Winter Versus Summer Habitat Selection in a Threatened Ground Squirrel

Hibernation is a strategy many species employ to survive periods of thermal stress or resource shortage (e.g., harsh thermal conditions, food limitations) and habitat requirements of hibernating species may differ between summer (the active season) and winter (during hibernation). Accounting for seasonal differences in habitat affinities will help ensure that management actions are more beneficial and land-use policies are more appropriate. The northern Idaho ground squirrel (Urocitellus brunneus) is a federally listed threatened species that is in decline and hibernates for approximately 8 months per year. We collared northern Idaho ground squirrels in Adams County, Idaho from 2013–2017. The majority of northern Idaho ground squirrels we collared selected hibernacula outside of the areas they used during the active season. Furthermore, habitat features of hibernacula locations differed from habitat features of active-season areas. Hibernacula locations had greater canopy closure compared to active-season locations (36.9% and 7.0% canopy closure, respectively) and hibernaculum habitat features (particularly distance to nearest log) influenced overwinter survival. Our results suggest that recovery efforts for northern Idaho ground squirrels should include protection and management for the full range of habitat conditions used throughout summer and winter. More broadly, we emphasize the need to identify and protect habitat during all seasons because habitat requirements can differ substantially during different portions of an animal's annual cycle and effective conservation will require management of year-round habitat needs. © 2020 The Wildlife Society.     

Distribution and Habitat Use of King Rails in the Illinois and Upper Mississippi River Valleys

ABSTRACT The migratory population of the king rail (Rallus elegans) has declined dramatically during the past 40 years, emphasizing the need to identify habitat requirements of this species to help guide conservation efforts. To assess distribution and habitat use of king rails along the Illinois and Upper Mississippi valleys, USA, we conducted repeated call-broadcast surveys at 83 locations in 2006 and 114 locations in 2007 distributed among 21 study sites. We detected king rails at 12 survey locations in 2006 and 14 locations in 2007, illustrating the limited distribution of king rails in this region. We found king rails concentrated at Clarence Cannon National Wildlife Refuge, an adjacent private Wetlands Reserve program site, and B. K. Leach Conservation Area, which were located in the Mississippi River floodplain in northeast Missouri. Using Program PRESENCE, we estimated detection probabilities and built models to identify habitat covariates that were important in king rail site occupancy. Habitat covariates included percentage of cover by tall (>1 m) and short (>1 m) emergent vegetation, percentage of cover of woody vegetation, and interspersion of water and vegetation (2007 only) within 50 m of the survey location. Detection probability was 0.43 (SE = 0.12) in 2006 and 0.35 (SE = 0.03) in 2007 and was influenced by observer identity and percentage of cover by tall herbaceous vegetation. Site occupancy was 0.11 (SE = 0.04) in 2006 and 0.14 (SE = 0.04) in 2007 and was negatively influenced most by percentage of cover by woody vegetation. In addition, we found that interspersion of vegetation and water was positively related to occupancy in 2007. Thus, nesting king rails used wetlands that were characterized by high water-vegetation interspersion and little or no cover by woody vegetation. Our results suggest that biologists can improve king rail habitat by implementing management techniques that reduce woody cover and increase vegetation-water interspersion in wetlands.     

Using California Gnatcatcher to Test Underlying Models in Habitat Conservation Plans

Abstract: Habitat Conservation Plans are a widely used strategy to balance development and preservation of species of concern and have been used in southern California, USA, to protect the coastal California gnatcatcher (Polioptila californica). Few data exist on gnatcatcher abundance and distribution, and existing data have problems with issues of closure (i.e., sampling occurs in a short enough time period such that abundance or distribution are not changing), detectability, and proper attention to probability-based sampling schemes. Thus, a habitat model has been relied upon in reserve design. California gnatcatchers are the flagship and umbrella species of many plans and we provide the first estimates that incorporate probabilistic sampling and test predictions from the habitat model. Probability of occurrence was 26% (SĚ = 0.06); however, occupancy varied by modeled habitat quality with slopes <40%, warm, and wet sagebrush habitat having higher occupancy probabilities. Interpreting abundance and occupancy probabilities by vegetation type was complicated by error detected in Geographic Information System vegetation metadata files. The slope (1.08, SĚ = 0.66), temperature (0.79, SĚ = 0.70), and precipitation (—2.62, SĚ = 1.21) variables associated with habitat models were stronger influences on occupancy than was patch size (0.48, SĚ = 0.66). Previous models weight patch size equal to slope and climate. Our work demonstrates that probabilistic sampling can be carried out on a large scale and the results provide better information for managers to make decisions about their reserves.     

