Tests of aggregative preferences of wandering salamanders (Aneides vagrans)

Plethodontid salamanders usually exhibit territorial spacing patterns and behaviors. Previous works suggest that plethodontids from Vancouver Island, Canada lack strong territoriality. In one Vancouver Island species, Aneides vagrans, salamanders may even be found in the field in small aggregations. We investigated preferences of A. vagrans for occupied vs unoccupied cover objects and for cover objects occupied by conspecifics of different age/size classes. We also tested A. vagrans preferences for conspecific vs heterospecific salamanders in an attempt to determine if the lack of territoriality by A. vagrans is species-specific and perhaps related to habitat segregation. A. vagrans did not avoid occupied cover objects or exhibit a preference for occupied vs unoccupied sites. Age class did not affect cover object choice. A. vagrans did not avoid heterospecifics that exhibit the highest degree of resource overlap (Plethodon vehiculum), which we believe might be attributable to a benign and resource-rich habitat, although alternative explanations exist. A. vagrans did avoid syntopic newts (Taricha granulosa), though this is probably due to toxic newt skin secretions.     

Fine‐scale habitat preferences and habitat partitioning by three mycophagous mammals in tropical wet sclerophyll forest,north‐eastern Australia

Abstract Fine‐scale habitat preferences of three co‐occurring mycophagous mammals were examined in a tropical wet sclerophyll forest community in north‐eastern Australia. Two of the three mammal species responded to fine‐scale variation in vegetation and landform around individual trap locations. At a broad scale, the northern bettong (Bettongia tropica), an endangered marsupial endemic to the Australian wet tropics region, showed a preference for ridges over mid‐slopes and gullies, irrespective of forest type. In contrast, the northern brown bandicoot (Isoodon macrourus), a widespread marsupial, displayed a preference for Eucalyptus woodland over adjacent Allocasuarina forest, irrespective of topographic category. The giant white‐tailed rat (Uromys caudimaculatus), a rodent endemic to the wet tropics, showed no particular preference for either forest type or topographic category. A multiple regression model of mammal capture success against three principal habitat gradients constructed from 21 habitat variables using principal component analysis indicated strong species‐specific preferences for fine‐scale vegetation assemblages. Bettongs preferred areas of Eucalyptus woodland with sparse ground cover, low densities of certain grass species, high density of tree stems and few pig diggings. Bandicoots, in contrast, favoured areas in both forest types with dense ground cover, fewer tree stems and greater numbers of pig diggings; that is, characteristics least favoured by bettongs. The striking differences in fine‐scale habitat preferences of these two mammals of similar body size and broad habitat requirements suggest a high degree of fine‐scale habitat partitioning. White‐tailed rats did not show preference for any of the habitat gradients examined.     

Habitat structure and predators: choices and consequences for rodent habitat specialists and generalists

Summary Both habitat structure and risk of predation are thought to influence rodent community composition in different habitats, but experiments on the degree to which these factors determine the use of habitat by rodents are lacking. I sought to discover (1) if cover density altered habitat choice and (2) if cover density affected the vulnerability to predators of two rodents, a habitat specialist and a habitat generalist. In laboratory experiments, the habitat specialist, the red-backed vole (Clethrionomys gapperi), preferred greater densities of both vertical (wall) and horizontal (ceiling) cover. The habitat generalist, the deer mouse (Peromyscus maniculatus), also preferred greater densities of vertical and horizontal cover, but its preferences were weaker and more inconsistent than those of C. gapperi In tests of vulnerability to domestic ferrets, C. gapperi were more vulnerable in arenas with less vertical cover, while P. maniculatus did not differ in vulnerability between the two vertical cover densities used. Vulnerability to predators in differing densities of horizontal cover was not tested because of the reduced differences in preference for this cover type between the rodent species. Risk of predation is one explanation for C. gapper's inherent preference for denser cover.     

