264 research outputs found
Long-term monitoring by roadkill counts of mammal populations living in intensively cultivated landscapes
No full textElusive behaviour and financial constraints hamper the long-term monitoring of mammal population, particularly in intensively cultivated and urbanised landscapes, where most survey methodologies cannot be applied effectively. Provided that there is a direct relationship between each species’ density and frequency of road casualties, roadkill counts may represent a cost-effective alternative method to collect abundance data over long periods. We quantified the numbers of casualties of mammal species from 2001 to 2016 along two routes (65 km) crossing the heavily altered central River Po plain (N Italy). Each route was surveyed by car 10 times per month, covering 123,987 km and recording 15,589 road-kills from 15 species (15.3 roadkills/100 km/year). Most widespread mammals previously reported for the study area were recorded. Variation in each species’ roadkill numbers throughout the study period was consistent with available information on their distribution and abundance and the consistency of the patterns outlined on the two roads supported the hypothesis that the frequency of roadkills was related to each species’ density. Seasonal fluctuations in roadkill records could be related to either their reproductive cycles or dispersal patterns. For meso- and large species, the relationship between the occurrence of casualties and a set of 13 habitat variables was assessed by Logistic Regression Analysis. Based on our results, we believe that roadkill counts should be implemented to outline species’ population trends wherever high road density fragments wildlife habitats, and may represent a powerful citizen science-based method to collect large amounts of data over long periods
Long-term monitoring of the endemic Rana latastei: suggestions for after-LIFE management
No full textWe monitored egg clutch numbers of a population of the endemic Italian agile frog Rana latastei in a Site of Community Interest in northern Italy (SCI IT 209000) during 1997–2017 with the aim of assessing the long-term variation in its abundance. We walked along the banks of canals and small ponds (n = 22) 1–3 times per week between early February and mid-April each year to detect egg clutches. The relationships between the start of the breeding season, yearly egg mass counts, rate of yearly change in the number of recorded egg masses and 15 climatic and environmental variables were assessed by multiple regression. The first deposition of eggs occurred progressively later in the year throughout the study period and mean air temperature during the breeding season decreased over this period. Agile frogs showed high deposition site-fidelity. Despite large variations in the number of egg clutches detected from year to year, the population size remained stable in the long term. Peaks in the number of egg clutches occurred 2 years after the dredging of canals, carried out every 4–6 years to improve water availability, starting in 2004 as part of a LIFE Nature Project. This was the only predictor of the number of egg clutches deposited, suggesting that periodical management is needed to support the agile frog population. Our results reinforce the need for multi-year monitoring to determine both the long-term success of habitat restoration projects and the status of residual populations
Embryonic and larval defensive responses of agile frog (<i>Rana dalmatina</i> ) to alien crayfish
No full textRed swamp crayfish Procambarus clarkii, a widespread invasive alien crayfish, represents a serious threat for several freshwater species, including amphibians, which are declining at a global scale. As a shared coevolutionary history is the main factor determining the emergence of antipredator responses, Anuran tadpoles may not be able to cope effectively with this introduced predator. We performed two experiments to assess agile frog's (Rana dalmatina) defensive responses to both P.clarkii and native dragonfly larvae (Anax imperator). First, we conditioned embryos (collected from two ponds 30km away from each other) with predators' chemical cues to explore possible variation in hatching time caused by predation risk. In the second experiment, to evaluate how predators' diet affects tadpole behavior, we conditioned tadpoles for a 5-week period with cues from tadpole-fed and gammarid-fed predators and recorded behavioral and morphological responses. Embryos did not alter hatching time in the presence of any predator cue, while tadpoles from both populations strongly reduced activity and visibility when raised in the presence of tadpole-fed dragonfly larvae. Morphological changes were less straightforward and were induced only in one population, for which broader tails and a slight increase in body size of tadpoles exposed to tadpole-fed predators were observed. The lack of defensive responses in crayfish-exposed tadpoles suggests that the spreading of this invasive species in agricultural lowlands of northern Italy may represent a further threat to their conservation
Interspecific den sharing: a study on European badger setts using camera traps
No full textMany mammals, both potential competitors and preys, have been reported to use the complex burrow system of European badger Meles meles setts as shelter, mainly in northern Europe and during winter, when badgers are lethargic. Nonetheless, until recent times observations of den sharing have been largely restricted to anecdotal information, because of the mainly nocturnal activity of most sett occupants. Using camera-trapping, we investigated both the mammal fauna associated with 24 badger setts located in northern and central Italy, and seasonal variation in the composition of specific assemblages, without interfering with the occupants’ activity. Trapping effort was 1,605 camera trap-days from December 2010 to December 2013. Badgers (two to six individuals per sett) shared their setts with a total of eight mammal species: crested porcupine Hystrix cristata, Eastern cottontail Sylvilagus floridanus, red fox Vulpes vulpes, pine marten Martes martes, stone marten Martes foina, wood mouse Apodemus sp., brown rat Rattus norvegicus and coypu Myocastor coypus. Den sharing was observed throughout the year, with a significant reduction of sharing during winter, when badgers were probably induced to move to alternative setts to avoid breeding porcupines. Eastern cottontails used badger burrows permanently and, at least in one occasion, reared their pups inside, although they can be easily preyed upon by badgers. Badger sett sharing may have favoured both the recent northward expansion of crested porcupines and settling of introduced cottontails in agricultural habitats
Factors determining badger Meles meles sett location in agricultural ecosystems of the NW Italy.
No full textThe effect of thinning and cue:density ratio on risk perception by Rana dalmatina tadpoles
No full textThe “risk assessment hypothesis” considers prey density as an important variable to properly assess the actual level of risk, and predicts that, when the ratio between predator cue concentration and prey density is constant, the level of risk perceived by prey is the same. All previous studies which tested this hypothesis with Anurans manipulated density by placing tadpoles into experimental tubs at fixed group sizes. As predation is a process that produces a progressive decrease in prey density, i.e. “thinning”, prey may respond to the rate of group size reduction rather than the absolute number of conspecifics in a given place at a given time. To test if Rana dalmatina tadpoles perceive the progressive decrease in population density due to predation and are able to use this information to fine-tune anti-predator responses, we combined thinning with a constant cue:density ratio and evaluated how these two types of information affected the level of activity of tadpoles. Our results showed no effect of density reduction on prey level of activity, and thinning did not interact with cue intensity to modify tadpoles’ behaviour. However, we observed no difference in tadpole behavioural responses between treatments with the same cue:density ratio
Elementi per il processo partecipativo
No full textI processi di interazione e di partecipazione nelle politiche e nei piani
sono spesso descritti come itinerari aperti a prospettive diverse (Bobbio 2002), mai come forme compiute e già poste in essere. Nei paesi dell’area Mediterranea e, in particolare nel nostro Paese,
difficilmente sono state avviate sperimentazioni che abbiano innescato processi consolidati di democrazia partecipativa, in cui i soggetti non sono primariamente solo le istituzioni.
La dimensione interattiva pone tre ordini di problemi:
come si definisce, ed eventualmente perché varia, il corpo civico; l’individuazione dei momenti di interazione collettiva nelle pro−−
cedure;
le modalità di combinazione delle capacità decisionali e gli strumenti per esercitare effettivamente la cittadinanza
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