Population assessment of the Red-tailed Amazon (Amazona brasiliensis) (Psittacidae) in the state of Parana, Brazil

Abstract

The population of the Red-tailed Amazon (Amazona brasiliensis) is distributed along the coastal regions of the states of Sao Paulo and Parana to the northern portions of the coastal region of Santa Catarina. We observed the species in Paranagua and Guaraquecaba bays, flying in flocks or in pairs trough traditional routes from the mainland to the islands of Superagui, Pecas, Mel and Rasa. We initially estimated this population to count about 3500 birds and confirmed the islands of Pinheiro, and Rasa and Mel as the major roosting points for the species. A methodology was developed in order to estimate the number of Red-tailed Amazons and we conducted 123 counts from 1989 to 2000. In Pinheiro island, the average number was 735.5 (+/- 70.1); in 1989, the largest annual average estimate was 953.2 (+/- 62.8) birds. The minimum and maximum numbers were recorded in January 1997 and April 1996 with 45 and 1615 amazons, respectively. In Rasa island, the overall average was 402 (+/- 65.1) and the largest annual average was recorded in 1990 with 602.8 (+/- 71.8) amazons. The maximum and minimum were recorded in May 1996 and June and December 1995 with 50 and 1019 amazons, respectively. For Mel island, the largest annual average was 1055 (+/- 20.3) and the overall average was 722.3 (+/- 68.9) amazons, with a maximum of 1346 recorded in August 1992, and a minimum of 14 in December 1996. Nonparametric ANOVA indicated that the overall number of Red-tailed Amazons differed between years (P < 0.0001). Moreover, the analysis of number of Red-tailed Amazons between islands indicated no difference between Mel and Pinheiro islands (P = 0.9738), while the number of Red-tailed Amazons on Rasa island differed significantly from those in Mel (P = 0.0028) and Pinheiro (P = 0.0064). Our research revealed that the Red-tailed Amazon population of this island group varied from 369 to 3672 birds across the study period, which coincides with the first evaluations. The Red-Tailed amazon population shows good conditions to be monitored through the continuity of the census and can help in their conservation in situ.