Habitat requirements for the conservation of wood cricket (Nemobius sylvestris) (Orthoptera: Gryllidae) on the Isle of Wight, UK

In the UK, wood cricket (Nemobius sylvestris) is a ‘Species of Conservation Concern’, being restricted to only three areas in southern England. Little information is available on the specific habitat requirements of this species. In 2006, a field investigation within three woodlands on the Isle of Wight was undertaken to identify its habitat preferences. Factors positively influencing wood cricket presence within woodlands included the presence of a well-developed leaf litter layer, relatively low ground vegetation cover and height, low canopy cover and relatively short distances between individual populations. Regression models identified the degree of isolation and variables describing vegetation structure as the main predictors for wood cricket presence within woodland fragments. The results of this study indicate the preference of wood cricket for open wooded edges. Conservation efforts for this species should focus on continuation of regular management activities aimed at providing permanent open edge habitat within woodlands, to maintain viable populations.     

Patterns of food and microhabitat resource use by two benthic gobiid fishes

The mechanisms responsible for different patterns of habitat use by two benthic gobiid fishes, Acentrogobius sp. 1 and A. sp. 2, which displayed identical food use but resided in shallow and deep zones of coarse and fine sediments, respectively, in Lake Hamana, Shizuoka Prefecture, Japan, were investigated by field removal and laboratory sediment-grain size selection experimentation. Following field manipulation, involving removal of both species, the distribution patterns of each were found to be similar in both control and manipulated quadrats, suggesting their differential habitat use patterns may be the outcome not of competition but of differing preferences for habitat characteristics. Results of a sediment-grain size selection experiment in the laboratory suggested a weak preference of A. sp. 2 for fine sediment, while A. sp. 1 showed no grain size preference. The observed difference in the distribution patterns between these two species, therefore, may possibly have resulted from, at least in part, a combination of differences in their preference for sediment grain size and other habitat characteristics such as water depth.     

Habitat heterogeneity as the key determinant of the abundance and habitat preference of prey species of tiger in the Chitwan National Park,Nepal

Studies on the relationship between habitat heterogeneity and animal abundance are essential for understanding what determines biodiversity. Transect-based direct observations of eight principal prey species of tiger in the Chitwan National Park (CNP) were used to determine their abundances and habitat preferences. Chital was the most abundant prey species of tiger (Panthera tigris). Each of the prey species had significantly different habitat preferences except sambar deer and chital. Habitat preference was measured using Manly’s preference index, which revealed that short grassland, mixed forest, and riverine forest were the most preferred habitats of the prey species. The results indicate that large species of deer tend to be found in more diverse habitats than small species, except muntjac. The abundance of the principal prey species of tiger was positively correlated with habitat heterogeneity. The habitat, which contributes significantly to the heterogeneity of the landscape, is grassland in large patches of forest. The ongoing increase of forest cover in the CNP has led to a reduction in the area of grassland, which may negatively affect the abundance of the prey species of tiger. Hence, it is suggested that the restoration of landscape heterogeneity is the best way to manage the habitats in the CNP.     

Combining larval habitat quality and metapopulation structure – the key for successful management of pre-alpine Euphydryas aurinia colonies

This study aims to analyse larval habitat preferences and landscape level population structure of the threatened Marsh Fritillary butterfly, Euphydryas aurinia, and discusses implications for the conservation and management of this strongly declining species in central Europe. Whereas current management strategies are mainly based on studies of habitat requirements of adult individuals, we intend to emphasise larval habitat quality and population processes at the landscape level as additional key factors. Microhabitat preference analysis of egg-laying females showed that eggs were predominantly laid on prominent large-sized host plant individuals. Additionally, when Succisa pratensis was used as a host plant (as opposed to Gentiana asclepiadea), host individuals in open vegetation structure were preferred. Optimal oviposition conditions were present in recently abandoned calcareous fen meadows and at the edges of such meadows currently in use. A two-year patch-occupancy study in the northern pre-alpine region of south-west Germany indicated that E. aurinia lives in a metapopulation. In a logistic-regression model, patch size, isolation, and habitat quality explained 82% of the observed patch-occupancy pattern in 2001. Our data suggest that a suitable conservation strategy must incorporate both the conservation of a network of suitable habitat patches, and efforts to maximise local habitat quality by ensuring that host plants can grow to a large size and are surrounded by sparse and low vegetation cover.     

