VU
Giant Antpitta Grallaria gigantea



Justification

Justification of Red List Category
This species has a very small range, within which its habitat is continuing to decline. It consequently qualifies as Vulnerable (Collar et al. 1992).

Population justification
The population is estimated to number 1,000-2,499 individuals based on an assessment of known records, descriptions of abundance and range size. This is consistent with recorded population density estimates for congeners or close relatives with a similar body size, and the fact that only a proportion of the estimated Extent of Occurrence is likely to be occupied. This estimate is equivalent to 667-1,666 mature individuals, rounded here to 600-1,700 mature individuals.

Trend justification
This species's population is suspected to be declining slowly, in line with rates of habitat loss within its range.

Distribution and population

Grallaria gigantea has three subspecies in the Andes of Ecuador and south-west Colombia. In Colombia, subspecies lehmanni is known from historical specimens taken on both slopes of the Central Andes in Cauca and Huila, while both recent records (1988 and 1989) are from La Planada Nature Reserve, Nariño (subspecies unknown) (de Soye et al. 1997). In Ecuador, the only recent records of the nominate subspecies are from west Napo, but older records exist from eastern Carchi and Tungurahua; and the subspecies hylodroma is known from a few localities on the west slope of the Andes in Pichincha and Cotopaxi (Krabbe et al. 1994b, N. Krabbe in litt. 1999, Ridgely and Greenfield 2001). Some uncertainty surrounds the origin of two old specimens described as hylodroma from El Tambo (probably in western Cañar province) and Cerro Castillo, western Pichincha (J. F. Freile in litt. 2000, 2002, 2007).

Ecology

It inhabits humid montane forest in the upper subtropical to temperate zones, with lehmanni known from 3,000 m, gigantea from 2,200-2,600 m or above, and hylodroma from 1,200-2,000 m. It frequents swampy areas in humid cloud-forest understorey, but has also been recorded in adjacent pastures (presumably only for brief foraging periods) and secondary forest (Krabbe et al. 1994b). Observations of hylodroma and gigantea indicate that giant earthworms Rhynodrilus are important dietary components, with beetle larvae and slugs also eaten (Krabbe et al. 1994b, de Soye et al. 1997). Information on nesting is provided by Solano-Ugalde et al. (2009).

Threats

At the latitude where subspecies lehmanni occurred, land use on both slopes of the Central Andes has been almost wholly agricultural at lower to mid-elevations since the early 20th century or before, and forest loss continues at higher altitudes where the species may persist. Cloud-forests in the West Andes of Nariño, Colombia have suffered extensive deforestation through logging and conversion to agriculture and narcotics plantations, while logging and agricultural conversion have also lead to extensive deforestation in Pichincha, Ecuador. Habitat destruction continues throughout the Pacific slope (Krabbe et al. 1998, Robbins and Stiles 1999, P. G. W. Salaman in litt. 1999, 2000). The east slope forests in Ecuador are more intact and secure but deforestation is occurring in at lower altitudes (around 1,000 m).

Conservation actions

Conservation Actions Underway
If the Colombian race lehmanni is extant, it probably occurs in Puracé National Park, where it was collected in 1941 (Wege and Long 1995, P. G. W. Salaman in litt. 1999, 2000). Searches for the species at La Planada Nature Reserve in the 1990s were unsuccessful (de Soye et al. 1997, P. G. W. Salaman in litt. 1999, 2000). Subspecies hylodroma is protected in the Mindo-Nambillo Protection Forest and Maquipucuna, Otonga and Río Guajalito Reserves in Ecuador, and may occur in other protected areas (Robbins and Stiles 1999, Wege and Long 1995, J. F. Freile in litt. 2000, 2002, 2007). There are no records from the large Cotacachi-Cayapas Ecological Reserve, north of Pichincha, and only two recent records from the surrounding areas of Illinizas Ecological Reserve, but distribution models predict the occurrence of hylodroma in both protected areas (Freile et al. 2010). The nominate race is protected at San Isidro Lodge and at least partially at Antisana Ecological Reserve (J. F. Freile in litt. 2000, 2002, 2007). The species is considered Vulnerable at the national level in Colombia (Renjifo et al. 2014), and has been assessed as Endangered in Ecuador (Freile et al. 2010).

Conservation Actions Proposed
Survey to reconfirm historical, and locate additional, sites for the species (P. G. W. Salaman in litt. 1999, 2000). Estimate population densities at known sites. Increase the area of suitable habitat that has protected status.

Identification

26.5 cm. Huge antpitta with thick, heavy bill. Olive-brown above. Pale grey hindcrown and nape. Deep rusty sides of head and entire underparts, with black edged throat and breast feathers giving wavy, barred appearance. Similar spp. Undulated Antpitta G. squamigera is marginally smaller, with yellowish underparts and pale malar. Voice Low-pitched trill (14-21 notes per second), rising in pitch and amplitude, 4-8 seconds long with intervals from 4-12 seconds. Very similar to G. squamigera, but slightly longer in duration and delivery-rate does not decrease at the end of each song-bout.

Acknowledgements

Text account compilers
Sharpe, C.J., Isherwood, I., Symes, A., Harding, M.

Contributors
Salaman, P., Freile, J., Krabbe, N.


Recommended citation
BirdLife International (2020) Species factsheet: Grallaria gigantea. Downloaded from http://www.birdlife.org on 25/09/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 25/09/2020.