Diet, food availability and habitat selection of breeding Common Sandpipers Actitis hypoleucos

The diet of the Common Sandpiper, as studied by faecal analysis, includes a wide variety of prey, the majority of which are of terrestrial rather than of aquatic origin. Observation of feeding activity confirms that much time is spent feeding in grassland, although shingly river edges are also important. The feeding activity of young chicks is also largely confined to wet grassy areas, but older chicks feed almost entirely along the     

Spatial distribution, connectivity, and the influence of scale: habitat availability for the endangered Mona Island rock iguana

The Caribbean region is one of the five leading biodiversity hotspots in the world. Analysis of the spatial structure of critical habitats and how it affects endemic species in this region is essential baseline information for biodiversity monitoring and management. We quantified and evaluated the spatial structure and connectivity of depression forests on Mona Island and their potential impact on Mona Island rock iguana habitat, as a framework to assess spatial distribution, connectivity, and the issue of scale in small and widely dispersed habitats. Using IKONOS imagery, we mapped and delineated depression forests at four different scales (minimum mapping units: <100, 100, 500, and 1,000 m), and calculated landscape metrics describing their spatial structure, and connectivity, for each map resolution. Our approach resulted in a more detailed map than previously described maps, providing better information on habitat connectivity for iguanas. The comparison of the island landscape mapped at different scales provided evidence on how changing scales affect the output of spatial metrics and may have a significant impact when planning decisions and assigning conservation priorities. It also highlighted the importance of adequate ecological scales when addressing landscape management and conservation priorities. The analysis of landscapes at multiple scales provided a mechanism to evaluate the role of patch detection and its effect on the interpretation of connectivity and spatial structure of suitable areas for species with small and widely dispersed habitats. These methodologies can be applied other species, in different environments, with similar limitations related to connectivity and habitat availability.     

Home range and habitat selection of pampas deer

The southernmost subspecies of pampas deer Ozotocerus bezoarticus celer is an endemic and endangered cervid of the Argentine Pampas. The aim of our study was to describe the habitat use of this deer on the coast of Samborombón Bay. Twelve adult pampas deer (seven female and five male) were radiotracked and their home-range sizes and habitat selection studied from 1995 to 2001. The mean home-range size was 898±181 ha, and the core area was concentrated in 22% of their range. The home-range size of males was three times larger than that of females (1422 vs. 523 ha). Deer home ranges overlapped extensively. No sex differences were found regarding habitat selection. Celtis tala forests and Spartina densiflora grasslands were used more than expected by their availability, while wetlands, coastal grasslands and Salicornia ambigua beaches were avoided. Their habitat selection was affected by cattle presence, suggesting avoidance: they tended to use areas free of cattle, and their home ranges were larger when cattle were absent. An action plan for this endangered population of pampas deer should include initiatives involving private landowners in pampas deer conservation, the use of fire and cattle grazing management tools to improve deer habitat, and studies to provide biological and health data related to pampas deer coexistence with cattle.     

Bark stripping of hinoki cypress by sika deer in relation to snow cover and food availability on Mt Takahara,central Japan

Bark stripping of hinoki cypress (Chamaecyparis obtusa (Sieb. et Zucc.) Endl.) by sika deer (Cervus nippon Temminck) was monitored for 4years on approximately 300 trees at three sites on Mt Takahara, central Japan. We investigated the effects of snow cover and food availability on seasonal and yearly changes in bark stripping. Bark stripping occurred during snowy periods (January and February) when less food was available because of the snow cover. The most serious bark stripping was observed in 1996 when the snow was the deepest and food resources were the poorest among the 4years of the study. In contrast, bark stripping did not occur in 1999 when the snow was thin and, consequently, more food was available. These results suggest that snow cover and food avail-ability influence the occurrence and intensity of bark stripping both seasonally and annually.     

