Papers by Martina Carrete
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Résumé/Abstract Vulture restaurants are one of the most widely used tool for the management of vu... more Résumé/Abstract Vulture restaurants are one of the most widely used tool for the management of vulture populations worldwide. However, their effects on the population dynamics of these species have been rarely tested. Here, we show some consequences ...
PLoS ONE, 2012
The presence of conspecifics can strongly modulate the quality of a breeding site. Both positive ... more The presence of conspecifics can strongly modulate the quality of a breeding site. Both positive and negative effects of conspecifics can act on the same individuals, with the final balance between its costs and benefits depending on individual characteristics. A particular case of inter-individual variation found in many avian species is chromatic variability. Among birds, plumage coloration can co-vary with morphology, physiology and behavior as well as with age. These relationships suggest that cost-benefit balances of conspecific presence may be different for individuals with different colorations. We investigated whether inter-individual variability affects population regulation and expansion processes by analyzing potential differences in density-dependent productivity and settlement patterns in relation to plumage coloration in a population of a long-lived avian species recently undergoing a notable increase in numbers and distribution range. Our results show strong variation in the effect of density on productivity of breeding pairs depending on plumage coloration of their members. Productivity of dark birds decreased along the breeding density gradient while that of lighter breeders remained unchanged with conspecific density. In a similar way, our results showed an uneven occupation of localities by individuals with different plumage coloration in relation to local densities, with the breeding of lighter harriers more aggregated than that of dark-brown ones. At a population scale, darker birds had higher probability of colonization of the most isolated, empty sites. Explanations for species range expansion and population regulation usually make the inferred assumption that species traits are similar among individuals. However, in most species, there could be individual variation in niche requirements or dispersal propensities among individuals with different traits. Our results contribute to the growing appreciation that the individual traits, but not the average trait at the level of species, are important during population regulation and expansion processes. Citation: Cardador L, Carrete M, Mañ osa S (2012) Inter-Individual Variability and Conspecific Densities: Consequences for Population Regulation and Range Expansion. PLoS ONE 7(3): e33375.
Scientific Reports, 2013
Human-induced rapid environmental changes challenge individuals by creating evolutionarily novel ... more Human-induced rapid environmental changes challenge individuals by creating evolutionarily novel scenarios, where species encounter novel enemies, the new species sometimes being humans themselves. However, little is known about how individuals react to human presence, specifically whether they are able to habituate to human presence, as frequently assumed, or are selected based on their fear of humans. We tested whether fear of humans (measured as flight initiation distance in a diurnal owl) is reduced through habituation to human presence (plasticity) or whether it remains unchanged throughout the individuals' life. Results show an unusually high level of individual consistency in fear of humans throughout the adult lifespan of both rural (r 5 0.96) and urban (r 5 0.90) birds, lending no support to habituation. Further research should assess the role of inter-individual variability in fear of humans in shaping the distribution of individuals and species in an increasingly humanized world.
PLoS ONE, 2013
Reintroduction or reinforcement (RorR) of wild populations is a common conservation strategy. Man... more Reintroduction or reinforcement (RorR) of wild populations is a common conservation strategy. Many conservation projects involve the release of individuals of poorly studied species. This may lead to inefficient results or negative impacts on the conservation efforts. Here, we provide new insights into the conservation implications and potential consequences of a skew in the sex ratio of released birds and of the number of birds supplemented for the demography of a long-lived dimorphic bird species, the Andean condor (Vultur gryphus). We demonstrate that a RorR conservation program may be less effective in conserving a species if the sex ratios of the releases and the recipient populations are not considered. We also show that releases can reduce population declines but only if carried out over long periods (i.e., several decades). This can mean high costs for release programs and the added challenge of maintaining programs over time. If RorR programs are to be implemented, bearing in mind the importance of properly assessing their effectiveness, we urge conservation researchers and managers to consider the implications of sex ratio biases for wild populations, and particularly for dimorphic species with sexually despotic behaviour.