Fine-Scale Analysis of Mount Graham Red Squirrel Habitat Following Disturbance

ABSTRACT Habitat destruction and degradation are major factors in reducing abundance, placing populations and species in jeopardy. Monitoring changes to habitat and identifying locations of habitat for a species, after disturbance, can assist mitigation of the effects of human-caused or -amplified habitat disturbance. Like many areas in the western United States, the Pinaleño Mountains of southeastern Arizona, USA, have suffered catastrophic fire and large-scale insect outbreaks in the last decade. The federally endangered Mt. Graham red squirrel (Tamiasciurus hudsonicus grahamensis) is only found in the Pinaleño Mountains, and to assess effects of forest disturbance on habitat we modeled their potential habitat by identifying characteristics of cover surrounding their centrally defended middens. We classified high-spatial resolution satellite imagery into ground cover classes, and we used logistic regression to determine areas used by squirrels. We also used known midden locations in conjunction with slope, elevation, and aspect to create a predictive habitat map. Squirrels selected areas of denser forest with higher seedfall for midden sites. Among active middens, those in the densest and least damaged forests were occupied in more seasons than those in more fragmented and damaged areas. The future conservation of red squirrels and the return of healthy mature forests to the Pinaleño Mountains will rely on preservation of mixed conifer zones of the mountain and active restoration of spruce-fir forests to return them to squirrel habitat. Our ability to evaluate the spectrum of fine- to coarse-scale disturbance effects (individual tree mortality to area wide boundaries of a disturbance) with high-resolution satellite imagery shows the utility of this technique for monitoring future disturbances to habitat of imperiled species.     

Habitat Use of Fox Squirrels in an Urban Environment

Abstract: Tree squirrels are one of the most familiar mammals found in urban areas and are considered both desirable around homes and, conversely, a pest. We examined fox squirrel (Sciurus niger) habitat use in inner city and suburban areas using radiotelemetry. We estimated habitat selection ratios at differing scales by season and fox squirrel activity. Telemetry data suggests that during periods of inactivity radiocollared fox squirrels (n = 82) selected 1) areas with greater tree canopy, 2) live oaks (Quercus fusiromis and Q. virginiana), and 3) trees with larger diameters and canopies. When inactive during the winter and spring, fox squirrels also preferred, within their core areas, to use the inside of buildings, and during periods of activity in the autumn and spring, fox squirrels preferred grassy areas. During periods of activity, fox squirrels avoided using pavement but did not exclude it from their core-area movements. Fox squirrels' ability to use buildings and to tolerate pavement in core-area movements make vast areas of the urban environment available to fox squirrels. In evaluating habitat variables that increased fox squirrel activity in urban areas, we found the number of large and medium trees, amount of pavement and grassy areas, canopy cover, number of oaks, and the area covered by buildings were all important factors in predicting fox squirrel activity in an urban environment. Our data suggests urban planners, animal damage control officials, wildlife managers, and landscapers who want to control urban fox squirrel populations through habitat manipulation should consider the reduction of oaks trees, a reduction of the canopy cover, and restricting the access of fox squirrels to buildings. Alternatively, home owners and squirrel enthusiasts hoping to bolster fox squirrel populations in urban areas should consider increasing the number of large mast—bearing trees and canopy cover and providing nest boxes.     

