Migratory birds including the willow warbler, the plot warbler and the nightingale whitethorn yet halt flying southbound for the wintertime arsenic they walk longer successful their European breeding grounds.
Analysis of much than 50 years of vertebrate records from the Gambia and Gibraltar has recovered that immoderate migratory taxon that transverse the Sahara are spending betwixt 50 and 60 less days connected mean successful Africa each winter.
The study, published successful the diary Global Change Biology, examined changes successful accomplishment and departure dates successful the Gambia and Gibraltar alongside changes successful clime and vegetation.
While it was antecedently thought that birds timed their seasonal migration based connected daylight hours, the investigation suggests that birds are making much nuanced decisions based connected disposable vegetation and climatic changes.
Records from 1964 to 2019 analysed by scientists astatine Durham University recovered that taxon were arriving astatine their wintertime destinations aboriginal successful the autumn than successful the past and besides departing these locations earlier successful the spring, reducing the magnitude of clip spent successful their wintertime homes.
Over a 27-year period, migratory birds including reed warblers, bluish wheatears and communal whitethroats were recovered to summation their clip successful Europe by 16 days connected average.
Lead writer Kieran Lawrence astatine Durham said: “If the trends we person seen successful this survey continue, we whitethorn spot that, successful time, immoderate birds volition walk nary clip astatine each successful sub-Saharan Africa, and alternatively walk the afloat twelvemonth wrong Europe.”
Many of these tiny migratory birds are suffering important declines successful their British populations, with nightingales successful information of extinction and England’s breeding willow warblers down by 45% successful the past 24 years. But populations of chiffchaff, a short-distance migrant that mostly overwinters successful Europe oregon northbound Africa, person accrued by 114% implicit the aforesaid period.
While a simplification successful migration could assistance immoderate taxon survive, Lawrence said determination were wider imaginable implications successful some Europe and Africa. “In Europe, the longer beingness of traditionally migratory birds could pb to accrued contention for autumn/winter nutrient and resources for nonmigratory vertebrate taxon that bash not migrate,” helium said.
“Meanwhile, successful the accepted migration destinations of sub-Saharan Africa, a simplification successful the clip migratory birds walk determination could person implications for ecosystem services specified arsenic insect consumption, effect dispersal and pollination.”
Global heating has already changed immoderate patterns of short-distant migration to Britain, with galore much blackcaps present spending wintertime successful the state alternatively than moving to continental Europe. In Europe, the achromatic stork has reduced its migration to Africa, with galore birds wintering connected the Iberian peninsula alternatively than moving farther south.
Co-author Clive Barlow, a vertebrate adept from the Gambia, said: “It is precise satisfying to spot the constructive mode the Gambian migrant vertebrate records, collected by dedicated ornithologists implicit galore decades, are present being utilized to item the changing migratory patterns of these species. Until the existent research, nary 1 had realised the grade to which migrant birds are spending little of the twelvemonth successful sub-Saharan Africa.”