Does urbanization influence the diet of a large snake?

Urbanization facilitates synanthropic species such as rodents, which benefit the diets of many predators in cities. We investigated how urbanization affects the feeding ecology of dugites Pseudonaja affinis, a common elapid snake in south-west Western Australia. We predicted that urban snakes: 1) more frequently contain prey and eat larger meals, 2) eat proportionally more non-native prey, 3) eat a lower diversity of prey species, and 4) are relatively heavier, than non-urban dugites. We analyzed the diet of 453 specimens obtained from the Western Australian Museum and opportunistic road-kill collections. Correcting for size, sex, season, and temporal biases, we tested whether location influenced diet for our 4 predictions. Body size was a strong predictor of diet (larger snakes had larger prey present, a greater number of prey items, and a greater diversity of prey). We identified potential collection biases: urban dugites were relatively smaller (snout-vent length) than non-urban specimens, and females were relatively lighter than males. Accounting for these effects, urban snakes were less likely to have prey present in their stomachs and were relatively lighter than non-urban snakes. Other urban-adapted carnivores appear to benefit from urbanization through increased food supplementation, but we found the opposite of this: urban dugites were less likely to contain a meal, and their meals were smaller, indicating they did not make greater use of synanthropic species than was evident for non-urban snakes. In contrast to other carnivores, snakes do not appear to fit a consistent directional pattern for size differences between urban and non-urban populations

Global patterns of functional diversity and assemblage structure of island parasitoid faunas

Aim: The processes leading to the assembly of ecological communities can determine their functional structure. We assess the influence of biogeographical correlates associated with species diversity gradients on the global patterns of functional diversity of island parasitoid assemblages (Hymenoptera, Braconidae). We also evaluate whether island assemblages present a non-random functional structure. Location: Fifty-three archipelagos distributed world-wide.Methods: Six traits related to morphology, attack strategy and development were used to measure functional diversity and determine the level of departure from randomness on trait diversity between islands and their corresponding species pool, through null models. We used generalized and partial regressions to determine the influence of different predictors (climate, regional and local island characteristics) on the functional diversity of island assemblages, comparing results with those obtained for species richness. We also evaluated whether any of the predictors or particular species traits were related to the patterns obtained when comparing island assemblages with null models.Results: Most of the geographical variation in functional diversity was not explained by the predictors evaluated, while for species richness these explained over 70% of spatial variation. The abiotic characteristics of islands with functionally clustered parasitoid biotas (c. 40% of all islands) did not differ from those of other islands. Comparisons between functionally clustered assemblages and those expected randomly from the species pool indicated a higher percentage of that the former included proportionally fewer ectoparasitoid and idiobiont species, which attack fewer host orders and prefer the egg and larval stages of their hosts.Main conclusions: The predictors correlated with functional diversity differ from those driving species richness patterns. We argue that biotic filters associated with the structure of the host communities may be important determinants of the assembly of many island parasitoid faunas, leading to assemblages dominated by species presenting particular ranges of trait values that differ from those in their pool of potential colonists.A.M.C.S. was supported by a Brazilian CNPq junior postdoctoral fellowship (159763/2010-0), a Portuguese Fundação para a Ciência e a Tecnologia grant (SFRH/BPD/70709/2010) co-funded by the European Social Fund POPH-QREN programme, a Marie Curie Intra-European Fellowship (IEF 331623 ‘COMMSTRUCT’) and by the projects ‘Developing tools to unify range dynamics and community-level processes into a single analytical framework’ (cooperation project CSIC-CNPq P2011BR0071) and ‘Disentangling the geographic and evolutionary determinants of the diversity of Western Palaeartic dung beetles’ [Spanish DGCyT project CGL2011-29317/BOS].Peer reviewe

Delayed start of full incubation is related to a delayed brood patch development in Magellanic penguins

Capsule: Most bird species start full incubation before the clutch is complete, others long after laying the last egg, gradually increasing the incubation temperature as incubation progresses, as is the case in Magellanic Penguins Spheniscus magellanicus. Aims: In this study, we analysed the possible mechanisms underlying this delayed start of full incubation in Magellanic Penguins. We postulated two non-mutually exclusive, possible mechanisms: delayed development of the brood patch and/or variation in the adults’ incubation postures. Methods: We conducted our work at Isla Quiroga, Argentina during 2011–13. We measured the development of the brood patch area, its temperature, the egg temperature and observed the postures of adult penguins. Results: We found no association between the adults’ postures and the delayed start of full incubation, nor between brood patch temperature and the increase in egg temperature as incubation proceeded (egg age). The intercept of the curve between egg temperature and egg age was positively related to brood patch area, while the slope of the curve was negatively related. Conclusion: Our results support the hypothesis that the shape of the curve of the increase in egg temperature as incubation proceeds is a consequence of the increase in the extension of the brood patch area.Fil: Barrionuevo, Melina. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Frere, Esteban. Universidad Nacional de la Patagonia Austral. Unidad Académica Caleta Olivia. Centro de Investigaciones Puerto Deseado; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin