Urban forest fragmentation impoverishes native mammalian biodiversity in the tropics

Urban expansion has caused major deforestation and forest fragmentation in the tropics. The impacts of habitat fragmentation on biodiversity are understudied in urban forest patches, especially in the tropics and little is known on the conservation value of the patches for maintaining mammalian biodiversity. In this study, camera trapping was used to determine the species composition and species richness of medium‐ and large‐sized mammals in three urban forest patches and a contiguous forest in Peninsular Malaysia. We identified the key vegetation attributes that predicted mammal species richness and occurrence of herbivores and omnivores in urban forest patches. A total number of 19 mammal species from 120 sampling points were recorded. Contiguous forest had the highest number of species compared to the urban forest patches. Sunda Pangolin and Asian Tapir were the only conservation priority species recorded in the urban forest patches and contiguous forest, respectively. Top predators such as Malayan Tiger and Melanistic Leopard were completely absent from the forest patches as well as the contiguous forest. This was reflected by the abundance of wild boars. We found that mammal species richness increased with the number of trees with DBH less than 5 cm, trees with DBH more than 50 cm, and dead standing trees. In the future, the remaining mammal species in the urban forest patches are expected to be locally extinct as connecting the urban forest patches may be infeasible due to land scarcity. Hence, to maintain the ecological integrity of urban forest patches, we recommend that stakeholders take intervention measures such as reintroduction of selected species and restocking of wild populations in the urban forest patches to regenerate the forest ecosystems

Determinantes da riqueza específica e diversidade de vertebrados na região do Baixo Vouga Lagunar

The identification of the factors driving species richness and diversity variations in a landscape has key role in ecology and in biodiversity conservation plans. In this study, we focused our attention on different vertebrates’ taxa present in the Baixo Vouga Lagunar (BVL) and aimed to identify biodiversity hotspots in this Portuguese region. To achieve that goal, we reviewed ecological studies that targeted terrestrial vertebrates inhabiting the BVL and used their datasets as a basis for our study. Then, we collected ecologically relevant environmental variables, established three ecological hypotheses encompassing those variables (H1: Landscape composition; H2: Anthropic disturbance; H3: Water presence), and tested them to assess which drivers can restrain or promote the BVL vertebrates’ biodiversity patterns (species richness and diversity).The test of those hypotheses was implemented using an ecological modeling approach (Generalized Linear Mixed Models - GLMM) and later, based on the identified drivers, we forecasted species richness and diversity values to the study area. We expected to be able to identify vertebrates’ richness and diversity hotspots in the BVL, which would be a crucial tool to efficiently manage this area and assure the maintenance of its biodiversity values. Unfortunately, we faced data limitations, which affected model building robustness, resulting in low accuracy, and consequently in limited feasibility of the models’ predictive capacity. Therefore, in our forecasted map we could not define specific areas as hotspots, which is unrealistic. In the future, a well-defined sample design and more intense sample effort is needed in order to encompass a broader range of sampling points and promote a more robust model.A identificação dos fatores que determinam as variações de riqueza e diversidade de espécies na paisagem tem um papel fundamental em ecologia e nos planos de conservação da biodiversidade. Neste estudo, focamos a nossa atenção em diferentes taxas de vertebrados terrestres presentes no Baixo Vouga Lagunar (BVL) e definimos como objetivo a identificação de hotspots de biodiversidade nesta região portuguesa. Para atingir o objetivo, revimos os estudos ecológicos centrados nos taxa modelo deste trabalho e que abrangiam a área do BVL e usamos os seus dados como base para o nosso estudo. De seguida, recolhemos variáveis ambientais com importância ecológica e estabelecemos três hipóteses (H1: Composição da paisagem; H2: Perturbação antrópica; H3: Presença de água), contendo essas variáveis de forma a testar quais os fatores que restringem ou promovem os padrões de riqueza e diversidade dos vertebrados no BVL. Assim, recorrendo a uma abordagem de modelação ecológica e depois, baseando-nos nesses fatores estimamos os valores de riqueza e diversidade de espécies para toda a área de estudo. Era expectável conseguirmos identificar os hotspots de riqueza e diversidade de vertebrados terrestres no BVL, que seriam uma ferramenta crucial para gerir eficazmente esta área e assegurar a manutenção dos seus valores de biodiversidade. No entanto, deparamo-nos com uma limitação de dados, que se revelou um problema na construção dos modelos, resultando numa baixa precisão e consequentemente numa limitada capacidade de predição do modelo. Portanto, a nossa projeção da métrica para o BVL não permitiu identificar hotspots. No futuro, é necessária uma amostragem melhor delineada e um esforço de amostragem mais intenso para abranger um leque mais vasto de pontos de amostragem e promover assim a recolha de um maior volume de dados que permitam a construção de modelos mais robustos.Mestrado em Ecologia Aplicad

