Breeding biology of the Madagascar Paradise Flycatcher,Terpsiphone mutata,with special reference to plumage variation in males

This study was undertaken to understand the migratory strategies of the Dunlins (Calidris alpina) caught in Eilat, Israel, before and after they accomplish the crossing of the combined ecological barrier of the Sinai, Sahara and Sahel deserts. Between 1999–2001, a total of 410 adults and 342 juveniles were banded. The significant difference in mean wing length between birds caught in autumn and spring reflects the degree of abrasion of the outer primaries during over-wintering in Africa. Dunlins caught in Eilat in autumn and early winter had a mean wing length 1.4–1.9mm longer than in the spring. The rate of body mass increase was comparatively high and the mean body mass of the heaviest 10% of Dunlin at Eilat was 56.2g (SE ± 0.6, N = 80). The heaviest birds from Eilat carried on average about 10g of fat with a lipid index (fat mass as a percentage of total body mass) of 18%. These reserves allow a flight of approximately 1 000km, which is probably sufficient for continued migration to more southerly wintering grounds.     

湖北巴东寿带鸟繁殖行为观察

20 0 2年 5月～ 2 0 0 4年 8月 ,在湖北省巴东县沿渡河镇的东圩口、小溪、锯锯湾、两河口等 4个村 ,对寿带鸟 (Terpsiphoneparadisiincei)的繁殖生态进行了初步研究。研究结果显示 ,寿带鸟在湖北巴东的繁殖时间为 5月下旬～ 7月上旬 ,主要在农田居民区附近的阔叶树上营巢 ,巢材主要有青苔、草叶、草茎、细草根、棕丝、树耳、蜘蛛网等。筑巢工作主要由雌鸟承担 ,一般需要 5～ 7d即可完成。巢距离地面高度1 72～ 6 45m ,巢外径 6 0～ 8 8cm ,巢内径 4 9～ 6 4cm ,巢深 2 9～ 4 1cm ,巢高 6 3～ 9 5cm。雌鸟每天产 1枚卵 ,产卵时间均在清晨。窝卵数 4枚 (n =1 1 ) ,卵产齐后即开始孵化 ,雌雄鸟轮流孵卵 ,孵化期 1 3d。雏鸟晚成性 ,雌雄共同育雏 ,育雏期 9d。寿带鸟对不同的外界干扰反应明显不同 ,当有对其卵和雏鸟构成威胁的动物接近时 ,护巢行为表现十分强烈 ;而对其没有威胁的物种接近其巢时则无动于衷。面对同样的干扰 ,雌雄亲鸟的反应存在显著差异。     

Breeding ecology of the Seychelles Black Parrot Coracopsis barklyi

Knowledge of breeding ecology is required for many conservation interventions. The Seychelles Black Parrot Coracopsis barklyi, endemic to the island of Praslin, is vulnerable to extinction. We aimed to improve understanding of C. barklyi breeding ecology to aid conservation planning. We present the results of four years of research, including nesting cavity characteristics and availability, reproductive success, breeding parameters, parental behaviour and reproductive strategy. Thirty-six breeding attempts were studied over the four seasons. Nests were mainly located in Coco de Mer palms Lodoicea maldivica. Deeper cavities with more canopy cover were preferred. There may be a shortage of high-quality nesting cavities in intensive breeding seasons. Average clutch size was 2.2 eggs, incubation period was c. 15 d and egg fertility was 71%. Rats were key nest predators, causing the failure of up to 33% of breeding attempts. The probability of nest success was 53%. At least 57% of fledglings survived their first year. This species breeds cooperatively and practices a highly unusual side-by-side copulation. We discuss the implications of the results in the context of former, ongoing and potential conservation measures for C. barklyi including translocation, invasive species management, nest box provisioning, habitat restoration and further research.     