Does prescribed burning mean a threat to the rare satyrine butterfly Hipparchia fagi? Larval-habitat preferences give the answer

The ecological effects of fire management, especially regarding arthropods are poorly investigated. Burning in winter was assumed to pose a threat to butterfly species hibernating as larvae. To assess the impact of prescribed burning on population viability, we analysed larval-habitat preferences of the highly endangered, xero-thermophilous butterfly Hipparchia fagi in vineyards of the Kaiserstuhl region (southern Germany). Microhabitat preference analyses for mature larvae and egg-laying females revealed a preference of H. fagi for Bromus erectus-dominated communities with sparse vegetation coverage and a distinct tuft growth of the host plant B. erectus on microclimatically benefited slopes. We explain the preference of B. erectus by a preference of vegetation structure. The grass tufts offer a suitable climatically buffered living space for larvae. Egg deposition took place on dry substrate at positions of high solar radiation, thus adapted to hot and dry microclimate. As the larval habitat was sparsely vegetated as well as generally legally protected, fire management was not applicable and therefore not affecting the populations. We think it is conceivable that H. fagi, occurring here at its northern range limit, might expand its larval habitat into denser, combustible B. erectus stands in the course of global warming. A change in habitat preferences would necessitate a re-evaluation of management options.     

A MULTIFACTORIAL BEHAVIORAL STUDY OF COEXISTING DROSOPHILID SPECIES IN NATURE

A multifactorial experiment was performed to differentiate among sympatric drosophilid species by their responses to several variable factors when selecting an oviposition site in nature. D. busckii, D. affinis, and S. pallida were significantly more photonegative when ovipositing 150 cm above the ground than when ovipositing 30 cm above the ground. D. busckii showed the greatest effect of height on photoresponse. D. affinis was the most photonegative at either height. There was no evidence for photobehavioral differentiation of the four species studied between two collecting sites within the habitat. Similarly, there was no difference in oviposition-site preference between flies laying eggs in the morning and the afternoon. Three of the four sympatric species can be distinguished from the others by their unique behavioral profiles, which are probably responsible for maintaining niche separation.     

Sex Differences in Mate Preference Between Two Hybridizing Species of Poeciliid Fish

When hybridization between two species in secondary contact is costly, natural selection should favor pre‐mating isolation barriers. The invasive Gambusia affinis has been introduced to habitats of a closely related species, the endangered Gambusia nobilis. Although other Gambusia species readily hybridize in secondary contact, previous studies in this system found low abundance of hybrids in sympatry. To examine whether hybridization is limited by behavioral pre‐mating isolation that may have evolved in allopatry, I examined each species’ mating preferences using individuals from allopatric populations in male and female visual/olfactory association preference tests as well as open mating tests with and without male–male competition. Gambusia affinis and G. nobilis males had significant association preference for conspecific females in visual/olfactory tests. Only G. nobilis females had statistically significant preference for conspecific males. In open mating tests, males of both species had lower chase times overall when in competition, but there was no difference in number of copulation attempts. Males of both species had higher copulatory success rates with conspecific females when in competition, suggesting females may exert some control over copulation success of males. These results suggest that there are differences in mating preferences between these species. This mate choice may act as a pre‐mating isolating barrier to reduce hybridization in sympatry, a proposed threat to the endangered G. nobilis.     

