Saturday, November 6, 2010

Migration started!

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.


  1. Hi Mike and Marion

    The blog is indeed a fantastic effort!

    Marion - Good to see both birds started first migrations. What are the dots on routes?

    Mike - do sooties normally take land routes or are these odd flights? Will the two sooties eventually go to Madagascar?

  2. Khalifa, We don't know much about sooty falcon migration. I think the bird tracked in Abu Dhabi 2 yrs ago travelled overland initially. They will be driven by their migratory instinct, but will need to feed themselves and react to the environmental conditions (weather). Remember also, these are birds that have never made the journey before.

  3. Hello Marion & Mike,

    Nice job, I'm just wondering why Sheba crossed the red sea to Sudan where his final destination is Madagascar? I think it is going to be a long journey for a juvenile bird.

  4. Hi Zahran, The simple answer is "We don't know" Migration is not a very precise activity, especially for birds that have never done it before. They also have to hunt and where they spend time depends on availability of food. The satellite tags are on a duty cycle and so do not transmit all the time, so the straight lines between clusters of dots can be misleading. The string of red dots for Sinbad in the southern Oman desert could be looked at to see just how fast the bird is moving and get an idea of a "typical" migration string.

  5. Hi all,

    my hypothesis is that they do behave as the juvenile Eleonora's do and that they will stop over somewhere in Central Africa for approximately two weeks. This is highly speculative for the moment but let's wait and see whether they just behave as their "big brothers" in West Africa. There are recent observations of Sooties in Cameroon actually (Ralph Buij), the paper is to be published soon... Our birds might not migrate as far as West Africa, but probably they do stop over somewhere all the same. Let's wait and see!

    Hello Kahlifa!! Good to read you here! The dots are the locations calulated by the satellite. That means, as Mike said, the lines are something we cannot be sure of but the dots are the positions we received from the ARGOS system (satellite provider).