Food abundance determines distribution and density of a frugivorous bird across seasons

Although food abundance is a principal determinant of distribution and abundance of many animals, most previous studies have not quantitatively assessed its importance relative to other factors that may also determine species distributions. We estimated frugivorous phainopepla Phainopepla nitens occupancy and density, food density, and vegetation structure on transects in fragmented mesquite and acacia woodlands over three years in non‐breeding and breeding seasons. Using an AIC framework and controlling for detection probability, we determined relative impacts of food abundance, vegetation structure, and habitat fragmentation on patch occupancy and density, and concomitant extinction and colonization probabilities of phainopeplas. Initial occupancy in winter 2002 was high (0.87 ± 0.047), and primarily positively correlated with food abundance and woodland area (Akaike weights w_i= 0.998 and 0.750 respectively). Woodland area more strongly influenced occupancy where food was scarcer. Phainopepla density in both seasons was strongly positively correlated with food abundance, especially in the 2002 drought when density was higher (w_i=1.0 for food and year). Density was higher in acacia than mesquite woodlands (w_i= 1.0), and moderately negatively correlated with elevation (w_i= 0.789). Extinction probability (patches vacated) was low (0.078 ± 0.040), and principally influenced by phainopepla density (w_i= 0.968) and tree height (w_i= 0.749). Colonization probability was low (0.15 ± 0.034) and determined by vegetation structure (w_i= 1.0). Much recorded colonization was reoccupancy of woodlands previously occupied by single males in winter, then vacated in a breeding season. These results suggest that for an animal occupying a highly fragmented landscape, distributions and densities at the habitat patch scale are driven by food abundance, are moderately affected by habitat fragmentation, and are slightly influenced by vegetation structure.     

Genetic diversity and population divergence in fragmented habitats: Conservation of Idaho ground squirrels

The Idaho ground squirrel, which consists of a northern (Spermophilus brunneus brunneus) and a southern subspecies (S. b. endemicus), has suffered from habitat loss and fragmentation, resulting in a reduction in both numbers and geographic range of the species. The northern Idaho ground squirrel (NIDGS) is listed as a threatened subspecies under the Endangered Species Act, and the southern Idaho ground squirrel (SIDGS) is a candidate. Because Idaho ground squirrel populations are small and often isolated, they are susceptible to inbreeding and loss of genetic diversity through drift. This research evaluates levels of genetic diversity and patterns of population divergence in both subspecies of Idaho ground squirrels. We hypothesized that NIDGS would exhibit lower genetic diversity and greater population divergence due to a longer period of population isolation relative to most SIDGS populations. Genetic diversity and divergence were quantified using 8 microsatellite loci. Contrary to expectations, SIDGS populations exhibited consistently lower levels of microsatellite diversity. Additionally, NIDGS exhibited only modest divergence among populations, while divergence levels among SIDGS populations were highly varied. Preliminary evaluations of mitochondrial DNA diversity and structure revealed lower diversity in NIDGS and some differences in gene flow that warrant further study. Based on our results, we suggest different management strategies for the two subspecies. Habitat restoration appears to be the most desirable conservation strategy for NIDGS populations. In contrast, low genetic diversity observed in SIDGS may warrant supplementation of isolated populations through translocations or captive breeding to mitigate further loss of genetic variability.     

Occupancy and detectability of Snowy Plovers in western Utah: an application to a low density population

Occupancy modeling can be used to identify habitat characteristics associated with species occurrence. Additionally, occupancy sampling can provide measures of detection probability, increasing confidence in monitoring efforts. Little is known about the distribution and habitat preferences of a small population of Snowy Plovers (Charadrius nivosus) in western Utah. We conducted a study to estimate occupancy and detection probability of Snowy Plovers in western Utah during 2011 and 2012. We made repeated visits to randomly selected survey plots during the breeding period, sampling 84 64‐ha plots in 2011 and 100 64‐ha plots in 2012 and recording the number of adults and habitat characteristics in each plot. We then modeled the relationship between detection, occupancy, and covariates that included distance to water, distance to roads, land cover types, and characteristics of the vegetation. We also included covariates for observer, Julian date, temperature, cloud cover, and wind speed when modeling detection probability. Detection probability was high (0.74, 95% CI = 0.57–0.86) and positively influenced by temperature. Occupancy of 64‐ha plots was low (0.27, 95% CI = 0.18–0.39) and did not vary by year. Occupancy of Snowy Plovers was negatively associated with distance to water (β = ?0.62 ± 0.31, 95% CI = ?1.23 to ?0.01) and percent shrub cover (β = ?0.28 ± 0.02, 95% CI = ?0.58 to ?0.01). Land cover types also influenced plot occupancy. Management actions that conserve shallow water and adjacent habitats or minimize disturbance in these areas are likely to have conservation benefits for Snowy Plovers where water is scarce. Because our detection probabilities were high, investigators involved in future monitoring efforts can achieve reasonable precision with limited revisits to sample plots.     

