The Black Kite (Milvus migrans) is a raptor found throughout Eurasia, Australia, Africa and can live in a range of habitats including human populated ones. Some species winter in West Asia and Africa and there are a range of research studies looking at their migration patterns, but the migration patterns from Siberia are mostly unknown. There is some evidence that they winter in India, China and Indonesian areas including a species known as the black-eared kite (M. m. lineatus).
Existing data showed migration patterns of raptors across the Western, Eastern, East-West Southern and Trans-Himalayan corridors. The Black Kites do not have continuous flapping power of e.g. geese species so will be affected by tailwinds for example. The researchers chose a fledgling site in Siberia and wanted to research the genetic background of two sub populations from Biysk (Altai Krai) and Kosh Agach (Altai Republic). They wanted to know more about the timing of autumn, spring migrations, home ranges in winter and summer and how they were affected by weather, especially in coping with the Himalayas.
They chose 19 Black Kites (11 females, 8 males) from both sites. They collected some feathers to analyse DNA and tagged the birds then fitted telemetry loggers whilst they were in nests, during 2018. GPS data was collected and sent via SMS to various centres. They used GIS and the ArcGIS software to create maps of the migration routes. They completed observations and used meteorological data, also elevation data from e.g. databasin.org
Several of the tagged birds survived and were studied over several years. The genetic profile included different haplogroup types in haplogroups A and B. The Black Kites originating from Biysk flew via the Western Circum-Himalayan Corridor – eastern Kazakhstan, Kyrgyzstan, Tajikistan and eastern Afghanistan to winter, mostly Pakistan and western India. They returned via the same route back to Biysk after winter. The kites from Kosh-Agach flew over Tian Shan and Taklaman desert in China then via Jammu and Kashmir to spend winter in western India and eastern Pakistan, then also flew back via the same route to Altai again.
The migration timings did not vary by age and none were found in Siberia during winter. They found a positive relationship between the tail speed and the flying patterns across the Himalayas with the Kosh-Agach kites crossing over 2 days. Generally both bird populations did not mix but they did find one kite from Biysk with the Kosh-Agach group during winter.
They were able to take advantage of wind conditions by changing their airspeed / ground speed and their return across the Himalayas to Siberia was quicker. They do not favour crossing large water bodies but some species do end up in Africa. Some populations are also wintering in Syria, Israel, Turkey and Egypt but the species are not well known.
When the weather was less favourable, they roosted in the Himalayan mountains above 5000m. In the future the researchers would like to investigate any additional physiological adaptation the kites make during their Himalayan crossings.
Literák, I., Škrábal, J., Karyakin, I.V. et al. Black Kites on a flyway between Western Siberia and the Indian Subcontinent. Sci Rep 12, 5581 (2022). https://doi.org/10.1038/s41598-022-09246-1