Morphological and ecological divergence in two populations of European glass lizard, Pseudopus apodus (Squamata: Anguidae).

Filesnakes (Acrochordus arafurae) are large (to 2 m), heavy-bodied snakes of tropical Australia. Sexual dimorphism is evident in adult body sizes, weight/length ratios, and body proportions (relative head and tail lengths). Dimorphism is present even in neonates. Two hypotheses for the evolution of such dimorphism are (1) sexual selection or (2) adaptation of the sexes to different ecological niches. The hypothesis of sexual selection is consistent with general trends of sexually dimorphic body sizes in snakes, and accurately predicts, for A. arafurae, that the larger sex (female) is the one in which reproductive success increases most strongly with increasing body size. However, the sexual dimorphism in relative head sizes is not explicable by sexual selection.The hypothesis of adaptation to sex-specific niches predicts differences in habitats and/or prey. I observed major differences between male and female A. arafurae in prey types, prey sizes and habitat utilization (shallow versus deep water). Hence, the sexual dimorphism in relative head sizes is attributed to ecological causes rather than sexual selection. Nonetheless, competition between the sexes need not be invoked as the selective advantage of this character divergence. It is more parsimonious to interpret these differences as independent adaptations of each sex to increase foraging success, given pre-existing sexually-selected differences in size, habitat or behavior. Data for three other aquatic snake species, from phylogenetically distant taxa, suggest that sexual dimorphism in food habits, foraging sites and feeding morphology, is widespread in snakes.

Habitat utilization by Sigmodon hispidus, Reithrodontomys fulvescens, and Oryzomys palustris was compared to habitat availability, by determining if capture locations were random samples of the trapping grid with respect to mean cover of 10 plant species. A methodology, designed for this purpose and detailed in a companion paper (Kincaid and Bryant 1983), was used in which the Euclidean distance between mean vectors representing habitat utilization and availability was compared to that for random draws from the available resource spectrum. This distance (the habitat differential) was partitioned into separate components representing differential composition and dif- ferential productivity in the occupied habitats. Interspecies differences in habitat utilization were also considered relative to habitat availability. Each species utilized a habitat subset that differed significantly from the average available habitat. Sigmodon and Reithrodontomys were the most similar species, differing only in the pattern of their associations with grasses and cover. Oryzomys usually occurred in habitats dominated by dicots. Deviations for all species were usually attributable to differential composition, except for Sigmodon and Reithrodlontomvs in winter, when both exhibited significant productivity components. Habitats occupied by these rodents were significantly less heterogeneous than random subsets, but only Ory- zomys habitat always had reduced dimensionality of variation relative to that of the available habitat. Differential responsiveness to patterns of statistical variation in a patchy environment can be sufficient to produce habitat separation and is offered as a neutral model for the examination of higher-order processes.

BackgroundCobia (Rachycentron canadum) is a cosmopolitan marine fish that inhabits tropical, sub-tropical, and temperate marine and estuarine waters and supports a major recreational fishery along the U.S. Atlantic and Gulf of Mexico coasts. Recent changes in U.S. cobia management have sparked controversy and highlighted limitations in our understanding of the species’ biology. This study utilized pop-up satellite archival tags (PSATs) to assess the movements, habitat utilization, and post-release survival of cobia that summer in Virginia waters.ResultsPSATs were deployed on 36 cobia caught in Virginia state waters using standard recreational techniques in August 2016 and August–September 2017. All fish larger than 37-in total length were tagged, and several of these were hooked deeply. No mortalities were inferred for the 20 cobia whose PSATs reported and remained attached for at least 10 days. Premature release of tags was an issue, and only five PSATs remained attached for the full 180-day deployment period. Some fish undertook long seasonal movements, with one individual entering Florida waters well beyond the current stock demarcation boundary. Several fish overwintered in waters offshore of North Carolina near the continental shelf break. Cobia demonstrated a strong affinity for waters ≥ 20 °C, even in the coldest months. They displayed distinct seasonal differences in habitat utilization, spending high proportions of their time near the surface during the summer months and extended periods at depths ≥ 20 m in the winter months.ConclusionsCobia are hardy fish with low post-release mortality when handled respectfully. Their migratory patterns are clearly temperature driven, and seasonal changes in habitat utilization means varied vulnerability to fishing gears. Further understanding of cobia migratory patterns, particularly in conjunction with spawning activity, is needed to best manage this species.