栖息地荒漠化对蜥蜴群落组成的影响

栖息地改变往往对动物群落及其物种多样性有重要影响,但是目前关于栖息地荒漠化如何影响蜥蜴的群落组成鲜有研究。在内蒙古自治区鄂尔多斯市准格尔旗和达拉特旗地区通过样线法调查了三类不同荒漠化程度样地上的蜥蜴群落组成差异,用典范对应分析探究了关键的影响因素。结果表明,栖息地荒漠化使蜥蜴的群落组成发生显著变化,从固定沙丘、半固定沙丘到流动沙丘,草原沙蜥均是蜥蜴群落的优势物种,密点麻蜥逐渐减少,丽斑麻蜥则消失于荒漠化严重的半固定沙丘和流动沙丘中。随栖息地荒漠化程度的增加,蜥蜴的数量显著减少,密度显著降低,蜥蜴物种的丰富度、香农-威纳(Shannon-Weaver)多样性指数和皮洛(Pielou)均匀性指数均逐次显著下降,而辛普森(Simpson)优势度指数则逐次显著升高。这说明荒漠化不仅使蜥蜴群落组成变得简单,同时造成了蜥蜴物种多样性的下降甚至丧失。荒漠化也使蜥蜴的栖息条件发生显著变化。植被高度、油蒿比例、裸地比例、隐蔽度、表层土壤含水量和表层土壤孔隙度在三类栖息样地之间均存在极显著差异。典范对应分析结果表明,这些环境因子与蜥蜴群落组成的变化密切相关。总体而言,草原沙蜥偏好裸地,密点麻蜥偏好隐蔽性好且土壤湿润又疏松的区域,而丽斑麻蜥则偏好植被高的区域。     

Habitat and History Influence Abundance of Bog Turtles

Conservation of rare and endangered species requires assessment of factors that influence the current habitat associations of a species and the role of past habitat degradation in limiting occupancy or abundance. The objective of our 2011–2014 study was to determine how habitat characteristics and wetland history can predict occupancy and abundance patterns of bog turtles (Glyptemys muhlenbergii) at the fringe of their range in the southeastern United States. We used a hurdle model to examine occupancy and abundance patterns while addressing problems associated with zero-inflated data. Occupancy patterns were weakly related to percent of the wetland containing emergent vegetation, whereas abundance patterns were predicted by the percent silt in the wetland substrate, percent forest cover, amount of habitat degradation, and recovery time since past habitat degradation. The effect of historical habitat degradation on abundance rather than occupancy patterns has rarely been documented and its effect is rarely studied in vertebrate populations. Identification of predictors of occupancy and abundance patterns will aid discovery of new populations of bog turtles and improve management of occupied wetlands. © 2019 The Wildlife Society.     

Habitat use and movement patterns by dependent and independent juvenile Grasshopper Sparrows during the post‐fledging period

The post‐fledging period is a critical life stage for young grassland birds. Habitat selection by recently fledged birds may differ from that of adults and may change as juveniles transition from the care and protection of parents to independence. To describe patterns of habitat selection during these important life stages, we studied habitat use by juvenile Grasshopper Sparrows (Ammodramus savannarum) in a Conservation Reserve Program grassland in Maryland. We used radio‐telemetry to track daily movement patterns of two age classes of Grasshopper Sparrows during the post‐fledging period. Sparrows were classified as either dependent (<32‐d‐old) or independent (≥32‐d‐old). We characterized the vegetation at 780 vegetation plots (390 plots where birds were located and 390 paired random plots). Microhabitats where dependent birds were found had significantly more bare ground, litter, and plant species richness than paired random plots. In addition, dependent birds were found in plots with less bare ground, more warm‐season grass cover, more total vegetation cover, and more forb cover than plots used by independent birds. Plots where independent birds were located also had significantly more bare ground than random plots. Dependent birds are less able to escape from predators because their flight feathers are not fully grown so they may benefit from remaining in areas of greater vegetation cover. However, juveniles transitioning from dependence to independence must forage on their own, possibly explaining their increased use of more open areas where foraging may be easier. To properly manage habitat for grassland birds, management strategies must consider the changing needs of birds during different stages of development. Our results highlight the importance of diverse grassland ecosystems for juvenile grassland birds during the transition to independence.     

