Factors affecting the seasonal distribution of red deer (Cervus elaphus) at Glen Dye, north-east Scotland

Part of a red deer herd found on an estate in north-east Scotland in summer spent more time on neighbouring ground during the winter where they damaged farms and woods. Factors associated with the deer's seasonal distribution were studied to help understand how to keep more deer on the estate in winter. There were no indications that food species or food quality were responsible for the observed changes in deer distribution, or that other animals or disturbance influenced distribution over a long period. Deer sought shelter from chilling winds, and areas occupied by deer in winter had more sheltered ground from wind, and the quality of this shelter was higher than on the areas little used. Home-range behaviour and tradition appeared to determine which areas particular deer occupied in winter. The main recommendation for management was to re-open mature woodland to provide more and better shelter on the estate in order to get more control over the deer stock and to reduce marauding.     

Shelter characteristics of mountain hare resting sites

Mountain hares in Scotland live on open tree-less moorland in a harsh winter environment with frequent high winds and drifting snow. By day they rest in forms in tall heather, seats in shorter heather or snow, or scrapes in snow or peat. All these reduce wind speeds by 84-90%, but vary in the degree of shelter and concealment. Forms afford the best concealment and shelter and occur as often on flat ground as elsewhere. Seats and scrapes are commoner on sheltered slopes. They command a wide field of view but offer little concealment. During snow-lie, when forms may be covered, hares move to seats and scrapes, often at the edge of snowfields and gather, sometimes in large groups, on sheltered slopes.     

Windchill influence on thermal conditions in North Patagonia

The occurrence of windy conditions in Patagonia is well known. However there has been little attempt made concerning the wind cooling effect in the area. Because of windchill, equivalent temperatures may be quite different to the actual temperature. In Patagonia, constancy and wind strength determine a yet unexplored bioclimatic factor. This paper deals with windchill and the resulting equivalent temperatures in Puerto Madryn, Chubut, North Patagonia. This location may be considered as having the most favourable thermal conditions south of latitude 42°S, being a sheltered place near the sea-shore. Hourly values of windchill were calculated using Steadman's formula, based on records over 11 years. The results show that, even in such favourable conditions, windchill is an important feature of the Patagonian climate, and is perceived as being cooler than it actually is.     

Thermal constraints and optimization of winter feeding and habitat choice in white-tailed deer

I examined the activity and habitat choice of white-tailed deer in winter to determine how deer balance feeding in habitats which may expose them to cold with resting in sheltered habitats. Average heat gain or loss of deer for feeding, resting and walking in four habitats in each of 24 h were estimated for two winter periods (early-mid and late winter). These values were used in a dynamic optimization model to predict the hourly behavior-habitat choices which enable deer to maintain thermal homeostasis, minimize the risk of exceeding lethal body temperatures and satisfy daily energy requirements. The behavior and habitat choices observed under natural conditions were consistent with the model predictions. Deer foraged for the maximum time that was thermally possible in both sampling periods and they used exposed habitats without incurring high heat losses. Deer appeared to avoid overheating in sheltered habitats during daylight and avoid hypothermia in exposed habitats at night.     

Red deer <Emphasis Type="Italic">Cervus elaphus</Emphasis> resting place characteristics obtained from differential GPS data in a forest habitat

We recorded 30 24-h monitoring periods with 10-min sampling intervals on seven (three female; four male) Global-Positioning-System-collared adult free-ranging red deer (Cervus elaphus), from June 1999 to December 2000, in the Parc National des Cévennes, France. We observed the duration of resting bouts (n = 385) and then microhabitat variables (aspect, slope, presence of edge and litter, visibility, abundance of vegetation consumed or not) at 178 resting places. Resting bouts were shorter during the night than during the day from June to October but did not vary between sexes. Resting place visibility was lower during the day, especially in August. Daytime resting places generally offered more litter. Females used steeper slopes than males. We found higher variability in visibility and slope during the night. Aspect used did not vary from month to month or between day and night. Observed differences between day and night resting place characteristics suggest that red deer were probably facing a tradeoff between feeding and cover. Use of cover prevailed during the daytime whereas night resting place characteristics were more variable, indicating less constrained behaviour. Thus, cover (as a protection from disturbance), as well as food, is an important factor in red deer habitat use (at least during the day in disturbed areas) and should not be neglected in forest carrying capacity management.     

