Climate change forces birds to rethink migration patterns

Delhi witnessed its warmest winter in 2015 in several years and the impact of global warming could also be seen on the biodiversity in south Delhi. The influence of the seasonal shift is such that the birds whose breeding calls were earlier heard in the month of March were heard in January end this year. Also, migratory birds that earlier came to Delhi in summer have already arrived in winter. For example, Indian courser can already be seen in Sultanpur.

“Brown headed barbets, coppersmith barbet, common hawk cuckoo, Asian koel have started marking their territory, making courtship calls and some have even started nesting which is very interesting to note. Birds like ruffs and purple sunbirds have started showing signs of breeding at least three weeks before than they generally do, said environmentalist Surya Prakash .

“These birds are already showing signs of breeding like moulting at least three-four weeks earlier than usual,” he said.

Many waders and waterfowls have started preparing for reverse migration though there might be other factors adversely affecting the behaviour of birds like rapid urbanisation and habitat loss, but we can’t rule out climate change for the pattern, said Prakash.

Some of the migratory birds that come from central Asia in winter and go back when the temperature goes up here are already flying back to their territory due to warm conditions that Delhi witnessed this year. Birds green sandpiper, northern shovellers showed this trend, he added. M Shah Hussain, scientist in charge at Aravalli Biodiversity Park, said, “The impact of climate change is not the only factor responsible for the changed behaviour, but other factors like urbanisation and destruction of habitat are also behind the climatic shift.”