Browsing by Author "Menezes, Dília"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
- Invasive Argentine ants prey on Bulwer’s petrels nestlings on the desertas islands (Madeira) but do not depress seabird breeding successPublication . Boieiro, Mário; Catry, Paulo; Jardim, Carolina S.; Menezes, Dília; Silva, Isamberto; Coelho, Nádia; Oliveira, Paulo; Gatt, Marie Claire; Pedro, Patrícia I.; Granadeiro, José PedroInvasive ants have the potential to cause severe impacts on the structure and composition of native invertebrate communities and interfere with the natural processes of pollination and seed dispersal. Less frequently reported, direct and indirect impacts on vertebrates, namely birds, are also known to occur. The Argentine ant Linepithema humile is one of the worst invasive species worldwide, and is responsible for economic and ecological impacts in Madeira since its introduction. Previous reports indicated that Argentine ants may be a frequent predator of nestlings on the Desertas Islands which harbour internationally important seabird colonies. Here, we provide a survey of the records of bird predation by Argentine ants in the Desertas. Furthermore, we also assessed if these invasive ants affected the most abundant crevice-nesting seabird on Deserta Grande, the Bulwer’s petrel Bulweria bulwerii, by nest monitoring in the years of 2014–2016. We found that breeding success varied annually between 0.56 and 0.63 chicks produced per nesting attempt. Ant predation of chicks was observed in only two out of 294 study nests. Furthermore, no relationship was found between local abundance of Argentine ants and breeding success of Bulwer’s petrels. We conclude that Argentine ants do not seem to pose a major threat to nesting petrels on the Desertas, although we acknowledge the possibility that environmental changes and episodic population explosions of this invasive species may lead to a greater impact on seabirds’ reproductive success.
- Mysterious attendance cycles in Cory’s shearwater, Calonectris diomedea: An exploration of patterns and hypothesesPublication . Granadeiro, José Pedro; Alonso, Hany Rafael de Drummond Ludovice Garcia; Almada, Vítor Carvalho; Menezes, Dília; Phillips, Richard A.; Catry, PauloSeveral species of seabirds show cyclic patterns of attendance at their nesting colonies.We examined the patterns of variation in the numbers of Cory’s shearwater at three colonies (two oceanic and one located on the continental shelf), including the world’s largest, at Selvagem Grande, Madeira, Portugal and considered several hypotheses concerning their causal mechanisms. At Selvagem Grande, cycles were exceptionally marked and regular, with a periodicity ranging from 7.8 to 11 days, and involved both breeders and nonbreeders. In contrast, variation in numbers was aperiodic at a nearby and much smaller colony (Selvagem Pequena), and also at the colony located off the Portuguese coast (Berlenga Island).We found no relationships between number of birds ashore and environmental variables such as wind direction and speed or lunar cycle. Cycles did not seem to be driven by oscillations in food availability or accessibility, given that they did not correlate with daily chick growth rates (which were acyclic) or diet. Despite their regularity, cycles were slightly out of phase in different sectors of Selvagem Grande, which suggests that social interactions at the colony could act as an entrainment agent for an endogenous rhythm, and so cycles are probably more likely to occur in large and dense colonies. Observations are consistent with the hypothesis that cycles facilitate social interactions by maximizing the probability of encounters at the colony. However, the exact mechanisms through which these remarkable cycles are controlled are still completely unknown, and clearly further research is needed.
- White-faced storm-petrels Pelagodroma marina predated by gulls as biological monitors of plastic pollution in the pelagic subtropical northeast atlanticPublication . Furtado, Ricardo Miranda; Menezes, Dília; Santos, Carolina Jardim; Catry, PauloMarine plastic pollution is rapidly growing and is a source of major concern. Seabirds often ingest plastic debris and are increasingly used as biological monitors of plastic pollution. However, virtually no studies have assessed plastics in seabirds in the deep subtropical North Atlantic. We investigated whether remains of white-faced storm-petrels (WFSP) present in gull pellets could be used for biomonitoring. We analysed 263 pellets and 79.0% of these contained plastic debris originating in the digestive tract of WFSP. Pellets with no bird prey did not contain plastics. Most debris were fragments (83.6%) with fewer plastic pellets (8.2%). Light-coloured plastics predominated (71.0%) and the most frequent polymer was HDPE (73.0%). Stable isotopes in toe-nails of WFSP containing many versus no plastics did not differ, indicating no individual specialisation leading to differential plastic ingestion. We suggest WFSP in pellets are highly suitable to monitor the little known pelagic subtropical Northeast Atlantic.