Foraging strategies of an aerial-hawking insectivore, the common noctule bat Nyctalus noctula

Movement is a key signature of life. Yet, the integration of movement ecology and biodiversity concepts was only recently formalize. In this framework, an individual’s movement path and the underlying drivers are used to explain interactions between individuals and eventually species coexistence. Interactions influence the individual’s environment including species assemblage, and thereby feed back on the individual’s movement path. Foraging represents one of the most common movements of many animals, and thus has been of interest for ecologists ever since. Yet, classical foraging ecology predominantly focused on optimality models to explain the behaviour of single foragers, but rarely took into account the interactions between moving individuals. The overarching question of the three studies in this thesis thus was “How can different foraging strategies support coexistence?”. Being highly mobile and showing a large niche overlap with several other species, the insectivorous Common noctule bat Nyctalus noctula (Schreber, 1774) is an ideal model species to study intra- and interspecific interactions during foraging movements. I therefore investigated movement behaviour and space use of N. noctula during aerial foraging, and evaluated the potential role of different foraging strategies for the coexistence of competing bat species in the light of different competitor densities and prey distributions. In chapter one, I asked whether foraging N. noctula adjust their space use to abiotic factors (i.e. moonlight) which might be linked to prey distribution. I used GPS (global positioning system) loggers to investigate the habitat use of nine N. noctula during high and low moonlight intensities. During moonlit nights, N. noctula hunted preferentially over open fields, whereas they avoided open fields in dark nights. I suppose that foraging activity followed changes in insect activity triggered by the lunar cycle. The results suggest that N. noctula might be able to predict cyclic changes in prey distribution. The exploitation of prey aggregations in lit habitats might be an advantage towards competing bat species that are less light tolerant. In chapter two, I asked whether the use of social foraging by N. noctula depends on season, possibly as a response to changes in insect availability. I quantified N. noctula activity at foraging sites in early and late summer during acoustic playbacks of either hunting conspecifics or heterospecifics. N. noctula activity increased during heterospecific playbacks in early summer, but decreased in late summer. There was no clear reaction towards conspecific playbacks, irrespective of the season. The results suggest that external factors determine the strengths of intraspecific and interspecific competition, but that insectivorous bats mitigate different competitive pressures through flexibility in foraging strategy and fine scale space use. I argue that conspecific might impair each other by acoustic interference of echolocation calls and competition for flight space. However, niche segregation might make social foraging with heterospecifics beneficial, given that there is low competition for prey items. In chapter three, I asked whether the foraging strategy of N. noctula depends on the combination of conspecifics density and landscape features that might determine prey distribution. I used combined GPS-ultrasound loggers to record the nightly foraging movements and hunting activity of 27 N. noctula above farmland and forested landscape. Acoustic records also allowed quantification of nearby conspecifics. I deduced two movement states - area restricted movement and directed movement - from the GPS tracks. Above farmland, N. noctula switched to area restricted movements after encounters with conspecifics, and foraging activity was highest during those movements. Above forested landscape, encounters with conspecifics had little influence on the movement behaviour of N. noctula, and foraging activity occurred during directed and area restricted movements alike. N. noctula encountered more conspecifics above the forested landscape than above farmland. I argue that N. noctula was able to integrate prey distribution and competitive pressure when deciding whether or not to pursue a social foraging strategy. The use of a social foraging strategy might be a prerequisite for survival in agricultural landscapes where prey is patchily distributed and ephemeral. In contrast, solitary foraging might be the optimal strategy in forested landscapes that offer evenly distributed prey and support larger populations. In conclusion, the results showed that N. noctula integrated environmental factors that probably influenced prey distribution, adverse effects from intra- and interspecific competition, and public information about prey availability provided by hunting con- and heterospecifics. N. noctula used this compiled information to decide where to forage and whether to forage solitary or socially. The studies highlighted that N. noctula can adjust its foraging strategy context dependently. This flexibility was achieved through dynamic feedbacks between the movement paths and the perceived environment. These dynamic feedbacks may play a pivotal role in promoting the coexistence of competing species. In particular, the similarity of movement behaviours and resulting foraging strategies among conspecifics might stabilize species assemblages through intraspecific competition, while slight differences in the movement behaviour among heterospecifics might allow fine-scale niche segregation and thereby equalize the fitness of coexisting species. I propose that dynamic foraging behaviour might act stabilizing and equalizing not only in insectivorous bats but on assemblages of highly mobile predators in general

