Pode a competição por ninhos afetar a monogamia genética dos cagarros?

A secção UAciência é coordenada pelo Professor Universitário Armindo Rodrigues.Apesar de 90% das espécies de aves serem socialmente monogâmicas, ocorrem copulas fora do casal, que poderão eventualmente resultar em paternidades extraconjugais, as quais já foram observadas em mais de 140 espécies. Considera-se que as copulas fora do casal permitem as fêmeas ajustar a escolha do seu macho social (ou seja, o macho com quem vão ficar desde a formação do casal ate a emancipação das crias) e aos machos que não conseguiram um ninho evitar perder um ano de reprodução, sobretudo quando uma disponibilidade baixa em sítios de nidificação constrange a escolha do parceiro social (nesta altura, quase qualquer macho pode ser escolhido desde que possua um ninho). […], um estudo de genética molecular (utilizando marcadores microssatélites) em 69 famílias de cagarros (os dois progenitores sociais e a sua única cria, uma vez que o tamanho da postura e de um ovo só) neste ilhéu em 2002 e 2003, revelou a existência de paternidades extraconjugais cada ano, com uma taxa global de 11.6%. […].info:eu-repo/semantics/publishedVersio

Impact of vagrant predators on the native fauna: a Short-eared Owl (Asio flammeus) preying on Madeiran Storm Petrels (Oceanodroma castro) in the Azores.

The impact of introduced predators on the native fauna of oceanic islands has proven to be catastrophic in many cases. In some instances, however, predation is caused by very few individuals arrived without any human assistance. Here, I report on the impact of a vagrant Short-eared Owl on the small population (200 breeding pairs) of cool-season Madeiran Storm Petrels from Praia Islet (0.12 km2), off Graciosa Island, Azores archipelago. The owl fed almost exclusively on storm petrels and killed between one and two individuals every night. The number of prey remains found suggests that it must have been present on the islet ca two weeks before its presence was noticed. Although the Short-eared Owl is a rare vagrant in the Azores, these observations show that a single individual may have a strong impact on a vulnerable population of Madeiran Storm Petrels

Why do Bulwer’s Petrels Bulweria bulwerii change nest?

Owning a nest is a prerequisite for breeding in Procellariiform seabirds, which can leave their single egg and/or chick unattended for long periods and show high nest fidelity. However, the determinants of nest fidelity vary among species. Amongst them, Bulwer’s Petrel Bulweria bulwerii lays the biggest egg relative to body size within the Family Procellariidae. Therefore, individuals should choose their nests carefully and change essentially if they can improve their reproductive performances. This study conducted on Vila islet, Azores, aimed to determine why Bulwer’s Petrels actually change nest. Nest fidelity exceeded 85%. Nest changes were most likely to occur after a breeding failure or a non-breeding year, but they did not allow improving breeding success and they often resulted in missed breeding years. On average, the new nests were not of higher quality than the old ones, except for the individuals whose first breeding attempt in the new nest was successful. In addition, the quality of the new nest was unrelated to the number of skipped years and to the distance moved. Almost half of changes occurred towards neighbouring nests. They were associated with a lower probability to skip years. Therefore, Bulwer’s Petrels might prioritize proximity over nest quality to reduce the costs of nest changes. communities.This study was part of the project PTDC/BIA-BDE/67286/2006 funded by FCT and by FEDER through the Programme COMPETE (Ref: FCOMP-01-0124-FEDER-007061). The Programmes ‘MARE’ (Integrated Management of Coastal and Marine Sites of the Azores, Life contract B4-3200/98-509), ‘OGAMP’ (Planning and Management of Marine Protected Areas, Interreg IIIB-MAC/4.2/A2), ‘MARMAC’ (Knowledge, Promotion and Valorization for a Sustainable Utilization of Marine Protected Areas in Macaronesia, Interreg IIIB/FEDER/MARMAC/003-4/2005-6 and Interreg IIIB-05/MAC/4.2/A4), and MoniAves, all coordinated by R.S. Santos, also provided support for fieldwork. IMAR-DOP/UAc is funded by FCT and DRCT-Azores as Research Unit 531 and Associate Laboratory 9 (ISR-Lisbon).info:eu-repo/semantics/publishedVersio

First attempted breeding of Manx Shearwater (Puffinus puffinus Brünnich, 1764) on Santa Maria, Azores

The Manx Shearwater Puffinus puffinus (Brünnich, 1764) is a north Atlantic seabird which mainly breeds in Europe. In the Azores, its breeding colonies occur exclusively on the islands from the western group (Flores and Corvo). Here, we report the first breeding attempt observed on Vila islet, Santa Maria (the easternmost island of the archipelago, situated circa 600 km from Flores and Corvo). Our observation confirms that Manx Shearwaters can settle far from their usual breeding localities and enhances the importance of Vila islet for the Azorean marine avifauna