Crab‐eating zorros, Cerdocyon thous, in Amazonian Brazil weighed 5.2 kg (S.D. 0.6, n= 19), exhibited no sexual dimorphism, lived in social units of 2‐5 adults of > 1 year old, and occupied territories (restricted polygons) of 532 ha (range 48‐1042 ha, n= 21). The zorros were omnivorous, fruit being the most frequent food (occurring in 57% of 72 faeces in the dry season) comprising 26.4% by volume of undigested faecal remains. Insects were frequently eaten (86%), and vertebrates rarely (15.2%). Zorros were territorial. The ranges of neighbours overlapped minimally and were very stable in configuration, both from month to month and between dry and wet seasons. Members of each social unit shared on average 88.3% of 200 × 200m grid cells within their territory. Members of male‐female breeding pairs were within 100 m of each other for 63% of the activity period, their proximity being greatest during the mating season (July‐August). Parents travelled in close company with their adult‐sized offspring, and stayed within 100 m for up to 93.3% of the activity period. Territories differed in habitat composition. Overall, zorros spent most time in wooded savanna (33.9%) and scrub (30.5%). They did not utilize habitats in direct proportion to their availability, using some more (e.g. scrub) and some less (e.g. open savanna) than expected. Habitat preferences differed between wet and dry seasons, with elevated habitats being favoured during the wet season. Individuals differed in their habitat utilization, and parents had different habitat usage to their yearling offspring; this difference was exaggerated in the dry season when the yearlings used lowlying habitats apparently disfavoured by the parents. Differences in habitat utilization between group members were least in the wet season, when widespread flooding forced the shared use of higher ground. Each of two social units larger than two individuals comprised a pair and their three adult‐sized offspring (totalling five males and one female). In three cases, a yearling daughter was present in the breeding season, but none of these bred. Non‐breeding offspring were seen frequently in the whelping area and in close company with the breeding pair's cubs. This is the first proof of group‐living in South American zorros. Five dispersal events were monitored, and revealed a ‘good neighbour’strategy in which newly formed pairs set up their territories adjoining their natal territories. In each case individuals returned intermittently to their original territory where they were in close and amicable company with their parents. One male, having dispersed, returned home frequently without his mate to tend the next generation of his parents’cubs. Of four dispersing males, two subsequently returned to their natal group following the deaths of their mates at least 3‐13 months after their initial dispersal, in one case after breeding elsewhere.

To adequately describe seasonal rhythms in habitat utilization by fish communities, observations are needed that occur at a relatively high frequency and over large temporal windows. For the first time, images col- lected from a cabled video-observatory (the western Mediterranean expandable SEAfloor OBservatory; OB- SEA) were utilized to examine habitat utilization by coastal fishes. Over the course of a year, hourly digital images of the water column and an artificial reef were obtained dur- ing daylight hours. For each image, the total number of species, an estimate of the abundance of individuals, and the Shannon Diversity Index were quantified. A total of 22 fish species commonly associated with nearshore western Mediterranean habitats were identified, and significant spatial (water column vs. artificial reef), seasonal (spring, summer, autumn, and winter), and daily (morning, midday, and sunset) differences in habitat utilization occurred. Four species (Diplodus vulgaris, Diplodus cervinus, Diplodus sargus, and Scorpaena porcus) were associated with the artificial reef, while one species (Pagrus pagrus) chiefly occurred in the water column. Chromis chromis and Diplodus annularis occurred at the site more frequently in the winter and autumn, respectively, while 14 other species utilized the site more frequently in either the spring (8 spp) or summer (6 spp). In addition, Dentex dentex and Spicara maena occurred more frequently at sunset, while D. cer- vinus displayed a crepuscular rhythm (occurring more frequently in the morning and at sunset). Species diversity was highest in the summer and lowest in the winter. If not taken into account when planning in situ sampling, such seasonal and/or diel differences may lead to spurious estimates of population sizes and biodiversity. We suggest that cabled video-observatories offer a non-invasive and reliable technology for faunistic sampling and population assessment in coastal water of the Mediterranean and likely elsewhere.

In the first part of this paper data are presented on the habitat segregation of the reptile species of Lake Prespa National Park. Twenty species of reptiles are present in the study area. Most of them are of East-Mediterranean origin, some are Balkan endemics and a few are of northern origin. Systematic surveys and counts of reptiles were conducted in each of the following habitats: marshes and reedbeds, wet meadows, rocky coastal areas and sandy beaches, cultivated land, grazing lands, mixed deciduous, oak and beech forests, sub-alpine and alpine meadows. A list is provided of the typical reptile species occurring in each of these habitats, with notes on abundance and habits. The highest reptilian diversity was found in man-made/modified habitats, namely the farmland zone, which structurally is the more diversified. There was a dramatic fall of species richness with increasing altitude. The second part of the paper describes qualitative differences in habitat utilization among the members of the two major reptilian groups, lizards and snakes. The Sand Lizard Lacerta agilis is found exclusively in the alpine and subalpine grasslands above 1600 m. asl., the Common Wall Lizard Podarcis muralis is the more euryecous while all other Lacertids show a clear specialization in habitat use though retaining various degrees of overlap. Among snakes the Adder Vipera berus is restricted to high mountain grasslands, the two Natrix species are common and more or less confined to areas close to the lakes while the Nose-horned Viper Vipera anmmodytes the third commonest species of the area prefers rocky/stony slopes.The notes on habitat utilization by the remaining species of snakes are only of indicative value because of small number of observations.

