Life on the edge: behavioural and physiological responses of Verreaux's sifakas (<i>Propithecus verreauxi</i>) to forest edges

Forest edges change micro-environmental conditions, thereby affecting the ecology of many forest-dwelling species. Understanding such edge effects is particularly important for Malagasy primates because many of them live in highly fragmented forests today. The aim of our study was to assess the influence of forest edge effects on activity budgets, feeding ecology, and stress hormone output (measured as faecal glucocorticoid metabolite – fGCM – levels) in wild Verreaux's sifakas (Propithecus verreauxi), a group living, arboreal lemur. We observed five habituated groups: three living in the forest interior and two at an established forest edge. There was no difference in average daily temperatures between edge and interior habitats; however, within the edge site, the average daily temperature incrementally increased over 450 m from the forest edge towards the interior forest of the edge habitat, and the population density was lower at the edge site. Activity budgets differed between groups living in the two microhabitats, with individuals living near the edge spending more time travelling and less time feeding. Groups living near the edge also tended to have smaller home ranges and core areas than groups in the forest interior. In addition, edge groups had elevated average fGCM concentrations, and birth rates were lower for females living in the edge habitat. Combined with lower levels of fruit consumption at the edge, these results suggest that nutritional stress might be a limiting factor for Verreaux's sifakas when living near a forest edge. Hence, Verreaux's sifakas appear to be sensitive to microhabitat characteristics linked to forest edges; a result with implications for the conservation of this critically endangered lemurid species.

Keanekaragaman Kupu-Kupu di Bendungan Ulung Peliang Kecamatan Tamako Kepulauan Sangihe, Sulawesi Utara

ABSTRAKKupu-kupu merupakan serangga yang termasuk dalam ordo Lepidoptera. Serangga tersebut memiliki peranan yang penting dalam suatu ekosistem yaitu mempertahankan keseimbangan ekosistem dan memperkaya keanekaragaman hayati di alam. Penelitian ini bertujuan untuk menganalisis keanekaragaman kupu-kupu di kawasan Bendungan Ulung Peliang, Kecamatan Tamako, Kabupaten Kepulauan Sangihe, Sulawesi Utara. Teknik pengambilan sampel menggunakan metoda transek. Pengambilan sampel dilakukan pada tiga tipe habitat yaitu habitat pinggir bendungan, hutan dan kebun. Pada masing-masing habitat dibuat transek dengan panjang 300m. Pengambilan sampel kupu-kupu dilakukan sepanjang garis transek menggunakan sweepnet. Komposisi kupu-kupu yang diperoleh terdiri dari 5 famili, 30 spesies dan 463 individu. Famili yang paling banyak ditemukan jumlah spesies dan individunya adalah Nymphalidae. Spesies yang memiliki kelimpahan tertinggi adalah Junonia hedonia intermedia dan Eurema tominia. Analisis keanekaragaman didapatkan bahwa indek kekayaan, indek keanekaragaman dan indek kemerataan spesies kupu-kupu tertinggi ditemukan pada habitat kebun, sedangkan kelimpahan spesies tertinggi terdapat pada habitat pinggir bendungan.Kata kunci: Keanekaragaman; kupu-kupu; Bendungan Ulung Peliang; Kepulauan SangiheABSTRACTButterflies are insects that are included in the order Lepidoptera. Theses insects have an important role in ecosystem that is to maintain the balance of the ecosystem and enrich the biodiversity in nature. This study aims to analyze the diversity of butterflies in the area of Ulung Peliang Dam, Tamako District, Sangihe Islands Regency, North Sulawesi. The sampling technique used the transect method. Sampling has been carried out in three types of habitats namely dam, forest and garden habitat. Each transect has been made with a length of 300m. Butterfly sampling was carried out along the transect line using. The composition of butterflies that habve been obtained consisted of 5 families, 30 species and 463 individuals. The most abundant family with a number of species and individuals is Nymphalidae. Species that have the highest abundance are Junonia hedonia intermedia and Eurema tominia. Diversity analysis found that the highest wealth index, diversity index and evenness species of butterfly species were found in the garden habitat, while the highest species abundance was in the dam edge habitat. Keywords: Diversity; butterfly; Ulung Peliang Dam; Sangihe Islands.

