How do global warming and climate change affect birds?

A good example is the study of great tits (Parus major) in Europe. These birds reproduce when caterpillars come out in spring when the buds burst out. The caterpillars gorge on the new leaves, great tits pick up the caterpillars to feed the nestlings. This maintains the bird’s survival rates.

Bird reproduction takes place just when the caterpillars are in abundance before they form their cocoons. Warmer temperatures have led to caterpillars emerging sooner. The birds lay eggs too late, and the caterpillars are gone. The cues the birds use to reproduce are not matching up with the peak prey availability. This can reduce the number of eggs they lay.

Pied flycatchers (Ficedula hypoleuca) spend the winter in tropical Africa before migrating to Europe in the spring to breed, They use day-length change in their wintering grounds as a cue for migration. But prey availability is based on temperature, and due to climate change, it starts earlier in the year. The birds do not arrive at breeding grounds in time to take advantage of peak prey. See the mismatch? The fly-catcher population has declined more than 90% in some areas.

The snow bunting is adapted to very specific mountain habitats. When climate changes, they cannot find food. The ranges of boreal birds in Northern Europe are predicted to decrease by more than 73% over the next century.

 

Picture Credit : Google