BackgroundParasites can exert selection pressure on their hosts through effects on survival, on reproductive success, on sexually selected ornament, with important ecological and evolutionary consequences, such as changes in population viability. Consequently, hemoparasites have become the focus of recent avian studies. Infection varies significantly among taxa. Various factors might explain the differences in infection among taxa, including habitat, climate, host density, the presence of vectors, life history and immune defence. Feeding behaviour can also be relevant both through increased exposure to vectors and consumption of secondary metabolites with preventative or therapeutic effects that can reduce parasite load. However, the latter has been little investigated. Psittaciformes (parrots and cockatoos) are a good model to investigate these topics, as they are known to use biological control against ectoparasites and to feed on toxic food. We investigated the presence of avian malaria parasites (Plasmodium), intracellular haemosporidians (Haemoproteus, Leucocytozoon), unicellular flagellate protozoans (Trypanosoma) and microfilariae in 19 Psittaciformes species from a range of habitats in the Indo-Malayan, Australasian and Neotropical regions. We gathered additional data on hemoparasites in wild Psittaciformes from the literature. We considered factors that may control the presence of hemoparasites in the Psittaciformes, compiling information on diet, habitat, and climate. Furthermore, we investigated the role of diet in providing antiparasitic secondary metabolites that could be used as self-medication to reduce parasite load.ResultsWe found hemoparasites in only two of 19 species sampled. Among them, all species that consume at least one food item known for its secondary metabolites with antimalarial, trypanocidal or general antiparasitic properties, were free from hemoparasites. In contrast, the infected parrots do not consume food items with antimalarial or even general antiparasitic properties. We found that the two infected species in this study consumed omnivorous diets. When we combined our data with data from studies previously investigating blood parasites in wild parrots, the positive relationship between omnivorous diets and hemoparasite infestation was confirmed. Individuals from open habitats were less infected than those from forests.ConclusionsThe consumption of food items known for their secondary metabolites with antimalarial, trypanocidal or general antiparasitic properties, as well as the higher proportion of infected species among omnivorous parrots, could explain the low prevalence of hemoparasites reported in many vertebrates.Electronic supplementary materialThe online version of this article (10.1186/s13071-018-2940-3) contains supplementary material, which is available to authorized users.

ABSTRACT. The progressive exploitation and destruction of nesting habitat in recent years, combined with the substantial pressure from legal and illegal removal of wild nestlings and adults, justifies the development of a comprehensive study on the reproductive biology of the Turquoise-fronted Parrot (Amazona aestiva). We analyzed breeding parameters in a wild protected population of Turquoise-fronted Parrots in the Chaco forest, Argentina, examining variation among years, over the course of the breeding season, and in relation to the age of the nest. Mean clutch-size per nesting attempt was 3.68 eggs. Hatching success (proportion of eggs laid that hatch) was 0.73. Fledging success (proportion of nestlings that fledge) was 0.88. The overall breeding success (mean number of fledglings per laying female per year) was 0.95. Clutch size did not vary among years but it decreased with the delay of the nest initiation date. Hatching failure was the greatest cause of egg partial losses, and brood reduction was the main cause of nestling partial loses. Brood reduction was positively correlated with clutch size and with egg-laying date. We did not find interannual variation in any of the clutch or brood size variables. Our results showed that the population of Turquoise-fronted Parrots in the dry Chaco forest has high values of clutch size and nestling survival, and low values of hatching success. However, some aspects of the breeding biology need more attention, especially if the species continues to be harvested.Paramètres de reproduction de l'Amazone à front bleu (Amazona aestiva) dans la forêt sèche du Chaco RÉSUMÉ. L'exploitation et la destruction progressives de l'habitat de nidification advenues ces récentes années, combinées à la pression élevée de captures légale et illégale d'oisillons et d'adultes sauvages, justifient la mise en place d'une étude globale sur la biologie de reproduction de l'Amazone à front bleu (Amazona aestiva). Nous avons analysé les paramètres de reproduction d'une population sauvage protégée de cette amazone dans la forêt du Chaco, en Argentine, examinant les variations interannuelles, tout au long de la saison de reproduction, en relation avec l'âge du nid. La taille moyenne de la ponte par tentative de nidification était de 3,68 oeufs. Le succès d'éclosion (proportion d'oeufs pondus qui ont éclos) était de 0,73. Le succès à l'envol (proportion de jeunes qui ont pris leur envol) était de 0,88. Le succès de nidification d'ensemble (nombre moyen de jeunes à l'envol par femelle nicheuse par année) était de 0,95. La taille de la ponte n'a pas varié d'une année à l'autre, mais était plus faible lorsque la date d'initiation du nid était retardée. L'échec de l'éclosion était la cause la plus importante de perte partielle d'oeufs et une couvée réduite était la cause principale de perte partielle d'oisillons. La couvée réduite était positivement corrélée avec la taille de la ponte et la date de celle-ci. Nous n'avons pas observé de variations interannuelles des variables relatives à la taille de la...

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Amphibian populations are declining globally. In this scenario, detailed information on their ecology is crucial to determine the status and extinction risk of their populations and, therefore, better plan conservation activities. The Valcheta frog Pleurodema somuncurense is a Critically Endangered species, which is endemic to the Valcheta Stream, Patagonia, Argentina. We assessed the status of this species at the metapopulation level, which we consider is a key step in planning management activities. We conducted visual encounter surveys from 2013 to 2019 to determine the distribution range of each local population of the Valcheta frog. During 2015, we also applied a capture-recapture survey to estimate the density and apparent survival of 1 local population. We used POPAN models for density estimation and the classic model of Cormack-Jolly-Seber to estimate apparent survival, using snout-vent length as a covariate. The metapopulation of the Valcheta frog is composed of 9 isolated local populations: 7 extant and 2 extinct. The extant populations have population sizes ranging from 243 to 4516 individuals. The small size of the smaller local populations makes their long-term viability in isolation unlikely. We found a positive correlation between the apparent survival and the snout-vent length of individuals. Our results showed that management strategies should be aimed at ensuring the long-term survival of this species, with a focus on the recovery of extinct populations, the restoration of disturbed habitats and the improvement of connectivity between local populations.