Sex-specific costs of reproduction on survival in a long-lived seabird

Costs of reproduction on survival have captured the attention of researchers since life history theory was formulated. Adults of long-lived species may increase survival by reducing their breeding effort or even skipping reproduction. In this study, we aimed to evaluate the costs of current reproduction on survival and whether skipping reproduction increases adult survival in a long-lived seabird. We used capture-mark-recapture data (1450 encounters) from two populations of Bulwer's petrel (Bulweria bulwerii), breeding in the Azores and Canary Islands, North Atlantic Ocean. Using a multi-event model with two different breeding statuses (breeders versus non-breeders), we calculated probabilities of survival and of transitions between breeding statuses, evaluating potential differences between sexes. Females had lower survival probabilities than males, independent of their breeding status. When considering breeding status, breeding females had lower survival probabilities than non-breeding females, suggesting costs of reproduction on survival. Breeding males had higher survival probabilities than non-breeding males, suggesting that males do not incur costs of reproduction on survival and that only the highest quality males have access to breeding. The highest and the lowest probabilities of skipping reproduction were found in breeding males from the Azores and in breeding males from the Canary Islands, respectively. Intermediate values were observed in the females from both populations. This result is probably due to differences in the external factors affecting both populations, essentially predation pressure and competition. The existence of sex-specific costs of reproduction on survival in several populations of this long-lived species may have important implications for species population dynamics

Will climate change affect the survival of tropical and subtropical species? Predictions based on Bulwer's petrel populations in the NE Atlantic Ocean

Climate change has repeatedly been shown to impact the demography and survival of marine top predators. However, most evidence comes from single populations of widely distributed species, limited mainly to polar and subpolar environments. Here, we aimed to evaluate the influence of environmental conditions on the survival of a tropical and migratory seabird over the course of its annual cycle. We used capture-mark-recapture data from three populations of Bulwer's petrel (Bulweria bulwerii) spread across the NE Atlantic Ocean, from the Azores, Canary, and Cabo Verde Islands (including temperate to tropical zones). We also inferred how the survival of this seabird might be affected under different climatic scenarios, defined by the Intergovernmental Panel on Climate Change. Among the environmental variables whose effect we evaluated (North Atlantic Oscillation index, Southern Oscillation Index, Sea Surface Temperature [SST] and wind speed), SST estimated for the breeding area and season was the variable with the greatest influence on adult survival. Negative effects of SST increase emerged across the three populations, most likely through indirect trophic web interactions. Unfortunately, our study also shows that the survival of Bulwer's petrel will be profoundly affected by the different scenarios of climate change, even with the most optimistic trajectory involving the lowest greenhouse gas emission. Furthermore, for the first time, our study predicts stronger impacts of climate change on tropical populations than on subtropical and temperate ones. This result highlights the devastating effect that climate change may also have on tropical areas, and the importance of considering multi-population approaches when evaluating its impacts which may differ across species distributions

Leapfrog migration and habitat preferences of a small oceanic seabird, Bulwer's petrel (Bulweria bulwerii)

Aim Our current understanding of migratory strategies and the reasons for their high variability along the phylogenetic tree remains relatively poor. Most of the hypotheses relating to migration have been formulated for terrestrial taxa; classically, oceanic migrations were considered as merely dispersive because of the scarcity of observations in the open ocean. We describe for the first time, the migration strategy of a small seabird, the Bulwer's petrel (Bulweria bulwerii), and provide new insights into the ecology and evolution of long-distance marine migrations. Location Subtropical and tropical Atlantic Ocean. Methods Using cutting-edge geolocators, we examined the year-round distribution and at-sea activity patterns of adult Bulwer's petrels sampled at five localities throughout the species' breeding range in the Atlantic, within the Azores, Salvages, Canary and Cape Verde archipelagos. We assessed the migratory connectivity of the species and its habitat use at population and metapopulation scales. Results Our results provide the first evidence of an oriented leapfrog migration in oceanic seabirds. Ecological niche models based on breeding-season data effectively predicted that subtropical waters of the South Atlantic would be the preferred habitat for the northern populations of Bulwer's petrels during the non-breeding season. Habitat modelling also highlighted similarities in distributions between the breeding and non-breeding periods for the southern populations. Data on at-sea activity patterns suggested that birds from the northern and southern populations behave differently during the breeding season, as well as in the northern and southern non-breeding ranges during the non-breeding period. Main conclusions These results indicate that specific habitat preferences, presumably related to differences in prey availability, explain the observed distributions and hence the pattern of leapfrog migration described for Bulwer's petrel. Our study demonstrates the utility of integrating diverse tracking data from multiple populations across international boundaries, and habitat modelling, for identifying important areas common to many marine species in the vast oceanic environments

Leapfrog migration and habitat preferences of a small oceanic seabird, Bulwer's petrel (Bulweria bulwerii)

