Search Results (3)

Population size estimates are essential for investigating numerous aspects of the ecology, evolution, and conservation of wildlife. However, the life cycles of many species include cryptic life stages that are difficult to detect or sample, such as the non-breeding fractions typical of many bird populations. Quantifying the proportions of breeders and non-breeders is crucial to better assess their conservation status and population trends. We propose a simple method applicable to species that show phenotypic differences between adults and juveniles. By quantifying the proportion of ages, the size of the whole population, and its productivity, the size of the non-breeding and breeding fractions can be inferred. We applied this approach to the red-spectacled amazon, Amazona pretrei, a threatened parrot endemic to the Brazilian Atlantic Forest. The entire global population aggregates in winter in a few localities to feed on the seeds of the Parana pine Araucaria angustifolia, a critically endangered tree whose range has declined >97% due to massive exploitation. From a global population of ~16,000 individuals in 2015 and ~20,000 individuals in 2017, our methodology allowed us to estimate a low proportion of juveniles (14%) and a large proportion of non-breeders (80%) within the adult population, with narrow confidence intervals. These proportions did not change between years, but the estimated number of breeding pairs increased, from ca. 1300 to 1700 pairs, in parallel with the global population increase. Our methodology, with its possible improvements to reduce uncertainty in estimates, can be applied to the long-term monitoring of this and many other species, to better understand their conservation challenges and inform effective management strategies. Full article

Amazona is the largest genus of the Psittacidae, one of the most threatened bird families. Here, we study four species of Amazona (Amazona brasiliensis, A. pretrei, A. vinacea, and A. rhodocorytha) that are dependent on a highly vulnerable biome: the Brazilian Atlantic Forest. To examine their distribution and abundance, we compile abundance estimates and counts, and develop site-occupancy models of their geographic range. These models integrate data from formal research and citizen science platforms to estimate probabilistic maps of the species’ occurrence throughout their range. Estimated range areas varied from 15,000 km² for A. brasiliensis to more than 400,000 km² for A. vinacea. While A. vinacea is the only species with a statistical estimate of abundance (~8000 individuals), A. pretrei has the longest time series of roost counts, and A. rhodocorytha has the least information about population size. The highest number of individuals counted in one year was for A. pretrei (~20,000), followed by A. brasiliensis (~9000). Continued modeling of research and citizen science data, matched with collaborative designed surveys that count parrots at their non-breeding roosts, are essential for an appropriate assessment of the species’ status, as well as for examining the outcome of conservation actions. Full article

South America presents the greatest Psittacidae diversity in the world, but also has the highest numbers of threatened parrot species. Recently, exotic viruses have been detected in captive native psittacine birds in Brazil, however, their impacts on the health of wild parrots are still unknown. We evaluated the presence of Chlamydia psittaci, Psittacid alphaherpesvirus 1 (PsHV-1), avipoxvirus and beak and feather disease virus (BFDV) in wild Amazona aestiva, A. brasiliensis and A. pretrei nestlings and in wild caught A. aestiva nestlings seized from illegal trade. Samples were collected from 205 wild nestlings and 90 nestlings from illegal trade and pathogen-specific PCR was performed for each sample. Chlamydia DNA prevalence was 4.7% in A. aestiva and 2.5% in A. brasiliensis sampled from the wild. Sequencing revealed that the C. psittaci sample belonged to the genotype A. PsHV-1, avipoxvirus and BFDV DNA was not detected. These results have conservation implications since they suggest that wild parrot populations have a low prevalence of the selected pathogens and, apparently, they were not reached by the exotic BFDV. Stricter health protocols should be established as condition to reintroduction of birds to the wild to guarantee the protection of Neotropical parrots. Full article