Herpetofauna responses to agricultural matrix management

Preventing biodiversity loss in fragmented agricultural landscapes is a global problem that requires knowledge of how species move through landscapes. Farming practices can increase the contrast between remnant patches of native vegetation and adjoining habitats, with negative consequences for species movement and the preservation of biodiversity. Yet, the relationships between habitat attributes and the presence of species are poorly understood, and the mechanisms influencing cross-habitat movement has rarely been empirically tested, particularly for less mobile organisms such as frogs, snakes and lizards (herpetofauna). To address this important knowledge gap, I used a large-scale, empirical experiment to examine herpetofauna abundance, species richness, body condition, risk of predation, and inter-habitat movement between remnant woodland patches, edges and four contrasting farm land use types: 1) crop fields, 2) pasture paddocks, 3) linear plantings, and 4) woody mulch applied to a crop paddock after harvest. I also examined the effect of crop harvesting and seasonal effects on the distribution and abundance of herpetofauna. In the second and third chapters of the thesis, I compared the habitat preferences and abundance and, richness and body condition (frogs only) of reptiles and frogs to predictions developed from a conceptual matrix model and literature review. I found the structure and quality of the matrix was a stronger influence on reptile abundance, species richness and movement than the temporal effect of crop harvesting (chapter 2). My results demonstrate remnant patches and farmland, particularly those with woody vegetation plantings, can provide suitable habitat for common reptile species, but this environment is not readily interchangeable as habitat for uncommon reptile species. The negative response of uncommon reptile abundance and species richness to farmland, irrespective of restoration, indicate that farmland not only reduced their abundance but also the likelihood of presence. I also observed a negative trend in uncommon reptile abundance in remnant patches adjacent to crop paddocks. These findings suggest that crop paddocks and associated farming activities may be negatively influencing animals within both patches and matrix, further isolating populations, and reinforcing the negative consequences of conversion to agriculture for reptile populations. In Chapter three, my study revealed while frog abundance was positively associated with woody vegetation plantings within farmland, many frog species were found ubiquitously throughout the landscape, reflecting the dominance of a few disturbance tolerant species in the amphibian assemblage. My movement data demonstrated that frogs used multiple farmland types, moved between remnant patches and farmland, and into and out of cropped paddocks across harvesting periods. Unexpectedly, I found crop harvesting did not reduce frog abundance in crop paddocks, with some individuals persisting in farmland after harvesting. Body condition analyses indicated that farmland areas may provide good quality habitat for frogs and allow movement, dispersal, and foraging opportunities. My findings provide important insights into the utilisation of highly modified farmland as terrestrial habitat for frogs. This new knowledge is valuable in the context of land use intensification, and global amphibian declines. While much effort has focused on the protection of aquatic habitats for amphibians, management strategies must also consider the range of contrasting farmland types present in cropping areas, and the habitat requirements of the target species. In the fourth chapter, I explored how contrasting habitats and farm management influences predation risk in lizards using wildlife cameras and plasticine replica lizard models. I found predation pressure from multiple predators, operating across the landscape, could be compounding the effects of habitat degradation and fragmentation. Predation attempts on models were highest at habitat edges, with a reduced risk within farmland and remnant patches. My findings suggest edge habitats are ‘risker’ for lizards than farmland, and may act as a population sink, preventing reptiles from moving into the farmland if individuals suffer increased mortality at the edge. Such trends have not been previously reported for cropped landscapes. Finally, in the fifth chapter, I examined detailed movement patterns and behavior of a patch-dependent gecko species, Eastern Tree Dtella Gehyra versicolor, using radio-telemetry, fluorescent powder and an experiment displacement to examine movement and avoidance behaviour in response to different woodland to farmland edges. Unexpectedly, I found edge effects with a strong partitioning of individuals away from farmland, irrespective of the presence of complex habitat (e.g. linear plantings), in preference for remnant patches. We found pasture environments promoted direct movements of displaced geckos at a set distance from remnant patches into pastures. However, none of the radio-tracked geckos crossed the woodland-pasture edge, suggesting pastures may reduce homing ability of geckos. These findings contrast with the known ecology of the species and suggest, despite efforts to improve farmland quality by planting, farmland is not a preferred habitat for this species and does not promote longer distance dispersal movements. By examining the influence of anthropogenic habitat change on herpetofauna it is possible to improve our understanding of the distribution of species outside of remnant native vegetation. My research findings provide new insights into the complex responses of herpetofauna to contrasting farmland uses in cropping landscapes. I provide evidence for potential drivers to explain herpetofauna distribution within highly disturbed areas. Importantly, I have demonstrated the relative value of different farmland types for facilitating and reducing movement and providing habitat across diverse agricultural landscapes. Through my series of inter-connected studies, I highlight important opportunities to promote herpetofauna conservation in agricultural landscapes by protecting remnant native vegetation and by increasing restoration efforts in cropping landscapes by establishing linear plantings. I also identify management practices to reduce mortality risk in areas where dispersal may be important by focusing on implementing strategies that increase shelter opportunities for lizards and to reduce the size of edges particularly where dispersal may be important (such as between remnants and linear plantings). This new knowledge is valuable in the context of promoting landscape connectivity, targeted restoration programs, and arresting global herpetofauna decline

