Spatial ecology of a threatened python (Morelia spilota imbricata) and the effects of anthropogenic habitat change

Abstract Large predators play important ecological roles, but often are sensitive to habitat changes and thus are early casualties of habitat perturbation. Pythons are among the largest predators in many Australian environments, and hence warrant conservation‐orientated research. Carpet pythons (Morelia spilota imbricata) have declined across much of south‐western Australia presumably because of habitat clearance and degradation. Information on habitat use, home range sizes and movements is needed to plan for the conservation of this important predator. We studied pythons at two study sites (Garden Island and Dryandra Woodland) with markedly different climates, habitat types and disturbance histories. We surgically implanted radio‐transmitters in 91 pythons and tracked them for periods of 1 month to 4 years. Dryandra pythons remained inactive inside tree hollows during cooler months (May–September), whereas some (especially small) pythons on Garden Island continued to move and feed. Overall weekly displacements (mean = 100–150 m) were similar at the two study sites and among sex/age classes, except that reproductive females were sedentary during summer while they were incubating eggs. Home ranges averaged 15–20 ha. Adult male pythons had larger home ranges than adult females at Dryandra, but not at Garden Island. Radio‐tracked snakes at Dryandra exhibited high site fidelity, returning to previously occupied logs after long absences and reusing tree hollows for winter shelter. Many of the logs used by snakes had been felled during plantation establishment >70 years ago, with little subsequent regeneration of source trees. In contrast, Garden Island snakes usually sheltered under dense shrubs. Habitat usage was similar among different sex/age classes of snakes at each site, except that juvenile pythons were more arboreal than adults. Although carpet pythons demonstrate great flexibility in habitat use, certain habitat elements appear critical for the persistence of viable populations. Fire plays a central role in this process, albeit in complex ways. For example, low‐intensity fires reduce the availability of hollow logs on the ground at Dryandra and fail to regenerate shrub thickets required by prey species. Paradoxically, high‐intensity fires stimulate shrub thickets and fell trees creating new logs – but might also threaten overwinter trees. Thus, the impact of disturbances (such as wildfires) on the viability of python populations will be mediated in complex ways by alteration to important microhabitats such as vegetation cover or log availability. At Dryandra, landscape management should include occasional fire events to generate new logs as well as shrub thickets used by prey. Strategic burning may also be required at Garden Island to regenerate some vegetation communities.     

The effects of prey,habitat heterogeneity and fire on the spatial ecology of peninsular Diamond Pythons (Morelia spilota spilota: Pythonidae)

Understanding an organism's home range is an important component of effective wildlife management. However, home ranges can vary spatially and temporally within and between populations. Landscape ecology theory can provide a framework for understanding spatio‐temporal variability in animal traits. We used radio‐telemetry in a population of diamond python Morelia spilota spilota Lacépède (Pythonidae) from a biologically rich and structurally heterogeneous reserve in eastern Australia to explore the relationship between home range size, optimal foraging theory and vegetation mosaic theory. Twelve adult snakes were tracked between September 2004 and February 2008. Male home ranges were significantly larger (P < 0.05) and more variable (41 ± 30 ha) than female home ranges (23 ± 5 ha), and males moved further between observations (123 m c.f. 65 m). Core activity centres varied significantly among habitat (P < 0.05) with larger home ranges observed in heathland, a vegetation community which supported comparatively low mammal diversity. No other variables examined including number of fixes, body length, prey abundance, vegetation heterogeneity or fire history explained home range variability. In this system, relatively high mammalian prey diversity and rapid post‐fire vegetation succession may limit prey availability and fire effects as being significant determinants of home range variability in M. spilota.     

Factors affecting hematology and plasma biochemistry in the southwest carpet python (Morelia spilota imbricata)

Despite increased worldwide popularity of keeping reptiles as pets, we know little about hematologic and biochemical parameters of most reptile species, or how these measures may be influenced by intrinsic and extrinsic factors. Blood samples from 43 wild-caught pythons (Morelia spilota imbricata) were collected at various stages of a 3-yr ecological study in Western Australia. Reference intervals are reported for 35 individuals sampled at the commencement of the study. As pythons were radiotracked for varying lengths of time (radiotransmitters were surgically implanted), repeated sampling was undertaken from some individuals. However, because of our ad hoc sampling design we cannot be definitive about temporal factors that were most important or that exclusively influenced blood parameters. There was no significant effect of sex or the presence of a hemogregarine parasite on blood parameters. Erythrocyte measures were highest for pythons captured in the jarrah forest and at the stage of radiotransmitter implantation, which was also linked with shorter time in captivity. Basophil count, the only leukocyte influenced by the factors tested, was highest when the python was anesthetized, as was globulin concentration. Albumin and the albumin:globulin ratio were more concentrated in summer (as was phosphorous) and at the initial stage of radiotransmitter placement (as was calcium). No intrinsic or extrinsic factors influenced creatinine kinase, aspartate aminotransferase, uric acid, or total protein. This study demonstrates that factors including season, location, surgical radiotransmitter placement, and anesthetic state can influence blood parameters of M. s. imbricata. For accurate diagnosis, veterinarians should be aware that the current reference intervals used to identify the health status of individuals for this species are outdated and the interpretation and an understanding of the influence of intrinsic and extrinsic factors are limited.     

