Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Caprimulgiformes Apodidae

Scientific Name: Hydrochous gigas
Species Authority: (Hartert & Butler, 1901)
Common Name(s):
English Waterfall Swift, Giant Swiftlet
Hydrochrous gigas gigas Collar et al. (1994)
Hydrochrous gigas gigas BirdLife International (2004)
Taxonomic Source(s): del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A. and Fishpool, L.D.C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Lynx Edicions BirdLife International.

Assessment Information [top]

Red List Category & Criteria: Near Threatened ver 3.1
Year Published: 2012
Date Assessed: 2012-05-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Facilitator/Compiler(s): Benstead, P., Gilroy, J., Taylor, J.
This poorly known species has a disjunct and probably small population, which is thought to be in decline owing to the loss and degradation of forests within its range. It is currently considered Near Threatened, although more detailed surveys are urgently needed to clarify its status.

Previously published Red List assessments:
2008 Near Threatened (NT)
2004 Near Threatened (NT)
2000 Lower Risk/near threatened (LR/nt)
1994 Lower Risk/near threatened (LR/nt)
1988 Threatened (T)

Geographic Range [top]

Range Description: Hydrochous gigas occurs highly sporadically in the Main Range, Peninsular Malaysia, and the mountains of Sumatra and West Java, Indonesia (Collar et al. 2000). Records from Borneo, in Sarawak and Sabah, Malaysia, and Brunei, involve no specimen evidence and are thus treated provisionally here. All individual populations appear to be small, although one, at Gede-Pangrango, Java, was once fairly large but has seemingly now vanished.

Countries occurrence:
Indonesia; Malaysia
Continuing decline in area of occupancy (AOO): Unknown
Extreme fluctuations in area of occupancy (AOO): No
Estimated extent of occurrence (EOO) - km2: 108000
Continuing decline in extent of occurrence (EOO): Unknown
Extreme fluctuations in extent of occurrence (EOO): No
Continuing decline in number of locations: Unknown
Extreme fluctuations in the number of locations: No
Lower elevation limit (metres): 300
Upper elevation limit (metres): 1500
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: The global population size has not been quantified, but the species is described as rare and local (del Hoyo et al. 1999).

Trend Justification:  This species is extremely poorly known, but several colonies have apparently declined or disappeared in recent years, suggesting that population size may be falling. This is likely to be related to forest loss in areas surrounding breeding colonies. A slow decline is suspected overall.
Current Population Trend: Decreasing
Additional data:
Number of mature individuals: Unknown Continuing decline of mature individuals: Unknown
Extreme fluctuations: No Population severely fragmented: No
Continuing decline in subpopulations: Unknown
Extreme fluctuations in subpopulations: No All individuals in one subpopulation: No

Habitat and Ecology [top]

Habitat and Ecology: This species occurs over steeply mountainous rainforest, being largely dependent on waterfalls as breeding sites. Altitudinal limits are poorly known, but there are records from 800 m in Peninsular Malaysia, 440 m on Sumatra and 300-1500 m on Java (del Hoyo et al. 1999). Although this species lacks echolocation, it has acute poor-light vision and may be a crepuscular feeder, potentially contributing to the paucity of records.

Systems: Terrestrial; Freshwater
Continuing decline in area, extent and/or quality of habitat: Yes
Generation Length (years): 7.2
Movement patterns: Not a Migrant

Threats [top]

Major Threat(s): This species may be dependent on areas of forest cover surrounding breeding sites, and therefore be susceptible to the effects of logging and landscape conversion for agriculture. The restricted nature of their waterfall breeding sites may pose an inherent limitation to population size, increasing their susceptibility to disturbance.

Conservation Actions [top]

Conservation Actions: Conservation Actions Underway
No targeted conservation actions are known for this species.

Conservation Actions Proposed
Conduct surveys throughout the known range in order to determine current status and population size. In particular, clarify its presence, abundance and distribution on Borneo. Conduct ecological studies to explore habitat requirements, particularly the link to rainforest cover surrounding breeding sites. Protect areas of suitable habitat from clearance, degradation and disturbance.

Citation: BirdLife International. 2012. Hydrochous gigas. The IUCN Red List of Threatened Species 2012: e.T22686485A38003173. . Downloaded on 09 October 2015.
Disclaimer: To make use of this information, please check the <Terms of Use>.
Feedback: If you see any errors or have any questions or suggestions on what is shown on this page, please provide us with feedback so that we can correct or extend the information provided