Differential habitat utilization by size classes of map turtles, Graptemys geographica, was examined in the Raystown Branch of the Juniata River, Pennsylvania. A total of 924 captures or sightings was made of 92 males, 76 females, and 11 juveniles. Significant positive relationships were found between size (carapace length) and four variables: distance from shore, water depth, surface current and swimming speed. Medium-sized turtles were pushed off basking sites by large turtles significantly more often than the inverse. Relative swimming speeds, basking interactions, and predator avoidance may all play a role in size-related differential habitat utilization.

The last surviving wild population of the Kashmir red deer (Cervus elaphus hanglu) or Hangul inhabits the Dachigam National Park located near Srinagar city of Kashmir, India. This paper presents data from February 2001 to December 2009 on habitat use patterns and food habits of the Kashmir red deer. Investigations based on surveys along trails indicate that Hangul showed significant differences in the use of different habitat types (F = 6.49; P = 0.001) between seasons. Males showed significant differences in habitat utilization both within a season (F = 3.63; P ≤ 0.013) and between seasons (F = 1.50; P ≤ 0.087). Females showed differences in their habitat use within season but not between seasons (F = 14.771; P ≤ 0.577). Surveys showed the deer predominantly using the lower and middle altitudes (1700–1900 m and 1900–2300 m) with no significant gender differences. The riverine and mixed oak forests showed the highest mean deer pellet density/ha (153.71 ± 173.43, n = 418 and 188.60 ± 56.41, n = 114, respectively). The grassy/rocky cliff habitat showed the lowest mean pellet density/ha (55.92 ± 18.32, n = 228). The Hangul diet constituted mainly of dicotyledonous shrubs and trees (45.45 and 80.77%), forbs/herbs (36.36 and 19.23%), monocotyledon grasses and herbs (18.18 and 16.22%) in spring and winter, respectively. Summer diet comprised 42.86% forbs, 19.05% grass/sedges and 38.10% browses. In autumn, Hangul fed mainly on dicotyledonous shrubs. The habitat use patterns of Hangul are comparable with those of the European red deer and are influenced by availability of food, cover, shelter, altitude, slope, aspect and the level of disturbance. The habitats with ideal conditions for utilization but with a meager disturbance were avoided by Hangul. Recommendations are given for better and effective management, protection and conservation of this small and isolated population of red deer.

Wild waterbirds, and especially wild waterfowl, are considered to be a reservoir for avian influenza viruses, with transmission likely occurring at the agricultural-wildlife interface. In the past few decades, avian influenza has repeatedly emerged in China along the East Asian-Australasian Flyway (EAAF), where extensive habitat conversion has occurred. Rapid environmental changes in the EAAF, especially distributional changes in rice paddy agriculture, have the potential to affect both the movements of wild migratory birds and the likelihood of spillover at the agricultural-wildlife interface. To begin to understand the potential implications such changes may have on waterfowl and disease transmission risk, we created dynamic Brownian Bridge Movement Models (dBBMM) based on waterfowl telemetry data. We used these dBBMM models to create hypothetical scenarios that would predict likely changes in waterfowl distribution relative to recent changes in rice distribution quantified through remote sensing. Our models examined a range of responses in which increased availability of rice paddies would drive increased use by waterfowl and decreased availability would result in decreased use, predicted from empirical data. Results from our scenarios suggested that in southeast China, relatively small decreases in rice agriculture could lead to dramatic loss of stopover habitat, and in northeast China, increases in rice paddies should provide new areas that can be used by waterfowl. Finally, we explored the implications of how such scenarios of changing waterfowl distribution may affect the potential for avian influenza transmission. Our results provide advance understanding of changing disease transmission threats by incorporating real-world data that predicts differences in habitat utilization by migratory birds over time.

The a priori null hypotheses that responses to donor, orangethroat darter Etheostoma spectabile, johnny darter Etheostoma nigrum, logperch Percina caprodes, slenderhead darter Percina phoxocephala and blackside darter Percina maculata, extracts would be absent in the three test species, orangethroat darter, johnny darter and logperch, was rejected. This was because orangethroat and johnny darter responded with decreased activity to skin extracts derived from conspecifics and from other members of the assemblage. In contrast, logperch were notable by their lack of a detectable response to any species. Similarities and differences in habitat utilization are seen as a possible basis for these responses.

