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- Absence of haemosporidian parasite infections in the long-lived Cory’s shearwater: evidence from molecular analyses and review of the literaturePublication . Campioni, Letizia; Martínez-de la Puente, Josué; Figuerola, Jordi; Granadeiro, José P.; Silva, Mónica C.; Catry, PauloThe apparent scarcity or absence of blood parasites in some avian groups, such as seabirds, has been related to intrinsic and extrinsic factors including host immunological capacity, host-parasite assemblage, and ecological parameters, but also to reduced sensitivity of some methods to detect low parasite prevalence/intensities of infection. Here, we examined the haemosporidian parasite prevalence in a breeding population of Cory's shearwater Calonectris diomedea borealis, a long-distance migrant seabird, nesting in the Macaronesian region, in the Eastern Atlantic. Previous studies on Calonectris diomedea complex were based on small sample sizes providing weak evidence for a lack of infections by haemoparasites. Here, we investigated the presence of both parasite infections in C. d. borealis and larvae of potential mosquito vectors on the area. By employing a PCR-based assay, we extensively examined the prevalence of blood parasites belonging to the genera Plasmodium, Haemoproteus, and Leucocytozoon in 286 individuals from different life stages (i.e., chicks, immatures, sabbatical, and breeding adults), facing their specific energetic trade-offs (immunological functions vs. life history activities). We sampled immatures and adult shearwaters, of different sexes, ages, and migratory origins, from two sub-colonies. None of the sampled individuals were infected by these parasites, supporting the hypothesis that there was no in situ or ex situ transmission of vector-borne parasites in marine habitats irrespective of host's life stage and in spite of the presence of the potential Plasmodium vector Culiseta longiareolata breeding in the area. These results suggest that the lack of transmission of haemosporidian parasites on Selvagem Grande may be related to the lack of suitable dipteran vectors at the study sites, which may result from the geographic isolation of this area.
- Important At-Sea areas of colonial breeding marine predators on the Southern Patagonian ShelfPublication . Baylis, Matthew; Tierney, Megan; Orben, Rachael; Evans, Victoria Warwick; Wakefield, Ewan; Grecian, William James; Trathan, Phil; Reisinger, Ryan R.; Ratcliffe, Norman Arthur; Croxall, John; Campioni, Letizia; Catry, Paulo; Crofts, Sarah; Boersma, P. Dee; Galimberti, Filippo; Granadeiro, José Pédro; Handley, Jonathan; Hayes, Sean; Hedd, April; Masello, Juan; Montevecchi, William A.; Pütz, Klemens; Quillfeldt, Petra; Rebstock, Ginger A.; Sanvito, Simona; Staniland, Iain; Brickle, PaulThe Patagonian Shelf Large Marine Ecosystem supports high levels of biodiversity and endemism and is one of the most productive marine ecosystems in the world. Despite the important role marine predators play in structuring the ecosystems, areas of high diversity where multiple predators congregate remains poorly known on the Patagonian Shelf. Here, we used biotelemetry and biologging tags to track the movements of six seabird species and three pinniped species breeding at the Falkland Islands. Using Generalized Additive Models, we then modelled these animals' use of space as functions of dynamic and static environmental indices that described their habitat. Based on these models, we mapped the predicted distribution of animals from both sampled and unsampled colonies and thereby identified areas where multiple species were likely to overlap at sea. Maximum foraging trip distance ranged from 79 to 1,325 km. However, most of the 1,891 foraging trips by 686 animals were restricted to the Patagonian Shelf and shelf slope, which highlighted a preference for these habitats. Of the seven candidate explanatory covariates used to predict distribution, distance from the colony was retained in models for all species and negatively affected the probability of occurrence. Predicted overlap among species was highest on the Patagonian Shelf around the Falkland Islands and the Burdwood Bank. The predicted area of overlap is consistent with areas that are also important habitat for marine predators migrating from distant breeding locations. Our findings provide comprehensive multi-species predictions for some of the largest marine predator populations on the Patagonian Shelf, which will contribute to future marine spatial planning initiatives. Crucially, our findings highlight that spatially explicit conservation measures are likely to benefit multiple species, while threats are likely to impact multiple species.
- Evaluating the influence of diet-related variables on breeding performance and home range behaviour of a top predatorPublication . Lourenço, Rui; Delgado, Maria del Mar; Campioni, Letizia; Korpimäki, Erkki; Penteriani, VincenzoDiet composition is linked to reproductive performance directly or indirectly by other life-history traits, including home range behaviour. The relationships between prey abundance, diet and individual fitness have often been explored. However, these relationships are complex and difficult to disentangle, especially in vertebrate top predators. Here, we present the results of a longterm study using multi-model inference procedures to elucidate the influence of diet-related variables on breeding parameters and home range behaviour of a top predator, the eagle owl Bubo bubo. Superpredation, diet diversity, rat biomass and rabbit mean weight were the most important variables when analysing reproductive parameters, suggesting that less diverse diets with greater rabbit biomass percentage may benefit reproductive performance, whereas rat biomass percentage is apparently associated with greater variation of breeding success. Earlier laying dates seem to be associated with the consumption, on average, of smaller rabbits. On the other hand, edge density was the most relevant factor determining the variation in home range behaviour, with individual characteristics, such as age and sex, also being important. Although the relative importance of the diet-related variables was generally low, mean weight of alternative prey, diet diversity and rabbit biomass also helped to explain home range parameters. In an optimal foraging context, centred on the abundance of the main prey species, our results suggest that when rabbits are less available eagle owls may increase home range size in order to obtain alternative prey, increasing at the same time their dietary diversity, which may also require higher movement speed.