VU
Galapagos Hawk Buteo galapagoensis



Justification

Justification of Red List Category
This species has a stable population, which is currently not facing any major threats. As the population is small however, it is listed as Vulnerable.

Population justification
The population is difficult to measure except in terms of breeding territories. However the breeding system means that the population is larger than the number of territories suggests; for example, the population on Santiago may number 180 adults in the 50 territories, with a total of c.250 individuals (Faaborg 1984). The most recent overall population estimate is 400-500 mature individuals and 300-400 juveniles (T. de Vries in litt. 2000, 2007). Genetic research indicates there is little movement between island populations (Bollmer et al. 2005).

Trend justification
The population is thought to be stable (Jiménez-Utzcátegui et al. 2019).

Distribution and population

Buteo galapagoensis was apparently once common on most of the main islands of the Galápagos, Ecuador. Following a serious population decline in the past, it is now extinct on San Cristóbal and Floreana (Dvorak et al. 2017, 2019). It occurs on Santiago, Española, Isabela, Fernandina, Pinta, Marchena, Pinzón and Santa Fe (de Vries 1973).

Ecology

It is found in all habitats, from shoreline to bare lava-fields, open, rocky, scrub country, deciduous forests and mountain peaks. It feeds on a wide variety of sea and landbirds, rats, lizards, iguanas, invertebrates and carrion. It breeds throughout the year. It nests on a stick platform on a prominent lava outflow, rocky outcrop or in a small tree (Thiollay 1994). It is cooperatively polyandrous, with one female typically mating with two or three males (up to eight males have been recorded), and all males helping in raising the chicks (Faaborg et al. 1995).

Threats

The population is currently assessed as stable, although the small population and disjunct distribution renders it susceptible to stochastic events. The most probable cause of the species's historical decline is persecution by humans (de Vries 1973), which is now no longer considered a threat (D. Wiedenfeld in litt. 2012; Jiménez-Utzcátegui et al. 2019). A low genetic diversity in the small island populations is a potential threat (Bollmer et al. 2005; Jiménez-Utzcátegui et al. 2019); this has led to increased parasite loads and vulnerability to disease in certain island populations (Whiteman et al. 2006). Nevertheless, as the species has never had a large effective population size, this is unlikely to become a major threat to the species now (D. Wiedenfeld in litt. 2007). Habitat within the range is degraded and lost through agricultural expansion (Jiménez-Utzcátegui et al. 2019). Furthermore, the removal of introduced goats from some islands has led to local population declines, likely as a result of vegetation recovery in the absence of goats and a change in prey availability (T. de Vries in litt. 2000, 2007; Jaramillo et al. 2016; Bierregaard et al. 2020).


Conservation actions

Conservation Actions Underway
CITES Appendix II. Most of the archipelago is under national park and marine reserve protection and, in 1979, was declared a World Heritage Site. The species has been protected by Ecuadorian law since 1959 (de Vries 1973). The possibility of reintroduction to previously inhabited islands has been discussed (de Vries 1984; Faaborg 1984), but advised against as prey-supply may have declined, and the effects may be detrimental to other threatened species (de Vries 1984). Ecological research is ongoing and will result in detailed information on each island population (T. de Vries in litt. 2000, 2007). A study on natal dispersal collected from 1998 to 2009 from a banded population of 25 territorial groups (Rivera et al. 2011). Rats were eradicated from Rábida, Bartolomé and Bainbridge islands in 2011.

Conservation Actions Proposed
Produce an up-to-date estimate of the population size. Assess the population structure. Monitor the population trend. Investigate threats and their potential impacts on the population, including the loss of genetic diversity and the conversion of habitat.

Identification

55 cm. Large, dark hawk. Adult sooty-brown. Grey tail with narrow black bars. Immature browner with extensive white and buff mottling.

Acknowledgements

Text account compilers
Hermes, C.

Contributors
Benstead, P., Cruz, F., Derhé, M., Isherwood, I., McClellan, R., Sharpe, C.J., Symes, A., Vargas, H., Wiedenfeld, D. & de Vries, T.


Recommended citation
BirdLife International (2022) Species factsheet: Buteo galapagoensis. Downloaded from http://www.birdlife.org on 25/06/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 25/06/2022.