Trends in Ecology & Evolution, 2012
Ardeola, 2014
How birds adapt to urban life is a key question in evolutionary and conservation biology since ur... more How birds adapt to urban life is a key question in evolutionary and conservation biology since urbanization is one of the major causes of habitat loss worldwide. Some species are able to deal with these anthropogenic changes, but a shortage of nesting sites may preclude them from breeding in cities. We conducted a baseline survey of the cliff-nesting burrowing parrot Cyanoliseus patagonus around Bahia Bahía Blanca (Argentina), estimating a minimum of 1,361ca. 530 pairs breeding in 2419 sites (colonies) in 2013. The species showed a facultative colonial behavior, cColony size varied varying between 1 and 300250 pairs, showing a facultative colonial behavior in the species. Most colonies (66.774%) and pairs (73.894%) occupied humanmade substrates, mostly quarries but also water wells. Colony size was strongly correlated to the size of both natural and anthropogenic nesting substrates, suggesting an ideal free distribution of pairs according tolimited by the availability of nesting resources site availability. the population is limited by the availability of nesting sites. Anthropogenic substrates have surely allowed a population expansion of the species in this rather flat landscape with shortage of cliffs and ravines, as shown by but also urban breeding by a the largemost percentage of urban breeding pairs part (60.786%) of the surveyed population. This may currently constitute the third largest population for of burrowing parrots, a species otherwise abundant but progressively threatened by persecution and overharvesting for the international pet trade.
PLoS ONE, 2014
Invasive species can take advantage of resources unexploited by natives (opportunism hypothesis) ... more Invasive species can take advantage of resources unexploited by natives (opportunism hypothesis) or they can exploit the same resources but more aggressively or efficiently (competition hypothesis), thus impacting native species. However, invasive species tend to exploit anthropogenic habitats that are inefficiently used by natives such as urban environments. Focusing on the ring-necked parakeet (Psittacula krameri), one of the most invasive birds worldwide, we combined observations of interspecific aggressions, species-specific cavity-nest preferences and the spatial distribution of the native cavity-nesting vertebrate community to determine the invasion process as well as its potential impacts on native species in a Mediterranean city. Our results support the competition hypothesis, suggesting that ring-necked parakeets are outcompeting native species sharing nest-site preferences. Parakeets initiated and won most interspecific aggressions, which were directed towards competitors but also towards predators. This behaviour could explain the spatial arrangement of natives, with most bird species breeding close to parakeets possibly to take advantage of their effective antipredatory behaviour. However, temporal and spatial patterns of segregation suggest that a threatened bat species is negatively affected by parakeets. This demonstrates that common species gain benefits and threatened ones (in this study, a bat and possibly a falcon) lose nest sites due to invaders. Therefore, the conservation status of the native species that pay the costs of competition with invaders should be considered. This scenario of winners and losers may, however, shift towards more losers if the ring-necked parakeet population continues to grow, thus requiring close monitoring and control/eradication programs to avoid further impacts.
Frontiers in Ecology and the Environment
Scientific Reports, 2015
Global warming due to human-induced increments in atmospheric concentrations of greenhouse gases ... more Global warming due to human-induced increments in atmospheric concentrations of greenhouse gases (GHG) is one of the most debated topics among environmentalists and politicians worldwide. In this paper we assess a novel source of GHG emissions emerged following a controversial policy decision. After the outbreak of bovine spongiform encephalopathy in Europe, the sanitary regulation required that livestock carcasses were collected from farms and transformed or destroyed in authorised plants, contradicting not only the obligations of member states to conserve scavenger species but also generating unprecedented GHG emission. However, how much of this emission could be prevented in the return to traditional and natural scenario in which scavengers freely remove livestock carcasses is largely unknown. Here we show that, in Spain (home of 95% of European vultures), supplanting the natural removal of dead extensive livestock by scavengers with carcass collection and transport to intermediate and processing plants meant the emission of 77,344 metric tons of CO 2 eq. to the atmosphere per year, in addition to annual payments of ca. $50 million to insurance companies. Thus, replacing the ecosystem services provided by scavengers has not only conservation costs, but also important and unnecessary environmental and economic costs.
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Papers by Martina Carrete