Data Zone
Justification of Red List category
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence under 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 size may be moderately small to large, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (under 10,000 mature individuals with a continuing decline estimated to be over 10% in ten years or three generations, or with a specified population structure). The population trend is not known, but the population is not believed to be decreasing sufficiently rapidly to approach the thresholds under the population trend criterion (over 30% decline over ten years or three generations). For these reasons the species is evaluated as Least Concern.
Population justification
The global population size is estimated at 25,001-125,000 individuals (Wetlands International 2023), which equates to 16,700-83,300 mature individuals. The overall population trend is unknown (Wetlands International 2023).
Trend justification
.
Behaviour This species is largely sedentary although some individuals may make local movements to avoid river flooding (returning to exposed riverbanks as the water recedes) (del Hoyo et al. 1996). The timing of breeding is variable but generally coincides with the dry season or the early rains, with the species nesting solitarily (del Hoyo et al. 1996) or in loose associations of several pairs on riverine sandbars (Hockey et al. 2005). The species is usually observed foraging nocturnally (del Hoyo et al. 1996) in pairs or small groups (Hayman et al. 1986) but is also gregarious at times, gathering in flocks of 30 or more individuals during the non-breeding season (Urban et al. 1986). Habitat It inhabits riverbanks, lake shores, estuaries, mangrove swamps, undisturbed sheltered beaches (del Hoyo et al. 1996) and the shores of coastal creeks and islands (Hayman et al. 1986), showing a preference for habitats with bushes or shrubs providing cover (e.g. light woodland) (del Hoyo et al. 1996). It generally avoids heavily vegetated wetlands (Hockey et al. 2005) but occasionally forages more than 1 km from water (del Hoyo et al. 1996). Diet Its diet consists of insects (del Hoyo et al. 1996) (e.g. aquatic beetles, grasshoppers, locusts and termites) (Hockey et al. 2005), crustaceans (del Hoyo et al. 1996) (e.g. crabs with carapace widths of up to 50 mm) (Hockey et al. 2005), molluscs (del Hoyo et al. 1996), worms, frogs and tadpoles, millipedes and grass seeds (Hockey et al. 2005). Breeding site The nest is a scrape in the ground often positioned close to water (del Hoyo et al. 1996) on a sandbank, shoreline (Urban et al. 1986) or a small islet (Hayman et al. 1986) near a landmark such as a piece of driftwood or a bush (del Hoyo et al. 1996).
The species is threatened by human disturbance and predation by domestic dogs on beaches (Hockey et al. 2005).
Text account compilers
Rutherford, C.A.
Recommended citation
BirdLife International (2024) Species factsheet: Water Thick-knee Burhinus vermiculatus. Downloaded from
https://datazone.birdlife.org/species/factsheet/water-thick-knee-burhinus-vermiculatus 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.