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Mare d'oursi with acacia scrub in background Nightingale by Edmund Fellowes Scientists on fieldwork in West Africa Dry Sahelian habitat Turtle Dove by Mike Weston
Out of Africa
Investigating the declines of our migrant birds
Our summer migrant birds face incredible challenges in their daily lives but none more so than their annual journeys to and from Africa. To escape the British winter, migrant birds fly thousands of miles to reach warmer climates, returning again in spring. However numbers of our summer migrants, such as the Cuckoo and Turtle Dove, are declining and we don't know why. Read about the projects
How you can help
Watch clips on the A2B Arrival Calendar

Swiftly disappearing
The arrival of the Swift, reminding us of sweltering summer days, is always a delight. Shooting through our streets and screaming across the sky, around and over our houses, they really do signify that summer is really here. Unfortunately there seem to fewer in our skies year after year.

Swifts by John Black

On early morning walks though cool oak woodland two other summer characters are harder to find. Where's the descending trill of the Wood Warbler and the distinctive song of the Pied Flycatcher?

These are not the only changes that birdwatchers are noticing; about two thirds of all our African migrant species seem to be declining. The Cuckoo and Turtle Dove have now joined other migrants, like the Wood Warbler, as red on the List of Species of Conservation Concern.

Spotted Flycatcher by Edmund Fellowes
Changes between 1994 and 2007
(BBS results)

Where are our summer migrants?
It is hard to know what is happening to our birds to cause these drops in numbers, but
it looks likely that habitat change in Africa (south of the Sahara), caused by changes in land use and land degradation, could play a part. Migrant birds could also be facing hardships on their journeys to and from Africa and in the UK.

Yellow Wagtail by Jill Pakenham

Further research is crucial; without knowing what is causing the declines, how can anything be done to stop them? We have to act now because time is running out. Wood Warbler numbers have dropped by 60% in just 15 years.

The Out of Africa appeal will fund a range of projects in Africa, where our migrants spend the winter, others involving the analysis of data collected by volunteers in the UK and international collaborations that focus on the migratory journeys.

A2B—Africa to Britain

A) Knowledge gaps about wintering grounds
Our knowledge of ecology of migrants in their wintering grounds is extremely poor and severely hampers our ability to explain declines and our ability to conserve this group of species. We lack even basic information about when birds arrive, the habitats they use and how they move around within Africa. Could learning more in Africa help us explain what is happening?

There are striking differences in trends for those migrants wintering in different areas.Those closer to the Sahara are increasing whilst those wintering further south in the rainforests, are generally declining. This could indicate that there is a problem in Africa which is affecting migrant bird populations.



Diagram left shows results from BBS (1994-2007) and the difference in trends for Top Row A) Sand Martin B) Reed WArbler C) Whitethroat D) Chiffchaff and bottom row E) Nightingale F) Wood Warbler G) Spotted Flycatcher and H) Garden Warbler


2) Changing habitats could be having an effect

Habitat in Africa is changing; overgrazing, intensive farming and the consequent degradation of habitat is altering the landscape in areas where we believe migrants winter and stop over. Is this habitat change affecting how much food is available? This is of huge importance both during winter and as they fatten up before starting on their epic journeys back to the UK.
If birds can’t gain enough fat to fuel them for their journeys they may well not make it back to the UK or will arrive in poor condition and delay their breeding attempts. One of the new projects involves tracking Nightingales; once they arrive back this spring and are re-caught, we will be able to download their flight plans and identify the ‘service stations’ they have used whilst on their travels.


Map right shows Spotted Flycatcher migration map from 'Time to Fly' by Jim Flegg

Spotted Flycatcher with young by Edmund Fellowes

B) Nesting problems in the UK
Choosing a time to nest is very important. Resident British birds which winter in the UK have a head start on those that spend the winter elsewhere, as they are able to judge more easily when the warmer weather starts. This judgement is vitally important because, as soon as spring arrives, buds open on plants and trees and insects will start to feed. Birds need to match the rearing of their chicks with the time when insects are readily available.
Migrant birds in Africa must try to judge what the weather is doing back in Britain and time their arrival to coincide with the beginning of spring and the wealth of food - no easy feat! 

Some birds are nesting earlier. For the Cuckoo early nesting of its various hosts species, some of which remained in Britain over the winter, could be a real problem as egg laying needs to be in synchrony with these breeding attempts. If host species nest early and the Cuckoo has not yet completed its journey back from Africa it will miss its chance to plant an egg in the unsuspecting host’s nest.  
With traditional nesting sites disappearing, could some species like the Swift and Swallow, be finding it harder to find suitable spots for their breeding attempts? Data collected here in the UK by volunteers in the BTO Nest Record Scheme and the Ringing Scheme may well give us some clues about whether nesting is taking place earlier, and assess the relative sucess of breeding attempts, in an effort to understand what is happening to these birds in the UK.

  Read about the projects   Find out ways you can help

See BTO Scientists and media personalities including Chris Packham, Miranda Krestovnikoff and Stephen Moss talking about their favourite migrants on the A2B Arrival Calendar.

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Registered Charity Number 216652. This page last updated: 13 May, 2010