Still Adigala

In early August 2013 Assamo stayed very close to Adigala.  Although I have never been there, given the pattern of locations I'd guess the abattoir is on the western edge of town (Look back at the previous post).  Can anyone who has been to Adigala tell me where the abattoir is located?  Or can someone tell me what might be so attractive to this vulture out on what I think is called "Mosque Road"?

GPS locations of an Egyptian vulture around the town of Adigala, Ethiopia, August 2013.

Now for a little lesson about the data we get from the transmitter fitted to Assamo...

Two types of locational data are received: GPS and Doppler.  GPS locations are calculated by part of the transmitter on the bird's back.  It "looks" for satellites that are at known positions, then calculates from its position relative to those satellites its own location.  Doppler locations are determined by a series of moving satellites "listening" for a pulse from the transmitter on the bird's back.  Because the locations, paths and velocities of the satellites are known,  the Doppler shift in the pulse's frequency can be used to calculate the likely location of the bird.  The map below shows Doppler data (red) and GPS data (green)

Doppler (red) and GPS (green) locational data for Assamo in early August 2013.

You will notice a few features:  Doppler locations tend to be dispersed over a wider area.  This is because the Doppler system is less accurate than the GPS.  You may then ask: "Why collect the Doppler data?"  Well the main reason in this case is that the pulse used to calculate the Doppler location is also the means by which the GPS data that are held in the transmitter are transmitted to the satellite and on to us.  Using the Doppler system to calculate location also has the advantage of using less power.  While this is not so important when tracking an Egyptian vulture in Ethiopia because the bird is rather large and the transmitter is solar powered, it can make a difference when one is trying to track a smaller bird or using battery power only.  Thus, the really small satellite transmitters used to track things like cuckoos and Amur falcons, etc do not use the GPS system, but rely totally on the Doppler system to calculate bird locations.

Close up of locations around Adigala in early August 2013

The use of the transmitter pulse to transmit GPS data also results in many more GPS locations per Doppler location.  So, in the case of Assamo, a number of GPS locations will be calculated and stored on board the transmitter, then these will be transmitted via satellite to us, and the pulses used to transmit those data will be used to calculate a "Doppler fix".

Adigala

As the previous blog posts have stated, Assamo has spent most of the last month and a half around the Ethiopian town of Adigala.  Here is what Houssein Rayaleh of Djibouti Nature (a conservation NGO) has to say about Adigala:

Adigala is an underveloped large-sized village in eastern Ethiopia close to the border of Djibouti and Somalia; it has no industry. In common with many other important human settlements in the Somali region of Ethiopia, Adigala has no formal waste management system 

Ethnically Adigala’s population and that of the surrounding area is Somali, and are mainly pastoralists who use an open range rearing livestock system.  The lack of a waste management system coupled with the pastoral way of life of the inhabitants means that Adigala  produces large amounts of waste, including waste from its abattoir.

As with many areas in the Somali region of Ethiopia, the area around Adigala is underexplored, though recently petroleum reserves have been proven and prospecting for other mining resources occurs.

The recently constructed electricity transmission line that connects Ethiopia with Djibouti crosses Adigala. Pylons from the source of power to destinations in Djibouti are often used as perch sites for raptors, including Egyptian vultures.  Near villages like Adigala the use of pylons as perches by Egyptian vultures is particularly common.  The pylon design is similar to that found in Djibouti.  Large transmission pylons probably pose little threat of electrocution, but smaller power lines in and around settlements are likely to be more dangerous.

Satellite image of Adigala. Click on the image to enlarge or use the search function in Google Earth to explore more closely.

Assamo in late July 2013

In late July 2013, Assamo really did not move very far.  He spent the whole of the month within < 20 square km around the town of Adigala.  Does anyone know anything about this town? Does anyone visit it?  I suppose Assamo is perching on some power pylons to the north of town.  At some locations we have more than 15 individual fixes for him.  This suggests to me a favorite perch on a specific pylon.

Assamo's movements around the town of Adigala, Ethiopia in late July 2013.

Below is a zoomed out map, which shows just how small the area is that Assamo has been using, and its position relative to regional geography.

Assamo's locations in late July 2013 as seen at a regional scale.

 The Egyptian vulture is a globally endangered species, and huge declines in the population have been seen over the past 50 years or so.  Despite this, and the instances of human related deaths we have talked about in other blog posts, there are some stories of success that give us hope.  Here is a video about the release of a captive bred Egyptian vulture in Italy in 2005, and another release is scheduled for this month.  Good news is always welcome!

Sadly, in South Africa recently almost 50 vultures were found dead.  Click here to find out more.  The cause of death is suspected to be poisoning when they fed on poison-laced sheep carcasses, presumably laid to target jackals.  This incident highlights a number of things: vultures (and other animals) are being poisoned in large numbers, because of their foraging and feeding ecology large numbers of vultures can die at single poisoning events, and the number of adult vultures killed suggest a large impact on the population and its potential productivity because these species are normally long-lived and mature only after a number of years.