Monday, 22 August 2016



Geolocators are supplying precious data on the migration of cuckoos
THE focus fell on the cuckoo when BTO president Dr Andy Clements gave an information-packed talk on migration.

The first ringing recovery of the rapidly-declining species was in 1930 of a bird that turned up in a cooking pot in the Cameroon having been ringed 18 months earlier in Eton, Berkshire.

Ringing recoveries are, of course, few and far between and, though still of value, the technique hardly compares with the latest technology.

Geolocators, sometimes as small as shirt buttons, are now routinely attached to birds such as cuckoos and swifts in order  to track their international travels.

As a result of climate change, many migrants are now arriving a week or two earlier than in the past (three weeks in the case of sand martins).

However, there has been barely any change in arrival times for Cuculus canorus and Apus apus.

It seems both species fly north-west to West Africa from their wintering grounds in the Congo, then put their migration on hold until heavy rainfall prompts a burst of insect-hatching activity to provide sustenance in advance of their long flights over the arid sands of the Sahara, thence to Europe.

These rainfall events do not seem to have been affected by climate change - hence, according to some scientists, the continuing constancy of the arrival times of both  species in the UK.

Andy Clements - secrets of migration 

But is that a meaningful piece of data? Is the interpretation necessarily valid?

Swifts are far faster fliers than cuckoos, so why do they arrive here so much later - two weeks  or more?

Continuing, the BTO boss noted that a typical cuckoo only spends 15 per cent of its time in the UK - compared with 47 per cent in the Congo and 38 per cent in the process of migrating.

Dr Clements said it was important that the BTO’s data was made accessible to both birders and non-birders.

For this reason, cuckoos fitted with geolocators have been given individual names - for instance, one has been named “Chris” after Chris Packham, the broadcaster who is also BTO president.

Maybe, Packham is not the greatest of household names - would Madonna or Rooney  have been better choices?

But the idea is sound enough, and the initiative was sufficient to have garnered some headlines from the BBC and other media outlets.

“It’s really important to have  stories that resonate with the public,” he said.

Dr Clements ended with a reference to a headline to a feature  in The Independent newspaper about how the cuckoo’s springtime  migration was being tracked:

It read: “Now we can see spring coming from 4000 miles away.”

More fascinating  information on cuckoos, other species and the work of the BTO 
 * Cuckoo photo: Vogelartinfo/Wikimedia Commons

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