Demography of the Seychelles Black Paradise-flycatcher: considerations for conservation and reintroduction

The Seychelles Black Paradise-flycatcher Terpsiphone corvina is currently listed as Critically Endangered, on the basis of small population and restricted range. Currently, there is only one self-sustaining population comprising c. 150–200 individuals on the 10km² island of La Digue (Republic of Seychelles, western Indian Ocean), and consequently the creation of additional island populations has been identified as essential to improve its conservation status. We quantified the annual breeding success, adult mortality and juvenile recruitment of the flycatcher on La Digue, monitored tri-weekly over a two-year period (June 1999–June 2001), to determine factors affecting population demographics and assess the implications for the reintroduction of populations to other islands. A total of 267 breeding attempts were recorded with c. 45% of the documented world population of pairs systematically monitored each year. On average, pairs attempted to breed three times in a 12-month period (range 0–6), although not all attempts were successful. Breeding success was consistently low between years: 62% of nests (controlling for observation time) and 17–19% of study territories failed to produce any fledglings in each respective 12-month period. Daily failure rates were generally higher during incubation than in the nestling period. Nests close to the forest edge were more likely to fail. The majority (143) of the 152 failed nesting attempts were consistent with depredation and were characterised by the disappearance of nest contents and sometimes by egg and chick remains and the disappearance of the adult female. Predators were identified at 13 nests: five (3.3%) were depredated by birds, and eight (5.2%) were depredated by mammals and/or reptiles: Rattus sp. were confirmed as predators. Video monitoring conducted at 14 nests also confirmed the endemic Seychelles bulbul Hypsipetes crassirostris as a nest predator. Adult mortality was c. 21% and alien predators (Rattus sp. and Felis cattus) were identified in causing adult mortality. However, in the majority of cases, reasons for adult mortality were unknown. Of the 52 marked fledglings that could have been recruited to the plateau population, 45% (23) were observed away from their natal territory c. 9–10 months after fledging, 25% (13) of which were confirmed as territory-holding individuals. We present a simple model to predict population growth using the above data, and discuss implications for the creation of additional self-sustaining populations on suitable islands.     

Influence of helping and breeding experience on reproductive performance in the Seychelles warbler: a translocation experiment

Reproductive success of the cooperative breeding Seychelleswarbler (Acrocephalus sechellensis) increases with age. Thisage effect is not due to differential survival or increasedreproductive effort, but to accumulated helping and breedingexperience. In their first year of breeding, reproductive performanceof inexperienced warblers with neither helping nor breedingexperience was significandy lower than that of warblers of thesame age with either previous helping or breeding experience.Reproductive performance was the same for primiparae with helpingexperience and for birds with breeding experience. Female primiparaewith helping experience or breeding experience built betternests and spent more time incubating than inexperienced females,which led to increased hatching success. Male primiparae withhelping experience or males with breeding experience guardedthe clutch better than inexperienced males, which led to reducedegg predation. Even-aged warblers with different previous experienceswere transferred to unoccupied islands, where birds startedbreeding immediately in high-quality territories. The experimentshowed that birds with helping experience produced their firstfledgling as fast as experienced breeders, and significandyfaster than inexperienced birds. Breeding performance did notimprove further with experience after the first successful breedingattempt. Only birds with previous breeding experience who pairedwith inexperienced birds, were likely to change mate. The otherpair combinations remained stable. Thus, primiparous birds withhelping experience have greater lifetime reproductive successthan inexperienced primiparae of the same age. This experimentshows that helping behavior has not only been selected for inthe context of promoting an individual's indirect fitness, butalso in the context of gaining helping experience which translatesinto improved reproductive success when a helper becomes a breeder.[Behav Ecol 7: 326-333 (1996)]     

