Just a quick update on Einion. We're a little bit worried about some of the latest data coming through for him. The transmissions have been getting weaker since July 16th and no GPS points (the points you see on Google Earth) have been sent since July 22nd.

An in-depth look at his electronic data shows that from around July 15th onwards, his battery voltage has decreased sharply. It should be around 3.9 to 4.0 Volts. Below around 3.7V and the signals get weaker and sometimes impossible to interpret.

Lack of solar energy would explain a drop in voltage, but looking at the weather over in Senegal where he is, it's been partially sunny most days. Maybe feathers moulting through have obscured the little solar panel?

On the positive side, up to the last, GPS point sent July 22nd his movements look normal so it seems that the voltage drain is happening whilst Einion is behaving and moving normally. His next data download is due this Tuesday, July 31st. Fingers crossed.

UPDATE July 31st. 20:00. We've just received the latest batch of data from Einion and it's pretty much more of the same. The battery voltage has been as low as 3.3 but is now fluctuating between 3.5 and 3.6. The problem is, at these low voltage levels, the transmitter doesn't send any GPS points.

The activity readings are changing; however, indicating that the transmitter is moving but to be honest, at these low battery levels, it's hard to know which bits of the data are authentic and which are not. The solar panel on the tracker is receiving sunlight, there's no doubt of that, but not enough to transmit robust signals. We need a battery voltage of around 3.7 and over.

This is just my personal take on it.. I'm keeping positive. Einion's mantle (back) feathers will be moulting at around this time and he'll grow new adult feathers. If one or a few of these feathers are blocking the solar panel, then the behaviour of the data is consistent with this. And remember, the tracker started to lose voltage from July 15th onwards and Einion's data is completely normal for a week after this, meaning, Einion was seemingly fine whilst the tracker started to lose power. The next data download is due August 4th. Thinking positive.

UPDATE August 13th. We have not received any data from Einion's tracker at all since August 4th. We should have received downloads on August 8th and 12th.

It looks like his tracker is not receiving enough sunlight to power up properly and transmit signals back. We have seen this happen in other ospreys (and other species) only for the tracker to burst back into like once it is exposed to sunlight again. We obviously hope this is the case for Einion. We continue to remain positive. Remember, Einion was moving and behaving normally for the first week that the tracker started to lose electrical power, suggesting it is a power problem and not something more serious. Chin up.

UPDATE - August 24th. Still nothing from Einion's tracker but our friend Martyn who lives around 150 miles away from where Einion has been for the last few months, has been to look for him.

Nothing decisive, the ospreys there are in a sparsely populated area and take off readily as you approach them. Martyn did see "at least four ospreys, probably more". This is good news on two counts. Clearly, the area Einion is in is a good spot for ospreys but also, one of these birds may actually have been Einion. Remember that the vast majority of ospreys that wintered in this area will now be in Europe, so there are only one year old ospreys left. Statistically then, this results in a higher probability that one of the four birds Martyn saw was Einion as opposed to, say, in another month's time when the place will be awash with ospreys again.

Many thanks Martyn for taking the time to go looking for Einion on your week off and reporting your sightings back.