Dietary selection by yakushima macaques (Macaca fuscata yakui): The influence of food availability and temperature

I examined dietary selection by Yakushima macaques (Macaca fuscata yakui)in relation to food availability and air temperature. Multiple regression analysis indicates that both food availability and temperature influenced the selection of foods. Feeding on young leaves, seeds, and flowers was affected more by availability, while feeding on fruits, mature leaves, and fallen seeds was affected more by temperature. Feeding on insects is strongly correlated with temperature,perhaps because availability of insects increased with temperature. These results suggest that temperature influences dietary selection of Yakushima macaques by changing the energy expenditure required for thermoregulation and through its influence on the accessibility to insects, which are an important protein source for the monkeys.     

The influence of larval density, food availability and habitat longevity on the life history and population growth rate of the midge Chironomus riparius

Despite long‐standing interest in the forms and mechanisms of density dependence, these are still imperfectly understood. However, in a constant environment an increase in density must reduce per capita resource availability, which in turn leads to reduced survival, fecundity and somatic growth rate. Here we report two population experiments examining the density dependent responses under controlled conditions of an important indicator species, Chironomus riparius. The first experiment was run for 35 weeks and was started at low density with replicate populations being fed three different rations. Increased ration reduced generation time and increased population growth rate (pgr) but had no effect on survival, fecundity and female body weight in the first generation. In the second generation there was a six‐fold increase in generation time, presumably due to the greatly reduced per capita resource availability as the estimated initial densities of the second generation were 300 times greater than the first. Juvenile survival to emergence, fecundity, adult body weight and pgr declined by 90%, 75%, 35% and 99%, respectively. These large between‐generation effects may have obscured the effects of the threefold variation in ration, as only survival to emergence significantly increased with ration in the second generation. These results suggest that some chironomid larvae survive a reduction in resource availability by growing more slowly. In the ephemeral habitats sometimes occupied by C. riparius, the effects of population density may depend crucially on the longevity of the environment. A second experiment was therefore performed to measure pgr from six different starting densities over an eight‐week period. The relationship between pgr and density was concave, viewed from above. At densities above 16 larvae per cm², less than 1% of the population emerged and no offspring were produced. Under the conditions of experiment 2 – an 8‐week habitat lifespan – carrying capacity was estimated as 8 larvae per cm².     

Forest light and its influence on habitat selection

Light filtered through the forest canopy is the most variable physical factor in tropical forests, both in space and time. Vegetation geometry, sun angle, and weather generate five light environments, which greatly differ in intensity and spectrum. Forest light spectra can directly affect photosynthesis, plant morphogenesis, visual communication, and the effectiveness of plant-animal interactions. For animals, the apparent simplicity of five light environments is complicated by different types of contrast with the optical background which greatly modify the conspicuousness of visual signals. The purpose of this paper is to describe peculiarities of light in tropical forest, and to review the effects of light intensity and especially quality on plants and animals. Ecophysiological adaptations of plants to cope with contrasting light environments operate at daily, seasonal and life time-scales. Ambient light quality acts as a signal for both animals and plants, and consequences on plant growth, colour display, and signal design are examined. An analysis of the range of spectral parameters along a deforestation gradient is presented, testing if sites with more variation in light could support more species which are light-environment specialists. It is suggested that light quality measurement may be used to estimate the structural impact of forest exploitation, and that gives us the information necessary for a functional explanation of anthropogenic effects on tropical forest diversity.     

Foot morphology and distribution of Sika deer in relation to snow depth in Japan

The distribution of Sika deer (Cervus nippon) on Japanese islands is biased toward, the east where there is less snow. To explain this biased distribution in relation to snow, the foot morphology of Sika deer was measured. Hoof load was greatest in male adults (0.78 kg cm⁻²) and smallest in fawns (c 0.43 kg cm⁻²). The values were similar to those for white-tailed deer, and were smaller than those for snow-adapted species like caribou and chamois. Foreleg length wasc. 50 cm and 60 cm, and hind feet (lower half) length wasc. 40 cm and 45 cm for fawns and adult deer, respectively. Chest heights werec. 45 cm and 53 cm for fawns and adults, respectively. These figures suggest that areas where snow accumulates deeper than 50 cm are not favorable as a Sika deer habitat. The present distribution of Sika deer is clearly related to snow depth: they are mostly concentrated in the ‘preferable area’ of <50 cm of snow, some of them can live in the ‘habitable area’ of 50–100 cm of snow, and they rarely live in the ‘inhabitable area’ of >100 cm of snow.     