Artificial ground shelters for overwintering phytoseiid mites in orchards

Biological control in orchards strongly depends on winter survival of natural enemies, especially in temperate regions. Predacious phytoseiid mites overwinter on trees or on the ground depending on the characteristics of the species. However, the overwintering ecology of phytoseiid mites on the ground is less well known than that of those on trees. We investigated the usefulness of artificial overwintering shelters as a tool for studying the overwintering ecology of phytoseiid mites on the ground. Four kinds of artificial shelter (shading net, felt, cardboard, and urethane foam) were placed on the ground in an apple orchard in Korea. Two dominant phytoseiid species, Neoseiulus makuwa (Ehara) and N. womersleyi (Schicha) (Acari: Phytoseiidae), overwintered in the artificial ground shelters, and numbers were highest in the urethane foam among the four kinds of shelter, and next highest in the shading net. On the other hand, the numbers of phytoseiid mites collected in the ground vegetation plus soil samples under the ground shelters were not significantly different among the five shelter treatments, including the no-shelter control. Our results suggest that artificial overwintering shelters are efficient tools for investigating overwintering ecology of phytoseiid mites on the ground, as well as on trees, in orchards. Furthermore, the artificial shelters would be good sampling units because they are easily formed into identical sizes and can be used almost anywhere in the field with less laborious work. We also discuss some implications about the effects of sheltered structures on the ground on the populations of phytoseiid mites during winter.     

The ecological significance of resting sites and the seasonal habitat change in polecats (Mustela putorius)

The daytime resting sites of 13 radio-tracked polecats ( Mustela putorius ) were recorded in a mountainous and a lowland study area in Switzerland. Information on breeding sites was collected from questionnaires distributed throughout the country. At all resting sites, the polecats were completely invisible from more than a metre distant. During summer, when polecats mainly live in forests, individuals used many different hiding-places (e.g. small self-dug burrows, woodpiles, heaps of branches and dry leaves, dense vegetation). Such places were used for short periods, and then abandoned. Above ground, the polecats sometimes built nests of dry grass or moss. In winter, the polecats slept mainly inside barns, stables and other buildings. These resting sites were changed less frequently. In rainy weather throughout the year, subterranean places were preferred. Breeding polecats were often found inside houses, and obviously did not avoid human presence.
The importance of different types of resting sites for polecats is discussed. In summer, the quality of a resting place is of less importance than its distance from the foraging area, but in winter, warm resting places are essential and buildings are therefore considered an important resource for polecats in Switzerland. The seasonal habitat change can more readily be explained as a consequence of thermoregulatory problems than of food availability, and the distribution of polecats in Switzerland may be affected by the availability of suitable winter resting places. The northern limit of polecat distribution and its historical changes can be explained by the changing availability of human buildings which provide winter resting sites.     

Spatio-temporal patterns in the mortality of bay scallop recruits in North Carolina: investigation of a life history anomaly

