First excursions by Sheba!

The latest map of locations of the two juveniles fitted with satellite transmitters is above. The yellow track is Sheba's, the second juvenile we tagged on Fahal. There are two "high quality" locations marked on the map, indication that just today Sheba went on her first short excursions over the sea!... maybe her first attempt at hunting together with adult falcons. Sinbad still stays around Fahal; he seems to like the security of having terra firma underneath his wings, but he is also making short excursions around Fahal. Soon there might be the first locations on their way to Africa...

Sinbad and Sheba probably recently fledged

Latest map for Sinbad (red) and Sheba (yellow). Compared to the old maps, there are more precise locations deriving from Fahal indicating that the birds still stay on the island. The increase in locations on Fahal is due to the quality of data we receive now, as the birds are very probably more exposed to sunlight these days or are already flying short distances. This increases the battery power which in turn leads to a higher data quality.

First Locations for Sinbad and Sheba, 11 Oct 2010

Well, here are the first locations received from Sheba. Don't be deceived by the locations being out over the sea and on the mainland, Sheba has most certainly not left Fahal yet. However, this map shows characteristics of the data we will be receiving from both Sheba and Sinbad when they do leave, and so you might as well learn a bit about satellite tracking before they start to migrate.

The first thing to note is that the locations given are not GPS locations and are not as accurate as GPS locations. The locations are estimates made from the Argos System of satellites that are orbiting the earth from pole to pole. These satellites listen for the transmission from the radiotag (signal is a fixed frequency) and then calculate the location using the Doppler shift in the frequency. The accuracy of the location estimates depend upon the quality of the transmission heard by the satellite and the number of times the satellite hears the transmitter before disappearing over the horizon. In the best cases, accuracy is within 150 m, but in poor situations the location estimate may be out by a couple of km. In the map you can see the "spread" of locations, but like I said, Sheba is probably sitting tight on Fahal

Actually, that is just the short version of what is really happening. If you really want to know then ask your questions by sending us a comment, and one of us will try to answer them.

You may be asking: Why, if GPS is more accurate, aren't these tags GPS transmitters? The simple answer to that is that GPS transmitters are too heavy. Obviously, a bird that has to fly needs to carry a light transmitter that will not potentially impede its flight. The smallest satellite radio tags are Argos tags (the ones we are using weigh 9.5 g), and the smallest satellite GPS tags are over 20 g. If we had fitted tiny Sinbad or Sheba with a tag > 20 g, then they might have had a hard time flying, which would have affected hunting and migration.

The picture above is the map for Sinbad, and if those locations were 100% accurate then Sinbad would have been flying over Faisal's house!... Trust me. He hasn't...yet!

A few more points for you to consider or remember for later when you look at maps...

• The bare rock of Fahal is probably negatively affecting the signal by reflecting it .

• Error is greater from east to west than north to south

The transmitters and accuracy of tracking

The transmitter itself is quite small (9.5 g) and is fitted like a backpack using Teflon ribbon (because it is very smooth and does not degrade). These tags are solar powered. The picture to the right is of Sheeba wearing her satellite tag. Marion is just preparing to finish the harness by crimping the metal clamp and cutting off the excess harness material.

The need for a very small transmitter means we can not use the GPS system of satellites to determine the location of the bird, and so location accuracy is not as good as GPS. In the best cases the accuracy is within a few hundred metres, although sometimes locations are a couple of km out. The map above is for Sinbad during 2-6 October. Sinbad has probably not yet left the nest as is certainly not flying, though he may have stood out from under the roof of the nest. Although the potential inaccuracies seem like a lot, they aren't really that great when you think of the scale at which we will be working during the year. These birds (if they and their transmitters survive) will be tracked to their wintering grounds (probably) on Madagascar, and then as they move around and perhaps settle as breeders over the next few years.

Introducing the project and the birds

This is a blog where we will be posting maps of two nestling sooty falcons that we fitted with satellite received transmitters (PTTs) in Oman in 2010. The satellite tracking is part of a larger effort that has been running for 4 years on Oman. The goals of that effort were to:

• better understand the status of sooty falcon in Oman;
• better understand the ecology of sooty falcons in Oman;
• establish a monitoring scheme for sooty falcons in Oman;
  
• provide training opportunities to Omanis and others to enhance local capacity.

The four-year field work has been made possible through contributions by Natural Research, Ltd, ministries and agencies of the Oman government, Petroleum Development Oman, the Ford Foundation, Sultan Qaboos University, and the Environment Society of Oman.

The satellite radio tracking project is a joint effort of Natural Research Ltd. and global concepts for conservation. The project was financially supported by Microwave Telemetry Inc., University of Ulm, global concepts for conservation and Natural Research Ltd. Permissions were granted by ministries and agencies of the Oman government.

On 2 and 3 October 2010 we fitted satellite transmitters to two near-fledging sooty falcons on Fahal Island, Oman. At this very moment the birds are still in their nest sites, which are roofed ledges. This means that currently no satellite signals are being heard and so we have no maps to show. When fitting the birds with the transmitters we named the birds "Sinbad" and "Sheba". It must be said that one can not be 100% sure of the sex of the birds, so we don't know whether Sinbad is a male and Sheba is a girl.

Sinbad

Sinbad was fitted with a satellite transmitter on 2 October. His tag ID number is 94498. Sinbad is the offspring of a female sooty falcon that has nested in this territory on Fahal Island for at least the past three years. Sinbad had one sibling. The picture to the right is of Sinbad hiding behind his sibling, who seems to be giving us a piece of her mind. You can see on both birds the metal numbered ring and the green plastic microchip ring that allow us to identify these birds in the future. Such marking is an important tool in understanding longevity, migration routes, and details of the population including whether or not it is stable.

Sheeba

Sheeba was fitted with a satellite transmitter on 3 October on Fahal Island. Her tag ID is 94499. Sheeba has a single sibling. Sheeba's mother is a third year bird that bred for the first time in 2010, and who was reared as a chick on Fahal. The picture to the right is Sheeba's mother. You can see that this bird is not very old because it still has a "moustache" (dark areas under the eyes), and a light coloured chin.

Despite their names, we don't really know the sex of these birds. Currently there is no way we can distinguish the two sexes, but maybe after some more research we will find a way. Of course we may find out someday if we find them breeding.