1,721,095 research outputs found
An overlooked invader? Ecological niche, invasion success and range dynamics of the Alexandrine parakeet in the invaded range
No full textParrots and parakeets (Aves, Psittaciformes) are prominent among avian invaders, as more than 16 % of living species are currently breeding with at least one population outside their native range. Most studies have been carried out on ring-necked and monk parakeets, as they are the most successful invasive parrots globally. Recently, however, reports of invasive Alexandrine parakeet Psittacula eupatria have increased. Here, we summarize the current knowledge on the current occurrence of Alexandrine parakeets outside the natural range and assess the degree of niche conservatism during the invasion process. Our results show that Alexandrine parakeets have established invasive populations predominantly in Europe, parts of the Middle east and Far Eastern countries such as Japan and Singapore. During the ongoing invasion of Europe, the Alexandrine parakeet considerably expanded its niche into colder climates with respect to those occupied in the native range. Our results offer some support to the hypothesis that interspecific facilitation with previously established ring-necked parakeets Psittacula krameri may contribute to niche expansion and invasion success of congeneric Alexandrine parakeets. Species Distribution Models including both native and invaded range occurrence data predict a high invasion risk across multiple parts of the globe where the species is currently not yet present, thus indicating a high potential for the species for further invasion success and range expansion
No overall effect of urbanization on nest-dwelling arthropods of great tits (Parus major)
No full textUrbanization has been shown to strongly affect community composition of various taxa with potentially strong shifts in ecological interactions, including those between hosts and parasites. We investigated the effect of urbanization on the composition of arthropods in nests of great tits in Flanders, Belgium. These nests contain taxonomically and functionally diverse arthropod communities including parasites, predators, detritivores and accidental commensals. Using a standardized hierarchical sampling design with subplots (200 m x 200 m) nested in plots (3 km x 3 km) of varying urbanization levels, we collected arthropods from nests of resident great tits after the young had fledged. Arthropods were extracted, identified to Primary Taxonomical Groups (PTG) and counted. Using generalized linear mixed models (GLMMs) we found diverging effects of urbanization on PTG occurrences and abundances at various levels, but we did not find an overall signal in arthropod diversity or richness. Also, visual inspection of non-metric multidimensional scaling (NMDS) plots did not reveal any community differences between urbanization levels at plot or subplot scales. Land use and environmental variables at different distances around nestboxes did not contribute much to the variation between communities. Our results indicate that arthropod nestbox communities are generally not adversely affected by urbanization, and even city gardens and parks harbor comparable communities to forests and suburban areas. We thus found no evidence for a parasite release effect due to urbanization, nor an increased risk of parasitism in human-dominated environments
Systematic definition of threatened fauna communities is critical to their conservation
No full textAim: Most terrestrial ecological communities are defined primarily on their constituent flora. We aimed to develop a repeatable approach to defining a community, both intact and degraded, based on its fauna. We demonstrate how the approach can be used to guide conservation—for example, determining whether a multispecies community of animals is threatened. Location: Temperate and subtropical woodlands of Australia. Methods: We used expert opinion to develop a definition of the Australian Temperate and Subtropical Woodland Bird Community and metrics of its condition. Using continental-scale vegetation change mapping, and national bird atlas data, we assessed this community against criteria for listing as a threatened ecological community under national biodiversity conservation law. Results: We defined and described a recognizable and consistent Australian Temperate and Subtropical Woodland Bird Community. Although taxonomically and functionally very similar, we identified six community variants that show species- or genus-level substitutions. The community was evaluated to be Endangered or Critically Endangered across its extent based on criteria from Australia's Environment Protection and Biodiversity Conservation Act 1999. We used a novel metric of condition using historical changes in woodland extent and bird species, to demonstrate the community has declined substantially in geographical extent and integrity and is subject to severe and ongoing threats. Conclusions: The consequences of global change affect entire communities, not just single species; however, defining ecological communities based predominantly on plant species composition can fail to illuminate the complex associations of animals that are both sustained by, and sustain, the vegetation. In this study, we present a process for defining and evaluating the status of a fauna community against threat criteria. The explicit recognition and protection of fauna communities can be an important complement to the protection of plant-based ecological communities
Shape Analysis as an Additional Tool in Roe Deer (Capreolus capreolus) Management: A New Approach Based on the Relationship between Mandible Shape and Trophic Resources
Full text linkThe analysis of body shape variability has always been a central element in biology. More recently, geometric morphometry has developed as a new field in shape analysis, with the aim to study body morphological variations and the identification of their causes. In wildlife management, geometric morphometry could be a useful tool to compare the anatomical structures of an organism and quantify its geometric information in order to relate them to environmental factors, thus identifying the causes and effects of the variation and acting management and/or conservation plans. The aim of our study is to evaluate the relationship between roe deer mandible shape and trophic resources available during autumn and winter. We applied a geometric morphometry approach consisting of a Relative Warp analysis of landmark data in 26 roe deer fawn mandibles. Each sample was assigned to an age category and to an environmental category based on the territory carrying capacity. The mandible shape of samples under 8 months of age is likely influenced by the availability of trophic resources. Our findings suggest that the mandible shape is a reliable instrument to assess resource availability. Geometric morphometry could thus represent an additional tool for roe deer management