By timing reproduction to occur when predatory mortality on progeny is minimal, organisms may maximize recruitment to adult populations. Accordingly, an hypothesis to explain the greater importance of fall than spring spawning to North Carolina populations of bay scallops (Argopecten irradians) is that predatory mortality of bay scallop recruits is lower in fall and winter than spring and summer. To test this hypothesis, we measured predatory mortality of scallop recruits monthly. To infer the identities of predators that are most important in determining patterns of mortality of bay scallop recruits in spring and in fall, predatory mortality of bay scallop recruits was compared between the edge and interior of sheltered and exposed seagrass patches during the day and at night in May and November. Consideration of predatory mortality throughout the year indicated that mortality of scallop recruits over late spring and summer approaches 100% but is negligible over late fall and winter. In May, predatory mortality of scallop recruits was similar during day and night but greater at exposed than sheltered sites. In November, predatory mortality was greater during night than day and slightly greater at sheltered than exposed sites. In neither month did position within patch influence mortality, and at all times and places, missing and crushed scallops contributed a higher proportion than drilled scallops to the total dead. These spatio-temporal patterns of mortality of scallop recruits suggest that mud crabs, Dyspanopeus sayi, which are more abundant in exposed than sheltered seagrass beds during spring and can feed by day and night, are a likely major contributor to spatio-temporal pattern in mortality of scallop recruits in North Carolina. Blue crabs, Callinectes sapidus, which are many times more abundant in summer than winter, may also contribute to observed seasonal patterns in mortality. The dramatically lower rates of predation on bay scallops over the winter months appear to provide fall settlers with a temporal window of opportunity to recruit to the adult population. Although spring spawning contributes little to adult populations in most years because of high rates of predatory mortality during summer, we hypothesize that spring spawning persists because infrequent devastating perturbations, such as hurricanes and red tides, can result in complete failure of fall recruitment.     

Air movement near windbreaks and a hypothesis of the mechanism of the accumulation of airborne insects

Different components of wind were measured to leeward of artificial windbreaks to show which most affected accumulations of airborne insects there. Horizontal motion was the most important. Accumulations of small airborne insects in sheltered places are probably caused when the insects are diffused or convected into the recirculating air behind barriers. The concentrations likely to occur theoretically in this way were compared with concentrations measured in the field.     

WINTER HABITAT SELECTION BY SITKA BLACK-TAILED DEER

Abstract: Identifying and managing Sitka black-tailed deer (Odocoileus hemionus sitkensis) habitat has been an important wildlife issue for many years on the Tongass National Forest of southeastern Alaska, USA. We evaluated habitat selection of Sitka black-tailed deer in the central portion of the region during a winter with snowfall 43% above average using telemetry relocations from 30 individuals that survived the winter. Ivlev indices for habitat selection within home ranges indicated that deer used less than expected, based on availability, north, east, and west aspects, areas >244-m elevation, noncommercial forests, and the low-timber volume stratum while selecting south aspects, areas <153-m elevation, and areas within 305 m of saltwater. Deer used less than expected moderately coarse-canopied forests in the medium- and high-timber volume strata typically found on north slopes while selecting moderately fine-canopied forest in the high-timber volume stratum on south slopes. The lower than expected use of higher volume gap-phase old growth was likely because these were on north aspects where snow accumulated and persisted due to protection from maritime storms. Point relocations suggested less use than expected in clearcuts <41 years of age, while data from 7.2-ha error polygons showed deer were neutral to clearcuts. This suggests that if deer do avoid clearcuts they remain close to the forest-clearcut edge. Of 4 habitat-mapping methods evaluated, the method that incorporated timber volume strata and a wind disturbance-related aspect had greatest utility in identifying areas selected for or used disproportionately little by deer during the deep snow winter. We found that deer exhibited marked changes in habitat use during deep snow conditions compared to a low snow winter, and we agree with previous researchers that providing habitats selected by deer during deep snowfall is an important consideration in Sitka black-tailed deer habitat management.     

Thermal flight budget of a woodland butterfly in woodland versus agricultural landscapes: An experimental assessment

We assessed the impact of vegetation structure and type of landscape on microclimatic conditions for flight activity, using the heliothermic butterfly Pararge aegeria as a model. Dummies (i.e., dead specimens with spread wings, on a hypodermic needle with a thermocouple) that initially were warmed up to similar thorax temperatures were able to cover larger distances, and they heated up faster, with higher ambient temperature and with lower wind speed. Convective cooling decreased with increasing degree of shelter, and with lower flight height. Simulated flight bouts bridged 140±23 m under unsheltered, 81±13 m under partly sheltered and 29±6 m under sheltered conditions. Ambient temperature and wind force were higher in highly fragmented, agricultural landscapes than in continuous woodland landscapes. Males, and not females, were furrier in agricultural landscapes. This sexual difference is interpreted in terms of differences in life history among the sexes.     