高黎贡山羚牛生境选择初步研究

2004年1月~2005年12月,在高黎贡山自然保护区内开展了羚牛指名亚种的生境调查研究,在调查点内对与羚牛生存有关的生境因子(植被型、郁闭度、坡向、坡位、水源、人为干扰、距主要公路距离、距农用地距离)进行了调查统计。在研究中,将这些生态因子分别分成了3个等级进行回归分析,建立羚牛在不同生境中出现概率的预测方程,通过分析后发现,影响高黎贡山羚牛生境选择的主要生态因子是人为干扰和隐蔽条件,其次是距农业用地距离、距主要公路距离和水源,坡度、坡向和植被型对羚牛生境选择的影响不明显。     

人工林赤腹松鼠危害程度与生境因子的关系研究

2009年3～6月,采用样方法对四川省洪雅县人工林赤腹松鼠危害相关的生境因子进行了调查。共设置了240个样方。样方调查中记录了2个反应危害等级的变量(危害株数和乔木总数)和11个生境变量(森林类型、海拔、坡向、坡度、坡位、距最近道路距离、距最近水源距离、乔木均高、乔木平均胸围、灌木盖度和草本盖度)。通过广义线性模型研究这些因子与人工林赤腹松鼠危害程度的关系。结果显示,赤腹松鼠危害程度与森林类型、坡度、坡向、乔木平均胸围呈显著性相关,与其他因子无显著相关性,在柳杉-杉木林中的危害高于纯柳杉林,在阴坡的危害低于其他坡向,危害程度随坡度和乔木平均胸围的增加而增加。     

Forces structuring tree squirrel communities in landscapes fragmented by agriculture: species differences in perceptions of forest connectivity and carrying capacity

The North American red squirrel ( Tamiasciurus hudsonicus ) has expanded its range into the central hardwoods of the United States in conjunction with increasing forest fragmentation and declining gray squirrel ( Sciurus carolinensis ) populations. We used translocation experiments and patch occupancy data to test for interspecific differences in mobility and sensitivity to habitat loss and modification by agriculture. We released squirrels in fencerows to test the hypothesis that gray squirrels display inferior mobility relative to red and fox ( S. niger ) squirrels. Elapsed time to movement from fencerows for 76 individuals increased with distance to forest patches and harvesting of crops. Gray and red squirrels took longer to move from fencerows than fox squirrels, and gray squirrels were less successful at moving from fencerows than red and fox squirrels. Ecologically scaled landscape indices revealed the degree to which interspecific differences in mobility and individual area requirements accounted for the occurrence of these species across landscapes. Gray squirrel distribution was constrained both by individual area requirements and dispersal ability. Occurrence of red and fox squirrels was related to patch size but was unaffected by landscape connectivity.     

Red Fox Use of Landscapes with Nesting Shorebirds

Predation of nests and young is one of the limiting factors in the conservation of birds; understanding environmental covariates of predator distribution can assist with decisions regarding the best management strategies to reduce predation risk. The habitat of beach-nesting birds is often reshaped by storms in ways that may affect nest predation, such as by flattening vegetated dunes where mammals hunt, but human management of beaches tries to prevent the effects of storms on the landscape with unknown implications for predator distributions. Moreover, human development may affect predator distributions by subsidizing food and shelter. To determine the relationship between predator occupancy and landscape features in beach-nesting bird habitat, we repeated mammalian predator track surveys 8 times/year at 90 plots in southern New Jersey, USA, from 2015–2017. We used dynamic occupancy models to estimate the probability of use by red foxes (Vulpes vulpes) and to document changes in habitat use as related to landcover types over the avian breeding season within years. We had 373 red fox detections with years pooled. Detection probability for red foxes varied by year, and probability of use decreased as the distance to the nearest primary dune increased. We found no evidence that red fox habitat use depended on distance to human development. Our results suggest that conserving nesting habitat that includes open areas (i.e., storm overwash [whereby vegetation is scoured by tidal flooding]) may reduce predation risk because beach-nesting birds would not be forced into nesting close to dunes, which are typically used for hunting by red foxes. © 2020 The Wildlife Society.     