Variation in mating systems and sexual size dimorphism between populations of the Australian python Morelia spilota (Serpentes: Pythonidae)

Although adaptationist hypotheses predict a functional relationship between mating systems and sexual size dimorphism, such predictions are difficult to test because of the high degree of phylogenetic conservatism in both of these traits. Taxa that show intraspecific variation in mating systems hence offer valuable opportunities for more direct tests of evolutionary-ecological hypotheses. Based on a collation of published and unpublished records, we document intraspecific geographic variation in mating systems (presence versus absence of male-male combat) within the widely-distributed Australian python Morelia spilota. Radiotelemetric monitoring of 19 free-ranging pythons in a population in north-eastern New South Wales showed that these animals display a mating system of female defence polygyny. Previous studies on a southern population of the same species found that males engaged in long mate-searching movements, showed no overt agonistic behavior, and formed long-term (>2 months) aggregations around reproductive females. In strong contrast, our adult male carpet pythons (i) moved about relatively little (mean displacement <11 m/day) during the mating season, (ii) remained with females only briefly (<5 days), and (iii) engaged in male-male combat in the vicinity of females. This male-male combat included vigorous biting as well as ritualised wrestling matches, resulting in a high incidence of bite scars in adult males. In keeping with predictions from sexual selection theory, males attain larger body sizes than females in this population, whereas females grow larger than males in the previously-studied southern population where males do not engage in physical combat for mating opportunities.     

基于生境可获得性的完达山地区马鹿(Cervus elaphus xanthopygus)冬季生境选择

于2004～2005年冬季研究了完达山地区马鹿的生境利用和选择。在野外调查的基础上,获取了研究地区马鹿种群水平上的生境利用数据;利用地理信息系统和遥感技术,从区域尺度上测度了各类生境因子的可获得性。通过比较被利用生境与可获得生境,测度了马鹿冬季对各类生境或生态因子的选择。结果表明,马鹿对植被类型、海拔、坡向、NDVI等级、到公路距离表现出非比例利用,对坡度的利用与其可获得性则没有显著性差异。马鹿选择采伐迹地,低郁闭度生境（第2、3NDVI等级）,200～300m海拔区间,南坡,距离公路600～700m的区间。马鹿采食生境和卧息生境对各类因子具有不同的选择性,表现出不同功能生境分离的特征。对于采食生境,马鹿选择采伐迹地、阔叶疏林,低郁闭度（第2、3NDVI等级）,南坡;对于卧息生境,马鹿仅选择采伐迹地,低郁闭度（第2、3、4NDVI等级）。根据马鹿活动样点的出现与否,建立了马鹿冬季生境选择的逻辑斯谛回归模型。模型回判结果表明,该模型对马鹿活动样方与对照样方的总体正确预测率为74．4％,对马鹿活动样方的正确预测率为84．2％,对对照样方的正确预测率为62．4％,能够较好的预测生境利用概率。     

Habitat distribution and habitat preference in Barbary macaques (Macaca sylvanus)

Barbary macaques (Macaca sylvanus,L.) occur at varying densities in a number of different habitat types in Morocco and Algeria. Taub (1977) has argued that the abundance of the species in cedar forests of the Moyen Atlas, Morocco, is an indication of a habitat preference. A reexamination of available data on the distribution and abundance of Barbary macaques suggests that monkey numbers reflect the distribution of habitat size rather than habitat types. Differences between populations relative to habitat types can be seen only between forest and scrub localities. Human factors are considered more important in determining the present status of this eclectic feeder. The modern distribution of the Barbary macaque is inadequate evidence for a habitat preference.     

