3 research outputs found
Limiting Factors in Colonial Seabirds, with Emphasis on Predation, Disease, Parasites and Diet, and Implications for Monitoring Studies
Marine habitats have undergone dramatic changes, particularly over the last few decades. Human-related causes, such as habitat alteration, overexploitation, pollution, climate change and introduction of alien species have affected marine ecosystems worldwide, with severe impacts on many species, including several seabirds. Seabirds, and particularly (but not exclusively) those species that act as top-predators, are excellent monitors of the health of marine ecosystems. However, in order to make use of them as bioindicators, we have to understand how potential limiting factors influence their ecology. In turn, this information is also useful for the conservation of their populations.
In this thesis I study a diversity of limiting factors of potential importance for the breeding ecology of two threatened seabirds, the southern rockhopper penguin and the black-browed albatross, at a mixed seabird colony on the Falkland Islands. An analysis of nesting habitat quality (Chapter 2) indicated that this did not explain variation in rockhopper penguin breeding success, which was most likely influenced by predation. An analysis of spatial and temporal variability of nesting success of black-browed albatrosses has shown that disease (Chapter 3), possibly coupled with parasites (Chapter 4) was the main cause for chick mortality differences between areas and years, whilst the consequences of a diet (Chapter 5) with a strong fisheries-related component for breeding success and chick development are still to be determined conclusively.
This multi factor approach together with a relatively long-term set of data are important to produce more robust conclusions (with atypical years put into context), and to tentatively assign changes in breeding parameters to individual factors. My results help to provide a more complete insight of the potential factors threatening two species of conservation importance at this colony and in the context of the Falklands
NEOTROPICAL ALIEN MAMMALS: a data set of occurrence and abundance of alien mammals in the Neotropics
Biological invasion is one of the main threats to native biodiversity. For a species to become invasive, it must be voluntarily or involuntarily introduced by humans into a nonnative habitat. Mammals were among first taxa to be introduced worldwide for game, meat, and labor, yet the number of species introduced in the Neotropics remains unknown. In this data set, we make available occurrence and abundance data on mammal species that (1) transposed a geographical barrier and (2) were voluntarily or involuntarily introduced by humans into the Neotropics. Our data set is composed of 73,738 historical and current georeferenced records on alien mammal species of which around 96% correspond to occurrence data on 77 species belonging to eight orders and 26 families. Data cover 26 continental countries in the Neotropics, ranging from Mexico and its frontier regions (southern Florida and coastal-central Florida in the southeast United States) to Argentina, Paraguay, Chile, and Uruguay, and the 13 countries of Caribbean islands. Our data set also includes neotropical species (e.g., Callithrix sp., Myocastor coypus, Nasua nasua) considered alien in particular areas of Neotropics. The most numerous species in terms of records are from Bos sp. (n = 37,782), Sus scrofa (n = 6,730), and Canis familiaris (n = 10,084); 17 species were represented by only one record (e.g., Syncerus caffer, Cervus timorensis, Cervus unicolor, Canis latrans). Primates have the highest number of species in the data set (n = 20 species), partly because of uncertainties regarding taxonomic identification of the genera Callithrix, which includes the species Callithrix aurita, Callithrix flaviceps, Callithrix geoffroyi, Callithrix jacchus, Callithrix kuhlii, Callithrix penicillata, and their hybrids. This unique data set will be a valuable source of information on invasion risk assessments, biodiversity redistribution and conservation-related research. There are no copyright restrictions. Please cite this data paper when using the data in publications. We also request that researchers and teachers inform us on how they are using the data
Neotropical freshwater fisheries : A dataset of occurrence and abundance of freshwater fishes in the Neotropics
The Neotropical region hosts 4225 freshwater fish species, ranking first among the world's most diverse regions for freshwater fishes. Our NEOTROPICAL FRESHWATER FISHES data set is the first to produce a large-scale Neotropical freshwater fish inventory, covering the entire Neotropical region from Mexico and the Caribbean in the north to the southern limits in Argentina, Paraguay, Chile, and Uruguay. We compiled 185,787 distribution records, with unique georeferenced coordinates, for the 4225 species, represented by occurrence and abundance data. The number of species for the most numerous orders are as follows: Characiformes (1289), Siluriformes (1384), Cichliformes (354), Cyprinodontiformes (245), and Gymnotiformes (135). The most recorded species was the characid Astyanax fasciatus (4696 records). We registered 116,802 distribution records for native species, compared to 1802 distribution records for nonnative species. The main aim of the NEOTROPICAL FRESHWATER FISHES data set was to make these occurrence and abundance data accessible for international researchers to develop ecological and macroecological studies, from local to regional scales, with focal fish species, families, or orders. We anticipate that the NEOTROPICAL FRESHWATER FISHES data set will be valuable for studies on a wide range of ecological processes, such as trophic cascades, fishery pressure, the effects of habitat loss and fragmentation, and the impacts of species invasion and climate change. There are no copyright restrictions on the data, and please cite this data paper when using the data in publications