Patch occupancy by squirrels in fragmented deciduous forest: effects of behavior

We tested whether species-specific behavioral traits could explain patterns of habitat patch occupancy by five different squirrel species in Ontario, Canada: the northern and southern flying squirrel (Glaucomys sabrinus and Glaucomys volans), the North American red squirrel (Tamiasciurus hudsonicus), the eastern chipmunk (Tamias striatus), and the eastern gray squirrel (Sciurus carolinensis). Flying squirrel species exhibit group nesting in winter, which may put them at risk of extirpation in small patches with few individuals to contribute to group nests. Flying squirrels are also volant, potentially making non-treed matrix a barrier. Our surveys revealed that G. sabrinus was most likely to occur in large patches that were embedded in landscapes with low connectivity, and least likely to occur in small patches in highly connected landscapes. Conversely, G. volans was most likely to occur in large, well-connected patches and least likely to occur in small, unconnected patches. Patch occupancy by the cursorial squirrels was not strongly influenced by patch area or isolation. These findings reinforce previous studies suggesting that an understanding of species-specific traits such as behavior is an important consideration when interpreting habitat fragmentation effects.     

Nest predation in forest birds: influence of predator type and predator's habitat quality

We used the introduction of a generalist nest predator, the red squirrel Tamiasciurus hudsonicus, and of a large herbivore, the Sitka black-tailed deer Odocoileus hemionus sitkensis, to the islands of Haida Gwaii (Queen Charlotte Islands, British Columbia, Canada) to study how predator assemblage and habitat quality and structure influenced nest predation in forest birds. We compared losses of natural nests to predators on islands with and without squirrels. We selected nine islands with or without squirrel or deer and used 506 artificial nests put on the ground or in shrubs to further analyse variation of nest predation with predator assemblage and habitat quality for the predators. For both natural and artificial nests predation risk was higher in presence of squirrels. But predation risk varied within island categories. In presence of squirrels it was highest in stands with mature conifers where it fluctuated from year to year, in response to fluctuations in squirrel abundance. Vegetation cover around the nest had little effect on nest predation by squirrels. Where squirrels were absent, nest predation concentrated near predictable food sources for corvids, the main native predators, and increased with decreasing vegetation cover, suggesting that removal of the vegetation by deer increased the risk of predation by native avian nest predators that use visual cues. Predation risk in these forests therefore varies in space and time with predator composition and with quality of the habitat from the predators' perspective. This temporal and spatial variation in predation risk should promote trade-offs in the response of birds to nest predation, rather than fine-tuned adaptations to a given predation pattern.     

Post-Soviet fire and grazing regimes govern the abundance of a key ecosystem engineer on the Eurasian steppe,the yellow ground squirrel Spermophilus fulvus

Aim

Grazing intensity and fire patterns across the Eurasian steppes have changed dramatically over the past decades due to the collapse of the Soviet Union in 1991, and Kazakhstan is now a global fire hotspot. The implications of these changes for ecosystem functioning are largely unclear. We aimed to understand the effects of changed grazing intensity and fire frequency on a key ecosystem engineer, the yellow ground squirrel Spermophilus fulvus, on a very large scale.

Location

Kazakhstan.

Methods

Ground squirrels were surveyed in an area of ca. 100,000 ha in the dry steppe of central Kazakhstan, using hierarchical distance sampling at more than 200 random points, stratified by fire frequency and livestock grazing intensity. We modelled abundance as a function of different variables, grouped at the landscape scale (fire and grazing), meso-scale (soil and vegetation structure) and at burrow scale (plant traits such as palatability, digestibility and nutrient content).

