Cuckoos’ migration from South Korea to the South of Africa
Common cuckoos are found in Eurasia, from Europe to Korea. All over the continent, they migrate to Africa, while they parasite different birds’ nests. Tracking them using Argos helps understand the similarities and differences between all of them.
The common cuckoo (Cuculus canorus), like the great spotted cuckoo (Great spotted cuckoos tracked far from the nest by Argos) is migratory. It is found widely in Eurasia during its breeding periods. It migrates to winter in tropical Africa mostly, even when breeding in far-east Asian countries such as Korea. As the chicks never meet their biological parents, their migratory behaviors are fully innate.
Even if it is considered a species, common cuckoos are genetically different depending on the host species that they parasitize (more than 200 of them have been observed). Does a gens, as a group of individuals sharing the same host species can be called, has the same migratory behavior? including migration timing, route, and duration, major stopovers and non-breeding locations. Does all gentes? Or do different gentes have different behaviors?
Tracking common cuckoos from South Korea to Africa, and back
Ten adult male common cuckoos were tagged with 5 g solar Argos PTT in South Korea during the breeding season (May-June) in 2019 and tracked until August 31, 2020, or until transmission was lost. They were chosen in three different populations in South Korea (Yangypeong, Muan and Jeju Island), representing two different gentes – In Yangypeong and Muan, the cuckoo parasitizes primarily the vinous-throated parrotbill, in Jeju Islands the meadow bunting.
Five cuckoos of each gens was tagged. Five individuals (four parrotbill gentes and one bunting gens) arrived on the non-breeding grounds in Africa with tags, and returned to Korea. They seem to show site fidelity to their breeding ground.
The followed routes were similar for all recorded paths, irrespective of the gentes. The cuckoos migrated along a narrow corridor, with three stopovers on winter migrations, one in spring. Going from Korea to Africa, the birds stopped in an area across Myanmar and Bangladesh, then in South India (over 10 days in both cases) and finally in Somalia. On the trip back, they only stopped significantly in Somalia before crossing the Arabian Sea. This crossing is in fact the major difficulty in the whole migration, with about 3000 km of open water to overfly.
Moreover, the monsoon winds change with the seasons (southwesterly winds from April to September, northeasterly winds October to March — approximately), probably timing the stopovers and afterward sea crossing of the cuckoos – they left India at the end of October in winter, Somalia end of April in spring. One individual made a detour to Oman during the journey over the Arabian Sea, due to cyclone Kyarr
After a short stopover in Somalia, they moved along the coast of Somalia and Kenya to reach the non-breeding grounds located mostly in Tanzania and Mozambique. One bird (parrotbill gens) went further south, to Botswana.
Similarities and differences with the common cuckoo European populations
The Korean cuckoos’ migration patterns and even the final destination are very different from the ones recorded for European populations. The whole travel is of course completely different but also the distance (22,000 km vs 16,000 km), the timing –departures are later in the year, possibly due to a warmer climate in South Korea, the fact they come back roughly along the same path both ways (while European cuckoos make a loop), etc. There are some analogies, though, such as having a stopover after crossing a harsh environment (Arabian Sea or Sahara).
Other studies tracking Chinese and Mongolian cuckoos showed use of the same stopover areas, which should thus be considered critical for conservation of the species.
Tracking more cuckoos from the same two gentes and also others, tagging females as well as males and more generally examining environmental data in correlation with those locations will be worthwhile to better understand such long-range migrations.
- Jin-Won Lee, Seung-Gu Kang, Ji-Yeon Lee, Hae-Ni Kim, Sue-Jeong Jin, Geun-Won Bae, Wee-Haeng Hur, Jin-Young Park, 2023, Long-distance migration of Korean common cuckoos with different host specificities, Global Ecology and Conservation, Volume 43, e02426, https://doi.org/10.1016/j.gecco.2023.e02426.
Main Photo: A male cuckoo with a tag in Muan, 2019 (ID62399 (Credit Jin-Won Lee)