Ocorrência e forrageamento de psitacídeos em paisagem antropogênica do noroeste paulista, limítrofe mata atlântica-cerrado

Abstract

Anthropogenic landscape is the reality of planet earth. The situation is so extreme, that the term "antroma'' (anthropogenic biome) was introduced in allusion to the enormous capacity that man has to occupy and modify natural areas. Undoubtedly, these changes have threatened many species with extinction. As a result, reserves (or protected areas) have been established as key measures of species protection. However, many conservationists are convinced that the future of biodiversity depends mainly on the impacts and management of anthropogenic landscapes. So there is a great need to research the species in these landscapes, in order to understand their ecological requirements and establish affective environmental management practices, aimed at conserving biodiversity beyond reserve. Following this growing trend conservationist, I studied an assembly of parrots (macaws, parakeets, parrotlets and amazons) in an anthropogenic landscape of southeastern Brazil. Parrots are severely threatened by landscape modification and some species have been forced to live in anthropogenic environments, where the habits and the elements necessary for the persistence of them have been little examined. Parrots are primary consumers and therefore my initial hypothesis is that some plant species, mainly due to their phenological attributes, play an important role in the persistence of these birds in anthropogenic landscapes, even in a short timescale. I studied the parrots in the Ilha Solteira municipality, which is located in the bordering region of the Atlantic Forest and Cerrado biomes (northwest of the state of São Paulo). Ilha Solteira has an area of 63,900 ha and 98% of the natural vegetation was modified by man. Parrots herein studied are: Ara ararauna (Blue- and-yellow Macaw), Diopsittaca nobilis (Red-shouldered Macaw), Aratinga leucophthalma (White-eyed Parakeet), A. auricapillus (Golden-capped Parakeet), Forpus xanthopterygius (Blue-winged Parrotlet), Alipiopsitta xanthops (Yellow-faced Amazon), Amazona amazonica (Orange-winged Amazon) and Amazona aestiva (Turquoise-fronted Amazon). I used nine transects line (each with 5 km) to evaluate the parrots occurrence and foraging for 24 months. As the reproductive phenology of plants is a factor regulating parrots populations, simultaneously, I also evaluated the temporal availability of flowers and fruits in plants located in transects. Parrots foraged 96 plant species belonging 30 families. The average plant species foraged was 25.0 (SD = 11.9), ranging from six (for A. amazonica) to 44 (for A. leucophthalma). Botanical families whose species are abundant in the area, such as Anacardiaceae, Arecaceae, Fabaceae and Myrtaceae, were representative in the parrots foraging. Overall, all parrots foraged exotic plants, which were particularly significant in the A. ararauna and D. nobilis diet. Seeds was the most consumed item by all parrots studied, reflecting the potential role of these birds in the plant populations regulation, consequently in the plant communities diversity. Aratinga auricapillus was the only species with broad feeding niche, being generalist in dry and rainy seasons. The other parrots, although used several plant species, presented narrow food niche, focusing 1-3 plant species, suggesting that have a specialist dietary. The phenological pattern in the study area is consistent with that expected for the Neotropical region, with dry and fleshy fruits abundant, respectively, in the dry and rainy seasons. The occurrence of D. nobilis, A. leucophthalma and F. xanthopterygius seems primarily regulated by the fleshy fruits availability, but the reproductive activity may also have been a factor regulator. The phenological pattern, however, did not clearly explain seasonal shifts in parrots feeding niche breadth. Alipiopsitta xanthops is probably a nomadic species, feeding and occurring in the study area only in the dry season. Plants whose fruiting extends for more than six months (extended pattern) or repeated fruiting episodes in a year (bi-annual pattern), appears to be the most important in the parrots foraging requirement and local persistence. Therefore, it may be the target species for restoration of degraded areas. Importantly, some exotic species have high relevance in parrots foraging. Thus, it is likely that the eradication of these plants generate negative impacts in parrots that depend greatly on its fruit. My main management purpose is to keep the exotic plants and increase the abundance of certain native food plants species, overall that fruiting throughout the year. I believe that such practices can minimize, in longterm, the extensive use of exotic plant species by the parrots.