Bird species that occupy river edge in continuous forest tend to be less sensitive to forest fragmentation

Along a distance gradient from a given river, two types of habitat can be recognized: natural river edge and forest interior, each one with its own vegetation characteristics and dynamics. In a continuous area of the Brazilian Atlantic Forest, we investigated (1) if bird communities are different between a riverbank of a small stream and an inland forest habitat; (2) if the species of the river edge habitat are the ones that persist in the most in forest fragments after deforestation of a continuous forest; (3) if the river edge habitat species are those that are less sensitive to forest fragmentation. It is expected that there are differences in the bird communities and the occupancy of some species between the two habitats. We allocated 16 sampling points in each of the habitats and sampled the birds by point counts with a short radius of 30 m. Results suggest that there is a significant difference between the composition of the bird communities of the river edge and forest interior habitats, although the species richness is similar. Six species were more likely to occupy the river edge and 14 species had a greater probability of occupancy in the forest interior. Species associated with the river edge habitat (15 species) tend not to be sensitive to forest fragmentation (12 species). In this study, we demonstrated that river-border species of continuous forest areas form a significant part of the bird communities that persist in small forest fragments, with intense edge effect. This shows that not all forest edge species are the result of the colonization from open areas. Congruently, species that occupy the most distant areas from the river vegetation in a continuous forest are those more sensitive to forest fragmentation.

Spatiotemporal Patterns and Mechanisms of Chinese Tallowtree (Triadica sebifera) Spread along Edge Habitat in a Coastal Landscape, Mississippi, USA

Chinese tallowtree [Triadica sebifera(L.) Small] has reached unprecedented prevalence in coastal landscapes in the Gulf of Mexico, especially along edge habitat with low competition and abundant resource (e.g., light) availability. This study investigated the spatiotemporal patterns and mechanisms ofT. sebiferaspread along roadways and fire lines.Triadica sebiferaindividuals and landscape and community features were surveyed in equally spaced, spatially mapped plots. AllT. sebiferaindividuals were felled to determine tree age and status (seed trees or non-seed bearing trees), andT. sebiferaseed and seedling (≤2 yr old) densities and community and landscape features (over- and understory conditions, distance to seed trees) were measured. A zero-inflated negative binomial model was used to evaluate factors affectingT. sebiferaseed dispersal and seedling recruitment contributing to the observed spatiotemporal patterns. Introduced into the Grand Bay National Wildlife Refuge around 30 yr ago,T. sebiferatrees distribute in clustered patterns along roadways and fire lines and exhibit an exponential growth in density. HighT. sebiferaseed and seedling densities mainly occurred in sites that are ≤250 m from seed trees or have sparse overstory and high understory grass/herb coverage. With respect to the avian seed dispersal mechanism, the spatiotemporal patterns ofT. sebiferaspread along roadways and fire lines could be simply characterized by using landscape and community features that influence avian behaviors, including distance to seed trees, overstory tree density, and ground grass/herb coverage.

Edge-habitat Use by Northwestern Gartersnakes (Thamnophis ordinoides) in Saanich, British Columbia

Understanding habitat requirements of species is fundamental for their conservation and urban parks can provide key habitat for species in otherwise disturbed settings. Northwestern Gartersnakes (Thamnophis ordinoides) are common in parks in Saanich, British Columbia, but their specific habitat requirements are poorly understood. Based on previous studies and thermoregulatory needs of snakes, we predicted that edges, particularly field margins, would be heavily used by active snakes. We therefore used surveys that focused on edges to find snakes and measured edge-habitat use by comparing habitat variables at locations where snakes were found to the same variables at nearby random locations. Habitat variables included composition and structure of vegetation, substrate temperature, aspect, and slope. Overall, litter depth, canopy cover, a lack of bare ground and woody vegetation were the most important habitat variables for determining where snakes were found. our results provide a preliminary assessment to improve our understanding of habitat use for this species. The abundance of snakes found while surveying edges supports our initial assumption that edges are important habitat features but more work is required using multiple survey methods to further test this hypothesis.