identified at the 3 : 1 (M/F) sex ratio. At 3 : 1 (M/F), all males were eventually harvested as 2-year olds, and males were reduced to 25% of pre-harvest levels. A more conservative harvest strategy of 2 : 1 (M/F) resulted in a 30% reduction of males and a reduction of the mean age of males from 10.0 to 7.7 years post-harvest. We thus recommend that sex-selective harvesting of polar bears do not exceed 67% males (i.e. a harvest ratio of 2 : 1), a demonstrably safe and sustainable harvest strategy, to avoid depletion of males and possibly reduce recruitment by having too few sexually mature males in the population. When females are harvested below MSY, then harvest strategies that select for males at rates > 2 : 1 (M/F) can be conservative because the increase in females also increases the reproductive performance of the population. In the absence of information on density effects, managers should be conservative in their expectations of increases in the female population.
Many researchers use bridges as search sites to monitor freshwater otter species along watercourses. Bridges enable rapid and easy access to their habitat, but for most otter species little is known on whether these anthropogenic structures affect their distribution, their marking preferences, and consequently, the ability of such surveys to detect their presence. We investigated the bridge survey method using data gathered during four winters of survey along the rivers and streams of Kouchibouguac National Park and surrounding area in New Brunswick, Canada. Our results show that sign surveys using bridges as search sites can have the same capability to detect river otter Lontra canadensis occurrences as surveys using randomly distributed sites. Future surveys can be improved by increasing search distance at bridge sites. This will increase detection rates and safeguard against results underrepresenting otter occurrence in the landscape, which could prompt unnecessary conservation actions. Researchers choosing to increase search distance are advised to augment survey efforts in order to maintain large sample sizes, ensuring sufficient statistical power for tests aiming to detect trends in river otter occurrence.
We related annual and seasonal survival of four populations of elk Cervus elaphus in the Pacific Northwest, USA, to measures and indices of individual nutritional condition. Among populations, for all mortality (human and non-human causes) sources inclusive, annual survival of adult females was correlated with a rump body condition score (rs = 0.627, P = 0.071), and survival over spring-summer-autumn (SSA) was correlated with mean ingesta-free body fat (IFBF; rs = 0.567, P = 0.088) and rump body condition score (rBCS; rs = 0.615, P = 0.050). For non-human mortality sources only, survival through SSA was correlated with IFBF (rs = 0.567, P = 0.088) and rBCS (rs = 0.615, P = 0.050), and survival over winter was correlated with withers body condition score (rs = 0.677, P = 0.045). For human-caused mortality sources only, survival over SSA was correlated with rBCS (rs = 0.696, P = 0.036) and IFBF (rs = 0.696, P = 0.036). For individuals, logistic analysis found that individual likelihood of dying from all mortality sources inclusive was best predicted (χ2 = 8.3, P = 0.004, β = −1.24) by longissimus dorsi (loin) muscle thickness, a measure of protein catabolism. For only non-human mortality sources, a model (χ2=16.1, P = 0.0003) containing both loin muscle thickness (χ2 = 5.7, P = 0.017, β = −1.02) and percent ingesta-free body fat (χ2 = 4.9, P = 0.027, β = −0.35) best predicted individual susceptibility to mortality. Odds ratios indicated that odds of dying increased approximately 3X for each centimeter of loin muscle catabolized and 1.4X for each percent less body fat. No condition indices at the individual level were related to survival from human-caused mortality sources. Our study populations were characterized by low-marginal condition (i.e. mean ingesta-free body fat levels of 5.9-12.3% for lactating cows in late autumn); this likely increased the prominence of measures of muscle catabolism relative to fat accretion in influencing individual elk survival. Elk populations throughout the Pacific Northwest likely show similar condition levels, and consequently individuals are predisposed to mortality to a much greater degree than under optimal foraging conditions. Management strategies which assume that nutritional condition affects vulnerability only at or near condition levels associated with ecological carrying capacity (i.e. near starvation mortality) may overestimate the impact of proximate mortality factors on adult female elk.