Effects of Green Tree Retention on Birds of Southern Pine Plantations

In the southern United States, institutional forest owners engaged in forest certification programs often retain unharvested or less-intensively harvested vegetation when clearcut harvesting intensively managed pine (Pinus spp.) forests (“IMPFs”), a practice called ‘green tree retention’. I investigated resultant patterns of land cover and retained structural elements in recently-harvested IMPF management units (“MUs”) and related them to avian biodiversity to provide information to support harvest decisions. First, to provide forest managers baseline data on retention, I screen-digitized land cover on 1187 MUs (totaling 51646 ha) and characterized green tree retention levels and internal land cover attributes (Chapter 2). I found MU land cover was dominated by regenerating clearcuts (mean: 80.5%), streamside management zones (“SMZs”; vegetated buffers surrounding intermittent and perennial streams; 14.0%) and stringers (buffers surrounding ephemeral streams; 3.3%). Next, I surveyed 60 MUs for vegetation stem density and cover (Chapter 3). Concurrently, I surveyed avian community density and richness (Chapter 4). Vegetation and avian metrics were compared and contrasted across the dominant cover types (with emphasis on stringer/SMZ similarity) to understand impacts of retained structural elements on biodiversity outcomes. I found that snag and log density, midstory pine density, understory deciduous cover, and ground cover were not different in stringers and SMZs; however, overstory (pine and deciduous) and midstory (deciduous) tree density was lower in stringers than in SMZs, and understory pine density was greater in SMZs. Species overlap between cover types was high (74% to 84%), but SMZs and stringers provided 27% of MU species richness. Stringers appeared to benefit both shrubland- and forest-associated birds. Finally, I sampled land cover across 4450 sq-km surrounding the 60 MUs, and performed ordination analyses to identify associations between local-scale (MU interiors) and landscape-scale (3-km buffers around MUs) land cover and avian guild diversity (Chapter 5). I found the region to be \u3e90% forested. Cover type data explained 41% of the partial variation in avian density and total species richness. Local-scale MU characteristics appeared more important than landscape-scale characteristics in explaining avian biodiversity responses. My results suggest that retained structural features support and enhance MU biodiversity in harvested IMPFs

Riparian Ecological Community Assessment with an Emphasis on Wood Turtles (Glyptemys insculpta) in the Cacapon River Watershed, West Virginia