Dynamics of habitat distribution in breeding mallards: assessing the applicability of current habitat selection models

The applicability of ideal free, ideal despotic and ideal preemptive habitat selection models to explain dynamics of habitat distribution of breeding mallards ( Anas platyrhynchos ) was explored. Data from 35 lakes studied between 1985 and 2000 were used to examine overall habitat distribution of breeding pairs, breeding success in different habitats, within-year order of habitat occupation, and density dependence of habitat distribution and breeding success. Two habitat types, rich and poor, were defined based on the structure and luxuriance of shore vegetation; each lake belonged to one or the other of the habitat types. Breeding pairs used the rich habitat more than expected, breeding density also being higher there than in the poor habitat. Both average brood density and breeding success were higher in the rich habitat than in the poor. Breeding success was not density dependent, neither when analysed separately for the habitat types, nor in the study area in general. Within season, arriving mallard pairs did not occupy rich lakes earlier than poor lakes. An isodar analysis based on between-year variation of the breeding density in rich and poor habitats revealed that habitat distribution of breeding pairs was not density dependent. By contrast, density in the rich habitat increased and proportional use of the poor habitat decreased with increasing overall population density, i.e. the rich habitat got increasingly crowded. None of the habitat selection models considered was applicable to explain the dynamics of habitat distribution of breeding mallards.     

甘肃兴隆山自然保护区马麝夏季栖息地特征及生境选择格局

2006—2008年夏季(7—8月),对甘肃兴隆山自然保护区马麝(Moschus Sifanicus)的栖息地特征和夏季生境选择格局进行了研究。用Mann-Whitney U检验和χ2检验比较了马麝夏季利用生境样地(n=71)和对照性非利用样地(n=264)间的海拔等17个生态变量的差异,结果表明,兴隆山马麝夏季利用生境的郁闭度[(53.87±3.09)%]和乔木均高[(7.57±0.83)m]均显著大于非利用样地[郁闭度:(49.07±1.66)%,乔木均高:(6.33±0.32)m],喜食植物多度[(12.97±1.80)]株也显著大于非利用样地[(9.61±0.67)株]。此外,与非利用样地相比,兴隆山马麝夏季倾向于选择位于中坡位较陡(67.61%)、距离水源较近(<1000m,77.46%)、隐蔽度(88.73%)和避风性均较好(90%)及距人为干扰较远(>1000m,76.06%)的生境;主成分分析结果表明,前4个因子的累积贡献率达72.45%,由乔木胸径和乔木郁闭度变量组成的乔木因子是决定马麝夏季生境选择的首要因素,此外,海拔因子,由地表植被盖度和食物多度组成的食物因子,由灌木盖度、乔木密度和灌木...     

Cleaner wrasse influence habitat selection of young damselfish

The presence of bluestreak cleaner wrasse, Labroides dimidiatus, on coral reefs increases total abundance and biodiversity of reef fishes. The mechanism(s) that cause such shifts in population structure are unclear, but it is possible that young fish preferentially settle into microhabitats where cleaner wrasse are present. As a first step to investigate this possibility, we conducted aquarium experiments to examine whether settlement-stage and young juveniles of ambon damselfish, Pomacentrus amboinensis, selected a microhabitat near a cleaner wrasse (adult or juvenile). Both settlement-stage (0 d post-settlement) and juvenile (~5 weeks post-settlement) fish spent a greater proportion of time in a microhabitat adjacent to L. dimidiatus than in one next to a control fish (a non-cleaner wrasse, Halichoeres melanurus) or one where no fish was present. This suggests that cleaner wrasse may serve as a positive cue during microhabitat selection. We also conducted focal observations of cleaner wrasse and counts of nearby damselfishes (1 m radius) to examine whether newly settled fish obtained direct benefits, in the form of cleaning services, from being near a cleaner wrasse. Although abundant, newly settled recruits (<20 mm total length) were rarely (2 %) observed being cleaned in 20 min observations compared with larger damselfishes (58 %). Individual damselfish that were cleaned were significantly larger than the median size of the surrounding nearby non-cleaned conspecifics; this was consistent across four species. The selection by settlement-stage fish of a microhabitat adjacent to cleaner wrasse in the laboratory, despite only being rarely cleaned in the natural environment, suggests that even rare cleaning events and/or indirect benefits may drive their settlement choices. This behaviour may also explain the decreased abundance of young fishes on reefs from which cleaner wrasse had been experimentally removed. This study reinforces the potentially important role of mutualism during the processes of settlement and recruitment of young reef fishes.     

