GULF OF GUINEA CONSERVATION GROUP: ORNITHOLOGY

Janine R. Clemmons, Dept. Zoology, Birge Hall, 430 Lincoln Dr., University of Wisconsin, Madison, WI 53706, USA.

Martim P. Melo, Percy FitzPatrick Institute of African Ornithology, University of Cape Town, 7701 Rondebosch, South Africa

The African Grey Parrot, Psittacus erithacus, has a wide distribution, across the tropical belt of Africa, including the islands of Bioko and Príncipe in the Gulf of Guinea. This species is harvested intensively for the pet trade. Few data exist on the impact of the harvest: the grey parrot is still common in most of its range, but some populations show signs of decline, while others have already gone extinct.

The population of Príncipe is under great pressure due to intensified trapping over the last 20 years. Estimates of harvested nestlings range from 600 to 3000 per year (Juste 96), depending on the year. Because parrots are long-lived and exploitation is heavily directed at nestlings, there is the uncertain danger that the population will plummet catastrophically once the adults die. Thus, even apparently healthy populations may be doomed within the near future. Additionally, the rate of adult capture outside of the reproductive season, has risen in recent years. The practice of harvesting both non-breeding adults and nestlings ensures that no parrot is safe from capture, including those originating from nests that are inaccessible to parrot trappers.

Casual observations of parrots indicate that the birds are highly variable in morphology and behaviour throughout their range. Based on morphological variation alone, as many as three different subspecies have been suggested, including P. e. princeps from Príncipe and Bioko islands. Differences that characterize this taxon are attributed to clinal change, and therefore this subspecies has been considered invalid.

Lack of adequate data on population variation in grey parrots has prevented the institution of effective protection measures to control collection of parrots for the pet trade. The threatened population of Príncipe island had to be removed from the Appendix I of CITES because no unequivocal way of assigning birds to this population is available. The present study will determine the taxonomic status of island and mainland populations using morphological, genetic and behavioural data. This study will represent the first systematic attempt to gather inclusive data on population differences in this species (or complex of species). A conservation plan will be designed for Príncipe's population, which will include protection of the primary forest where the parrots are most abundant and where nesting hollows in old growth trees are most dense. The study will also investigate the potential of developing alternative sources of income for parrot-traders, such as through low-impact ecotourism and possibly sustainable harvesting.

Martim P. Melo will search for genetic markers with enough resolution to address such population level studies in the African grey parrot. The control region of the mitochondrial genome is the main target, but the cytochrome b and ND2 genes will also be amplified. From the nuclear genome the b -fibrinogen gene will be amplified. These genes will be sequenced, and those with enough resolution will be used for the genetic differentiation analyses. Microsatellites developed for other species will also be tested and used if successful.

Assessment of behavioural differences, performed by Janine R. Clemmons, will employ vocalisation analyses, which are economically feasible and highly sensitive for identifying differences between populations and even social groups among parrots. The vocal analysis will consist of two parts: 1) sound recording and acoustic analysis of variation of mainland and island populations, and 2) playback of calls to determine whether the birds recognise and respond differently to their own vs. another population’s calls. Differences in responses between the populations would indicate that behavioural isolation mechanisms may exist.

Blood and feather samples for the genetic analyses and vocalisations recordings have already been carried out. Gabon was the mainland area sampled.

ECOFAC and the Bom Bom Island Resort have provided valuable logistic support in the field.

Martim P. Melo and the genetic research are supported by Programa PRAXIS XXI from the Fundação para a Ciência e a Tecnologia (Portugal)

Juste B., J. 1996. Trade in the gray parrot Psittacus erithacus on the island of Príncipe (São Tomé and Príncipe, Central Africa): initial assessement of the activity and its impact. Biological Conservation 76: 101-104.