Functional responses in the habitat selection of a generalist mega‐herbivore,the African savannah elephant

Resource selection function (RSF) models are commonly used to quantify species/habitat associations and predict species occurrence on the landscape. However, these models are sensitive to changes in resource availability and can result in a functional response to resource abundance, where preferences change as a function of availability. For generalist species, which utilize a wide range of habitats and resources, quantifying habitat selection is particularly challenging. Spatial and temporal changes in resource abundance can result in changes in selection preference affecting the robustness of habitat selection models. We examined selection preference across a wide range of ecological conditions for a generalist mega‐herbivore, the African savanna elephant Loxodonta africana, to quantify general patterns in selection and to illustrate the importance of functional responses in elephant habitat selection. We found a functional response in habitat selection across both space and time for tree cover, with tree cover being unimportant to habitat selection in the mesic, eastern populations during the wet season. A temporal functional response for water was also evident, with greater variability in selection during the wet season. Selection for low slopes, high tree cover, and far distance from people was consistent across populations; however, variability in selection coefficients changed as a function of the abundance of a given resource within the home range. This variability of selection coefficients could be used to improve confidence estimations for inferences drawn from habitat selection models. Quantifying functional responses in habitat selection is one way to better predict how wildlife will respond to an ever‐changing environment, and they provide promising insights into the habitat selection of generalist species.     

Rodent acorn selection in a Mediterranean oak landscape

Quercus suber, Quercus ilex and Quercus coccifera (Cork, Holm and Kermes oaks, respectively) are common evergreen oak species that coexist in the landscapes of the western part of the Mediterranean basin. Rodents are the main acorn predators and thus one of the main factors for understanding recruitment patterns in oaks. In this paper we analyse to what extent mice prefer acorns from one oak species over another in three oak species studied using acorn removal experiments and video tape recordings. Twenty labelled acorns from each of the three Quercus species (60 acorns) were placed in 40 cm×40 cm quadrats on each plot. Because selection might vary as a result of the vegetation context, we performed the trials in the five main vegetation types within the study area (four replicates in each vegetation type) in order to control for habitat influences on rodent acorn preferences (a total of 20 plots). The removal of 1,200 acorns occurred within 68 days. Mice removed 98.7% of the acorns. Q. ilex acorns were preferred over Q. suber and Q. coccifera in all vegetation types except in pine forest, where no acorn preferences were detected. Acorn removal rates differed with vegetation type, correlating positively with shrub cover. The distance at which acorns were displaced by rodents (mean =4.6 m±5.1 SD) did not differ between acorn species, but varied among vegetation types. Bigger acorns of Q. coccifera were selected only after Q. ilex and Q. suber acorns were depleted, while no size selection was detected for the latter two species. Thus, we conclude that rodents show preference for some oak acorns and that landscape context contributes significantly to rodent activities and decisions.     

Active military training areas as refugia for disturbance-dependent endangered insects

Oedipoda caerulescens (blue-winged grasshopper) and Cicindela hybrida (northern dune tiger beetle) are protected insects in Germany and elsewhere. They are known to occur on sparsely vegetated, sandy soil. Populations of the two insects were evaluated in relation to physical soil disturbance on four military training areas in Germany to determine if the military disturbance regime occurring there is conducive to the survival of the species and to provide insight into the nature of the disturbance that may be necessary as conservationists seek ways to maintain, establish or re-establish suitable habitat. Adults of O. caerulescens exhibited statistically significant preference for areas with between 60% and 100% surface disturbance, corresponding to 50–70% plant cover, depending on the location. C. hybrida adults preferentially occupied areas with >40% disturbance resulting in an average of 61% plant cover. The results confirm suggestions that both species are disturbance-dependent. Military training areas represent some of the last, large remnants of sparse, dry, sandy grasslands in Europe. The nature of land-based military training creates suitable habitat patches as well as habitat connectivity needed for the maintenance of metapopulations. As a result, military training areas represent some of the last remaining vestiges of a habitat and disturbance regime that are highly favored by O. caerulescens and C. hybrida and other species with similar habitat requirements.     