Oviposition habitat selection by the mosquito, Culiseta longiareolata: effects of conspecifics, food and green toad tadpoles

Abstract. 1. Ovipositing females should choose egg-laying sites which maximize the growth and survivorship of their offspring. Accordingly, they should avoid habitats with high densities of competitors and predators and should choose sites with adequate food. We tested experimentally the oviposition response of the mosquito, Culiseta longiareolata Macquart, to extra food and two species which are both potential competitors and predators of its offspring: conspecific larvae and green toad ( Bufo viridis ) tadpoles.
2. We conducted the experiment in outdoor artificial pools where wild C. longiareolata females were presented with choices of all combinations of the presence or absence of: (1) C.longiareolata larvae, (2) B.viridis tadpoles, and (3) extra food (a mixture of ground fish food and mouse chow).
3. Oviposition rates averaged approximately 4 times greater in response to extra food.
4. The presence of the tadpoles, particularly later in the experiment when they were larger, caused a significant reduction (approximately 50%) in oviposition rate.
5. We did not detect a statistically significant effect of conspecific larvae on oviposition habitat selection.
6. Our results indicate that Culiseta females choose habitats for oviposition based on food availability. They also tend to avoid habitats containing Bufo tadpoles, presumably to avoid predation and/or competition.     

Dietary selection by yakushima macaques ( Macaca fuscata yakui ): The influence of food availability and temperature

I examined dietary selection by Yakushima macaques (Macaca fuscata yakui)in relation to food availability and air temperature. Multiple regression analysis indicates that both food availability and temperature influenced the selection of foods. Feeding on young leaves, seeds, and flowers was affected more by availability, while feeding on fruits, mature leaves, and fallen seeds was affected more by temperature. Feeding on insects is strongly correlated with temperature,perhaps because availability of insects increased with temperature. These results suggest that temperature influences dietary selection of Yakushima macaques by changing the energy expenditure required for thermoregulation and through its influence on the accessibility to insects, which are an important protein source for the monkeys.     

A mass-mortality of Sika deer on Kinkazan Island,northern Japan

A Sika deer (Cervus nippon) population had been maintained at a level of around 600 head on Kinkazan Island (960 ha), northern Japan during the 1970s and the early 1980s. However, in the spring of 1984 which followed an uncommonly cold winter, a mass-mortality occurred and about half of the deer population died. A total of 293 recovered carcasses indicated that many had died during a short period (late March and mid-April). More carcasses were found in the lower altitudinal areas than expected numbers relative to area sizes, suggesting that the deer had moved down from the higher areas to avoid snow. Rumen contents of the carcasses contained much low quality food. Malnutrition caused by the exceptional coldness and late snow was considered to be the factor responsible for mortality.     

A case study on the effects of a transmission-line corridor on Sika deer habitat use at the foothills of Mt Goyo,northern Honshu,Japan

Forage biomass and habitat use of Sika deer (Cervus nippon) at a transmission-line corridor were studied at the foothills of Mt Goyo, northern Japan. Summer forage biomass in the corridor was five times greater than in the adjacentBetula grossa forest. Among the plants that increased in the corridor,Sasa nipponica (a dwarf bamboo), an important forage plant for Sika deer, was predominant. Winter utilization ofS. nipponica by Sika deer was slightly heavier in the corridor, and estimated removal ofSasa leaves was twice as great there as in the forest. However fecal pellets were more prevalent in the adjacent forest in winter. Sika deer seemed to use the transmission-line corridor as a feeding site and the adjacent forest as cover as it reduces wind speed. A transmission-line corridor is more beneficial than a large clear-cut area because it provides more forest edges.