In 1644 a Dutch artist painted an image which turned out to be the first record of the Grey-breasted Parakeet (Pyrrhura griseipectus), a severely threatened species endemic to north-eastern Brazil. The parakeet was formally described scientifically in 1900, but for a long time was considered a subspecies of the then more widespread and commoner White-eared Parakeet (Pyrrhura leucotis). This led to the neglect of griseipectus until it had reached the precipice of extinction.
However, astute detective work by Aquasis, a Brazilian NGO, not only culminated in its recognition in 2005 as a full species, but also brought to light its precarious situation. From late 2006, the Loro Parque Fundación commenced its support to a project managed by Aquasis to determine the parakeet’s actual geographical distribution, research its biology and use the resulting information for appropriate conservation action. Across four north-eastern states, the Aquasis team searched 16 sites of known historical occurrence, but the only existing wild population they found at the time was in the Serra do Baturité (Baturité Mountains) of Ceará State. The total population of this location was estimated at no more than 250 individuals, and the species was classified as ‘Critically Endangered’ in the IUCN Red List of Threatened Species. The alarming historical decline in the geographical distribution was caused mainly by habitat loss and the illegal traffic of wild-caught individuals.
In the Baturité Mountains, the humidity from the clouds sustains moist forest above 500m, this being the naturally restricted and fragile habitat of the Grey-breasted Parakeet. Subsequent searches by Aquasis have revealed smaller subpopulations in three other isolated mountain ranges, being the Serra do Mel, Quixadá, the Serra Azul, Ibaretama and, much more recently, the Serra do Parafuso, Canindé, all in Ceará. Although formerly in the lower-lying areas there could have been sufficient natural vegetation to promote the movement of parakeets between the mountain ranges, massive agricultural conversion has left a modern-day landscape hostile to such natural transfers. Clearly the geographical distribution of the Grey-breasted Parakeet is fragmented and discontinuous.
Aquasis has found that 90% of mature individuals are only in the subpopulation of the Baturité Mountains, where the parakeet nests in tree cavities. The other three locations have much less forest habitat and the Grey-breasted Parakeet has possibly adapted by nesting in crevices in the rocky cliffs. Therefore, Aquasis has directed most of its attention to the Baturité Mountains where it conducts research on the biology of the species, has mobilized landowners to form a strong protection network, participates in public policies for species and habitat protection, supports the creation and management of private and public protected areas and, through environmental education, involves the local people. Since 2010, Aquasis has installed and managed nest-boxes for Grey-breasted Parakeets in Baturité, and in 10 years has overseen the fledging of no less than 1,165 young Grey-breasted Parakeets from these nests. The total population is currently estimated to be 656-866 individuals, which roughly equates to 437-577 mature individuals.
The positive change in the fortunes of the Grey-breasted Parakeet achieved its down-listing in 2017 to ‘Endangered’ in the IUCN Red List and, in accordance with the listing criteria, is coded as B1ab(i,iii). The main criterion B refers to the geographical distribution, which B1 specifies in the form of Extent of Occurrence (EOO), being less than 5,000 km2 for an ‘Endangered’ category species. The sub-criterion ‘a’ indicates a distribution which is severely fragmented or with five or less locations. The sub-criterion ‘b’ connotes a continuing decline observed, estimated, inferred or projected in the EOO (bi), and area, extent and/or quality of habitat (biii).
Under IUCN guidelines the EOO is preferentially calculated using the Minimum Convex Polygon (MCP) method. The MCP is the smallest polygon in which no internal angle exceeds 180º and which contains all locations of occurrence of the species. However, when there are discontinuities in the geographical distribution of a species, as is the case for the Grey-breasted Parakeet, the MCP method can result in a substantial overestimate of the distribution. The IUCN guidelines include an alternative method, called the α-hull, which deals with the external shape of a species’ distribution by breaking it into several discrete patches when it spans uninhabited regions, i.e. the low-lying agricultural land in the case of the Grey-breasted Parakeet.
Using specialised computer software to analyse the occurrence data, a new study* has applied the α-hull method to estimate the Grey-breasted Parakeet’s EOO, and to examine the effect of this method on the threat category of the species. The smaller the value of α, the finer the resolution of the method, and the IUCN recommends an α value of 2 as a good starting point. The new study includes α values from 1 to 9. It also includes the four previously mentioned locations with confirmed presence of the species and compares the effect of using different methods.
The IUCN/BirdLife International value for the EOO (using MCP) of the Grey-breasted Parakeet is 3,300 km², but this is derived from only three locations, with Serra do Parafuso excluded because confirmation of presence of the species there is so recent. The EOO (using MCP) value from the new study, including the four locations, is 5,079 km², which according to the study would trigger the re-assignment of P. griseipectus to the category of ‘Vulnerable’ in the Red List. Using the α-hull method, all values of α from 5 to 9 give the area of the EOO as sufficiently large to maintain the Grey-breasted Parakeet in the ‘Endangered’ category. However, the more recommendable values of α from 1 to 4 all give the EOO as only 84 km². Given that this is below the threat category threshold of 100 km², the new study argues that the α-hull method with these values returns the Grey-breasted Parakeet to the category of ‘Critically Endangered’.
List Threat Category
|IUCN – MCP||3,300||EN|
|New study – MCP||5,079||VU|
|New study – α-hull, where α = 1, 2, 3 and 4||84||CR|
Table 1. Comparison of methods to estimate the Extent of Occurrence and Red List status of the Grey-breasted Parakeet.
All the methods exclude two additional locations, distant from Ceará, of possible presence of the Grey-breasted Parakeet, because confirmation is pending the results of genetic analysis.
Despite the interesting findings of the new study, the very positive impact of the project for the future of the Grey-breasted Parakeet is undeniable. It could lead to the re-colonisation of more isolated mountain forests by the translocation of parakeets from Baturité (and/or from a captive breeding programme), making ‘Critically Endangered’ truly a thing of the past for this handsome parakeet.
* Xavier, H. D. F. (2019) Avaliação da extensão de ocorrência e do risco de extinção de (Evaluation of the extent of occurrence and risk of extinction of) Pyrrhura griseipectus Salvadori 1900. BSc Thesis, Federal University of Ceará.
Author: David Waugh, Correspondent, Loro Parque Fundación
Photos: title – F. Nunes/Aquasis; 1,4,6 – F. Nunes/Aquasis ; 2 – Adapted from BirdLife, 2020; 3 – Palmacea Ceara-Wiki; 5 – Aquasis ; 8 – Adapted from Xavier, 2019