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 <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 has not been quantified, 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.
The global population size has not been quantified, though in Europe the population is estimated at 250,000-700,000 calling or lekking males, which equates to 500,000-1,400,000 mature individuals (BirdLife International 2015). Europe forms c.10% of the global range, so a very preliminary estimate of the global population size is 5,000,000-14,000,000 mature individuals, although further validation of this estimate is needed. The population is therefore placed in the band 5,000,000-14,999,999 mature individuals.
The population is suspected to be stable in the absence of evidence for any declines or substantial threats. The European population is estimated to be stable (BirdLife International 2015).
This species has an extremely large range, breeding from European Russia in the west to Japan and northern Siberia in the East. During winter, birds occur throughout Indonesia, the Philippines, Papua New Guinea and in northern and eastern Australia.
The species is found in forest canopy, open wooded areas and orchards, often in hill country, also in coniferous forest and in birch (Betula) above the tree-line (Payne and Kirwan 2015). In Russia, it favours high coniferous forests of spruce (Picea), pine (Pinus), silver fir (Abies alba) and mixed coniferous and broad-leaved trees such as birch and aspen (Populus). It is sometimes found in pure broad-leaved forests, steppe birch copses, riverside willows, and thickets. It also uses northern taiga to forest edge, riversides, ravines, wetland fringes and slopes of wooded hills and mountains.
It is a brood parasite, mainly using the nests of small warblers of the Phylloscopus genus. In central Russia the eggs are laid in June and July in nests belonging to Arctic Warbler (Phylloscopus borealis), Common Chiffchaff (P. collybita), Willow Warbler (P. trochilus) or other Phylloscopus species, as well as Olive-backed Pipit (Anthus hodgsoni) (Snow and Perrins 1998). It feeds on insects, mainly caterpillars, and some fruit. It winters in the Malay Peninsula and Philippines and south through Sumatra, Java, Borneo, Sulawesi, Moluccas, Lesser Sundas and New Guinea, to the coastal parts of northern and eastern Australia (Payne and Kirwan 2015).
There are currently no known serious threats to this species.
Conservation Actions Underway
There are currently no known conservation measures for this species within its European range.
Conservation Actions Proposed
No conservation measures for this species are currently needed within its European range.
Text account compilers
Bird, J., Butchart, S., Symes, A., Taylor, J., Ashpole, J
BirdLife International (2019) Species factsheet: Cuculus saturatus. Downloaded from http://www.birdlife.org on 18/06/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 18/06/2019.