Habitat requirements of the Socorro Mockingbird Mimodes graysoni

The population size of the Socorro Mockingbird Mimodes graysoni, which represents a monotypic genus endemic to Socorro Island, México, has declined dramatically within the last 40 years. Postulated causal factors include competitive exclusion by Northern Mockingbirds Mimus polyglottos, predation by feral cats and overgrazing by feral sheep. Habitat degradation looms as the primary candidate because surviving Socorro Mockingbirds live mainly in areas of the island with little apparent habitat damage, and because Northern Mockingbirds and cats both arrived on Socorro after much of the decline had occurred. Isolating key factors is difficult, however, because the present distributions of cats and Northern Mockingbirds coincide broadly with patterns of habitat degradation. To investigate habitat requirements of the endemic mockingbird in detail, we measured vegetation characteristics at localities with and without Socorro Mockingbirds, and observed their foraging behaviour. Socorro Mockingbirds occupied sites in montane regions covered with Ilex socorroensis, Guettarda insularis, Triumfetta socorrensis and Eupatorium pacificum; they were also abundant in pristine lowland forests. Socorro Mockingbirds were scarce in disturbed forests where Dodonaea viscosa has replaced the original understorey, and they were absent from low-elevation Croton masonii scrub, even in areas with no signs of degradation. Restoration of degraded habitat could help the population of Socorro Mockingbirds grow and reoccupy more of its former range.     

Habitat requirements of boreal forest caribou during the travel seasons

Understanding space-use patterns of highly mobile animals, such as woodland caribou, is required for ecosystem conservation. We tested for seasonal differences in migration habitat used by woodland caribou while travelling from winter to summer and summer to winter range in northwest Ontario, using radio-telemetry locations of 33 caribou collected from 1995 to 2000. Forest management guidelines in Ontario presume that woodland caribou select specific habitats during the migrating seasons including conifer dominated forests and waterways (rivers and lakes). Results showed few differences between real travel routes and straight-line routes during both high movement periods (post-calving to late winter and late winter to calving). Caribou selected less deciduous forest than available during early winter and spring but contrary to expectations they did not use more open areas and waterways than available. Possible migration corridors, or habitat used during early winter and spring, were not distinguished by one particular habitat type, although caribou were more likely to avoid water and open areas, while using more conifer forests. They did not avoid disturbed habitat such as recently burnt or cut areas. There were some sex-specific differences with males using deciduous forest more than females. Caribou did not choose more than expected of waterways such as chains of lakes or large rivers which, to some extent, run counter to management recommendations. Our findings should be considered when developing local forest management plans and designing harvest patterns with the intent to mitigate negative impacts on woodland caribou habitat.

Zusammenfassung

Das Verständnis der Raumnutzungsmuster von sehr mobilen Tieren, wie den Waldkaribus, ist für den Ökosystemschutz notwendig. Wir untersuchten die saisonalen Unterschiede in der Habitatnutzung von Waldkaribus während der Wanderung (frühe Winter- und Frühjahrsrouten) im nordwestlichen Ontario, indem wir von 1995–2000 die Standorte von 33 Karibus per Radiotelemetrie bestimmten. Richtlinien für Waldmanagement in Ontario setzen vorraus, dass Waldkaribus während der Wanderungszeit spezifische Habitate wählen, die nadelbaumdominierte Wälder und Wasserwege (Flüsse und Seen) einschließen. Die Ergebnisse zeigten einige Unterschiede zwischen den realen Wanderrouten und geradlinigen Routen während der beiden Wanderperioden (nach dem Kalben bis zum späten Winter und später Winter bis nach dem Kalben). Die Karibus wählten weniger als den verfügbaren Laubwald im frühen Winter und Frühjahr, aber sie nutzten entgegen den Erwartungen offenere Areale und Wasserwege nicht mehr als verfügbar. Mögliche Wanderkorridore oder Habitate, die während des frühen Winters und Frühjahrs genutzt wurden, unterschieden sich nicht durch einen bestimmten Habitattyp, auch wenn die Karibus mit größerer Wahrscheinlichkeit Wasser und offene Areale mieden, während sie Nadelwälder nutzten. Sie mieden gestörte Areale nicht, wie kürzlich abgebrannte oder abgeholzte. Es gab einige geschlechtsspezifische Unterschiede, da die Männchen Laubwälder mehr als Weibchen nutzten. Die Karibus wählten Wasserwege, wie Ketten von Seen oder große Flüsse, nicht mehr als erwartet, was in gewissem Ausmaß den Managementempfehlungen zuwiderläuft. Unsere Ergebnisse sollten berücksichtigt werden, wenn örtliche Waldmanagementpläne entwickelt und die Einschlagsmuster entworfen werden, mit der Absicht die negativen Auswirkungen auf das Habitat der Waldkaribus zu mildern.     

