Time filter

Source Type

Lourenco P.M.,Instituto Superior Of Psicologia Aplicada Ispa | Lourenco P.M.,University of Lisbon | Catry P.,Instituto Superior Of Psicologia Aplicada Ispa | Catry P.,University of Lisbon | And 4 more authors.
Marine Ecology Progress Series | Year: 2013

Wading birds are important predators in intertidal communities. Their ecology and distribution have been widely studied in estuarine wetlands, but little is known about the factors determining their abundance and diversity in the more common non-estuarine coasts. We analysed data from a large-scale survey of wader (Charadrii) populations in the non-estuarine coasts of Portugal (length = 1096 km), during winter, together with variables related to disturbance, habitat and geophysical characteristics of the coast to explain the patterns of wader abundance and diversity. The wintering community is composed of 13 species and dominated by ruddy turnstones Arenaria interpres and sanderlings Calidris alba. Wader abundance was limited by direct disturbance from humans and the presence of peregrine falcons Falco peregrinus. Overall human presence, availability of rocky intertidal areas, presence of nearby estuarine wetlands and low winter temperatures favoured higher wader densities. Areas dominated by igneous and metamorphic rocks (basalts, granites, schists and greywackes, and diabases) harboured a more diverse wader community than areas with sedimentary rocks or with sandy beaches, suggesting that coastal geology may have a structuring role for wader communities, which had not yet been described. Understanding these patterns gives useful directions as to where one should focus conservation efforts in non-estuarine coastal areas. © Inter-Research 2013.

Ceia R.S.,Sociedade Portuguesa Para O Estudo das Aves SPEA | Ramos J.A.,University of Coimbra | Heleno R.H.,CSIC - Mediterranean Institute for Advanced Studies | Hilton G.M.,Royal Society for the Protection of Birds RSPB | And 2 more authors.
Bird Conservation International | Year: 2011

The Azores Bullfinch is endemic to the island of São Miguel (Azores, Portugal). Its status was uplisted to Critically Endangered in 2005 on the basis of an extremely small and declining population that was considered to be restricted to a very small mountain range (43 km2), in a single location, within which the spread of invasive plants constituted a threat to habitat quality. Nevertheless, information was mostly inferred, or the product of, non-systematic studies. In order to carry out a complete assessment of the conservation status we analysed: (i) population trend, calculated from annual monitoring 1991-2008, (ii) population size, and (iii) range size, obtaining estimates in a single morning study in 2008 involving the simultaneous participation of 48 observers. Contrary to previous inferences, the population is no longer decreasing, although quality of laurel forest habitat continues to decline due to the persistent threat of invasive species. Population size (mean ± SE) was estimated at 1,064 ± 304 individuals using distance sampling methods, although the estimate was very sensitive to the survey method used. Range size estimates (extent of occurrence and area of occupancy) were 144 km2 and 83 km2 respectively. Given the present information, we propose the downlisting of Azores Bullfinch to Endangered on the IUCN Red List. © 2011 BirdLife International.

Lecoq M.,Eco Ethology Research Unit | Lecoq M.,University of Lisbon | Lourenco P.M.,University of Lisbon | Catry P.,Eco Ethology Research Unit | And 3 more authors.
Wader Study Group Bulletin | Year: 2013

Population estimates of wintering waders on the non-estuarine European coasts are largely based on extrapolated data from relatively small stretches of coast. In Portugal, the previous and only national estimate of waders wintering on the non-estuarine coast was based on just 7.3% of the coastline. In this study we carried out the first survey of waders wintering on almost the whole of the non-estuarine coast of Portugal, in order to improve knowledge on their abundance and distribution and to set a baseline for interpreting future population trends. The majority (96%) of the 198 5 × 5 km UTM squares, covering 1,096 km of coastline, were counted by observers walking along the shore within ±3 h of low tide during the 2009/2010 winter. 6,866 waders, of 13 species, were counted and we estimate the entire Portuguese population at 7,175. Sanderling (2,897–3,027), Ruddy Turnstone (2,191–2,289) and Kentish Plover (581–607) were the most abundant species. Highest wader numbers were found on the north and central (mainly around the Tagus estuary) coasts. The non-estuarine coast holds a significant proportion of the Portuguese winter populations of Sanderling (83.6%), Purple Sandpiper (83.3%), Ruddy Turnstone (80.1%), Whimbrel (33.5%), Kentish Plover (17.0%), Common Sandpiper (16.0%) and Eurasian Oystercatcher (15.7%). The study also highlights the international importance of the Portuguese non-estuarine coast for wintering Sanderling, Ruddy Turnstone and Kentish Plover, as the counts for these species represent ≥1% of the relevant biogeographic populations. © 2013, International Wader Study Group. All rights reserved.