Habitat correlates of the distribution and biomass of Seychelles' reef fishes

Synopsis Relationships between quantitative measures of habitat type and the biomass of Chaetodon, Scarus and Parupeneus species were investigated across 35 reef sites in the Inner Seychelles Group. Multiple regression was used to determine the proportion of variance in biomass between sites which could be explained by depth, exposure, vertical relief, topographic complexity, live coral cover, coral rubble cover, rock cover, sand cover, underlying carbonate substrate, underlying sand substrate, underlying rock substrate and an index of fishing intensity. A significant proportion of the variance in biomass was explained by habitat variables and the index of fishing intensity for 7 of 12 Chaetodon species (23–52% of variance explained), 3 of 6 Parupeneus species (33–40%), and 10 of 13 Scarus species (14–46%). Within genera, different groups of habitat variables explained the variance in biomass for different species and, of the variables studied, only the proportion of underlying sand substrate failed to explain a significant proportion of the variance in biomass for any species. Quantitative relationships between the biomass of Chaetodon and habitat were often in accordance with those suggested by previous studies of their ecology, life-history and distribution at other Indo-Pacific locations. However, the habitat associations of the Parupeneus and some Scarus species have not been studied at other locations and clearly warrant further investigation. It was concluded that habitat was an important determinant of the distribution of many Seychelles reef fishes, but that the habitat variables examined were rarely the most important determinant of biomass. However, the inclusion of a procedure to collect habitat data provided a useful means by which to reduce the unexplained variance associated with visual census biomass estimates and therefore improves the possibility of elucidating the effects of other factors on the biomass of Seychelles reef fishes.     

Temperature influences habitat preference of coral reef fishes: Will generalists become more specialised in a warming ocean?

Climate change is expected to pose a significant risk to species that exhibit strong behavioural preferences for specific habitat types, with generalist species assumed to be less vulnerable. In this study, we conducted habitat choice experiments to determine how water temperature influences habitat preference for three common species of coral reef damselfish (Pomacentridae) that differ in their levels of habitat specialisation. The lemon damselfish Pomacentrus moluccensis, a habitat specialist, consistently selected complex coral habitat across all temperature treatments (selected based on local average seasonal temperatures naturally experienced in situ: ambient winter 22°C; ambient summer 28°C; and elevated 31°C). Unexpectedly, the neon damselfish Pomacentrus coelestis and scissortail sergeant Abudefduf sexfasciatus, both of which have more generalist habitat associations, developed strong habitat preferences (for complex coral and boulder habitat, respectively) at the elevated temperature treatment (31°C) compared to no single preferred habitat at 22°C or 28°C. The observed shifts in habitat preference with temperature suggest that we may be currently underestimating the vulnerability of some habitat generalists to climate change and highlight that the ongoing loss of complex live coral through coral bleaching could further exacerbate resource overlap and species competition in ways not currently considered in climate change models.     

