Migrating?

Dear all,

It has been another interesting month here in the Makgadikgadi. The first month since August 2009 where I can’t remember any rain falling and where the mosquitoes have been happy to bite anything repeatedly and regardless of whether repellent was applied or not! Fortunately, they now appear to be slowly diminishing as the weather starts to turn colder and the shallow pools are gradually drying up. The deep waterholes remain and will do so for a considerable time to come as evaporation rates slow down.

Of the 10 collars which were deployed in late March and early April, there are only 4 collars still working and only 2 of these working as they should. Unfortunately, this means that I have to replace all but the 2 working collars with replacement collars that are being provided by the collar company. Not only has this lost valuable fieldwork time as well as valuable GPS data which have not been collected, but I will also have the additional costs associated with darting zebra. I am hoping that I will be able to change the collars in June but this depends on when the replacement collars are available.

Fieldwork has continued during May with the assistance of Rob, Dutch and Matt who have been kind enough to brave the mosquitoes with me. I have visited over 200 known waterholes, as well as found quite a few more, in order to record water availability and quality. I have also sampled grazing sites, collected faecal samples and conducted behavioural observations. It’s amazing how quickly a month can disappear.

As a result of the collar problems, it has proven to be significantly more challenging to find the zebra. It is amazing how well herds of 1,000 or more zebra can seem to disappear in the Makgadikgadi. They tend to stay very close to each other and move slowly across the ecosystem to find fresh grazing each day. When you see them like this they appear to be like a shoal of Sardines or a flock of Quelea: constantly changing shape but always linked.

Starting in the east, where some remain, during May the zebra have moved across much of the Makgadikgadi towards the centre of the Park. Some, however, have gone a step further and have migrated west to the Boteti and there are now two collared zebra in the Boteti region.

This migration was unexpected as there is still so much rain water remaining in the surface waterholes of the eastern Makgadikgadi. Exactly how many are in the Boteti is unknown but I am hoping to fly this weekend which will allow me to look at the bigger picture. All of the remaining collared zebra are still grazing in the centre of the park and it will be interesting to see whether they choose to go east or west as there does not appear to be much surface water remaining in this area.

The migration of zebra back to the Boteti raises some interesting questions. Why have they migrated when there are still large quantities of water and grass in the eastern Makgadikgadi? What triggered this movement? Will the zebra remain in the Boteti region for the rest of the dry season? Will the remainder of the zebra in the Makgadikgadi migrate west as well or will there be two groups – 1 in the west and 1 in the east? How do the grazing resources differ between the two areas?

I will look to collect data to help answer these questions in the coming weeks as well as continuing to monitor the movements of the zebra.

If you have any comments or questions then please feel free to contact me at any time.