Ontogenetic shifts in habitat use by the endangered Roanoke logperch (Percina rex)

1. Conservation of the federally endangered Roanoke logperch (Percina rex, Jordan and Evermann) necessitates protection of habitat that is critical for all age classes. We examined habitat use patterns of individual logperch to determine: (1) if age classes of logperch in the Nottoway and Roanoke Rivers exhibit habitat selectivity, (2) if age classes differ in habitat use, and (3) if ontogenetic patterns of habitat use differ between the Roanoke and Nottoway river populations. 2. In the summers of 2000 and 2001, we observed 17 young‐of‐year (YOY) logperch [<4 cm total length (TL)], 13 subadult logperch (4–8 cm TL), and 49 adult logperch (>8 cm TL) in the upper Roanoke River, and 40 subadult and 39 adult logperch in the Nottoway River, Virginia. 3. All size classes of Roanoke logperch demonstrated habitat selectivity and logperch used a wide range of habitats in the Roanoke and Nottoway rivers during ontogeny. Habitat use by logperch varied among age classes and between rivers. 4. In the Roanoke River, adult and subadult logperch primarily preferred run and riffle habitat, often over gravel substrate. Subadults were found in lower water velocities and slightly more embedded microhabitats than adults. YOY logperch were found in shallow, stagnant backwaters and secondary channels. In the Nottoway River, both adult and subadult logperch were found over sand and gravel in deep, low‐velocity pools and runs. Subadults were observed in slightly more silted, lower velocity habitat than adults. Shifts in habitat use were more distinct between age classes in the Roanoke River than the Nottoway River. 5. Successful conservation of this species will involve sound understanding of spatial variation in habitat use over logperch life history and preservation of the ecological processes that preserve required habitat mosaics.     

九龙山保护区黑麂栖息地选择的季节变化

2005年7月至2006年6月,以浙江省九龙山国家级自然保护区上寮坑保护站为中心,在其周围随机设置6条样线,每隔200m地面距离设置固定样方,共设定442个20m×20m的固定样方,并在其中设置灌木测量样方442个,草本植物盖度测量样方2210个。分春、夏、秋、冬4季记录样方的植被类型、乔木盖度、灌木盖度、草本盖度、坡位、坡度、坡向、食物丰富度、海拔、人为干扰距离和水源距离等11类生态因子,并用痕迹法检查样方是否被黑麂利用。通过Vanderloeg选择系数(Wi)和Scavia选择指数(Ei)研究影响黑麂栖息地利用和选择性的各生态因子,并采用主成分分析的方法研究影响黑麂栖息地选择的关键因子,得到了黑麂栖息地选择的主要特征及其季节变化。结果表明:黑麂总体上倾向选择在针阔混交林、乔木盖度60%-80%、灌木盖度中等(20%-60%)、草本盖度中等(20%-60%)、食物丰富度高(68%)和人为干扰距离远的生境,对海拔高度和坡位的选择表现出季节迁移性。     

Habitat selection by wapiti (Cervus elaphus xanthopygus) in Wandashan Mountains, China, based on habitat availability

In 2004 and 2005, we studied winter habitat use and selection by wapiti in Wandashan Mountains, Heilongjiang Province, China. Using Geographic Information System (GIS) and Remote Sensing (RS), we measured habitat availability in terms of the area of each habitat category in the study area. We compared winter habitats used by wapiti and their availability. The results showed that the habitats used by wapiti were disproportional to their availability. Wapiti preferred clear-cuttings, low vegetation coverage (No. 2, 3 NDVI classes), 200–300 m elevation range, south aspect, and 600–700 m distance range away from roads. They also showed different preferences for feeding and resting. The feeding sites tended to be located at broad-leaved stands and clear-cuttings, No. 2, 3 NDVI classes, and south slope, whereas the bedding sites tended to be clear-cuttings, and No. 2, 3, 4 NDVI classes. Using the logistic regression model to predict the probability of habitat use by wapiti in winter, we found that the overall prediction accuracy was 74.4% for the total habitat samples, with 84.2% for the habitat samples used by wapiti and 62.4% for the control samples correctly predicted by using this model.     

Habitat distribution influences dispersal and fine-scale genetic population structure of eastern foxsnakes (Mintonius gloydi) across a fragmented landscape

