Medium-sized exotic prey create novel food webs: the case of predators and scavengers consuming lagomorphs

Food web interactions are key to community structure. The introduction of species can be seen as an uncontrolled experiment of the addition of species. Introduced species lead to multiple changes, frequently threatening the native biodiversity. However, little is known about their direct effect on the upper level of the food web. In this study we review empirical data on the predator prey relationship between the introduced lagomorphs and their consumers, and use meta-analytical tools to quantify the strength of their interactions. We expect that exotic lagomorphs will destabilize food webs, affect ecological processes and compromise the conservation of the invaded regions. We found 156 studies on the diet of 43 species of predators that consume lagomorphs as exotic preys in South America and Oceania. We found an average exotic lagomorphspredator link of 20% which indicates a strong interaction, given that the average for the strongest links with native prey (when lagomorphs are not included in the predator diet) is about 24%. Additionally, this last link decreases to 17% when lagomorphs are present. When lagomorphs arrive in a new environment they may become the most important resource for predators, producing an unstable equilibrium in the novel food web. Any disruption of this interaction could have catastrophic consequences for the native diversity by directly impacting predators or indirectly impacting native preys by apparent competition. Eradication or any change in their abundances should be carefully considered in conservation actions since those will have great impacts on predator populations and ultimately in the whole communitiesPeer reviewe

Potential functional and numerical response in a large sized raptor may be mediated by the abundance of an exotic lagomorph

Predators relying on a particular prey as their main food resource are especially susceptible to fluctuation in prey availability. When prey abundance decreases they show a functional response by adjusting their diet. After this, predators may suffer a numerical response. These responses have been poorly studied in presence of alien invasive preys. The black-chested buzzard-eagle (Geranoaetus melanoleucus) is a large raptor inhabiting open areas of South America. Here we present the first long-term study on this eagle population tendency, analyzing functional and numerical responses associated with changes in the abundance of the exotic European hare (Lepus europaeus). We measured breeding performance and studied eagles? diet during the breeding seasons of 1991, 1992, 2006, 2011 and 2012. We also estimated the relative abundance of hares at each count site. Eagles diets changed over the years with a decrease in hare consumption. The number of eagles decreased from 1992 to less than half in 2012. Forty one percent of the total eagles observed in 1992/92, and 27% in 2006 were immature, while in 2011 and 2012 no immature were observed. We found similar tendencies of decrease in the abundance of hares which suggest that the decrease in eagles population may be related with the decreasing tendency of hares. No other factor that may have affected immature eagles abundance was evident in the area during this period. Our data suggest that changes in the abundance of an exotic lagomorph can lead numerical and functional responses in a top predator by affecting its diet, age structure, and ultimately abundance.Fil: Ignazi, Gonzalo Oscar. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Departamento de Zoología; Argentina. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Laboratorio de Ecotono; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Barbar, Facundo. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Laboratorio de Ecotono; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Departamento de Zoología; ArgentinaFil: Hiraldo, Fernando. Consejo Superior de Investigaciones Científicas. Estación Biológica de Doñana; EspañaFil: Donázar, José Antonio. Consejo Superior de Investigaciones Científicas. Estación Biológica de Doñana; EspañaFil: Trejo, Ana Raquel. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Departamento de Zoología; ArgentinaFil: Lambertucci, Sergio Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Laboratorio de Ecotono; Argentin

Data set for : Emerging ecosystems change the spatial distribution of top carnivores even in poorly populated areas

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Introduced lagomorph produce stronger potential apparent competition in invaded communities than any other species in a similar but native food web

Apparent competition is an indirect interaction that can strongly influence ecosystem functioning, altering species populations within the same trophic level. As a new resource, an introduced species can generate strong apparent competition in invaded communities, and even stronger if it becomes the primary resource for consumers. We explore how the European hare (Lepus europaeus), an introduced species in Patagonia, could be generating these stronger effects since many native predators shifted their diets towards them. We constructed and compared two food webs, one in which this primary prey role is played by a native species (the European rabbit, Oryctolagus cuniculus, in Spain) and another in which it is played by an introduced one (the European hare, in Patagonia), to explore their effects in the generation of this indirect interaction. Both were the primary prey in their respective food web and caused the strongest cases of potential apparent competition in each region. Potential apparent competition generated by introduced European hares in Patagonia double that produced by the European rabbit in Spain and was several times higher than any other native prey species. This strong potential apparent competition in an invaded ecosystem highlights the threats that some exotic species may produce, even indirectly.Fil: Barbar, Facundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Lambertucci, Sergio Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentin

Medium-sized exotic prey create novel food webs: the case of predators and scavengers consuming lagomorphs

Food web interactions are key to community structure. The introduction of species can be seen as an uncontrolled experiment of the addition of species. Introduced species lead to multiple changes, frequently threatening the native biodiversity. However, little is known about their direct effect on the upper level of the food web. In this study we review empirical data on the predator–prey relationship between the introduced lagomorphs and their consumers, and use meta-analytical tools to quantify the strength of their interactions. We expect that exotic lagomorphs will destabilize food webs, affect ecological processes and compromise the conservation of the invaded regions. We found 156 studies on the diet of 43 species of predators that consume lagomorphs as exotic preys in South America and Oceania. We found an average exotic lagomorphs-predator link of 20% which indicates a strong interaction, given that the average for the strongest links with native prey (when lagomorphs are not included in the predator diet) is about 24%. Additionally, this last link decreases to 17% when lagomorphs are present. When lagomorphs arrive in a new environment they may become the most important resource for predators, producing an unstable equilibrium in the novel food web. Any disruption of this interaction could have catastrophic consequences for the native diversity by directly impacting predators or indirectly impacting native preys by apparent competition. Eradication or any change in their abundances should be carefully considered in conservation actions since those will have great impacts on predator populations and ultimately in the whole communities

Detection probabilities for all species modeled for the N-mixture approach.