Time as a constraint on the distribution of feral goats at high latitudes

We use data on feral goats on the Isle of Rum to explore the hypothesis that time is a major constraint on the latitudinal and altitudinal distribution of this species. Daylength and temperature were the principal factors influencing the main time budget elements (feeding, moving and resting). Because the goats do not feed at night due to low ambient temperatures, they faced particular problems during winter when daylengths were at their shortest. A mean monthly windchill‐adjusted temperature of 5°C appeared to be a critical threshold in terms of the animals’ ability to survive on Rum. We used these data to model the animals’ time budgets at different latitudes and altitudes. We show that winter daylength would be shorter than the required feeding time north of about 60° latitude, with a narrowing altitudinal cone approaching sea level at this latitude. Biogeographic evidence confirms that feral goat populations are not self‐sustaining north of this latitude.     

Food supply, grazing activity and growth rate in the limpet Patella vulgata L.: a comparison between exposed and sheltered shores

The limpet Patella vulgata L. is an important microphagous grazer on intertidal rocky shores of north-west Europe, occurring across the wave exposure gradient. Groups of P. vulgata were selected at mid-tide level of two exposed shores and two sheltered, fucoid dominated shores on the Isle of Man, British Isles, and manipulated to equivalent densities and population structure. The level of grazing activity and growth rate were determined over a 1-year period. At the same time, the abundance of epilithic microalgae, measured as the concentration of chlorophyll a, was determined as an estimate of food supply. Microagal abundance showed a seasonal pattern in both exposed and sheltered conditions, with higher levels in winter compared to summer. In both seasons, the microalgal resource was more abundant on the sheltered shore studied. The level of grazing activity in P. vulgata showed a seasonal pattern on the exposed but not the sheltered shores. Averaged over the year, grazing activity on the exposed shores was over double that on sheltered shores. Thus, in sheltered conditions, food supply for limpets was high and grazing activity low; in exposed conditions, food supply was low and grazing activity high. The growth rate of P. vulgata, measured as increase in shell length, showed no significant difference between exposed and sheltered shores. Growth rate was also determined in P. vulgata at natural densities. Although the overall density declined with decreasing exposure to wave action, the density per unit area of grazeable substance was higher in shelter. In these populations, the mean growth rate was over twice as high on exposed compared to sheltered shores.     

鸿雁迁徙对停歇地的选择特征

建立合理的湿地水鸟保护地是缓解水鸟栖息地丧失和种群下降的重要手段。以往的保护地设计中,由于越冬地和和繁殖地水鸟停留时间长、种群数量大,受到较多的关注。分析湿地水鸟对停歇地的选择偏好,掌握停歇地的自然条件和人类活动特征可为水鸟保护网络优化和保护地管理提供决策依据。而在水鸟迁徙过程中,停歇地作为保护网络的重要节点也发挥了重要作用。因此选择鸿雁为伞护种,获取了29只鸿雁项圈追踪数据,分析蒙古国Khukh湖-中国东北鸭绿江口秋季迁徙路线对停歇地生境选择偏好,识别了鸿雁在湿地周边不同距离梯度下的活动频率变化。根据鸿雁停歇数据共识别停歇地63处,以此为基础分析停歇的自然条件和人类活动因素特征。结果表明,鸿雁除选择湖泊和沼泽为停歇地外,周边250m内的裸地和草地也是重要栖息地;当鸿雁停歇地人类活动较少时,鸿雁倾向于选择土壤肥沃、食物丰富区,而人类活动强度加大时,栖息地植被条件提高能够为鸿雁提供遮避条件,也吸引了更多鸿雁停歇。研究建议,在水鸟迁徙重要廊道区应增加水鸟停歇地保护区,保护区的设计应根据关键保护对象活动频率加强对湿地周边的栖息地保护,减少水滨人类活动对鸿雁停歇的负面影响;在人类活动强度较大的地区设立水鸟保护地,还应加强对植被的保护,在水鸟利用频率较高的停歇地周边进行植被修复。     