The orthopteroids of the Seychelles: a threatened island fauna

Although they are conspicuous components of the native fauna, the orthopteroid insects of the Seychelles islands have attracted little attention from ecologists and conservationists throughout most of the twentieth century. Yet, at a complex crossroads, where the Afro-tropical, Malagasy and Oriental faunal regions overlap, they are potentially valuable biogeographical indicators in a region with an extremely complex palaeogeography. The taxonomic isolation of a number of species, incipient speciation among others, as well as possible interisland divergence in some cases make them worthy subjects of evolutionary studies. Most of the endemic species are indicators of undisturbed habitats and some play a role in food chains as the prey of endemic birds and hunting wasps (Sphecidae). The Seychelles orthopteroids are vulnerable to habitat disturbance caused by human activity and are now mainly confined to patches of native vegetation. They are threatened by further encroachment and by introduced predators and competitors.     

Habitat requirements and foraging behaviour of the Corsican nuthatch Sitta whiteheadi

We examined the relationship between the Corsican nuthatch Sitta whiteheadi , a passerine endemic to the island of Corsica and Corsican pine Pinus nigra laricio forest, its virtually exclusive habitat, currently restricted to inland mountains. The Corsican nuthatch prefers older Corsican pine stands with tall, large trees, and avoids younger stands, both in the breeding and wintering seasons. This preference is explained by the greater availability of pine seeds from older trees. Territorial adults are almost completely sedentary, a trait that is influenced by seed hoarding behaviour. From late autumn to early spring (i.e., when cones are mature), and during sunny weather (i.e., when cones are open), nuthatches remove pine seeds from cones and cache them on branches and under the bark of trunks. The birds retrieve the cached seeds in cold and wet weather. The presence of old Corsican pine stands appears to be a key-factor in the survival of the Corsican nuthatch, whose habitat is currently threatened by logging and fires.     

Habitat requirements of endangered species in a former coppice of high conservation value

Transformation of coppices to high forests has caused fundamental changes in site conditions and a decline of many species across Central Europe. Nevertheless, some formerly coppiced forests still harbour a number of the declining species and have become biodiversity hotspots in the changing landscape. We focused on the best-preserved remnant of formerly grazed and coppiced subcontinental oak forest in the Czech Republic – the Dúbrava forest near the town of Hodonín. To improve our understanding of the ecology of declining species, we studied local habitat requirements of vascular plants most endangered at the national level. We recorded vegetation composition and sampled important site variables in plots with the largest populations of endangered species and in additional plots placed randomly across all major forest habitats. We demonstrated that sites with endangered species have a highly uneven distribution in ecological space and that their species composition is often similar to open-canopy oak forests. Within this habitat, the endangered species are concentrated in places with a high light availability and high soil pH. Light-demanding species characteristic of subcontinental oak forests are the best indicators of these sites, while broadly distributed shade-tolerant and nutrient-demanding species avoid them. These results support the view that the occurrence of many endangered species in the Dúbrava forest is a legacy of the long history of traditional management that kept the canopies open. Light-demanding species are now threatened by ongoing successional changes. Therefore, active conservation measures are recommended, including opening up the canopies, early thinning of young stands, control of expansive and invasive species and understorey grazing or mowing.     