Dispersal is a fundamental attribute of species in nature and shapes population dynamics, evolutionary trajectories and genetic variation across spatial and temporal scales. It is increasingly clear that landscape features have large impacts on dispersal patterns. Thus, understanding how individuals and species move through landscapes is essential for predicting impacts of landscape alterations. Information on dispersal patterns, however, is lacking for many taxa, particularly reptiles. Eastern foxsnakes (Mintoinus gloydi) are marsh and prairie specialists that avoid agricultural fields, but they have persisted across a fragmented region in southwestern Ontario and northern Ohio. Here, we combined habitat suitability modelling with population genetic analyses to infer how foxsnakes disperse through a habitat mosaic of natural and altered landscape features. Boundary regions between the eight genetic clusters, identified through assignment tests, were comprised of low suitability habitat (e.g. agricultural fields). Island populations were grouped into a single genetic cluster, and comparatively low F(ST) values between island and mainland populations suggest open water presents less of a barrier than nonsuitable terrestrial habitat. Isolation by resistance and least-cost path analysis produced similar results with matrices of pairwise individual genetic distance significantly more correlated to matrices of resistance values derived from habitat suitability than models with an undifferentiated landscape. Spatial autocorrelation results matched better with assignment results when incorporating resistance values rather than straight-line distances. All analyses used in our study produced similar results suggesting that habitat degradation limits dispersal for foxsnakes, which has had a strong effect on the genetic population structure across this region.     

Multiscale habitat relationships of snowshoe hares (Lepus americanus) in the mixed conifer landscape of the Northern Rockies,USA: Cross‐scale effects of horizontal cover with implications for forest management

Snowshoe hares (Lepus americanus) are an ecologically important herbivore because they modify vegetation through browsing and serve as a prey resource for multiple predators. We implemented a multiscale approach to characterize habitat relationships for snowshoe hares across the mixed conifer landscape of the northern Rocky Mountains, USA. Our objectives were to (1) assess the relationship between horizontal cover and snowshoe hares, (2) estimate how forest metrics vary across the gradient of snowshoe hare use and horizontal cover, and (3) model and map snowshoe hare occupancy and intensity of use. Results indicated that both occupancy and intensity of use by snowshoe hares increased with horizontal cover and that the effect became stronger as intensity of use increased. This underscores the importance of dense horizontal cover to achieve high use, and likely density, of snowshoe hares. Forest structure in areas with high snowshoe hare use and horizontal cover was characterized as multistoried with dense canopy cover and medium‐sized trees (e.g., 12.7–24.4 cm). The abundance of lodgepole pine (Pinus contorta) was associated with snowshoe hare use within a mixed conifer context, and the only species to increase in abundance with horizontal cover was Engelmann spruce (Picea engelmannii) and subalpine fir (Abies lasiocarpa). Our landscape‐level modeling produced similar patterns in that we observed a positive effect of lodgepole pine and horizontal cover on both occupancy and use by snowshoe hares, but we also observed a positive yet parabolic effect of snow depth on snowshoe hare occupancy. This work is among the first to characterize the multiscale habitat relationships of snowshoe hares across a mixed conifer landscape as well as to map their occupancy and intensity of use. Moreover, our results provide stand‐ and landscape‐level insights that directly relate to management agencies, which aids in conservation efforts of snowshoe hares and their associated predators.     

A review of habitat selection by the swamp rat,Rattus lutreolus (Rodentia: Muridae)

Abstract This review clarifies important points on habitat selection by the Swamp Rat Rattus lutreolus (Rodentia: Muridae), a species that has been the subject of much research in Australia and has provided a useful model for understanding ecological and biological processes. It also provides an opportunity to cite important earlier research, not readily available through electronic search engines, thus bringing it into current literature to avoid its disappearance into Internet obscurity. We comment on some papers in the literature to correct errors detected and to emphasize the importance of due care in all aspects of a research project, including its reporting. We show that both floristic and structural components have been reported as important to an understanding of habitat and microhabitat selection by R. lutreolus and conclude that it is vegetation density that is of paramount importance. Female R. lutreolus are clearly dominant in driving microhabitat selection, occupying the ‘best’ or densest habitats with male R. lutreolus occupying the next best and Pseudomys or other species, where present occupying the remainder. This demonstrates the important role that intraspecific and interspecific competition play in determining habitat selection. Direct predation and the perception of predation risk may also play a role in habitat selection, again perceived to be pushing individuals towards denser vegetation, representing ‘better cover’. Whether these effects operate as bottom‐up or top‐down needs careful consideration. Climatic variables, such as ENSO‐affecting productivity, and related variables such as temperature and humidity may also play important roles in habitat selection, as can disturbance effects such as wildfire. The relative importance of all of these potential determining factors may vary from place to place, particularly when climatic clines are involved.     