Red deer Cervus elaphus, even in wilderness areas, are increasingly exposed to disturbance from human recreation as well as hunting, and it has been suggested that both types of disturbance may be perceived as a predation risk. We studied the vigilance behaviour of red deer in the Scottish Highlands, in sites with traditionally high numbers of visitors (‘disturbed’) and sites with relatively few visitors (‘less-disturbed’) during the main recreational season (spring and summer), and in their mating grounds during the hunting season (autumn and winter). We carried out direct observations, using scan sampling at 3-minute intervals for 1-hour periods, and recorded the number of animals in each group that were vigilant and their mode of vigilance. During the recreational season, in both the disturbed and less-disturbed sites, data were collected in habitats with different levels of cover (grassland, heather and woodland). The percentage of animals that were vigilant was higher in disturbed than in less-disturbed sites, and higher in disturbed grassland (poor cover) and heather (intermediate cover) than in disturbed woodland (good cover). The majority of the vigilant animals in disturbed heather and woodland habitats and in all the less-disturbed habitats were standing. In disturbed grassland, however, lying was the main posture whilst vigilant. In both disturbed grassland and heather, the percentage of vigilant animals that were moving was higher than in woodland or the less-disturbed habitats. In disturbed sites, the deer were more likely to be aggregated when vigilance levels were high. During the hunting season, the overall level of vigilance was higher than at any sites during the recreational season, and the majority of vigilant animals were moving. We conclude that red deer respond to disturbance from human recreational activities by increasing their level of vigilance, but that the nature of their response varies with the level of cover available. We suggest that red deer may lie down when keeping vigil in grasslands, because lying animals are less conspicuous and the low cover will still allow animals to scan their surroundings. We conclude that, although they respond to both types of disturbance by increasing vigilance, red deer perceive human recreation as a less acute threat than hunting.
Habitat use and separation in relation to human disturbance of two sympatric species, red deer Cervus elaphus xanthopygus and roe deer Capreolus pygargus bedfordi, were studied in the Wandashan Mountains, Heilongjiang Province, China. We measured 19 variables describing macrohabitat (e.g. distance to roads or forest type) and microhabitat (e.g. escape cover or snow depth) characteristics at each plot where red or roe deer occurred. Statistical analysis of macrohabitat characteristics for the two deer species identified a statistically significant difference in the distance to human disturbances, especially settlements, for sites utilised by red deer and roe deer. Despite range overlaps between red deer and roe deer in the study area, each species exhibited different patterns in microhabitat use. The two deer species do not seem to be impacted to the same degree by human disturbance. Red deer occurred at sites characterised by mature mixed coniferous and broadleaf stands, at higher elevations, and deeper snow cover. Additionally, red deer occurred at sites further from human settlement, cropland or logged areas than did roe deer. Conversely, roe deer occurred at sites with sparse forest cover and denser shrub cover, at lower altitudes, with less snow, and more abundant food of common plant species eaten by both deer. Overall, roe deer seemed to cope with human disturbance near settlements better than red deer. We suggest that human disturbance may be important in determining both species' utilisation of resources and thus may contribute to the observed patterns of red and roe deer habitat separation. Moreover, understanding any differential effects of human disturbance on the two species may contribute to understanding the population dynamics of these two species as human disturbance in China is expected to continue increasing.
In this study, we compared kernel estimates of home-range size between VHF and GPS monitoring. We used three types of data to assess the monthly estimates of individual home-range size (VHF data based on 17 locations, subsampled GPS data based on 17 locations (with 1,000 replicates) and GPS data based on 720 locations) using three estimation methods for the smoothing parameter, h (reference, least-squares cross-validation (LSCV) and fix). For all the three smoothing parameters, individual home ranges estimated from VHF and GPS data using 17 locations had very similar size. On the other hand, the use of reference or LSCV h values led home-range sizes from VHF or GPS data using 17 locations to be larger than the estimate obtained from the whole set of GPS data (720 locations). Such results emphasise the influence of using too few locations per month. On the contrary, using h fixed at 60 led to a home-range size close to that obtained from the whole set of GPS locations. The centroid of locations for a given individual in a given month only changed a little according to the data set used (the difference being <100 m), suggesting a high accuracy for our locations. VHF and GPS areas can therefore be pooled within the same analysis of habitat use, provided that the smoothing parameter and the number of locations are standardised.