Insights into the feeding ecology of the Seychelles Black Parrot Coracopsis barklyi using two monitoring approaches

Feeding ecology is an important factor for the survival of a species and knowledge of its parameters is a prerequisite for successful conservation work. In this study we describe the feeding ecology of the endemic Seychelles Black Parrot Coracopsis barklyi on Praslin, Seychelles, the only island on which this parrot is resident. We compared two methods to evaluate feeding choices: incidental observations and feeding walks on 25 transects in all habitat types. Black parrots fed on 46 different species, bringing the total number of known food plants to 53 species. They predominantly consumed endemic and native species (58% of observed feeding bouts), mainly their fruit pulp (in 68% of feeding bouts), followed by buds (15%) and seeds (37%) with occasional observations of leaves, bark and scale insects. The incidental method rendered many more observed bouts than the transect approach and the ratios of consumed species differed between methods but the transect results are regarded as more representative. The incidental method is not suitable for quantitative conclusions but complements the transect method, providing information about rarely occurring feeding events.     

Habitat and shelter requirements of the stone crayfish,Austropotamobius torrentium Schrank

The attractiveness of shelters and the relationship between crayfish size and refuge size were investigated in the stone crayfish Austropotamobius torrentium. Shelter suitability was mainly determined by water velocity, stone surface area and stone width. Water depth and stone height had no influence on crayfish occupancy of stones. Austropotamobius torrentium avoided shelters in areas of water velocities exceeding 25 cm s^–1. They preferred large stones with a bearing surface greater than 300 cm². The probability of crayfish occupation rose quickly as stones' bearing surface increased up to 900 cm². Crayfish were exclusively caught underneath stones at least 3.19 times longer and 1.25 times wider than the carapace length of the refuge occupant. Large males occupied larger stones, where no relationship was detected between female size and stone refuge size.     

Habitat diversity, ecological requirements of species and the Small Island Effect

Aim  To explore the causal factors leading to a significant Small Island Effect (SIE), that is, the absence of the commonly found species–area relationships below an island size, on the terrestrial isopod communities from a large number of islands.
Location  Ninety islands of the Aegean Sea (Greece).
Methods  The detection of a significant SIE is assessed through the application of all three methods available in the literature. Species are divided into generalists and specialists. We tested if the minimum area and the area range of each species' occurrences differ between generalists and specialists. Next, we searched for differences in the ratios of specialists to generalists above and below the SIE threshold, and tested their cumulative ratios when islands are arranged according to increasing area, altitude or habitat diversity in order to identify the threshold where they become statistically indistinguishable from the ratio of the total set of islands.
Results  Our results indicate a strong effect of habitat availability on the SIE. Communities of islands within the SIE range, host a higher percentage of generalists. An analysis of the specific habitat requirements shows that, for isopods, the crucial factor is the lack of habitats related to inland waters from small islands.
Main conclusions  The distribution of habitats on islands of different size is of major importance for the occurrence of a SIE. The relative representation of specialist and generalist species on islands of different size plays an important role in shaping SIE-related patterns. Conservation efforts should pay special attention on freshwater habitats, especially on small Aegean islands. Identifying the causal factors of SIE, combined with a thorough knowledge of the ecological requirements of species can offer insights into identifying habitat types and groups of species that are more vulnerable to alterations of the environment.     

Testing a Mahalanobis Distance Model of Black Bear Habitat Use in the Ouachita Mountains of Oklahoma

Abstract: Regional wildlife-habitat models are commonly developed but rarely tested with truly independent data. We tested a published habitat model for black bears (Ursus americanus) with new data collected in a different site in the same ecological region (i.e., Ouachita Mountains of Arkansas and Oklahoma, USA). We used a Mahalanobis distance model developed from relocations of black bears in Arkansas to produce a map layer of Mahalanobis distances on a study area in neighboring Oklahoma. We tested this modeled map layer with relocations of black bears on the Oklahoma area. The distributions of relocations of female black bears were consistent with model predictions. We conclude that this modeling approach can be used to predict regional suitability for a species of interest.     

