!"#$% &'(% )*"#+(% "#$% ,-+."#/% 0-.$'% -#% /*(% '"*(!1% !"#"$!%&' (!)"*' + Migrant t 5IF4BIFMJTBOJNQPSUBOUGPSUSBOT4BIBSBONJHSBOUCJSETJOUIF &VSPQFBOXJOUFS.BOZPGUIFTFTQFDJFTBSFJOEFDMJOF and t *OUIF4BIFM CJSETPDDVSPOMBOEJOUFOTJWFMZVTFEGBSNMBOET  HSBTTMBOETBOEXPPEMBOET t -BOEVTFJOUIF4BIFMJTDIBOHJOHJOSFTQPOTFUPBXJEFSBOHFPG Environmental TPDJBM FDPOPNJDBOEFOWJSPONFOUBMGBDUPST t 5IFNPTUJNQPSUBOUMBOEVTFDIBOHFTGPSCJSETJOWPMWFDIBOHFT JOUIFFYUFOUPGUSFFTBOETDSVCJOSVSBMMBOETDBQFT5IFJNQBDUT Change in PGMBOETDBQFDIBOHFNBZCFQPTJUJWFPSOFHBUJWFGPSEJòFSFOU TQFDJFT t .PSFSFTFBSDIJTOFFEFEPOUIFJNQBDUTPGMBOEVTFDIBOHFPO the NJHSBOUCJSETJOUIF4BIFM Sahel Over 2 billion songbirds migrate between Europe and Africa1, many concentrating south of the Sahara in the farming and grazing lands of the semi-arid Sahel zone. Migrant birds are exposed to threats in breeding grounds in Europe, on migration, and in their wintering grounds in . Many trans-Saharan migrants are falling in numbers2. It is not know why, but it is widely believed that changes in non-breeding and staging areas in Africa are important.

The Sahel is subject to pressure from human-in!uenced climate change and increasingly intensive economic exploitation. There is still limited understanding of the implications of present and future land use change in the Loss of trees and scrub will impact even open country such as (© Paul Hilllion) Sahel for African-Eurasian migrant birds3. Land Use Change in the Sahel There have been profound changes in land use in the Climatic Variability and Birds Sahel in the last four decades. As farmers, livestock keepers It is beyond doubt that Sahel rainfall has a major impact on and other landholders have responded to drought and migrant numbers. Rainfall in the Sahel is 200-600mm economic and social change8. per year, and is highly variable between years. There was t Agriculture has extended onto previously uncultivated an intense drought from 1968-74, and another in the early land, and become more intensive (with shorter fallow 1980s. Birds arrive in the Sahel at the end of the wet season periods, and increased use of pesticides and irrigation). (July-September), and stay though the ensuing dry season, t Areas of dryland forest have been more intensively in increasingly dry conditions. cut for fuelwood and livestock browse, and forest and grazing reserves have been subject to more intensive Numbers of Common Whitethroats in Europe declined use (both legal and illegal). markedly in the 1970s4. Rainfall in the Sahel has been t Livestock management has evolved, with changes in linked to survival or change in population size for at least cattle ownership, in movements by pastoral people 13 migrant species, including both birds that overwinter in between ecological zones and across borders, and the Sahel but also others such as Nightingale, Swallow and because of agricultural expansion. White Stork that pass through to winter further south5. t The extent of Sahelian wetlands has been reduced by the construction of upstream dams for hydro Land Use Change and Birds power and irrigation. There is less certainty about the impacts of land use change on birds, although bird researchers have suggested that Changes to Bird Habitat land use changes have had important impacts on migrant Analysis of the habitat preferences of 68 Sahel migrant birds, for example in woodlands and wetlands6. A series of birds suggests that the most signi"cant changes in habitat workshops were held in Cambridge in 2010 to explore the are: the amount of closed woodland, the amount of woody impacts and causes of habitat change in the Sahel7. scrub, the density of trees and scrub on open land and the !"#$% &'(% )*"#+(% "#$% ,-+."#/% 0-.$'% -#% /*(% '"*(!1% !"#"$!%&' (!)"*' +

