Justification of Red List category
This species has a very small range, and occurs in a small number of locations, therefore it approaches the thresholds for Vulnerable under the range size criterion B, and meets the threshold for Vulnerable under criterion D2, as the plausible threat of fire is present in all the areas it inhabits. The population trend appears to be increasing, and hence the species does not approach the thresholds for Vulnerable under the population size reduction criterion (criterion A). The probability of extinction has not been calculated for this species, therefore criterion E cannot be applied. The population size is very small, and approaches the thresholds for Vulnerable under the population size criteria C and D. However, the population size has only increased and exceeded the threshold for Endangered under criterion D within the past five years. Considering this and the high risk of fire, which threatens the species' habitat, its previous status of Endangered is maintained under the 5-year rule.
The population size is estimated to be 430 individuals, with 362 at Inagua (36 km2) and 68 at La Cumbre (21 km2) (Carrascal et al., 2019), estimated from breeding surveys, suggesting a total population of 645 individuals. These form part of the same subpopulation, as colour-marked birds from Inagua were first found breeding at La Cumbre, before captive-reared birds were released there to reinforce the wild population. Population density estimates vary: apart from the two years following the 2007 forest fire, densities in Inagua have remained stable, around 10 birds / km² (Moreno et al., 2018), with the highest recorded density of 17.7 chaffinches / km² in 2019 (Carrascal et al., 2019). In La Cumbre, estimates have increased from 1.12 in 2016 to 3.3 chaffinches / km² in 2019 (Carrascal et al., 2019).
The results of the annual monitoring scheme show clearly that the species population is currently increasing, and can best be described as having fluctuated within a fairly narrow range over most of the last twenty years (Carrascal et al. 2016). Although the devastating fire in 2007 caused the population to halve in 2008, it subsequently recovered rapidly at an average annual rate of 24% (Moreno et al., 2018) with numbers back up to pre-fire levels by 2011, around 50% higher again by 2016, and continuing to increase as shown by the 2015-2020 annual surveys (Carrascal et al., 2019).
Fringilla polatzeki is found only on Gran Canaria in the Canary Islands, Spain, where it is presently known from only two locations: Reserva Natural Integral de Inagua-Ojeda-Pajonales (36 km2) and La Cumbre (21 km2) (Carrascal et al. 2020, Delgado et al. 2016). It was formerly more widespread, but is now restricted to patches of woodland at these two sites. A forest fire in 2007 caused the population at Inagua to halve by 2008, but it recovered rapidly to its pre-fire levels by 2011, and has since increased further (Carrascal et al. 2016).
A habitat specialist, the Gran Canaria Blue Chaffinch is largely dependent on Canary Pine Pinus canariensis, which currently have a very fragmented and reduced surface area; the species will inhabit reforested areas where these fall within the natural distribution of this tree. It is found in pinewoods at 700-1,800 m with a high proportion of broom Chamaecytisus proliferus in the understorey - Inagua's orography imposes an altitudinal restriction of c. 1300 m. Highest habitat suitability is found within stands with more than 21m of pine height, tree cover between 35%-55%, and summer rainfall between 13-20 mm (Carrascal et al. 2017). Although Canary pine seeds constitute its main food source, birds occasionally feed outside pinewoods during severe weather, and invertebrates are an important food source during the breeding season.
The breeding season lasts from April to early August. Breeding success is low, with only ca. 1.5 fledglings per successful nesting attempt, and 1.4 clutches per breeding season (Rodríguez and Moreno 2008), estimated to be between 54% and 65% (Carrascal et al. 2019). The main cause of breeding failure is predation, mostly by the Great Spotted Woodpecker Dendrocopos major.
The main causes of decline in the past were habitat destruction and fragmentation due to land use change, and collection of specimens for natural history museums. Currently, wildfires, increasing in frequency and magnitude, are considered their greatest threat (Delgado et al. 2021). This was seen most recently in 2007, when significant areas were destroyed, including at the most important site at Inagua, leading to a 50% reduction of the population. Recent fires in September 2017 and August 2019 degraded part of the potential colonisation habitat in La Cumbre and Tamadaba, and another forest fire in February 2020 broke out in areas occupied by the species in Inagua. Mature pine forests are also suffering forest dieback as a consequence of climate change (Martin et al. 2015), where models predict increases in temperature and a decrease in precipitation over the next century (Expósito et al. 2015). Protected areas are heavily used for recreation and leisure on Gran Canaria, and this may cause disturbance. Inbreeding may also be a significant threat (Barov and Derhé 2011). It suffers from being captured and kept in cages, and possibly also still from illegal trade, primarily to Italy, Germany and Belgium, which may have an effect on population levels. Its pinewood habitat has been subject to intense commercial exploitation which has resulted in habitat fragmentation and population isolation. The main cause of breeding failure is predation, mostly by the Great Spotted Woodpecker Dendrocopos major (Rodríguez and Moreno 2008). Other predators include sparrowhawks (Accipiter nisus), feral cats (Felis catus), long-eared owl (Asio otus) and potentially raven (Corvus corax). The common kestrel (Falco tinnunculus) and the rat (Rattus sp.) could also prey on nests, although there are no direct observations that confirm this (Delgado et al. 2021).
Conservation Actions Underway
It has been legally protected from hunting, capture, trade, egg or chick collection since 1980. Key areas have been protected since 1982, and six important areas were designated as National Parks or Natural Areas in 1987. Inagua has been a Special Protection Area (SPA) of the EU since 1979, and was declared as a Strict Nature Reserve in 1994. A conservation programme was initiated in 1991 by the Canary Island Government, and a captive breeding programme began in 1992. An action plan was published in 1996 (González 1996). Captive breeding started anew in 2005, and the first chicks were released in 2010 (Delgado et al. 2016). Fire prevention measures are implemented, particularly during the summer, and access to suitable habitat is limited. There is also an ongoing project that focuses on the restoration of fire-damaged pine forest (LIFE07NAT / E / 000759 “Restoration of endemic pine forests affected by forest fires and recovery of its flora and fauna ”). Cats have been controlled since 1996. Research is being conducted into the potential threat of inbreeding (Barov and Derhé 2011). A new recovery plan has been ongoing since 2013 to establish new population centres (F. Rodríguez in litt. 2016), and from 2015-2020, a LIFE+ PINZON Project was conducted, aiming to increase the population and create sustainable population centres through various means, such as captive breeding and the enhancement of ecological corridors (see http://lifepinzon.org/). Through the project, the SPA "Cumbre de Gran Canaria" was established in 2020, extending the SPA "Ojeda, Inagua and Pajonales"; thus, the habitat is protected by Natura 2000 Network and integrated into the Canary islands Network of Natural Protected Spaces. A conservation plan titled "After-LIFE" sets objectives for the maintenance of the conservation of the species following on from the LIFE+ PINZON project (Aguilar et al. 2020). The species is in Annex 1 of the Birds Directive as a "priority species".
Text account compilers
Iñigo, A., Lorenzo, J.A., Moreno, Á., Lifjeld, J., Carrascal, L., Garcia-del-Rey, E., Suárez, N., Westrip, J.R.S., Taylor, J., Ekstrom, J., Capper, D., Bird, J., Derhé, M., Peet, N. & Burfield, I.
BirdLife International (2023) Species factsheet: Fringilla polatzeki. Downloaded from http://datazone.birdlife.org/species/factsheet/gran-canaria-blue-chaffinch-fringilla-polatzeki on 24/09/2023. Recommended citation for factsheets for more than one species: BirdLife International (2023) IUCN Red List for birds. Downloaded from http://datazone.birdlife.org on 24/09/2023.