Endemic and Threatened Amazona Parrots of the Atlantic Forest: An Overview of Their Geographic Range and Population Size

Abstract

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.

Annual Censuses and Citizen Science Data Show Rapid Population Increases and Range Expansion of Invasive Rose-Ringed and Monk Parakeets in Seville, Spain

“…However, single counts at communal roosts, such as those performed here, do not allow for the identification of uncertainty in population size estimates related to detection errors, which may lead to the underestimation of real population numbers [67,68]. Despite these limitations, roost counts allow a reasonable lower bound for estimating the total population size (e.g., [66]) and its temporal changes (e.g., [68]) when individuals concentrate in well-known localities, thus reducing the probability of overlooking large flocks during census [68]. In the case of rose-ringed parakeets in Seville, we cannot discard small counting errors that may slightly affect annual population sizes, but they are overweighed by the easy locating of the largest roosts [47].…”

“…Monk parakeets, on the other hand, have grown exponentially but seem to have reached a stability of about 1500 individuals, distributed in several breeding nuclei scattered throughout the study area. Population censuses, through counts of individuals at roosts, are suitable for communal roosting species, such as some parrot species [44,[65][66][67][68]. However, single counts at communal roosts, such as those performed here, do not allow for the identification of uncertainty in population size estimates related to detection errors, which may lead to the underestimation of real population numbers [67,68].…”

“…Population censuses, through counts of individuals at roosts, are suitable for communal roosting species, such as some parrot species [44,[65][66][67][68]. However, single counts at communal roosts, such as those performed here, do not allow for the identification of uncertainty in population size estimates related to detection errors, which may lead to the underestimation of real population numbers [67,68]. Despite these limitations, roost counts allow a reasonable lower bound for estimating the total population size (e.g., [66]) and its temporal changes (e.g., [68]) when individuals concentrate in well-known localities, thus reducing the probability of overlooking large flocks during census [68].…”

Population Size, Non-Breeding Fraction, and Productivity in a Large Urban Population of Burrowing Parrots (Cyanoliseus patagonus)

“…Nonetheless, it is worth noting that our results reflect reasonable estimations rather than accurate population censuses. On the one hand, although counts of individuals at roosts are suitable for estimating population sizes of communal roosting parrots that concentrate in well-known localities [39,40], single counts such as those performed here do not allow for identifying uncertainty in population size estimates related to detection errors [41,42]. Despite these limitations, roost counts allow for estimating a reasonable lower bound for total population sizes [43] and their inter-annual changes (e.g., [42,44]).…”

“…On the one hand, although counts of individuals at roosts are suitable for estimating population sizes of communal roosting parrots that concentrate in well-known localities [39,40], single counts such as those performed here do not allow for identifying uncertainty in population size estimates related to detection errors [41,42]. Despite these limitations, roost counts allow for estimating a reasonable lower bound for total population sizes [43] and their inter-annual changes (e.g., [42,44]). On the other hand, our censuses of breeding pairs, ranging from 1363 to 1612 pairs across years, slightly underestimated the actual breeding population sizes since a few pairs breeding in natural nesting substrates could not be accurately surveyed.…”