Aim Our current understanding of migratory strategies and the reasons for their high variability along the phylogenetic tree remains relatively poor. Most of the hypotheses relating to migration have been formulated for terrestrial taxa; classically, oceanic migrations were considered as merely dispersive because of the scarcity of observations in the open ocean. We describe for the first time, the migration strategy of a small seabird, the Bulwer's petrel (Bulweria bulwerii), and provide new insights into the ecology and evolution of long‐distance marine migrations. Location Subtropical and tropical Atlantic Ocean. Methods Using cutting‐edge geolocators, we examined the year‐round distribution and at‐sea activity patterns of adult Bulwer's petrels sampled at five localities throughout the species' breeding range in the Atlantic, within the Azores, Salvages, Canary and Cape Verde archipelagos. We assessed the migratory connectivity of the species and its habitat use at population and metapopulation scales. Results Our results provide the first evidence of an oriented leapfrog migration in oceanic seabirds. Ecological niche models based on breeding‐season data effectively predicted that subtropical waters of the South Atlantic would be the preferred habitat for the northern populations of Bulwer's petrels during the non‐breeding season. Habitat modelling also highlighted similarities in distributions between the breeding and non‐breeding periods for the southern populations. Data on at‐sea activity patterns suggested that birds from the northern and southern populations behave differently during the breeding season, as well as in the northern and southern non‐breeding ranges during the non‐breeding period. Main conclusions These results indicate that specific habitat preferences, presumably related to differences in prey availability, explain the observed distributions and hence the pattern of leapfrog migration described for Bulwer's petrel. Our study demonstrates the utility of integrating diverse tracking data from multiple populations across international boundaries, and habitat modelling, for identifying important areas common to many marine species in the vast oceanic environments

Monitoring butterfly abundance: beyond Pollard walks.

Most butterfly monitoring protocols rely on counts along transects (Pollard walks) to generate species abundance indices and track population trends. It is still too often ignored that a population count results from two processes: the biological process (true abundance) and the statistical process (our ability to properly quantify abundance). Because individual detectability tends to vary in space (e.g., among sites) and time (e.g., among years), it remains unclear whether index counts truly reflect population sizes and trends. This study compares capture-mark-recapture (absolute abundance) and count-index (relative abundance) monitoring methods in three species (Maculinea nausithous and Iolana iolas: Lycaenidae; Minois dryas: Satyridae) in contrasted habitat types. We demonstrate that intraspecific variability in individual detectability under standard monitoring conditions is probably the rule rather than the exception, which questions the reliability of count-based indices to estimate and compare specific population abundance. Our results suggest that the accuracy of count-based methods depends heavily on the ecology and behavior of the target species, as well as on the type of habitat in which surveys take place. Monitoring programs designed to assess the abundance and trends in butterfly populations should incorporate a measure of detectability. We discuss the relative advantages and inconveniences of current monitoring methods and analytical approaches with respect to the characteristics of the species under scrutiny and resources availability

The sensitivity of seabird populations to density-dependence, environmental stochasticity and anthropogenic mortality

The balance between economic growth and wildlife conservation is a priority for many governments. Enhancing realism in assessment of population‐level impacts of anthropogenic mortality can help achieve this balance. Population Viability Analysis (PVA) is commonly applied to investigate population vulnerability, but outcomes of PVA are sensitive to formulations of density‐dependence, environmental stochasticity and life history. Current practice in marine assessments is to use precautionary models that assume no compensation from density‐dependence or rescue‐effects via “re‐seeding” from other colonies. However, if we could empirically quantify regulatory population processes, the responses of populations to additional anthropogenic mortality may be assessed with more realism in PVA. Using Bayesian state‐space models fitted to population time series from three sympatric seabird populations, selected for varied life histories, we inferred the extent to which their dynamics are driven by environmental stochasticity and density‐dependence. Based on these inferences, we conducted an exhaustive PVA across credible parameterizations for intrinsic and extrinsic population regulation, simulated as a closed and re‐seeded system. Scenarios of anthropogenic mortality, along a sliding scale of precaution, were applied both proportionally and as a fixed quota using Potential Biological Removal (PBR). Baseline results from fitting revealed clear environmental regulation in two of our three species. Crucially, we found that for our empirically derived, realistic model parameterizations there are risks of decline to real populations even under very precautionary mortality scenarios. We find that PBR is dubious in application as a sustainable tool for population assessment when we account for regulation. Closed versus re‐seeded models showed a large divergence in outcomes, with sharper declines in closed simulations. Fixed‐quota mortality typically induced greater population declines comparative to proportional mortality, subject to regulation and re‐seeding. Synthesis and applications. Practitioners using arbitrary formulations of population regulation risk over‐precaution (economic constraint) or under‐precaution (endangering populations). The demands of increased economic development and preservation of wildlife require that methodologies apply techniques that confer reality and rigour to assessment. The current practice of employing models lacking density‐dependence and empirical environmental information imposes limitations in the efficacy of estimating impacts. Here, we provide a method to quantify the conditions that predominantly regulate a population and exacerbate the risk of decline from anthropogenic mortality. It is in the interests of both developers and conservationists to apply methods in population impact assessments that capture realism in the processes driving population dynamics