Habitat requirements, short-term population dynamics and coexistence of native and invasive Impatiens species: a field study

The genus Impatiens (Balsaminaceae) includes three widespread species in the Czech Republic, central Europe: the native I. noli-tangere, and two invasive species, I. parviflora and I. glandulifera, differing in the dynamics of invasion. They all occur in similar habitats and share basic life-history characteristics, which make them a suitable model for studying species traits associated with invasiveness. In this study we investigated differences in habitat requirements of these Impatiens species, their coexistence and short-term population dynamics in the field. We established 84 1 × 1 m permanent plots in five localities where all three species co-occurred. In each plot vascular plant species were determined, their cover estimated and all individuals of Impatiens species counted. Site characteristics including tree canopy cover, soil moisture, nitrogen and carbon content, and slope were measured directly. Nutrients, light, humidity and soil reaction were estimated using Ellenberg indicator values. The presence of I. noli-tangere was strongly correlated with high soil moisture, that of I. parviflora with high tree canopy cover and low soil moisture. Impatiens glandulifera exhibited a unimodal response to tree canopy cover, avoiding both very shaded and fully open sites. The current-year abundances of all species were negatively related to those of congeneric species. These results suggest that the coexistence of Impatiens species in the same habitat is due to microsite differentiation. Further spread of I. glandulifera to new habitats, and reduction of the native I. noli-tangere niche, can be expected in areas where the latter species co-occurs with competitively strong invasive congeners.     

Habitat requirements and local persistence of three damselfly species (odonata: coenagrionidae)

Habitat requirements and population persistence were investigated in three damselfly species, all coastal plain pond specialists: Enallagma recurvatum, E. laterale, and E. pictum. Because of geographic restriction, two are of special concern to conservation, E. recurvatum and E. laterale. We surveyed more than 70 ponds on Cape Cod, Massachusetts, and collected adult presence-absence data during the summers of 1999 and 2000. We achieved a detection rate approaching 100% for each species by visiting each pond up to three times. We looked for relationships between the presence of each damselfly species and presence of specific aquatic vegetation, the presence of the other Enallagma species, and the number of ponds within various distances of the 72 surveyed ponds. Using stepwise logistic regression, we found the following significant associations: E. recurvatum with the rush Juncus militaris; E. laterale with water lilies (Nuphar variegatum and Brasenia schreberi) the damselfly E. pictum, and the number of ponds within 2 km; and E. pictum with the water lily Nymphaea odorata, the damselfly E. laterale, and the number of ponds within 1.5 km and 2.5 km. Presence-absence data were used to calculate turnover and local extinction rates for each species between the two years. E. recurvatum's turnover and local extinction rates (33.3% and 41% respectively) were much higher than either E. laterale (9.8%, 11.5%) or E. pictum (7.7%, 10%). These results suggest that E. recurvatum occurs in a metapopulation, and that patch colonization rates might be important to local population persistence.     

Habitat requirements of Tetanocera elata (Diptera: Sciomyzidae): case study of a dry meadow in western Ireland

1. Terrestrial slugs are pervasive pests of agriculture throughout temperate regions and have the potential to disrupt the germination of seedlings, cause damage to fruiting bodies of crops, and vector plant pathogens.
2. Tetanocera elata Fabricius (Diptera: Sciomyzidae), a widely distributed Palaearctic species, is an obligate mesoparasitoid and predator of pestiferous slugs including Deroceras reticulatum Müller (Stylommatophora: Agriolimacidae). It has the potential to be developed as a native natural enemy in a conservation biological control programme as an alternative to chemical molluscicides.
3. To better understand the ecological requirements of this species, a detailed observational study was conducted at a site in the west of Ireland possessing naturally occurring T. elata populations.
4. Comparison of local patches where T. elata were recovered revealed no association with plant community composition.
5. Taller dead vegetation was associated with T. elata presence throughout the site. Within the area of greatest T. elata aggregation, there was a significantly greater percentage cover of dead vegetation where T. elata occurred. Abundance of T. elata was also significantly correlated to hedgerow proximity. Results of this study are directly applicable for the design of a conservation biological control programme, which effectively satisfies the principal habitat requirements of T. elata populations.