Use of exclusion fencing is an effective method to reduce moose-vehicle collisions, and exclusion fences are commonly erected along Swedish highways. However, exclusion fences may pose a threat to the viability of wildlife populations because they serve as barriers to individual movements and may limit accessibility to resources. Various types of wildlife crossings intended to reduce road-kills and increase habitat connectivity across fenced highways have been constructed throughout the world. However, few studies have evaluated the effectiveness of these crossing structures with respect to movements before, during and after construction of highways and exclusion fencing. We studied movements of 24 GPS-collared moose Alces alces before, during and after an existing two-lane road was reconstructed to a fenced four-lane highway with three wildlife crossings designed for moose. We recorded 135 movements across the highway during 8,830 moose-monitoring days. Of these, 47 occurred before the construction began, 76 occurred during the construction, and 12 occurred after the highway was fenced. All movements registered after the fencing occurred across two of the three wildlife crossings. The average number of highway crossings per moose-day decreased by 67-89% after fencing. The number of moose-vehicle collisions decreased after the exclusion fencing, but the fenced highway served as a barrier to moose movements even though three wildlife crossings were created. Thus, exclusion fencing may reduce moose mortality and provide safer conditions for automobile travellers, but the fencing may have a negative impact on moose accessibility to resources, gene flow and recolonisation rates.
Infectious keratoconjunctivitis (IKC) is worldwide known as a common infection by Mycoplasma conjunctivae affecting the eyes of domestic sheep and goats where it generally leads to moderate symptoms known as ‘pink eye’. IKC also occurs in severe outbreaks in free-ranging alpine chamois Rupicapra r. rupicapra and alpine ibex Capra i. ibex. It is characterised by grave clinical symptoms resulting in blindness and perforations of the cornea of the affected animals, and finally leads to their death. Transmission of M. conjunctivae from domestic sheep to wild Caprinae has been demonstrated by molecular epidemiological studies of the infectious agent. The relatively high prevalence of M. conjunctivae in sheep populations that share pastures in the Alps with wild Caprinae, in which outbreaks occur infrequently but with high virulence, raised an important question concerning the role of host-specificity of various strains of M. conjunctivae. Investigations on genetic variations of M. conjunctivae strains allowed subtyping of M. conjunctivae isolates using a molecular genetic method that can be directly applied to samples taken by eye swabs. Our studies revealed that sheep with IKC are frequently infected simultaneously with up to four different strains of M. conjunctivae. In contrast, affected chamois only showed infections with a single strain. Furthermore, among the different strains of M. conjunctivae that have been determined until now, 36 strains are repeatedly found in sheep, while only a few different strains, all belonging to a phylogenetically related cluster, were found in chamois with IKC. These few strains were responsible for all severe outbreaks of IKC in chamois during the last four years in Switzerland, Austria and Italy. Our studies indicate that a particular cluster of strains of M. conjunctivae has a host predilection for chamois where they cause severe infections.
This study compares the impact of falconry and shooting in the same area on game and its distribution. We initiated a short-term assessment to test the hypotheses that falconry is more efficient than hunting with guns and that flying with birds of prey results in less game available for the gun. Rates of encountering and killing prey were compared for a hunting party with five goshawks and, one week later, a hunting party with five guns on the same land in Croatia. Encounter rates of game were similar for hunting with hawks (112 game flushed) and with guns (110 game flushed) one week later. However, the kill rate was higher when hunting with guns (40 game killed out of 110 flushed, 36%) than when hunting with goshawks (9 game killed out of 112 flushed, 8%). Our preliminary study thus suggests that falconry can contribute recreational and financial value to local communities as a complement to shooting, because it does not extract a large number of game animals or reduce the number of game animals available to gun-hunters.
The Eurasian woodcock Scolopax rusticola is a sedentary bird in the Azores archipelago, where it is an important game species. In S. Miguel island, hunting has been forbidden for at least two decades, but this measure seems to have failed in its purpose of increasing population size. Our work aims to determine woodcock distribution and relative abundance during the breeding season in S. Miguel, identify the proximate habitat factors related to the species occurrence and evaluate the role of reminiscent natural Azorean forest for the conservation of its populations. We conducted censuses at 71 observation points, systematically distributed along the island using UTM 1 × 1 km grid cells. During the breeding season, male woodcock performs display (roding) flights. Census consisted in recording the number of contacts with roding birds, during the evening roding period. The species was detected in only 30% of the points and its relative abundance was generally low. The species was mainly distributed in the most mountainous regions of the Eastern part of the island. Several habitat variables were measured at each observation point and their relationship with species occurrence was determined with logistic regression. The presence of roding birds was negatively correlated with the distance to natural vegetation and positively correlated with arboreal vegetation surface. The model had a high prediction success (88.9% for presences, 83.3% for absences and 85% overall, for a 0.3 cut-off point) and explained the distribution of the species well. The observed restricted distribution and overall low abundance supports the maintenance of the hunting interdiction. The preference for natural vegetation during the breeding season is an important aspect. Reforestation with endemic species, control of invasive species and the maintenance of forest edges and small patches of vegetation between pastures would contribute to woodcock conservation in the island.