Riparian zones serve to maintain high water quality, low water temperatures, and structural complexity in aquatic and terrestrial environments, among other beneficial services. Riparian buffers provide habitat and corridors linking forest patches for terrestrial wildlife. High riparian vegetative structure and complexity attract a high diversity of wildlife, including birds, herpetofauna, and small mammals. Devegetated riparian zones, often a result of developmental and agricultural practices, lose their beneficial functions and require restorative actions to regain them. The Cacapon River watershed in West Virginia is agriculturally-dominated with many areas of riparian zone degradation. A section of the Cacapon River was selected for natural stream channel design restoration during 2009 to 2011. Our objectives were to: (1) monitor birds, small mammals, anurans, and vegetation along the restoration reach, 2 control (impaired) sites, and 2 reference (unimpaired) sites following a before-after control-impact design along the Cacapon River; (2) survey natural history characteristics of wood turtles (Glyptemys insculpta) using the riparian zone along the Cacapon River; and (3) assess factors limiting wood turtles along the southern extent of their geographic range along the Lost and North rivers, tributaries of the Cacapon River. We expected (1) the diversity of the riparian wildlife to remain stable or increase post-restoration, (2) wood turtles to undergo all natural history aspects within the riparian zone, and (3) geographical and environmental features to limit wood turtles along the southern border of their range in the Cacapon River watershed.;Monitoring of riparian wildlife along the Cacapon River occurred pre- (April 2009 to April 2010) and post-restoration (May 2010 to August 2011). Overall, 6 small mammal species, 79 bird species, 8 anuran species, and 96 plant species were recorded. Small mammal abundance declined initially in the restoration reach post-impact, but began to recover. Overall bird abundance, richness, and diversity increased along the restoration reach post-impact. The anurans were unaffected by the restoration activities, but showed species-specific timing of reproductive activities across the sites. Shrub and tree diversity, richness, and evenness increased over time, possibly indicating that the restoration reach began improving in vegetative complexity post-impact. The restoration was considered a success because the diversity of the riparian wildlife remained stable or increased post-restoration.;Monitoring of wood turtles along the Cacapon River occurred during spring 2009 to summer 2011. The turtles were observed primarily using the riparian zone (80.7%) instead of the surrounding agricultural land (19.3%). Adult males and females were larger than juveniles. Reproductively active males were longer, thicker, and heavier than reproductively active females. Home ranges were 0.62 -- 36.97 ha. Low bare ground and rock cover and high vertical density differentiated the turtles\u27 habitat from random vegetation plots. The turtles were typically terrestrial during spring and summer and aquatic in autumn and winter. Mating occurred in autumn (64.3%) after 1300 hrs (75%), sometimes terrestrially (35.7%). Nesting attempts were made on sandy substrate in the early mornings and early evenings of spring. Basking occurred at 45°, angled to the sun, on a variety of surfaces. Dietary preference was for slugs (67%), although other invertebrates, plant matter, and animal matter were consumed. The riparian zone provided the wood turtles with all of their natural history needs.;Monitoring of wood turtles along the Lost and North rivers in the Cacapon River watershed was conducted during summer 2010. Habitat characteristics, potential dispersal barriers, and the approximate southern geographic boundary of the species in the watershed were assessed. Sixty-four of 100 randomly-selected sites contained wood turtles. Increasing stream depth, canopy cover, soil temperature, and proximity to the Cacapon River, and low elevation and slope positively influenced presence of the turtles. Field layer (woody and herbaceous plants \u3c1 m tall) species richness and diversity were greater in sites with wood turtles than without the turtles. Witch-hazel (Hamamelis virginianus) and ironwood (Ostrya virginiana) weakly separated sites without turtles from sites with them. The factors limiting wood turtles at the southern limits of their range in West Virginia included (1) inability to disperse over high elevations, (2) agricultural influences decreasing habitat availability and turtle survivorship, and (3) an intolerance to high temperatures. In agricultural areas bordering waterways, riparian buffers should be restored if they are degraded, managed to promote structurally complex vegetation, and monitored to determine whether the buffers are providing essential habitat for a diverse array of terrestrial wildlife that should promote adult survivorship and population stability