A discriminant analysis on vegetational variables was performed in order to determine differences in habitat utilization by two sympatric Chilean rodents. Akodon olivaceus brachiotis is associated with vegetational variables that provide greater cover from above. Oryzomys longicaudatus philippii, on the other hand, is related with structural variables such as foliage density, which provide dense areas with thick understory that offer protection from a horizontal viewing. A clear relationship was found between shrub and herbaceous cover and length of species hindfoot.

Populations of Peromyscus polionotus and Mus musculus following invasion of a 9-acre cornfield abandoned for one year were inversely related. This inverse relationship, plus differences in habitat utilization, suggested interaction between the two species of rodents. Results showed that the interaction between populations of P. polionotus and M. musculus , observed by Caldwell (1964) and Caldwell and Gentry (1965) in fenced enclosures, may also occur in a natural situation where emigration and immigration are present. The P. polionotus population reached a peak in September 1963 and gradually declined to an unusually low level by February 1964. It is speculated that the quantity and quality of available food may have been a significant influence on the old-field mouse population and that M. musculus reacted opportunistically when the P. polionotus population declined. Whether this interaction was competition for food or space, aggressive competition between individuals or a more subtle relationship could not be determined.

Polynuclear aromatic hydrocarbons (PAHs) from oil were present in some shrimp from Port Valdez, site of a ballast water treatment facility at the Alyeska Alaska Marine Terminal (AMT). Low-level petrogenic PAH concentrations were generally restricted to shrimp eggs in the vicinity of the AMT and extended along the southern shore of Port Valdez to Anderson Bay. Eggs had greater lipid content than other tissues and thus were the most vulnerable biological compartment to hydrocarbon accumulation. Petrogenic hydrocarbons were not observed in shrimp muscle and cephalothoraxes; thus, these tissues do not pose a human health risk. Risk for children older than age 2 years and adults consuming eggs also was low except for two unusual samples (of 32), collected about 17 km west of the treatment facility. In general, PAH loads were consistent with local time series data in other species. We infer that the accumulation mechanism was dissolved uptake from water, consistent with passive sampler observations completed more than a decade earlier. Hydrocarbon levels in the majority of samples were below toxic thresholds. Total PAH accumulation was substantially greater in some pink shrimp than in other species, thus differences in habitat utilization (muddy vs. rocky substrate) are potentially important.Electronic supplementary materialThe online version of this article (doi:10.1007/s00244-016-0279-3) contains supplementary material, which is available to authorized users.

Multivariate analysis on 15 habitat variables and quantitative data on foraging and interactive behaviour were used to investigate habitat selection in the White‐plumed Honeyeater (Lichenostomus penicillatus) and the Fuscous Honeyeater (Lichenostomus fuscus) at an area of sympatry in woodland in New England Tablelands. Thirty‐nine plots from four sites were used to examine significant differences in habitat utilization during the breeding period. The White‐plumed Honeyeater associated strongly with narrow belts of riverine Casuarina while the Fuscous Honeyeater was associated with Eucalyptus in the extensive eucalypt woodland. The narrow ecotone was used by both species, but the two occurred together only in an extremely narrow zone. Changes in foraging activities were observed between this overlap zone and non‐overlap zone. Both niche breadth and overlap in relation to four measures of foraging were reduced in plots where species were in joint occurrence compared with where they were not, although overlap in most measures of foraging remained high. The number of encounters between the two highly aggressive and abundant species was not great. Thus, the species appear generally to avoid each other. The observed spacing pattern may result from prior experience of intense aggressive interactions. Distinct habitat features could provide easily recognized cues for the maintenance of local horizontal separation. Other factors such as slight differences in morphology, habitat preference, foraging and physiology may enhance differences in habitat selection.

Native and native-stocked brown trout (Salmo trutta) in Lake Tesse, a regulated hydroelectric reservoir (southern Norway), were spatially segregated according to size: small individuals occurred mainly in the epibenthic habitat and larger individuals mainly in the pelagic habitat. In contrast, all size groups of non-native stocked brown trout were mostly restricted to the epibenthic habitat. Age-specific lengths were generally larger for non-native than for native stocked trout, which were larger than native fish. However, growth rate between age 3 and 4 was significantly lower for non-native stocked fish than for native and native stocked fish. Differences in body length were mainly due to strain but also to some extent to habitat. Native fish had significantly fuller stomachs in the pelagic than in the epibenthic habitat in summer. Epibenthic non-native fish had significantly fuller stomachs than native and native stocked fish in August but not in July. Native and native stocked fish fed mainly on surface insects and planktonic crustaceans in both habitats. We hypothesize that the non-native brown trout stocked in Lake Tesse do not use the pelagic habitat in the home lake and are therefore less adapted to utilize such habitat than populations originating from lakes where pelagic habitat is available.