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painted by Johanna Yourstone 2012
painted by Jenny Eikestam 2012

Weather and Migration

Weather conditions, Migration timing & Routes for trans-Caucasian migration

Any population may migrate through the Caucasus, but it is difficult to tell where exactly the birds will fly from year to year. From much of the migration literature it becomes clear that species that rely heavily on soaring flight - sustained by thermal lift or orographic updrafts (aka slope updrafts) - will have much more predictable routes compared to broad-front migrants that flap their way south. Some species may stop-over for the day when they encounter heavy rains, others may circumvents such bad weather systems and temporarily end up on a more easterly or westerly route.

Local weather conditions and flight strategies: Local routes and the altitude of flight

Apart from the regional effects on migration as detailed above it is crucial to gain insight in how the detecteability of raptors by observers may change according to weather conditions. For Batumi this means we need to show empirically where (1) the local routes used by raptors are situated (e.g. coast – lowland – mountains) and how these may shift in relation to weather.

Patterns in migration in relation to weather: Implications for migration monitoring

More than 800.000 raptors of ca. 30 species migrating over Batumi every autumn. Ten species observed in numbers constituting >1% of their world population (see Results & Prospects). Several others in (one of) the highest concentration known to ornithologists anywhere in the world. The list of arguments to show the importance of the Batumi bottleneck in an international context is quite impressive. So for the casual observer, the need for implementing a long-term monitoring of migratory raptors at the eastern Black Sea seems clear.

In conclusion

Ground-based counts of migrating raptors have great potential for monitoring purposes. However the causes of variability in counts need to be well understood before applying results and conclusions in conservation practice. Furthermore the investigation of the flight strategies employed by migrating raptors and the migration patterns (timing and routes) resulting from these strategies can be done on a relatively short term. For these reasons BRC considers this research topic to be of extremely high importance and is currently in the process of conducting such research or organizing the actions needed to conduct such research in the foreseeable future.

Our results and conclusions will be published on this website as soon as they are available.

If you have any questions on weather-related patterns in migration or if you wish to contribute to the research done at Batumi please contact BRC at batumiraptorcount@gmail.com or seek direct contact with Wouter Vansteelant who is coordinating such research on this site.

© Batumi Raptor Count  2008 - 2013