Home About us Contact
|
Home About us Contact | ||
|
|
||
Native Fauna (native + fauna)
Selected AbstractsCoupling long-term studies with meta-analysis to investigate impacts of non-native crayfish on zoobenthic communitiesFRESHWATER BIOLOGY, Issue 2 2006JULIA M. MCCARTHY Summary 1. Biological invasions are widely recognised as a significant component of human-caused environmental change and a primary threat to native biodiversity. The negative impacts of species invasions are particularly evident for freshwater crayfish faunas. 2. This study provides novel insight into the ecological effects of native and non-native crayfish on zoobenthic communities (with emphasis on the non-native rusty crayfish, Orconectes rusticus) across broad scales by combining a meta-analysis of small-scale experimental studies with a long-term observational study conducted over a 24 year period in Sparkling Lake, Wisconsin, U.S.A. (46°00,N, 89°42,W). 3. The meta-analysis summarised quantitatively the results of cage experiments for seven species of crayfish spanning four continents. We found that total zoobenthos densities (primarily Gastropoda and Diptera) were significantly lower in treatments containing crayfish relative to controls; a result that was significant for non-native crayfish but not for crayfish in their native range, perhaps owing to a small sample size. In contrast to other species, rusty crayfish were also negatively associated with Ephemeroptera. 4. Results from the time series analysis comparing temporal trends in rusty crayfish and invertebrate abundances from Sparkling Lake were consistent with the findings from the meta-analysis. Rusty crayfish were negatively correlated with the abundance of total zoobenthos, Diptera, Ephemeroptera and Odonata, as well as families of Trichoptera. 5. By coupling the results from short and long-term research, our study offers greater insight into the nature of crayfish-invertebrate interactions in aquatic systems, revealing consistent effects of invasive crayfish on native fauna. The control and management of invasive species is facilitated by the knowledge that well executed small-scale studies may be extrapolated to understand larger-scale ecological interactions. [source] Spatial and temporal patterns in the diet of the Andean condor: ecological replacement of native fauna by exotic speciesANIMAL CONSERVATION, Issue 4 2009S. A. Lambertucci Abstract The development of conservation strategies to protect viable populations of scavenging birds requires the existence of adequate and safe food supplies in the wild. Early reports on Andean condors Vultur gryphus diet recorded guanacos and rheas, the dominant herbivores since the Pleistocene, as their main food in Patagonia. However, in the past century, guanaco and rhea populations have notably decreased as a consequence of introduced livestock, and other exotic mammals have colonized the region. We study the spatial and temporal variation of the condors' diet to determine which species are being consumed by condors, and to test whether native herbivores still have a role as a food source. We analysed 371 pellets (517 prey items), collected along 500 km in northwestern Patagonia, Argentina. Our study shows that the Andean condor depends heavily (98.5%) on exotic herbivores. Their diet was made up of c. 51% sheep/goat, 24% hare/rabbit, 17% red deer and 6% cow/horse, with only 2% other mammal species. Samples from locations surveyed after 12,15 years showed a diet shift coincident with the local tendencies in the food source. The diet composition of condors using roosts within the same zone was very similar, which suggests that they may be feeding from the same area. Thus, unhealthy carcasses could impact the entire local populations. Our results show the abundance of the invasive species in northwestern Patagonia and support the idea that native mega-herbivores are ecologically extinct in this area. Exotic species management can have a decisive impact on scavenger's survival. It is necessary to apply a strategy that includes public environmental education about the problems of scavengers (e.g. use of poison, veterinary medicines and lead bullets), and a serious productive plan, including native species as a suitable source of economic development. [source] Methodology for drawing up a Red List of threatened freshwater fish in FranceAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 2 2002P. Keith Abstract 1.In 1995, the IUCN implemented new definitions to be used when drawing up red lists. However, in addition to being imprecise for fish species, these remain difficult to apply. 2.This paper describes a more exhaustive method under the IUCN (1995) definitions based on six quantitative and qualitative criteria where scientific data are given the greatest possible weight, as compared with ,expert opinion'. This dual system makes it possible both to allocate an IUCN category to each species, and to rank each species within a particular category according to given scores, so that priorities can be determined. 3.The new Red List for French Freshwater Fish drawn up with this method contains 27 species, or 54% of the French native fauna. Three species are extinct (EX), four are critically endangered (CR), two are endangered (EN), 14 are vulnerable (VU), and four are at lower risk (LR). 4.Based on sounder scientific grounds, this list modifies and replaces the one drawn up in 1992. In effect, it makes it easier to argue for the presence of one species in one category rather than in another. Copyright © 2002 John Wiley & Sons, Ltd. [source] Factors affecting Grey-headed Flying-fox (Pteropus poliocephalus: Pteropodidae) foraging in the Melbourne metropolitan area, AustraliaAUSTRAL ECOLOGY, Issue 5 2005E. MCDONALD-MADDEN Abstract Factors affecting the foraging of mobile native fauna in highly fragmented urban landscapes have seldom been quantified at large spatial scales. We investigated factors affecting foraging by Grey-headed Flying-foxes (Pteropus poliocephalus; ,flying-foxes') in the greater Melbourne metropolitan area. Flying-foxes established a continuously occupied colony site in the Royal Botanic Gardens Melbourne in 1986, and the size of the colony has subsequently increased greatly. We used a stratified-random sampling design to examine the importance of six variables on the detection of foraging flying-foxes: (i) distance from the colony site (0,10, 10,20 and 20,30 km); (ii) distance from the Yarra River (0,5 and 5,20 km); (iii) the relative tree density of the municipality; (iv) whether the site was a park or street; (v) whether there was a relatively high or low density of trees at the site; and (vi) whether food was or was not detected at the site. We surveyed 240 sites within a 30-km radius of the colony site for foraging flying-foxes in both May and October 2002. The probability of detecting a foraging flying-fox declined with increasing distance from the colony site, but increased with increasing tree cover, and was higher for parks compared with streets and when food was present. Flying-foxes were observed foraging in a number of plant genera that have no species that naturally occur in the Melbourne area. Flying-foxes in Melbourne thus forage on planted resources that are widely distributed within a fragmented landscape, and are an example of a positive response by a native species to the process of urbanization. [source] An invasive species imposes selection on life-history traits of a native frogBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 2 2010MATTHEW J. GREENLEES As well as their direct ecological impacts on native taxa, invasive species can impose selection on phenotypic attributes (morphology, physiology, behaviour, etc.) of the native fauna. In anurans, body size at metamorphosis is a critical life-history trait: for most challenges faced by post-metamorphic anurans, larger size at metamorphosis probably enhances survival. However, our studies on Australian frogs (Limnodynastes convexiusculus) show that this pattern can be reversed by the arrival of an invasive species. When metamorph frogs first encounter invasive cane toads (Bufo marinus), they try to eat the toxic invader and, if they are able to do so, are likely to die from poisoning. Because frogs are gape-limited predators, small metamorphs cannot ingest a toad and thus survive long enough to disperse away from the natal pond (and thus from potentially deadly toads). These data show that larger size at metamorphosis can reduce rather than increase anuran survival rates, because larger metamorphs are more easily able to ingest (and thus be poisoned by) metamorph cane toads. Our results suggest that patterns of selection on life-history traits of native taxa (such as size and age at metamorphosis, seasonal timing of breeding and duration of pondside aggregation prior to dispersal) can be modified by the arrival of an invasive species. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 329,336. [source] | ||||||||||