Justification of Red List Category
This species qualifies as Vulnerable because it occupies an extremely small range, comprising only two locations, and its status could change in a short space of time, such that it qualifies as Critically Endangered, or even Extinct, owing to potential future threats.
In 1971-1972, the population was estimated at 800 breeding pairs (Harris 1973). Between 1977 and 1985, it remained stable at around 650 to 850 mature individuals (Harris 1973, Valle 1986, Valle and Coulter 1987). However, during the severe El Niño event in 1983, the population declined drastically to 400 individuals, but recovered within a season (Valle and Coulter 1987). In 1986, the population was estimated at 1,000 mature individuals (Rosenberg et al. 1990). After the El Niño event in 1997-1998, growth in the cormorant population has been higher than ever before in the survey period (1977-2006). In 1999, a total of 900 individuals was counted during the census (H. Vargas and F. Cruz in litt. 2000). In 2006, a total of 1,396 individuals were counted. Still, results as of 2003 show a decrease in the rate of population growth and a low percentage of juveniles (3% in 2006), suggesting that the population is stabilizing at a new high (Jiménez-Uzcátegui and Vargas 2007). In 2013, the population was estimated to be 2,080 individuals (Jiménez-Uzcátegui 2013, Carrera-Játiva et al. 2014).
This species has undergone marked fluctuations since 1977, with the population estimate ranging from 400 individuals after the El Niño in 1983 (Valle and Coulter 1987) to 1,396 individuals in 2006 (Jiménez-Uzcátegui and Vargas 2007). From 2010 on, a different census methodology was used, and in 2013 the population was estimated in 2,080 individuals (Jiménez-Uzcátegui 2013, Carrera-Játiva et al. 2014). Currently, the population is thought to be stabilizing.
Nannopterum harrisi is endemic to the Galápagos Islands, Ecuador. It is found around most of the coast of Fernandina Island (mainly on the east), as well as on the north, northeast and west coasts of Isabela Island (Valle and Coulter 1987, H. Vargas and F. Cruz in litt. 2000).
The species usually nests in sheltered areas, just above sea level on shingle and flat lava outcrops, mostly within 100 m of the shoreline (Levéque 1963, Harris 1974). It is thought to breed near the coldest and richest waters (Harris 1974, Valle 1986). It nests in small groups of just a few pairs (Levéque 1963), mainly during the colder season (July-October), when marine productivity is highest and the risk of heat stress to chicks and incubating adults is reduced (Harris 1974). Some pairs may nest biannually (Valle and Coulter 1987). It is highly sedentary (Valle 1986) and fearless of humans (Levéque 1963). It preys on eels, octopuses and fish (Jiménez-Uzcátegui and Vargas 2007).
Flightlessness, disinclination to disperse, and small population sizes render the species vulnerable to a range of threats. El Niño Southern Oscillation (ENSO) events pose a significant risk to the species. Following the El Niño event in 1982-83, the population was halved and suffered complete breeding failure, but did subsequently recover (Valle and Coulter 1987). The effects of climate change and more frequent and/or severe ENSO events could have potentially catastrophic impacts on the species in the future (Vargas 2006, Wiedenfeld and Jiménez-Uzcátegui 2008, J. Freile in litt. 2010, G. Jiménez-Uzcátegui in litt. 2011, D. Wiedenfeld in litt. 2011).
The island of Fernandina is volcanically active and eruptions pose an unpredictable and inevitable threat to local populations (Wiedenfeld and Jimenez-Uzcategui 2008).
As with other island endemics, the species is highly vulnerable to invasion by non-native species. Dogs Canis familiaris were eradicated in 1981-82 (Calvopiña 1982 in Valle 1986). However, the likelihood of permanently eliminating all dogs from Isabela is considered to be low, because they are still present on the volcanoes Cerro Azul and Sierra Negra as well as on farms outside the national park boundaries. The risk of future invasions into nesting areas is high because of easy access along the coast (Valle 1986). Other introduced predators (rats Rattus spp., cats Felis catus) remain on several islands and pose a current threat to the species. Negative serologic findings suggest that the species is immunologically naive and may have a reduced capacity to cope with the introduction of novel pathogens (Travis et al. 2006), yet no severe disease outbreaks have been reported in the species as yet. The protozoan parasite Toxoplasma has been considered a threat, but although antibodies were found in birds sampled on both Fernandina and Isabela Island, no direct negative impacts have been noted (Deem et al. 2010).
Previous fishing activity on the Galápagos Islands was modest, but has now become an illegal industry, serving markets worldwide, evinced by the occasional uncovering of large illegal harvests (Boersma et al. 2005). The increase in illegal fishing activities around Fernandina and Isabela (H. Vargas and F. Cruz in litt. 2000, Wiedenfeld and Jiménez-Uzcátegui 2008) is likely to have detrimental side-effects (bycatch and injury from entanglement, competition for prey, disturbance) on resident seabird populations.
Human disturbance from tourism to the Galápagos Islands is regulated (capped at 120,000 visitors per annum) but annual visits of about 100,000 tourists may still be a contributory factor to other threats (Boersma et al. 2005).
Oil spills could have potentially catastrophic effects on the species as its foraging behaviour includes repeated diving and surfacing, which makes it particularly vulnerable to oiling. Oil spills have occurred in the vicinity of the population in the past (e.g. Jessica oil spill) and pose a severe future threat.
Although the species has proven capable of recovering from disastrous events in the past, further environmental changes and fluctuations will continue to be a threat, and may also be increasing in intensity.
Conservation Actions Underway
All populations are within the Galápagos National Park and Marine Reserve (A. Tye in litt. 2000, H. Vargas and F. Cruz in litt. 2000). In 1979, the islands were declared a World Heritage Site (Jackson 1985). A research project investigating the factors behind the species's decline commenced in August 2003 (H. Vargas in litt. 2003). Invasive species are controlled (Jiménez-Uzcátegui and Vargas 2007). The Charles Darwin Foundation (CDF) and Galapagos National Park Directorate (GNPD) are working on the long-term monitoring and research of the population covering issues as survival (mark-recapture studies), threats (presence of heavy metals, diseases, climate change and human interaction), stable isotopes, reproduction. In addition, the CDF-GNPD is controlling introduced species (cats and rats) at breeding sites. Also, the CDF are working with GNPD advising the changes in the Marine Reserve according the breeding places of this species.
Conservation Actions Proposed
Monitor the populations on both island annually on the long term (Rosenberg et al. 1990). Minimise human disturbance. Reduce or ban fishing activities and hunting (hogs and other animals) with household dogs in Iguana Cove and other places in Zone 8, where the largest growth in populations of Flightless Cormorant and Galápagos Penguin has been detected in the last few years (Jiménez-Uzcátegui and Vargas 2007). Stop net-fishing within the feeding range. Continue the cat control programme (Jiménez-Uzcátegui 2013).
89-100 cm. Unmistakable, very large, dark, flightless cormorant. Adults similar though male significantly larger. Tiny, tatty-looking wings. Almost black upperparts, brownish underparts, turquoise eye. Long, hooked beak. Juvenile glossy black with dull-coloured eye. Voice Adult makes low growl.
Text account compilers
Symes, A., Taylor, J., Fjagesund, T., Anderson, O., Lascelles, B., Benstead, P., Martin, R., Miller, E., Moreno, R., Pilgrim, J.
Freile, J., Vargas, H., Jiménez-Uzcátegui, G., Wiedenfeld, D., Cruz, F., Tye, A.
BirdLife International (2021) Species factsheet: Nannopterum harrisi. Downloaded from http://www.birdlife.org on 24/10/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 24/10/2021.