Systematic conservation planning in the high Andes of Bolivia : application of modelling tools for integrative management of natural areas
No full textAbstract: Effective management of protected areas is necessary to ensure they deliver socio-economic benefits to local communities while conserving the biodiversity they contain. In this thesis, we use targeted monitoring and remote sensing data combined with modeling tools to generate scientifically-based management recommendations designed to ensure the conservation of biodiversity and the delivery of ecosystem services in the Tunari National Park (TNP) in Bolivia. More specifically, we aimed to (1) investigate which characteristics of the remaining Polylepis fragments of the Southern Slope of the TNP are associated with bird species richness and the presence of species of conservation concern, (2) study habitat selection patterns for the most common forest-dependent bird species occurring in a mosaic landscape made of Polylepis fragments, agricultural fields and exotic plantations on the Southern Slope of the TNP, (3) identify, using species distribution models, the areas of highest priority for the conservation of the avifauna occurring in Polylepis forests of the Southern Slope and especially for conservation concern species and (4) use the conservation planning software Marxan with Zones to generate optimal land use plans that maximize the conservation of several bird species, including species of conservation concern, while minimizing opportunity cost for the local communities on the Southern Slope of the TNP. We then use these plans to explore the potential trade-offs between biodiversity conservation and the delivery of water-related ecosystem services, a limited resource in the area and important source of conflicts. Finally, we formulate scientifically-based management recommendations for the conservation of the avifauna of the Polylepis remnants in the TNP and especially on the Southern Slope. We confirm the importance of the Polylepis patches of the Tunari National Park and especially of its Southern Slope to support rare and/or threatened Andean species. We conclude that, while it is crucial to protect the biodiversity-rich Polylepis patches, managing the entire landscape in which these patches occur is necessary to meet conflicting conservation and socio-economic demands for the Southern Slope of the TNP. Therefore, conservation management should focus on (1) conserving and/or restoring existing Polylepis fragments, (2) establishing a reforestation scheme and (3) promoting agroforestry and silvopastoralism. We make spatially-explicit recommendations of where to prioritize conservation, restoration and reforestation and promote agroforestry and pastoralism to best support biodiversity, ecosystem services delivery and local livelihoods in a tropical protected area
Effects of forest fragmentation and resource availability on mobility and reproduction of two avian insectivores, and consequences for ecosystem functioning
No full textFrom the tropics to the temperate zone : a comprehensive exploration of thermoregulation in small passerines
No full textKennishiaten over de capaciteiten van organismen om hun ecofysiologische kenmerken aan te passen, beperken het potentieel van ecofysiologie bij het voorspellen van impacten van global change op de biodiversiteit. In deze scriptie test ik daarom hypothesen over hoe kleine zangvogels reageren op diverse klimaatomstandigheden. Als studieobjecten gebruik ik twee veelvoorkomende vogelsoorten: een tropische soort (Sint-Helenafazantjes, Estrilda astrild) en een soort uit gematigde streken (Koolmezen, Parus major). Mijn onderzoek toont aan dat beide soorten de capaciteit hebben om zich aan te passen aan verschillende temperaturen, voornamelijk door aanpassingen aan zowel hun basale als maximale metabolische snelheden. Tropische soorten zijn geëvolueerd in warme, stabiele klimaten en worden daarom verondersteld slechts een beperkte capaciteit te hebben voor ecofysiologische aanpassingen. Mijn onderzoek wijst echter uit dat tropische Sint-Helenafazanten hun energieverbruik verminderen bij koudere temperaturen. Dergelijke energiebesparende mechanismen kunnen bijdragen aan hun succes als invasieve soort, onder andere in Europa. Koolmezen in koudere gebieden blijken zoals verwacht in staat te zijn meer warmte te produceren vanwege hun aanzienlijk hogere maximale metabolische snelheden. In tegenstelling tot de verwachtingen was er echter geen sterk verband tussen de basale en maximale metabolische snelheid, zowel voor koolmezen als voor Sint-Helenafazanten. Meer onderzoek is daarom nodig om de precieze mechanismen te begrijpen die bepalen hoe vogels hun energiehuishouding reguleren
Avian SDMs : current state, challenges, and opportunities
No full textAbstract: Quantifying species distributions using species distribution models (SDMs) has emerged as a central method in modern biogeography. These empirical models link species occurrence data with spatial environmental information. Since their emergence in the 1990s, thousands of scientific papers have used SDMs to study organisms across the entire tree of life, with birds commanding considerable attention. Here, we review the current state of avian SDMs and point to challenges and future opportunities for specific applications, ranging from conservation biology, invasive species and predicting seabird distributions, to more general topics such as modeling avian diversity, niche evolution and seasonal distributions at a biogeographic scale. While SDMs have been criticized for being phenomenological in nature, and for their inability to explicitly account for a variety of processes affecting populations, we conclude that they remain a powerful tool to learn about past, current, and future species distributions - at least when their limitations and assumptions are recognized and addressed. We close our review by providing an outlook on prospects and synergies with other disciplines in which avian SDMs can play an important role
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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