<p>The first 6 species with lower dispersion were used for the individual analyses, while the others were discarded due the scarce records in our censuses.</p><p>Detection probabilities for all species modeled for the N-mixture approach.</p

Contaminants in the southern tip of South America: Analysis of organochlorine compounds in feathers of avian scavengers from Argentinean Patagonia

The aim of this study was to assess the exposure to organochlorine compounds (OC) in 91 primary wing feathers of avian scavengers, Turkey vulture (Cathartes aura), American black vulture (Coragyps atratus) and Southern crested caracaras (Polyborus plancus) from the southern tip of South America, in the Argentinean Patagonia. We analyzed for a series of OC including hexachlorocyclohexane (HCH) isomers, endosulfan, aldrin, dieldrin, endrin, dichlorodiphenyltrichloroethane (p,p’-DDT), dichlorodiphenyldichloroethane (p,p’-DDD), dichlorodiphenyldichloroethylene (p,p’-DDE), heptachlor and heptachlor-epoxide. This is the first study on OC in feathers of three terrestrial top carnivores from South America. OC concentrations found in the studied species were much higher than those found in feathers of raptors from Europe and Asia, which likely indicate their high use in the region, specifically in agriculture, and other possible uses of OC in this area. ∑HCH had the highest median concentration, followed by ∑Drins, ∑DDT, ∑Heptachlor, and ∑Endosulfan, similar to those reported in several food samples in Argentina. On the other hand, differences in OC profiles between species and areas may be related to feeding and migratory habits, as well as the molt period. Three individuals showed ∑DDT (DDT, DDD and DDE) concentrations in feathers related to sublethal effects. However, this comparison should be used with caution due to problems with extrapolating such data across tissues and species.Fil: Martínez López, Emma. Universidad de Murcia; EspañaFil: Espín, Silvia. Universidad de Murcia; España. University of Turku; FinlandiaFil: Barbar, Facundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Laboratorio de Ecotono; ArgentinaFil: Lambertucci, Sergio Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Laboratorio de Ecotono; ArgentinaFil: Gómez Ramírez, Pilar. Universidad de Murcia; EspañaFil: García Fernández, A. J.. Universidad de Murcia; Españ

Relationship between the total richness of raptor species observed and the anthropogenic variable that was the most influential in our model.

<p>Relationship between the total richness of raptor species observed and the anthropogenic variable that was the most influential in our model.</p

Estimated values obtained from the N-mixture models applied to determine the relationship between the distance to several human constructions and the abundance of the six more abundant species.

<p>We present the estimates, standard errors (SE) and the p-value (*p≤ 0.1; **p ≤ 0.05; ***p ≤ 0.01) for every variable in the models. In bold we highlight the most influential variable for each model, which is the one used to show the relationship in the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0118851#pone.0118851.g002" target="_blank">Fig. 2</a>. As the analyses were performed with the distance to the anthropic variables, negative estimate values indicate a positive relationship (and vice versa).</p><p>Estimated values obtained from the N-mixture models applied to determine the relationship between the distance to several human constructions and the abundance of the six more abundant species.</p

Protein electrophoresis in Andean condors (Vultur gryphus): Reference values and differences between wild and rehabilitating individuals

The study of wildlife health greatly contributes to understanding population dynamics and detecting conservation threats. The determination of the different fractions of plasma proteins (proteinogram) is an important laboratory tool to study wildlife health. The aim of this study was to characterize protein electrophoresis in wild Andean condors (Vultur gryphus) from north-western Patagonia and to evaluate differences according to age and sex classes. Once reference values of wild, apparently healthy individuals, were established, we compared these values to those of individuals received at the Buenos Aires Zoo in Argentina for rehabilitation due to various health problems. Reference proteinograms from wild Andean condors differed only in the α 1 and β 2-fractions between sex categories. Males showed higher concentrations of these protein fractions than females. We found clear differences between wild birds and rehabilitating individuals. Total proteins, globulins, α 1-globulins, total α-globulins, β 2-globulins, total β-globulins, and γ-globulins were significantly higher in rehabilitating than in wild individuals, whereas albumin, α 2, and β1-globulins were similar between these groups. The albumin/globulin ratio, as a general indicator of health, was significantly lower in rehabilitating than in wild individuals. The results indicate the effects on different protein fractions of pathologic processes occurring in individuals undergoing rehabilitation. Our results provide useful insights, contributing to improving diagnoses and prognoses in this species. This information may also be useful to assess the health status of Andean condors in studies of wild populations and for comparisons with other bird species.We thank the Buenos Aires Zoo staff and the Fundación Bioandina Argentina for caring for rehabilitating birds, and the Agencia Nacional de Promoción Científica y Tecnológica (ANPCYT–FONCYT, PICT (BID) 0725‐2014, Argentina), The Peregrine Fund, and Universidad Nacional del Comahue project 04/B227 for financial support