Mi­gra­tion and the de­cline of the cuckoo

Geographical - - DOSSIER -

Sav­ing the cuckoo re­quires sci­en­tists to look be­yond the bor­ders of the coun­tries within which it breeds. Breed­ing cuck­oos in the UK have de­clined by 70 per cent over the past 25 years, but only in the past few years, thanks to the ef­forts of the Bri­tish Trust for Or­nithol­ogy (BTO), has it been dis­cov­ered that UK cuck­oos mainly win­ter in and around the Congo rain­for­est and Gabon. The routes they take to reach the Congo are also in­creas­ingly un­der­stood and these high­light some of the threats the birds face. Satel­lite­tagged cuck­oos fol­lowed by BTO re­searchers use two dif­fer­ent routes from the UK to reach their win­ter­ing grounds: one through Spain and a sec­ond through

Italy and the Balkans; all of the birds make their spring re­turn via the western route.

Birds that used the western route through Spain faced higher lev­els of mor­tal­ity dur­ing the au­tumn mi­gra­tion. The BTO be­lieves that cli­mate change and chang­ing land use in south­ern Spain may be hav­ing an im­pact on these birds, re­duc­ing for­ag­ing op­por­tu­ni­ties and the abun­dance of the hairy cater­pil­lars on which they feed. These cater­pil­lars fuel the cuck­oos’ mi­gra­tion and if a bird can’t find suf­fi­cient food in these stopover ar­eas, then cross­ing the Sa­hara be­comes per­ilous.

Land-use pres­sures in sub-Sa­ha­ran Africa are also af­fect­ing the abil­ity of birds to for­age and thrive dur­ing the north­ern win­ter. Pres­sures in­clude the clear­ing of for­est to cre­ate space for oil palm plan­ta­tions. This change in land use ap­pears set to ac­cel­er­ate.

Newspapers in English

Newspapers from UK

© PressReader. All rights reserved.