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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Invasive herbivores shape food web structure: European rabbit and hare acting as primary prey are conservation challenges

As part of the current global change scenario, invasive species have caused many direct impacts on native biodiversity and the interactions among species. European rabbits and hares are two herbivore species that have been introduced worldwide, displacing native species within their trophic level, but also affecting native predators. Both species have become extremely abundant in their exotic distributions, becoming primary prey for many predators, a function that they also play in their native ranges. These relatively new and strong interaction links created with their consumers have the potential to destabilize food webs by precluding the occurrence of weaker links. Here, we have compiled the diet of 32 predator species from three food webs and compared them: one in Europe, where these species are native, and two where they are introduced, in South America and Oceania. We found that these lagomorphs are the primary prey in all study sites, generating a dietary shift of predators in the invaded regions. In all food webs studied, these two preys channeled most of the biomass input towards the higher trophic level, generating the strongest interaction links, affecting the food web configuration and stability. They destabilize food web structure by homogenizing predators' diets, augmenting their niche overlap and web vulnerability. Moreover, rapid population changes of these prey, either natural (e.g., diseases) or anthropic (e.g., control measures), create new conservation challenges for predators and scavengers. This highlights that invasive species can strongly affect interactions among species and it should be considered in management and conservation actions.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

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

Continental scale dietary patterns in a New World raptor using web-sourced photographs.

Dietary studies are essential to better understand raptor ecology and resource requirements through time and space, informing species habitat use, interspecific interactions and demographic rates. Methods used to collect data on raptor diets can constrain how dietary analyses can be interpreted. Traditional approaches to study raptor diets, such as analysis of pellets or prey remains, often provide dietary data at the local population level and tend to be restricted to pairs during the breeding season. The increasing use of citizen science data has the potential to provide dietary inferences at larger spatial, demographic and temporal scales. Using web-sourced photography, we explore continental-scale demographic and latitudinal dietary patterns between adult and non-adult Crested Caracaras (Caracara plancus), throughout the species' range across the Americas. We analysed 1,555 photographs of caracaras feeding and found no age effects on the probabilities of different food groups being included in photographs. The probability of reptiles being included in photographs of caracaras from the northern population was significantly higher than those from the southern population, with the opposite pattern for birds. There were significant latitudinal effects with the probabilities of fishes and invertebrates in the diet of northern caracaras increasing towards the equator. Contrastingly, the probability of mammals in the diet increased away from the equator for both populations. Assuming the focal species is well-sampled, web-sourced photography can improve our understanding of raptor diets at large-scales and complements more traditional approaches. This approach is more accessible to raptor researchers without access to the field or expertise in physical prey identification techniques

Kleptoparasitism from condors to eagles mediated by an exotic prey

The presence of alien invasive species can enhance competitive interactions between native species. A common type of direct competition is kleptoparasitism, i.e., the theft of food. This foraging strategy is closely linked to scavenging and can represent a central source of food for some populations and species. Here, we describe novel observations of an obligate scavenger, the Andean condor (Vultur gryphus), stealing invasive European hares (Lepus europaeus) hunted by a large raptor, the Black-chested Buzzard eagle (Geranoaetus melanoleucus), in southern Argentina. We re-analyzed data on food habits of sympatric, obligate scavengers to show that Andean condors consume more hare than two smaller vultures. Our observations suggest that the prevalence of European hare in the diet of Andean condors is partially due to opportunistic kleptoparasitism of the Black-chested Buzzard eagle. We propose that condors kleptoparasite eagles regularly, with cascading consequences for the population dynamics of condors, eagles, and hares. Our observation illustrates how novel food resources generated by invasive species can lead to new context-dependent competitive interactions between obligate scavengers and apex predators.Fil: Perrig, Paula Leticia. 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: Ballejo, Fernando. 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. 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

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