The daily pattern of autumn bird migration in the northern Sahara

The temporal pattern of migration by passerine birds during the night, and their arrival during the day at the Egyptian coast and in the northern Sahara Desert was investigated. The mean direction of nocturnal migration at the coast was south-southeast, while at all desert sites it was south-southwest.
Birds arrived at the Egyptian coast only during the second half of the night which is explained by the fact that no birds could have taken off from the Mediterranean Sea. At least some of the birds landed at the coast where they spent the day before taking off shortly after sunset. These birds passed the desert sites at the expected time of day assuming a ground speed of 18 m per second. However, the origin of the birds passing the desert sites early at night is unclear. They must either have spent the day in the desert north of the study sites or they had overflown the Egyptian coast in the afternoon without landing.
The landing of birds during the day at the desert sites was bimodal. This pattern of arrival is explained either by some birds having landed at the Egyptian coast in the early morning before continuing, or by deteriorating conditions later in the day during flight or when resting in the desert, that obliged them to seek shelter at the desert sites.
A correlation between the number of migrants observed during the night and the number of resting birds in the desert on the following day suggests that an unknown proportion of birds might regularly use an intermittent migratory strategy that includes rest periods by day when crossing the desert, whereas others might adapt a non-stop migratory strategy.     

Influence of body mass and environmental conditions on winter mortality risk of a northern ungulate: Evidence for a late‐winter survival bottleneck

1. A relationship between winter weather and survival of northern ungulates has long been established, yet the possible roles of biological (e.g., nutritional status) and environmental (e.g., weather) conditions make it important to determine which potential limiting factors are most influential.
2. Our objective was to examine the potential effects of individual (body mass and age) and extrinsic (winter severity and snowmelt conditions) factors on the magnitude and timing of mortality for adult (>2.5 years old) female white‐tailed deer (Odocoileus virginianus [Zimmerman, 1780]) during February–May in the Upper Peninsula of Michigan, USA.
3. One hundred and fifty deer were captured and monitored during 2009–2015 in two areas with varying snowfall. February–May survival ranged from 0.24 to 0.89 (mean = 0.69) across years. Mortality risk increased 1.9% with each unit increase in cumulative winter severity index, decreased 8.2% with each cumulative snow‐free day, and decreased 4.3% with each kg increase in body mass. Age and weekly snow depth did not influence weekly deer survival. Predation, primarily from coyote (Canis latrans [Say, 1823]) and wolves (Canis lupus [L., 1758]), accounted for 78% of known‐cause mortalities.
4. Our results suggest that cumulative winter severity, and possibly to a lesser degree deer condition entering winter, impacted deer winter survival. However, the timing of spring snowmelt appeared to be the most influential factor determining late‐winter mortality of deer in our study. This supports the hypothesis that nutrition and energetic demands from weather conditions are both important to northern ungulate winter ecology. Under this model, a delay of several weeks in the timing of spring snowmelt could exert a large influence on deer survival, resulting in a survival bottleneck.

     

Wolf (Canis lupus) feeding habits during the first eight years of its occurrence in Germany

Due to the fact that the feeding habits of large carnivores are the main contentious point when they start resettling regions they were absent from for several decades, the diet composition of the wolves in Germany was analysed from the beginning of this process. Wolves in Germany primarily feed on wild ungulates, which make up more than 96% of their diet. The dominating prey species is the roe deer (55.3%), followed by red deer (20.8%) and wild boar (17.7%). The second important food category are the leporids (2.9% of Biomass), whereas livestock makes up only 0.6% of all biomass consumed. Wolves clearly prefer hunting on juvenile to adult red deer; roe deer are not selected after their age. We found seasonal differences in the diet composition with a higher amount of wild boar in spring and winter, when a high amount of juveniles and weakened animals, respectively, are available. In the first years of the study the percentage of red deer was much higher, and the percentage of roe deer therefore was lower than the following years. The amount of wild boar in the wolf diet fluctuated most in the first three years. Diet composition remained constant during the last five years. Wolves needed less than two generations for adapting to the new conditions in the cultivated landscape of eastern Germany.     

