British cuckoo research news

This video is called BBC Natural World – Cuckoo.

From Wildlife Extra:

BTO cuckoos update

Poor summer and difficult conditions meant very poor survival rates on migration

January 2013. The BTO expanded their cuckoo tracking project in the summer of 2012 to include males from Scotland and Wales to add to the birds they tagged in East Anglia in 2011. They were keen to discover if Scottish birds, numbers of which do not seem to be declining, might have different migratory strategies (which may just be the case -read on!) and to look for east-west differences between Norfolk and Wales.

Cuckoos called BB, Chance, Mungo, Roy and Wallace were tagged in Scotland, whilst David, Indy, Iolo and Lloyd began their journeys south from Wales. John and Reacher joined Chris and Lyster as BTO East Anglian Cuckoos.

Many 2012 birds didn’t survive the migration

Most of the Class of 2012 failed to make it to the African wintering grounds – in complete contrast to the Class of 2011. Hopefully, as BTO analyse this year’s data, and start to add in data from future years, they will better understand the rules of the game of ‘snakes and ladders’ that Cuckoos face each autumn, winter and spring on their 10,000 mile round trips.

Wet summer may have been detrimental

The summer of 2012 was wet – very wet, with a real dearth of insects – and BTO were concerned that migratory birds may be in poor condition when it came time for departure. This was not the last of their problems, however, as the birds fared very badly over the autumn period. We can only speculate as to what proportion of the losses was associated with conditions on the ground in southern Europe and how much due to poor preparations in the UK.

Individual challenges

In 2011 migration was relatively straightforward but in 2012 there were a number of cases where birds returned northwards, presumably because they could not find food. Lloyd sampled sites in north-western and north-eastern Italy as well as in south and southwest France before making it across the Mediterranean, whilst John gave up on Spain and returned to France. We guess that Indy’s u-turn in the middle of the Mediterranean, as he flew back to northern Italy, must have been associated with running out of resources and going back to his last known feeding ground to refuel.

West not best

BTO were surprised when, in 2011, two of the tagged birds successfully used a previously-unknown westerly route through Spain and western Africa. In 2012, no bird that took this option completed the journey; see the map. John died in France, Reacher died in the droughts of Granada (Spain) and Lyster did not manage to complete his journey across the Sahara. Chris who was the only English Cuckoo to take the more easterly route, made it across the desert and south to his wintering area in Congo.

Different routes

It is early days and these are small samples but, looking at the routes taken by East Anglian, Scottish and Welsh birds, there do seem to be some interesting patterns. The only birds using the western route were tagged in England. Scottish and Welsh birds over-flew the southern coast of the Mediterranean in a broad wave, from Tunisia to Egypt, with two birds (and possibly a third) using countries to the east of the Adriatic as stop-overs, whilst Cuckoos tagged in England have crossed from coastal Morocco east through to Libya across the two years. Perhaps the westerly route is good in some years and not in others? Of the five birds to reach the wintering grounds, the two birds from Wales are wintering further east than the remaining English and Scottish birds.

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