Data Zone
Justification of Red List category
This species has a very large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km² combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be stable, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size may be moderately small to large, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
Population justification
The global population is difficult to quantify, and no robust estimates of the total population exist. Previously suspected to number less than 7,000 mature individuals, this value may have been an underestimate.
In Boyacá and Santander, densities of 0.2-0.4 individuals/ha could be observed (Mendoza Mendoza and Urrego Duarte 2022). Assuming that this density is representative for the entire range, and furthermore very precautionarily assuming that only 5% of the range is occupied to account for the strict habitat requirements (i.e., 5,000 km2), the global population may number 100,000-200,000 mature individuals. This roughly equates to 60,000-130,000 mature individuals.
Trend justification
Anecdotal evidence suggests that locally the species has been disappearing from previously occupied sites (C. J. Sharpe in litt. 2015, Renjifo et al. 2016). However, based on observational records the species appears to be expanding its distribution range, presumably as a consequence of the conversion of dry shrubland to more humid open pastureland with scattered trees (Sharpe et al. 2015, eBird 2022). The rapid expansion of the distribution range is likely causing an increase in the population size, which may outweigh local declines. Tentatively, the population is therefore suspected to be stable, though the overall trend may well be increasing.
This species occurs in north-west Venezuela around Lago Maracaibo and north Colombia.
This species inhabits lowland marshes, swamps, lagoons, the banks of slow-flowing rivers and seasonally flooded alluvial plains, often in areas surrounded by forest (del Hoyo et al. 1992). It is exclusively vegetarian, grazing the green parts of succulent aquatic plants (del Hoyo et al. 1992), although digging for unknown food items is regular (Naranjo 1986). The nest is a large mass of marsh vegetation built up from the water, and 2-7 eggs are laid mostly in October to November, but breeding continues throughout the year (del Hoyo et al. 1992).
The most severe threat is the loss and degradation of habitat owing to drainage of wetlands for cattle and agriculture, domestic and industrial pollution and sewage, urbanisation and mangrove cutting (Naranjo 1986, Carboneras et al. 2020). Hydroelectric schemes alter hydrological regimes which may impact on the species' habitat in some places. Construction of a pipeline and road through the wetlands of the Ciénaga Grande de Santa Marta and Isla de Salamanca in the mid-1970s obstructed tidal flow and caused extensive mangrove die-back, continuing until at least 1992 (Wege and Long 1995). Collection of eggs, capture as pets and possibly illegal hunting in some areas are further threats (A. Cuervo in litt. 1999, P. G. W. Salaman in litt. 1999, T. Donegan in litt. 2012, C. Ruiz in litt. 2012), though their impact on the population size has not been quantified.
Conservation and Research Actions Underway
The species occurs in several protected areas across its range, including Ciénagas de Juan Manuel National Park in Venezuela and Los Katíos National Park in Colombia (Sharpe et al. 2015, Renjifo et al. 2016). In Colombia, environmental education workshops have been carried out to raise awareness for the species (Renjifo et al. 2016). It is listed as Vulnerable at the national levels in Venezuela and Colombia (Sharpe et al. 2015, Renjifo et al. 2016).
Conservation and Research Actions Proposed
Survey to locate additional populations and to refine the distribution range. Produce an accurate quantification of the global population size. Quantify the impact of threats on the population size. Monitor the population trend. Monitor the expansion of the distribution range.
Increase the area of suitable habitat that has protected status. Improve the management of protected areas that are suffering encroachment and degradation. Control pollution in the species' habitats. Continue and expand environmental education and awareness programmes.
76-91 cm. Huge and heavy-bodied peculiar goose-like bird. Distinctive head pattern, with grey crown and shaggy crest. Broad white "chinstrap" across throat and sides of face, and black neck. Otherwise dull with grey underparts and dark glossed green upperparts. Sharp spurs on bend of wing. Very large reddish-pink legs, with unwebbed feet. Voice One of the loudest birds in the world, with powerful bugled klerr-a-ruk, cherio.
Text account compilers
Hermes, C.
Contributors
Ashpole, J, Benstead, P., Capper, D., Cortés, O., Cuervo, A., Diaz-Jaramillo, C., Donegan, T., Isherwood, I., Pilgrim, J., Ruiz, C., Salaman, P.G.W., Sharpe, C J, Stiles, F.G., Stuart, T. & Symes, A.
Recommended citation
BirdLife International (2024) Species factsheet: Northern Screamer Chauna chavaria. Downloaded from
https://datazone.birdlife.org/species/factsheet/northern-screamer-chauna-chavaria on 22/11/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 22/11/2024.