Saturday, November 6, 2010
Finally, our two juveniles are on their way! (If you click on the map it should open up in another window and be clearer)
Sheba (yellow) crossed the Red Sea between 3 and 5 November and arrived in Sudan on the night of 5 November. Sindbad (red) is taking his time and apparently another route; he is still in Oman but will soon cross the border into Yemen .
Note that the two Sooties departed in slightly different directions (one west, one southwest). The juveniles of the closely related Eleonora's do migrate independently from adults and therefore they must be guided by an inherited migration programme. This is especially the case when they depart from their breeding grounds and cross the Mediterranean. Juvenile Eleonora's obviously apply an internal navigation mechanism called "vector navigation". They navigate along these so called 'vectors', i.e. migrating 3 days southwest, then 8 days south, etc., until they arrive on their wintering grounds. When naive migrants (juvenile birds on their first migration of their life cycle) follow this inherited programme they should depart in similar directions without big deviations in the initial bearing. Here we see that the juvenile Sooties departing in slightly different directions and we don't know yet whether this is the case only for the first part of their trip or whether it is due to insect abundance or other reasons. It is also possible that Sooties show a completely different migratory behaviour than their sister species Eleonora's falcon.