Animals

UK’s Migratory Birds Arrive Earlier and Stay Longer Due to Climate Change

Climate change represents both a threat and opportunity for UK birdsWednesday, December 6, 2017

By Kieren Puffet
The common scoter is suffering population decline.

The arrival of birds often marks the start of spring, but it seems that migration to the UK starts earlier these days thanks to climate change. These changes mean migratory birds are arriving in the UK earlier in the spring and leaving later each autumn.

A new report, The State of the UK’s Birds 2017, was produced by a coalition of three NGOs (the Royal Society for the Protection of Birds (RSPB), the British Trust for Ornithology (BTO) and the Wildfowl & Wetlands Trust (WWT)) thanks to a network of volunteer bird counters that help monitor the UK’s bird population.

Migration changes

The swallow, one of the most distinctive feathered visitors to UK thanks to their long tail streamers, is one species that has already adapted its migration behaviour to the new conditions. Its flight from southern Africa each year is changing with the swallow now departing sooner to arrive in the UK some 15 days earlier and start breeding 11 days earlier than it did in the 1950s. Migration back to Africa is also being delayed. Swallows, along with other migratory birds such as garden warblers and whitethroats, are remaining in the UK for longer come autumn with some species delaying heading south up to four weeks.

The Scottish crossbill is in danger of extinction due to climate change.

Risk of extinction

The report highlights not just changes in migration patterns but also changes to the behaviour, distribution and numbers of bird species.

This is particularly noticeable in Scotland, where many of the UK’s rare breeding birds are found. These climatic changes mean some species are declining in numbers and face extinction according to the report’s projections.

Species vulnerable to the new conditions include the Scottish crossbill, the UK’s only endemic bird (ie found nowhere else in the world), which could face extinction if climate changes continue.

Heavy rainfall during the Slavonian grebe's breeding season has seen its numbers decline.

The breeding patterns of birds are also being hit by the change in climatic conditions including for the Slavonian grebe. Weather data reveals that Scotland is on average 11 per cent wetter between 2007 ­– 2016 than 1961 – 1990, and periods of very heavy rainfall during the Slavonian grebe’s breeding season has been shown to lead to smaller populations.

Other species recording declines in population include the dotterel, common scoter, snow bunting and whimbrel, whose UK breeding populations are almost entirely found in Scotland.

The Great Tit now lays its eggs 11 days earlier than 40 years ago, due to warmer temperatures.

Upside for some

It’s not all bad news though. For some species, the UK’s changing conditions have brought advantages. The nuthatch, goldfinch and chiffchaff have all extended their range into Scotland with large increases in the number of birds breeding there, while the cuckoo may have declined overall in the UK by 43 per cent between 1995 and 2015, but over the same period their population has increased by a third in Scotland.

Some of Britain’s most notable garden birds have also been affected by the new climate including the great tit which starts its family sooner by laying eggs 11 days earlier when compared to 40 years ago.

Dr David Douglas, principal conservation scientist at RSPB Scotland said: “The recent research compiled in this report shows that many birds in Scotland are being affected by a changing climate. For some birds, this means they are becoming increasingly vulnerable to UK extinction, including many species where most, if not all, of the breeding population is found in Scotland. Other birds appear to have thrived in this warmer, wetter climate, which has allowed them to expand their range further north.”