Habitat preferences of ungulates in closed savanna of central Africa

Habitat preferences of fifteen species of ungulate were studied between July and September 1975 in dry savanna woodland of Mwabvi Game Reserve, Southern Malawi, Central Africa. Thirteen vegetation types were recognized using vegetation transects and plotless sampling techniques (but three of these are omitted from further analysis here either because of the difficulty of sampling in a representative manner or because of their infrequency). A combination of six methods was used to study habitat preferences since each had particular advantages or disadvantages, although quadrat sampling of fresh pellets/spoor counts was the most satisfactory and so used predominantly. The most common and widely distributed species was the Greater kudu, although abundance estimates in different habitats varied according to the method used. Pellet/spoor counts showed heavy use of open grassland by kudu which was not detected by daytime drives. Temporal patterns of activity indicated that the species was moving into more closed woodland during the day and only coming out into open grassland at night. Relative abundance estimates of a species may also be affected by changing group size. The mean group size of kudu increased in more open vegetation, although group size in warthog did not show this relationship. Some species, e.g. impala, reedbuck, and klipspringer showed narrow habitat preferences, occurring in only one or a few vegetation types, whilst others, e.g. kudu, sable, duiker, suni, and grysbok showed much broader preferences. Mixed Colophospermum mopane /Acacia woodland had the highest species diversity but rather low abundance. Open grassland and Acacia/Albizia woodland had high species diversity together with the greatest abundance of ungulates. Open Julbernardia/Diplorynchus, Brachystegia/Julber-nardia woodland, and particularly Pterocarpus/Diplorynchus/Combretum hill woodland had the lowest species diversity and abundance of ungulates. Ready access to cover and availability of suitable food plants probably account for the preferences of certain vegetation types over others, whilst the different behavioural ecology and food preferences of each species account for individual species differences. Access to water probably also determines habitat preferences in particular species, and studies during the wet season may show different distributions.     

The fairy shrimp genus Branchinella Sayce (Crustacea: Anostraca: Thamnocephalidae) in Western Australia,including a description of four new species

The genus Branchinella is diverse in Western Australia, with 18 species, including four new species described here. B. complexidigitata n. sp. is characterized by an intricate frontal appendage, unlike any within the genus. The other three are less remarkable; B. halsei n. sp. is like B. lyrifera, B. kadjikadji n. sp. belongs to the B. affinis group and B. nana n. sp. is similar to B. simplex; similarities are based on frontal appendage and to a lesser extent on the second antennae and penis. Only two species, B. affinis and B. longirostris, are common and widespread; many of the remainder being localized endemics. The high diversity in Western Australia is explained by broad latitudinal range, habitat diversity, and great age and isolation of the landscape.     

Maximum entropy model: Estimating the relative suitability of cetacean habitat in the northern Savu Sea,Indonesia

An understanding of cetacean distribution is necessary to gain insights into crucial ecological processes for species conservation management. However, cetacean habitat preference and distribution in the northern Savu Sea, Indonesia, are still poorly understood. We use maximum entropy modeling with five environmental predictors to describe habitat preference and distribution of seven cetacean species in the northern Savu Sea. Our study confirms that static predictors are the most important variables in explaining habitat preferences of seven cetacean species in the northern Savu Sea. Seasonally, each cetacean species has a different environmental preference. Globicephala macrorhynchus prefers the open nearshore areas adjacent to deep waters. Stenella attenuata is associated with nearshore habitats and higher productivity areas. Stenella longirostris prefers nearshore habitat during coastal upwelling events. Tursiops truncatus prefers nearshore sheltered habitat. Grampus griseus habitats are highly related to depth and steep gradients around the isobaths of 200–1,000 m. Feresa attenuata are associated with deep waters and cooler sea temperature. Pseudorca crassidens prefers protective bays with productive waters. This study provides important information for reviewing marine spatial plans of the northern Savu Sea, specifically on managing species fisheries interaction, optimizing surveillance, and regulating marine traffic.     

Habitat preference of the Preuss's guenon<Emphasis Type="Italic">(Cercopithecus preussi), on Bioko island,Equatorial Guinea</Emphasis>

The Press's guenon (Cercopithecus preussi) is considered to be one of the most threatened African primates. There is little information on the ecology and status of this primate on Bioko island, where it is found in the form of an endemic subspecies. The Press's, guenon shows preference for theSchefflera forest and the mountain habitat on Bioko island. As on the mainland they also have semitterrestrial habits and are found usually at the understorey of the forest. Competitive exclusion between this guenon and other guenon species could be an explanation of these ecological preferences. Habitat use and vertical stratification of the activity in the forest canopy seem to reduce competition with other sympatric primate species that inhabit on the island. Habitat destruction, and isolation in a reduced habitat, show to be the major threats for the survival of this primate on Bioko island.