     

Restoration of a tropical island: Cousine Island,Seychelles

Tropical island species and ecosystems are threatened worldwide as a result of increasing human pressure. Yet some of these islands also lend themselves to restoration, as they are physically defined units that can be given focused attention, as long as resources are available and clear conservation targets are set. Cousine Island, Seychelles, is a tropical island that has received such intensive restoration. From a highly degraded island in the 1960s, the island has now been restored to what is believed to be a semblance of the natural state. All alien vertebrates have been eradicated, as have 25 invasive alien plants. Cultivated plants are now confined to one small section of the island. Poaching of nesting marine turtles has been stopped, leading to an increase in turtle breeding numbers. The shearwater population has increased in size with poaching activities under control. The Sooty tern has also returned to the island to breed. The coastal plain has been restored with over 2,500 indigenous shrubs and trees, which have now grown into a forest carpet. There are strict quarantine procedures on the island, keeping it free of rats, mice, various alien invertebrates and potentially invasive alien plants. Three threatened Seychelles endemic land birds (Seychelles warbler, Seychelles magpie robin and Seychelles white-eye) have been introduced and are thriving, with these introductions contributing to both the magpie robin and the white-eye being downgraded from CR to EN (the warbler remains at VU). Ecotourism, and nature conservation for the local inhabitants, have been introduced in a way that does not reduce the improved compositional, structural and functional biodiversity of the island. The result of the restoration effort appears to be sustainable in the long term, although challenges still remain, especially with regards to adequate clean water and a non-polluting power supply on the island. Cousine is thus paving the way in the art and science of tropical island restoration as a legacy for future generations.     

岷山黑熊生境选择的初步分析

1998 年3 月末至9 月, 作者在岷山山系对黑熊的生境选择进行了研究。野外工作中共设置了40 个20 ×20 m²样方和15 个生态因子, 以此为基准进行了定量分析。黑熊生境喜好程度分析表明, 黑熊喜欢选择向阳、坡度较大、避风性适中、郁闭度在30 %～50 %之间的山嵴或山坡面, 选择乔木密度和灌木密度适中、倒木密度和树桩密度较小的生境, 其他如乔木距离、灌木距离、倒木距离和树桩距离以适中为准。主成分分析表明,影响黑熊生境选择的主要因子有5 种, 依次为: 食物丰富度因子(包括乔木密度、灌木密度、乔木距离和灌木距离) 、干扰因子(包括倒木密度、树桩密度、倒木距离和树桩距离) 、地形因子(包括郁闭度、地理性和坡位) 、气候因子(包括避风性和坡向) 和海拔因子。其最适生境状况为: 乔木密度为1 226～1 625根/ hm², 灌木密度为1 425～1 976 根/ hm², 倒木密度为120～240 根/ hm² , 树桩密度为110～230 根/ hm² , 郁闭度为3519 %～4315 % , 地理性为0.6～0.7 (山坡面) , 坡位为0.5～0.7 (中坡位) , 避风性为0.4～0.7 (适中) , 坡向为49.8°～153°(东坡) , 海拔高度为1 993～2 276 m (阔叶林和针阔混交林带) 。     

Divergent character displacement in the song of two allospecies: the Pied Flycatcher Ficedula hypoleuca, and the Collared Flycatcher Ficedula albicollis

Songs of the three flycatcher forms, Ficedula hypoleuca hypoleuca, Ficedula albicollis albicollis and Ficedula albicollis semitorquata , were distinguishable from one another using a multivariate analysis. F. albicollis semitorquata , which has an intermediate song character, is considered to be a primary allopatric form while the nominate subspecies of albicollis is assumed to be dispersed into sympatry with F. h. hypoleuca . The differences in song between the nominate albicollis and F. hypoleuca are accentuated in their zone of sympatry and are mostly due to divergence in the albicollis song. The song is primarily an epigamic vocalization in the two species and conforms to the pattern characteristic of divergent character displacement associated with reproductive behaviour. Two alarm calls are quite similar in the two species and are the main vocalizations associated with territorial combat. Their interspecific territorial behaviour has apparently not been affected in areas of sympatry.