Results

Ground squirrels prefer areas of a high wormwood cover (Artemisia spp.) and high plant species richness, which are moderately grazed, preferably by cattle, with only rare fire occurrence. High squirrel densities were also related to the availability of nitrogen-rich plants of high nutritional value for herbivores.

Main Conclusions

Yellow ground squirrels seem to reach their density optima by balancing trade-offs between optimal foraging in areas of short, nutrient-rich vegetation and a good visibility of approaching predators. Post-Soviet changes in grazing pressure, resulting in higher fire recurrence rates due to grass encroachment and litter accumulation (i.e. fuel for wildfire), have likely affected the abundance of burrowing mammals and associated biodiversity across huge parts of the Eurasian steppes and semideserts.     

How does dune morphology shape coastal EC habitats occurrence? A remote sensing approach using airborne LiDAR on the Mediterranean coast

We examined the relationship between coastal habitats (sensu European Union Habitats Directive) and local dune morphology along a Mediterranean coastal dune system by integrating field collected vegetation data and remotely sensed imagery. Specifically, we described the morphological profile of each EC habitat based on the morphological variables that are most likely to affect their occurrence, including elevation, slope, curvature, northness, eastness and sea distance. In addition, we assessed the role and strength of each morphological variable in determining the occurrence of EC habitats.We used 394 random vegetation plots representative of six EC habitats (Habitat 1210: “Annual vegetation of drift lines”; Habitat 2110: “Embryonic shifting dunes”; Habitat 2120: “Shifting dunes along the shoreline with Ammophila arenaria”; Habitat 2210 and 2230: “Crucianellion maritimae fixed beach dunes” and “Malcolmietalia dune grasslands”; Habitat 2250: “Coastal dunes with Juniperus spp.”; Habitat 2260: “Cisto-Lavanduletalia dune sclerophyllous scrubs”) found along the Tyrrhenian coast of central Italy. We derived each morphological variable from a DTM (Digital Terrain Model) obtained from 2-m resolution LiDAR (Light Detection And Range) images. The mean value of each variable was calculated at different spatial scales using buffer areas of increasing radius (2 m, 4 m, 8 m) around each vegetation plot. Mean morphological values for each EC habitat were compared using Kruskal-Wallis rank test. The role and strength of the relationship between habitat type and the morphological variables were assessed using Generalized Linear Models.EC habitats occur differentially across dune morphology, and the role and strength of each morphological variable define habitat specificity. Dune elevation and sea distance were determined to be the key factors in shaping EC habitat occurrence along this section of the Mediterranean coast. Identification of the close relationship between habitat type and morphological variables deriving from airborne LiDAR imagery points to the high potential of such remote sensing tool for analyzing and monitoring the integrity of coastal dune ecosystems. As airborne LiDAR enables the rapid collection of extremely accurate topographic data over large areas, it also offers useful information for the management of these threatened and fragile ecosystems.     

Assessment of habitat quality for four small mammal species of the Monte Desert, Argentina

In the temperate desert of Argentina, the combined action of climatic and anthropogenic factors has contributed to the formation of a highly heterogeneous landscape. In the central region of the Monte desert, four small mammal species (Eligmodontia typus, Calomys musculinus, Akodon molinae and Graomys griseoflavus) coexist and show different habitat uses in response to spatial variability. Three main habitat types are present in the region: mesquite forest, the creosotebush community and sand dunes. These habitat types are present also in the surrounding grazing area.The objective of this study was to determine habitat quality for these species in a protected area (Reserve MaB Ñacuñán) and in the adjacent grazed area. For each species we estimated demographic parameters that are highly correlated to fitness in each habitat, and for both treatments (protected and grazed).We found that the protected area offered a higher quality habitat than the grazed area for all species, but principally A. molinae and G. griseoflavus. At a local scale, we found that A. molinae and C. musculinus clearly showed higher fitness in the more complex habitats as the creosotebush community and the mesquite forest. In contrast, for E. typus, open and simplest patches, such as sand dunes, were optimal for its survival and reproduction.