Browsing by Author "Tchantchalam, Quintino"
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- Ecology and behaviour of Palm-nut Vultures Gypohierax angolensis in the Bijagós Archipelago, Guinea-BissauPublication . Carneiro, Camilo André Ferreira Carneiro; Henriques, Mohamed; Barbosa, Castro; Tchantchalam, Quintino; Regalla, Aissa Said; Patrício, Ana Rita; Catry, PauloPopulations of many vulture species have undergone substantial declines. In Africa, 82% are threatened and although research on vultures has increased, the biology and ecology of several species is still poorly known. The Palm-nut Vulture Gypohierax angolensis has peculiar ecological characteristics, feeding on palm fruits, associated with the aquatic environment and taking a wide variety of prey. It has been over 40 years since the last thorough study on the ecology of the species was undertaken. This study investigated several ecological and behavioural aspects of Palm-nut Vultures, using a combination of direct observations, stable isotope analysis and Bayesian mixing models. The population of this species within the João Vieira and Poilão Marine National Park is estimated to be 21–30 birds km−2. Egg laying started in November (early dry season) and some chicks were still growing in early May. A minimum of 54% of nests produced a fledgling. Observations suggest that Palm-nut Vultures moult all flight feathers annually, between January and November. Their foraging behaviour is described and cafeteria trials showed their preference for fish over oil palm fruits. However, it is estimated that oil palm fruits account for almost 50% of the assimilated diet, followed by fish, crabs and Green Turtle hatchlings or eggs, as revealed by stable isotopes and Bayesian mixing models.
- Evidence for contrasting accumulation pattern of cadmium in relation to other elements in Senilia senilis and Tagelus adansoni from the Bijagós archipelago, Guinea-BissauPublication . Catry, Teresa; Figueira, Paula; Carvalho, Lina; Monteiro, Rui J. R.; Coelho, Pedro Duarte; Lourenço, Pedro Miguel; Catry, Paulo; Tchantchalam, Quintino; Catry, Inês; Botelho, Maria J.; Pereira, Eduarda; Granadeiro, José Pedro; Vale, CarlosShellfish harvesting in intertidal areas is a widespread and economically important activity in many countries across West Africa. However, in some areas, there is virtually no information concerning the levels of contaminants (and other elements related to nutritional aspects) in the harvested species. We collected sediments and several individuals of the West African bloody cockle Senilia senilis and of the razor clam Tagelus adansoni during the dry season of 2015 nearby three islands in the Bijagós archipelago, Guinea-Bissau. Aluminium, Ca, Fe, Mg, As, Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn were determined in sediments and whole soft tissues of the two bivalves. Sediments showed uniformly low trace element concentrations, pointing to an ecosystem with low levels of trace element contamination. T. adansoni presented higher concentrations of most elements than S. senilis, with the exception of Cd that showed up to 40 times higher values in S. senilis than in T. adansoni from the same sites. Furthermore, Cd concentrations (25±8.7 mg kg(-1), dw) in S. senilis are clearly above the maximum level established for human consumption. Future studies should clarify whether biological factors are the major responsible for this unusual situation.
- Nest-site characteristics and aspects of the breeding biology of the endangered Timneh Parrot Psittacus timneh in Guinea-BissauPublication . Lopes, Daniel C; Martin, Rowan O; Henriques, Mohamed; Monteiro, Hamilton; Regalla, Aissa Said; Tchantchalam, Quintino; Indjai, Bucar; Cardoso, Seco; Manuel, Celestino; Cunha, Manjaco; Cunha, Domingos; Catry, PauloTimneh Parrots Psittacus timneh are endemic to the moist forests of West Africa. Concerns over rapid declines in populations due to overharvesting for the pet trade and forest loss prompted the species’ categorisation as Endangered on the IUCN Red List of Threatened Species in 2016. Despite these threats, few data exist on their biology in the wild, impeding the development of effective conservation initiatives to protect populations. One of the few recorded breeding sites for this species occurs in the Bijagós Archipelago in Guinea-Bissau, where chicks have been historically harvested from nests and forest clearance for agriculture is common. We investigated the breeding ecology of Timneh Parrots in the Bijagós Archipelago focusing on two islands that harbour the densest populations. Specifically, we describe nest-site characteristics, breeding phenology and reproductive productivity. Timneh Parrots were found to use secondary nest cavities in 17 species of trees, predominantly nesting in trees between 20 m and 50 m in height. Nest cavities were generally aggregated, with a density of up to 14 nests ha−1 in some areas, although nests also occurred in isolated large trees. The distribution of nests likely reflected a heterogeneous distribution of large trees containing suitable nest cavities, emphasising the importance of protecting mature trees. Nesting efforts were initiated between early January until late March, suggesting that nest surveillance efforts to deter poaching can be efficiently focused at a small number of key sites during February to May each year, when fledgling chicks are most likely to be present. These data further suggest that the population may be limited by the availability of suitable nest cavities and that the installation of artificial nest cavities could help increase the breeding population.