Wolves Canis lupus may naturally achieve densities that contribute to significant changes in prey populations and entire ecosystems. We analyzed a time series of counts, index of recruitment, and estimates of survival for bighorn sheep Ovis canadensis during 1995-2005 to evaluate the prediction that sheep numbers would decrease in the northern portion of Yellowstone National Park, Montana and Wyoming, USA, owing to lower survival and recruitment following wolf reintroduction. The number of wolves residing in the northern range increased from 21 to a maximum of 106 in response to an abundant elk Cervus elaphus population and legal protection. Counts of bighorn sheep decreased following the severe winter of 1997, but then increased by 7% annually during 1998-2005 (95% CI: 2-11%). Recruitment followed a similar temporal pattern, decreasing to 7-11 lambs/100 ewes during the severe winter of 1997 and the following winter, but then increasing to 21-34 lambs/100 ewes during 1998-2005. Annual estimates of survival for 14 adult females and four males 1-3 years old were high (0.94; 95% CI: 0.89-0.97) and indicative of an increasing or constant population. Thus, the presence of wolves did not prevent the bighorn sheep population from increasing slowly during the decade following reintroduction. However, sheep counts remain low compared to the 487 sheep observed before an outbreak of keratoconjunctivitis caused 60% mortality during 1982, suggesting that other factors limited the recovery of this relatively isolated, high-elevation, native sheep population. Increases in abundance and recruitment of bighorn sheep during 1998-2005 were concurrent with a 50% decrease in the numbers of northern Yellowstone elk after wolf reintroduction. Thus, the potential effects of decreased competition for resources between elk and bighorn sheep on lamb recruitment and sheep population growth merit further investigation.
We studied the diets of low-density but increasing populations of sympatric Asian elephants Elephas maximus and greater one-horned rhinoceros Rhinoceros unicornis in the Bardia National Park in lowland Nepal. A microhistological technique based on faecal material was used to estimate the seasonal diet composition of the two megaherbivores. Rhinos ate more grass than browse in all seasons, and their grass/browse ratio was significantly higher than that of elephants. Both species ate more browse in the dry season, with bark constituting an estimated 73% of the elephant diet in the cool part of that season. Diet overlap was high in the resource-rich monsoon season and lower in the resource-poor dry season, indicating partitioning of food between the two species in the period of resource limitation. Both species consumed large amounts of the floodplain grass Saccharum spontaneum, particularly during the monsoon season. As the numbers of both species increase, intraspecific and interspecific competition for S. spontaneum in the limited floodplains is likely to occur. Owing to their higher grass diet and more restricted all-year home ranges within the floodplain habitat complex, rhinos are then expected to be affected more than elephants.
In order to address endangered Florida Key deer Odocoileus virginianus clavium vehicle collisions along a 5.6-km segment of United States Highway 1 (US 1), the Florida Department of Transportation (FDOT) constructed a 2.6-km long system of fencing, deer guards and two underpasses to exclude deer from roadway. The US 1 project was completed in 2002 for the purpose of minimizing Key deer mortality and maintaining deer permeability through the Big Pine Key (BPK) corridor, Florida, USA. We evaluated the potential impact of these modifications to Key deer movements by comparing 1) annual ranges and movements of Key deer pre- (January 1998 - December 2000) and post-construction (February 2003 - January 2004), 2) deer-vehicle collisions on US 1 pre- and post-construction, and 3) underpass use post-construction. Mean female and male annual ranges and core areas did not change (P>0.05) between pre- and post-construction. Deer movements within the US 1 project area were comparable pre- (six of 23 radio-collared deer crossed the corridor) and post-project (four of 16). Key deer-vehicle collisions were reduced by 94% inside the fenced segment. Experimental deer guards and fencing minimized Key deer entry into the project area to eight deer during the first-year resulting in two deer mortalities (one deer-vehicle collision, one severe removal injury). Infrared-triggered camera data indicate that underpass movements increased over time, suggesting that an acclimation period is necessary for highway underpasses to be successful. Collectively, post-project data indicate that highway alterations have not restricted Key deer permeability while minimizing Key deer mortality; however, our study results suggest changes in deer movement patterns within the corridor. We recommend continued monitoring to verify accurate trends in deer use of wildlife underpasses and permeability across fenced areas.
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