Estudar a ecologia do corvo indiano - corvus splendens - vieillot e seu impacto sobre a população humana da Ilha da Inhaca

Abstract

The present work was carried out from January to March 1998, with the aim of studying the ecology of the Indian crow Corvus splendens, and its impact on the human population of Ilha da Inhaca. To study the impact of the crow on the human population, four methods were used: 1- The P.R.A. (Quick Participatory Diagnosis) which consisted of meetings with the population. 2- Surveys of different age groups (by age and by sex). 3- Record of interactions between the crow, the human population and the indigenous fauna. 4- Interviews with key informants. The distribution, abundance and use of habitat were determined. To determine the distribution, preliminary trips were made to all neighborhoods and the places with the highest concentration of crows were identified. To determine the abundance, coordinated counts were made in the places of greatest concentration. For the study of the use of the habitat, the nests were located, and the heights and species of trees where they were found were recorded. Activity and food preference were determined, observations were made by telescope, and activity and food preference were recorded using a portable computer (Psion) with the program “The Observer”. The Indian crow is undesirable in Inhaca, because it causes many problems for the population; everyone wants its eradication and would participate in an eradication program, and they propose the method of poisoning. Few interactions were observed between the crow and the indigenous avifauna, which are not enough to draw any conclusions about the negative impact on the indigenous avifauna. But it has negative impacts on the human population.

The Indian crow is distributed in all districts, it is more concentrated in the Ribjene district, and less so in the Inguane district. It occurs in places close to homes and also in the mangroves; it does not occur in the forest and the swamp. Its population is estimated at around 2,280 individuals. The hotel is the place with the highest number of crows, but the Saco and Ribjene mangroves also have many crows. The ANOVA statistical test shows that there are significant differences between months and locations in abundance and distribution. As for the use of habitat, the crow prefers to build their nests in tall trees. In residential areas it builds nests in coconut trees, mango trees and other trees. In the mangrove the preferred species is Avicennia marina. The Ribjene neighborhood is the one with the most nests and Inguane the one with the least. The distance between nests is inversely proportional to their number. When active, he spends most of his time resting and occasionally flying in search of food. The most preferred and most abundant foods are seafood and fish, followed by other foods, which include: crumbs, food scraps, bread, insects etc... The residence is the most used habitat, and it also uses different places during its activity. An Indian crow eradication program is possible in Inhaca, this program would have a lot of support from the local population, local economic agents and others