Updates from our Cuckoos

In 2017, we have been trialling the very latest satellite tracking technology - this year’s cohort were tagged with 2g tags from Microwave Telemetry.

We have, unfortunately, ‘lost’ contact with most of them already. It would seem that the smaller size of the new tag allows the solar panel, used to recharge the tiny battery, to become shaded by feathers, resulting in much less efficient charging of the battery, and consequently lower contact with the tag. Although some may have died, the lack of transmissions from the tags makes it impossible to assess this and in all cases, there were no indications that the birds were in trouble when we last heard from their tags.

This is exacerbated during the winter months by the birds spending more time under the canopy in the Congo rainforest. We don’t know how the batteries will fare when the birds begin their northward migration back to the UK. On leaving the rainforest the tags should receive more sunlight which might be enough to overcome feather shading, and if this happens some of the ‘lost birds’ could pop-up again in February or March, but it is possible that the prolonged shading will have caused irreversible damage to the much smaller batteries in the 2g model. We all have our fingers crossed.

As we move forward we are continuously looking for effective ways to continue gathering this important data for Cuckoos, and other species, to benefit our knowledge and ultimately wildlife conservation. We hope that next year we will be able to track a cohort of cuckoos without these issues arising. 

The last signal we received from Carlton was on June 9 when everything appeared fine with both him and the tag's battery, however, there have been no transmissions since.

We're aware that increased feather coverage, due to the smaller size of the solar panel, means we are getting fewer signals from some of the new tags but we're concerned that we've had nothing for two months. Carlton should have been moving around and thus the tag would have been exposed to daylight during this time. It may be that something has happened to either Carlton, such as predation, or to his tag in this period. The tag's battery can degrade if they don't receive enough light and are then unable to switch back on.

We really don't know what has happened at the moment but we hope he may surprise us and pop up again in a new location in the next few weeks when we would have expected him to have left the country.