Predatory wasps learn to overcome the shelter defences of their larval prey

Larvae of Epargyreus clarus (Hesperiidae), the silver-spotted skipper, inhabit leaf-and-silk shelters that they construct on their leguminous host plants. In the field, Polistes spp. (Vespidae) wasps land on the shelters, quickly extracting and killing the larvae within. In marked contrast, wasps that emerge from field-collected colonies maintained in the laboratory visit and examine leaflets bearing sheltered caterpillars, but only rarely do they extract and kill the sheltered larvae. To examine whether learning is involved in the development of the ability of Polistes wasps to forage successfully on sheltered E. clarus larvae, we tested the responses of P. fuscatus and P. dominulus wasps to sheltered E. clarus larvae before and after their exposure to unsheltered larvae that were visible either on an opened host-leaf shelter (P. fuscatus and P. dominulus) or on a nonhost leaf in the absence of a shelter (P. fuscatus). After killing and processing an unsheltered larva that was visible on an opened leaf shelter, a majority of foragers subsequently extracted and killed larvae from closed shelters. Wasps that killed and processed an unsheltered larva on a nonhost leaf, on the other hand, generally did not later open shelters. Thus, it seems that experience with an exposed larva in the context of its shelter is necessary for a wasp to be able to prey on sheltered larvae. We conclude that the wasps must learn to associate the taste of the larva with shelter-related cues, such as presence of leaf damage and silk. In nature, this initial exposure may occur when the larva is visible in or near its shelter, perhaps when feeding or constructing a new shelter. Learning opportunities will thus depend on larval density. Our results show that invertebrate predators can learn to overcome their prey's defences, and are therefore able to make use of previously inaccessible prey.     

Age-sex differences in the diets of Sika deer on Kinkazan Island,northern Japan

Dietary differences in the ages and sexes of Sika deer (Cervus nippon) were studied on Kinkazan Island, northern Japan from October 1990 to July 1991. Larger deer consumed more graminoids than smaller deer except in spring, and less dicotyledonous leaves in all the seasons. Fecal nitrogen concentrations were lower in larger deer than in smaller deer in all the seasons. The age-sex differences in foods were smaller in summer and winter when foods were most abundant and scarce, respectively, while they were greater in spring and autumn when food availability was intermediate.     

Effects of sheltered ground habitats on the overwintering potential of the predacious mite <Emphasis Type="Italic">Neoseiulus californicus</Emphasis> (Acari: Phytoseiidae) in apple orchards on mainland Korea

Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) is an effective predator of spider mites. In Korea, it is distributed on Jeju Island, but is never found further north on the mainland. Due to poor natural control of spider mites by native predatory mites in mainland orchards, commercialization of the Jeju Island strain of N. californicus on the mainland is currently being considered. We conducted two field experiments in mainland apple orchards during winter 2008 and 2009 to assess the effects of sheltered ground habitats on the overwintering potential of N. californicus. In the first experiment, all of the N. californicus individuals that were experimentally placed on bare ground died within 27 days, whereas 70% of mites sheltered by fallen apple leaves or urethane foam survived for more than 27 days. In the second experiment, individuals were released directly onto the ground, either with or without urethane foam. More individuals were found within urethane foam plots than in plots without foam. Sheltered ground habitats would be an important factor for N. californicus when selecting overwintering sites, and could eventually lead to enhanced winter survival. On the other hand, no live N. californicus individuals were found by the end of the winter in either experiment, which suggests that N. californicus could not successfully overwinter in the study area, even in sheltered ground habitats.