Home‐range size and habitat use of European Nightjars Caprimulgus europaeus nesting in a complex plantation‐forest landscape

In Europe, the consequences of commercial plantation management for birds of conservation concern are poorly understood. The European Nightjar Caprimulgus europaeus is a species of conservation concern across Europe due to population depletion through habitat loss. Pine plantation‐forest is now a key Nightjar nesting habitat, particularly in northwestern Europe, and increased understanding of foraging habitat selection is required. We radiotracked 31 Nightjars in an extensive (185‐km²) complex conifer plantation landscape in 2009 and 2010. Home‐range 95% kernels for females, paired males and unpaired males were an order of magnitude larger than song territories of paired males, emphasizing the importance of habitats beyond the song territory. Nightjars travelled a mean maximum distance of 747 m from the territory centre each night. Home‐range placement relative to landscape composition was examined by compositional analysis. Pre‐closure canopy forest (aged 5–10 years) was selected at all scales (MCP, 95% and 50% kernels), with newly planted forest (aged 0–4 years) also selected within 50% kernels. For telemetry fixes relative to habitat composition within 2 km of their territory centre, individuals again selected pre‐closure and newly planted forest, and also grazed grass heath. Open ungrazed habitat was not selected, with implications for open habitat planning for biodiversity conservation within public‐owned forests. Despite the Nightjars’ selection for younger growth, moth biomass was greater in older forest stands, suggesting that foraging site selection reflects ease of prey capture rather than prey abundance. Within large plantation‐forest landscapes, a variety of growth stages is important for this species and our results suggest that grazing of open habitats within and adjacent to forest will additionally benefit the European Nightjar.     

Living on the edge: Multiscale habitat selection by cheetahs in a human‐wildlife landscape

Animals select habitats that will ultimately optimize their fitness through access to favorable resources, such as food, mates, and breeding sites. However, access to these resources may be limited by bottom‐up effects, such as availability, and top‐down effects, such as risk avoidance and competition, including that with humans. Competition between wildlife and people over resources, specifically over space, has played a significant role in the worldwide decrease in large carnivores. The goal of this study was to determine the habitat selection of cheetahs (Acinonyx jubatus) in a human‐wildlife landscape at multiple spatial scales. Cheetahs are a wide‐ranging, large carnivore, whose significant decline is largely attributed to habitat loss and fragmentation. It is believed that 77% of the global cheetah population ranges outside protected areas, yet little is known about cheetahs’ resource use in areas where they co‐occur with people. The selection, or avoidance, of three anthropogenic variables (human footprint density, distance to main roads and wildlife areas) and five environmental variables (open habitat, semiclosed habitat, edge density, patch density and slope), at multiple spatial scales, was determined by analyzing collar data from six cheetahs. Cheetahs selected variables at different scales; anthropogenic variables were selected at broader scales (720–1440 m) than environmental variables (90–180 m), suggesting that anthropogenic pressures affect habitat selection at a home‐range level, whilst environmental variables influence site‐level habitat selection. Cheetah presence was best explained by human presence, wildlife areas, semiclosed habitat, edge density and slope. Cheetahs showed avoidance for humans and steep slopes and selected for wildlife areas and areas with high proportions of semiclosed habitat and edge density. Understanding a species’ resource requirements, and how these might be affected by humans, is crucial for conservation. Using a multiscale approach, we provide new insights into the habitat selection of a large carnivore living in a human‐wildlife landscape.     

Long‐term changes in habitat selection and prey spectrum in a reintroduced Eurasian lynx (Lynx lynx) population in Switzerland

When wild‐caught Eurasian lynx (Lynx lynx) from the Slovak Carpathian Mountains were reintroduced to Central Switzerland in the early 1970s and spread through the north‐western Swiss Alps (NWA), they faced a largely unfamiliar landscape with strongly fragmented forests, high elevations, and intense human land use. For more than 30 years, radio‐collared lynx have been monitored during three different project periods (in the 1980s, 1990s, and 2010s). Our study explored, how lynx over generations have learned to adjust to the alpine environment. We predicted that (1) lynx nowadays select more strongly for open habitats, higher elevations, and steep slopes compared to the early stages of recolonization and that (2) consequently, there were significant changes in the Eurasian lynx’ prey spectrum. To test our predictions, we analyzed telemetry data (VHF, GPS) of 13 adult resident lynx in the NWA over 35 years, using Resource Selection Functions. Furthermore, we compared kills recorded from different individuals inhabiting the same region during three project periods. In general, lynx preferred forested areas, but over the years, they avoided open habitat less. Compared to the early stage of the recolonization, lynx in the most recent project period selected for higher elevations and the proportion of chamois in their prey spectrum surmounted that of roe deer. Potential driving factors for the observed changes could be increasing tolerance to human presence, intraspecific competition, or fitness benefits through exploitation of new resources. Long‐term studies like ours provide important insight into how animals can respond to sudden environmental changes, e.g., in the course of translocations into new areas or anthropogenic alterations of their habitats.