Table 1 - Negative Impacts of Habitat Change on Migrant Birds in the Sahel Habitat Trend Examples of negatively Examples of positively a!ected a!ected bird species bird species Amount of closed woodland More closed European Nightjar, Spotted Golden Oriole, Blackcap, Pied woodland Flycatcher, Common Rock Thrush Flycatcher, Common Nightingale Less woodland Common Redstart, Olivaceous Lesser Kestrel, Common Quail, Warbler Tawny Pipit, Stone-curlew Tree density in woodland Lower tree density Common Redstart, Olivaceous European Nightjar, Lesser Warbler Whitethroat, Spotted Flycatcher Amount of woody scrub More woody scrub Lesser Kestrel, Egyptian Vulture, Common Whitethroat, Willow Ortolan , Common Quail Warbler, Less woody scrub European Nightjar, Spotted Black Kite, Montagu’s Harrier, Flycatcher, European Bee-eater Northern Wheatear, White Stork Density of trees and scrub on Increased tree density Lesser Kestrel, Egyptian Vulture, Black Kite, European Turtle Dove, open land Greater Short-toed lark Northern Wheatear, White Stork Reduced tree density Black Kite, European Turtle Dove, Lesser Kestrel, Stone-curlew, Northern Wheatear, White Stork Common Quail, Egyptian Vulture Structural and !oristic diversity More structural and Northern Wheatear, Tawny Pipit, Common Whitethroat, Tree Pipit, of vegetation on open land !oristic diversity Stone-curlew European Turtle Dove

structural diversity of vegetation on open land9. 1 Hahn, S. et al. (2009) The natural link between Europe and Africa – 2.1 billion birds on migration’, Oikos 118, 624-626 All these changes are a#ected by the way farmers and other 2 Sanderson, F.J. et al. (2006) ‘Long-term population declines in Afro- resource users make their living (planting crops, grazing Palearctic migrant birds’ Biological Conservation 131: 93-105. livestock or cutting trees). Impacts may be negative for 3 The brief draws on a systematic review of published papers on birds some species, but positive for others. Examples of species in the Sahel, Small, R. et al. (in prep.) ‘Knowledge of the Impact of a#ected by the most important changes in habitats are Land use Change on Migrant Birds in the Sahel’. shown in Table 110. 4 Winstanley, D. et al. (1974) ‘Where have all the Whitethroats gone?’ Bird Study, 21 1-14; Peach, W. et al. (1991) ‘Survival of British Sedge Conclusions Warblers Acrocephalus schoenobaenus in relation to west African The impacts of environmental change in the Sahel on rainfall’, Ibis, 133: 300-305. birds are inadequately understood. Local land use change 5 See e.g. Berthold, P. (1973) ‘On the severe decline of populations of is linked to climatic variability, since the decisions of the Whitethroat and other song birds in Western Europe. Journal of rural people about land use re!ect their need to survive Ornithology’, 114: 348-360. economically in periods of drought. Sahelian rainfall is 6 Wilson, J.M. & Cresswell, W. (2006) ‘How robust are Palearctic mi- naturally highly variable, but human impacts on climate are grants to habitat loss and degradation in the Sahel?’ Ibis 148: 789- likely to increase this variability and have negative impacts 800; Cresswell, W.R.L. et al. (2007) ‘Changes in densities of Sahelian on both people and birds. bird species in response to recent habitat degradation’. Ostrich 78: 247-253; Roux, F. & Jarry, G. (1984) ‘Numbers, composition and dis- The implications of land use change for migrant birds are tribution of populations of Anatidae wintering in West Africa’, Wild- complex. Change may bene"t some species and harm fowl,35: 48-60. others. Reductions in European breeding numbers in some 7 Land Use Change and Migrant Birds in the Sahel (2011) Research species suggest that on balance changes are negative, but the balance of winners and losers is not well understood. Brief 4, Drivers of Land Use Change and Migrant Birds in the Sahel. 8 Raynaut, C. (1998) Societies and Nature in the Sahel, Routledge, There is an urgent need for more "eld research on migrant London; Mortimore, M. (1998) Roots in the African Dust: sustaining birds (particularly declining species) in the Sahel. Research the subSaharan drylands, Cambridge University Press, Cambridge. 9 must integrate an understanding of which birds use what Land Use Change and Migrant Birds in the Sahel (2011) Research habitats (and when), and how these habitats "t into the Brief 2, Key Habitats for Declining Migrant Birds in the West African farming and livestock economies of Sahelian people. Sahel. Farmland birds of the Sahel need the same careful study as 10 All species are listed as SPECC level 2 or 3 (http://www.birdlife.org/ those breeding in the subsidized countrysides of Europe. action/science/species/birds_in_europe/index.html).

These Research Briefs are an output of the project ‘Reversing the declines of African-Palaearctic migrants: understanding the social and economic factors driving land use change in sub-Saharan West African wintering areas’, funded by the CCI Fund and the Newton Trust. Project partners were the British Trust for Ornithology, the Royal Society for the Protection of Birds, and the Departments of Geography and Zoology, University of Cambridge. http://www.geog.cam.ac.uk/research/projects/landusemigrantbirds/