Phalacrocorax harrisi 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Suliformes Phalacrocoracidae

Scientific Name: Phalacrocorax harrisi Rothschild, 1898
Common Name(s):
English Flightless Cormorant, Galapagos Cormorant
Nannopterum harrisi ssp. harrisi (Rothschild, 1898) — Stotz et al. (1996)
Nannopterum harrisi ssp. harrisi (Rothschild, 1898) — Collar and Andrew (1988)
Taxonomic Source(s): SACC. 2005 and updates. A classification of the bird species of South America. Available at: #
Identification information: 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.

Assessment Information [top]

Red List Category & Criteria: Vulnerable D2 ver 3.1
Year Published: 2017
Date Assessed: 2016-10-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Cruz, F., Freile, J., Jiménez-Uzcátegui, G., Tye, A., Vargas, H. & Wiedenfeld, D.
Facilitator/Compiler(s): Anderson, O., Benstead, P., Lascelles, B., Moreno, R., Pilgrim, J., Symes, A., Taylor, J., Martin, R
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.

Previously published Red List assessments:

Geographic Range [top]

Range Description:Phalacrocorax harrisi is endemic to Galápagos Islands, Ecuador.  It is found around most of the coast of Fernandina (mainly on the east), but only on the north and west coasts of Isabela (Valle and Coulter 1987, H. Vargas and F. Cruz in litt. 2000) and few colonies in the north east of Isabela.  In 1971-1972, the population was estimated at 800 pairs (Harris 1973).  Between 1977 and 1985, it remained more or less stable at around 650 to 850 adults (Harris 1973, Valle 1986, Valle and Coulter 1987).  However, during the 1983 El Niño event, the population declined by 50% to 400 birds, but recovered within a season (Valle and Coulter 1987).  In 1986, it was estimated at 1,000 adults (Rosenberg et al. 1990).  In 1999, a total of 900 individuals was counted during the census (H. Vargas and F. Cruz in litt. 2000).  A total of 1,396 cormorants were counted in 2006, which is 10% less than the population counted in 2005.  Nevertheless, the total counted in 2006 is one of the four highest counts among all cormorant surveys conducted since 1977.  After the last El Niño event of 1997-1998, growth in the cormorant population has been higher than ever before in the survey period (1977-2006).  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).

Countries occurrence:
Ecuador (Galápagos)
Additional data:
Estimated area of occupancy (AOO) - km2:50Continuing decline in area of occupancy (AOO):Unknown
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:5900
Continuing decline in extent of occurrence (EOO):UnknownExtreme fluctuations in extent of occurrence (EOO):No
Number of Locations:2Continuing decline in number of locations:Unknown
Extreme fluctuations in the number of locations:No
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:In 2007, 1,602 individuals were recorded.  Therefore, the estimate of population size in 2007, according to the Valle (1994) methodology, was 1,937 individuals (Jiménez-Uzcátegui and Vargas 2007).  Since 2010 the census methodology has changed, and in 2013 the population was estimated to be 2,080 individuals (Jiménez-Uzcátegui 2013, Carrera-Játiva et al. 2014).

Trend Justification:  This species has undergone marked fluctuations since 1977, with the population estimate ranging from 400 individuals due to the 1983 El Niño (Valle and Coulter 1987) to 1,396 individuals in 2006 (Jiménez-Uzcátegui and Vargas 2007).  From 2010 the census methodology changed, and in 2013 the population was estimated in 2,080 individuals (Jiménez-Uzcátegui 2013, Carrera-Játiva et al. 2014).

Current Population Trend:Stable
Additional data:
Number of mature individuals:1602Continuing decline of mature individuals:Unknown
Extreme fluctuations:NoPopulation severely fragmented:No
No. of subpopulations:1Continuing decline in subpopulations:Unknown
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:Yes
No. of individuals in largest subpopulation:100

Habitat and Ecology [top]

Habitat and Ecology:It usually nests in sheltered areas, just above sea level, on shingle and flat lava outcrops (Levéque 1963), mostly within 100 m of the shoreline (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).

Systems:Terrestrial; Marine
Continuing decline in area, extent and/or quality of habitat:Unknown
Generation Length (years):11.1
Movement patterns:Not a Migrant
Congregatory:Congregatory (and dispersive)

Threats [top]

Major Threat(s): Its flightlessness and disinclination to disperse render it extremely susceptible to human disturbance (Levéque 1963) and catastrophes such as oil spills (Valle 1986).  Moreover, they may be affected by nest flooding or even volcanic eruptions (Jiménez-Uzcátegui and Vargas 2007, D. Wiedenfeld in litt. 2011).  Although the species has shown itself to be capable of recovery, further environmental changes and fluctuations will continue to be a threat, and may be increasing in intensity; the effects of climate change and more frequent and severe El Niño Southern Oscillation 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).  Introductions of rats, cats and dogs could have a significant impact on the species on Fernandina (they are present on Isabela) (Valle 1986, H. Vargas and F. Cruz in litt. 2000, D. Wiedenfeld in litt. 2011).  The introduction of parasites and pathogens is also a potential threat (J. Freile in litt. 2010, Carrera-Játiva et al. 2014).  Samples collected from birds on Islabela and Fernandina in 2003-2005 and 2008 tested positive for Toxoplasma gondii antibodies - a common protozoan parasite of humans and warm-blooded animals, thought to originate from feral cats, pointing to additional risks from this invasive predator beyond direct predation (Wiedenfeld and Jiménez-Uzcátegui 2008, Deem et al. 2010).  Illegal fishing activities are increasing around Fernandina and Isabela (H. Vargas and F. Cruz in litt. 2000, Wiedenfeld and Jiménez-Uzcátegui 2008).

Conservation Actions [top]

Conservation Actions:

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
Monitoring both island populations annually to long term (Rosenberg et al. 1990).  Minimise human disturbance.  Stop net-fishing within feeding range.  Continue the cat control program (Jiménez-Uzcátegui 2013).  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 penguin and cormorant populations has been detected in the last few years (Jiménez-Uzcátegui and Vargas 2007). 

Amended [top]

Amended reason: Edited: Geographic Range, Population Justification, Habitat and Ecology, Threats, Conservation Actions proposed, Underway and in Place. The estimated number of mature individuals were altered. Added references and also added a new Contributor and a new Compiler.

Citation: BirdLife International. 2017. Phalacrocorax harrisi (amended version of 2016 assessment). The IUCN Red List of Threatened Species 2017: e.T22696756A112375205. . Downloaded on 14 August 2018.
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