Martins I.,University of Coimbra | Arosa M.L.,University of Coimbra | Ceia R.S.,Sociedade Portuguesa para o Estudo das Aves SPEA | Parejo S.,Sociedade Portuguesa para o Estudo das Aves SPEA | And 2 more authors.
Ecological Modelling | Year: 2012

The Azores bullfinch Pyrrhula murina is an endangered endemic bird species restricted to the east of the island of São Miguel, Azores. In the past decades, the native habitat of the bird was gradually invaded by exotic plants and less than 30% of its range is currently occupied by native vegetation. The late winter has been suggested as a critical period for bird survival as a consequence of food shortage. We developed a model to understand how yearly and seasonal variations on the type and abundance of food items affect the winter energetic budget of the Azores bullfinch. The model is at steady-state as it simulates the winter-early spring period, when Azores bullfinches attain maximum weight, with non-significant fluctuations. The costs of basal metabolic rate (BMR), thermoregulation and other activities are included in the model. The potential energy available to Azores bullfinch between January and April in three different years was estimated based on day length, diet, pecking rates on different food items, their energetic content and assimilation efficiency. Simulations were run with probability distributions of the estimated available energy and the energy left for activities of the Azores bullfinch. Results indicate that between January and April, the bird's energetic requirement for BMR and thermoregulation range between 118 and 123kJd -1, peaking in March due to thermoregulation constraints. If the bird's energy with activities represent 36% of the energy spent with BMR plus thermoregulation, the estimated daily energy requirements of the Azores bullfinch fall within 160-167kJd -1. Results indicate that January and February are months when the bird may experience some kind of energy constraint due to low density of energy-rich items (<200kJfeedingarea -1). However, from March onwards and particularly in warmer years, the Azores bullfinch will have plenty energy for BMR, thermoregulation and activities, mostly due to the increasing consumption of Ilex perado flower buds. In relation to altitude variations, simulations indicate that thermoregulation costs increase 8 and 13% at mid- and high-altitude, respectively, compared to low-altitude. In terms of habitat management, we can infer that removing the exotic tree Clethra arborea should be undertaken with caution because, during winter C. arborea seeds constitute an important food item to the bird. Alternatively if C. arborea is replaced by other energetically rich items, particularly at lower altitudes, the Azores bullfinch will potentially benefit from it. © 2012 Elsevier B.V.

Paiva V.H.,University of Coimbra | Paiva V.H.,University of Kiel | Geraldes P.,Sociedade Portuguesa para o Estudo das Aves SPEA | Marques V.,Instituto Nacional Of Recursos Biologicos Ipimar L Inrb | And 3 more authors.
Marine Ecology Progress Series | Year: 2013

The effects of environmental change on the biodiversity, structure and functioning of marine ecosystems is still poorly understood. In fact, very few studies have focused on changes in the at-sea foraging tactics of pelagic seabirds in relation to environmental stochasticity. Aiming at filling this knowledge gap, from 2005 to 2010 we directly measured the influence of climate (as driven by the North Atlantic Oscillation phenomenon) on (1) marine productivity (i.e. chlorophyll a concentration), (2) fish prey abundances and (3) the foraging behaviour of a top marine predator, the Cory's shearwater Calonectris diomedea borealis. There was a dramatic change in the foraging strategy of the birds during 2010, which seems to be mostly related to a climatic event that occurred during the winter of 2009 to 2010. This event had a negative impact on the productivity of the surroundings of the breeding colony and decreased the abundance of pelagic prey fish, which in turn altered the spatial, feeding and trophic ecology of Cory's shearwater and decreased their reproductive success. However, the negative trend in the abundance of pelagic prey (estimated from acoustic surveys and commercial fisheries landings) may be of concern because it does not seem to be only related to the climatic event of 2010. Long-term monitoring of the interactions between top predators, their prey and lower strata of the food web is crucial for a comprehensive assessment of the impacts that environmental variation may have on coastal ecosystems worldwide. Copyright © Inter-Research 2013.

Loading Sociedade Portuguesa Para O Estudo das Aves SPEA collaborators
Loading Sociedade Portuguesa Para O Estudo das Aves SPEA collaborators