Studies of West Palearctic birds: Turtle Dove Stephen Browne and Nicholas Aebischer Ray Scally ABSTRACT The Turtle Dove Streptopelia turtur has declined, in terms of both range and abundance, throughout much of northern Europe over the last 30 years. Until recently, the species was relatively poorly studied in the modern agricultural landscape in Britain. Concerns over its conservation status prompted an intensive research programme to gather information on its breeding ecology, identify the causes of the recent decline and make recommendations to aid its recovery and conservation.Turtle Doves require tall, overgrown bushes for nesting and short weed-rich areas for feeding, but agricultural intensification has markedly reduced the availability and suitability of these habitats. Over the last 40 years,Turtle Doves have switched from foraging in ‘natural habitats’ to those created by humans, and their diet is now primarily seeds from cultivated plants.The number of chicks fledged per pair per year is today almost half that in the 1960s, while autumn migration has become significantly earlier. Many management options to help to conserve the species can be achieved within the current UK agri-environment policy framework. 58 © British Birds 98 • February 2005 • 58-72 Studies of West Palearctic birds: Turtle Dove he Turtle Dove Streptopelia turtur is a throughout Europe prompted The Game Con- summer migrant to Britain and Europe, servancy Trust, with support from English Tbut perhaps most people in Britain Nature and the World Wide Fund for Nature would associate the bird with the second day of (UK), to establish a dedicated research pro- Christmas rather than high summer, thanks to gramme focused on the species’ breeding the popular carol The Twelve Days of Christmas. ecology. In this paper, we outline the biology of This subversive, pro-Catholic hymn was sup- the species based on the results of a number of posedly written at a time when it was illegal to studies undertaken across Europe. We also make direct reference to Catholicism, and the present the findings and recommendations of ‘two Turtle Doves’ are thought to represent the our intensive four-year study, undertaken Old and New Testaments. Historically, human between 1998 and 2001, to show how the interest in the Turtle Dove was associated with breeding biology of the species has changed the bird’s faithfulness, and because it was an over the last 40 years. emblem of hope and peace. The writings of Saint Jerome (c. AD 320-420) and of Alain of Range and distribution Lille, in his twelfth-century work The Complaint The Turtle Dove is a small, slim member of the of Nature, state that a Turtle Dove would not Columbidae, with a thin neck, a protruding seek another mate should its original partner head and deep chest, giving it a pigeon-like die. Indeed, it was thought that if a Turtle Dove form, but with a long, wedge-shaped tail and lost its mate then it too would soon die. It was swept-back wings. The sexes are broadly similar, not until the eighteenth century that the species but females are slightly smaller than males and became more noted for its migratory abilities, somewhat less brightly coloured. Four races of being referred to in at least two of Gilbert Turtle Doves occur in the Western Palearctic, White’s letters. Today, however, most bird- with nominate turtur found throughout much watchers in southeast England and much of of Europe and western Asia. Slightly smaller Europe would associate its purring calls with and paler, with more white on the belly, S. t. warm summer evenings, rather than love or arenicola occurs across North Africa (including peace. In recent years, the calls of this small, the Balearics) and into the Middle East. The attractive and once-common dove have been two remaining races are much more restricted heard less frequently and its population decline geographically, with S. t. hoggara (also smaller and range contraction in Britain and and paler than nominate turtur, with broader Gordon LangsburyGordon 23. Turtle Dove Streptopelia turtur,Austria, May. British Birds 98 • February 2005 • 58-72 59 Studies of West Palearctic birds: Turtle Dove 2 1.5 1 CBC Index 0.5 0 63 65 67 69 71 73 75 77 79 81 83 85 87 89 91 93 95 97 99 Fig. 1. Index of abundance of Turtle Doves Streptopelia turtur in Britain from 1963 to 1998, derived from BTO Common Birds Census data.The index (solid line) and the 95% confidence limits (dashed lines) are shown. edging on the wing-coverts and on the tail) loway 1997). Some local declines were apparent inhabiting the central Saharan mountains, and from the 1950s (Goodwin 1989), but trends S. t. rufescens (more distinct than the other from census work suggest that the period of races, being smaller and more richly rufous- general increase lasted until about 1978/79 coloured) in Egypt and northern Sudan (Marchant et al. 1990). A few local studies (Cramp 1985; Gibbs et al. 2001). Both turtur showed that numbers of Turtle Doves fluctu- and arenicola are true migrants, spending the ated in a pattern similar to the national trend winter (late October to late March) chiefly in (Hongell & Saari 1983; Miller 1992). From the the Sahel region of Africa, roughly between late 1970s, however, a sustained decline in the 10°N and 20°N. The other two races are breeding population in Britain became thought to be sedentary or undertake only apparent, and this continues today (Baillie et al. small migratory movements (Cramp 1985). 2002) (fig. 1). The decline has been so severe In the breeding season (early May to mid that the majority of the British population is August), the range of turtur extends from the now restricted to southern and eastern counties Mediterranean to all but the most northern of England and, by extrapolation from the areas of Europe. In Britain, at the northwest 1988-91 census and subsequent rates of decline, edge of the species’ breeding range, it is a probably numbered only about 30,000 pairs in lowland bird, favouring warm, dry conditions 2001. These population trends are of such and avoiding the higher ground and rainfall of concern that Turtle Dove is now recognised as a the west and north (Gibbons et al. 1993). Con- ‘Red List’ species of conservation concern in the sequently, Turtle Doves are concentrated in the UK (Gregory et al. 2002), and the UK Govern- most intensively farmed, and now predomi- ment has placed it on the list of priority species nantly arable, areas of Britain. considered by the UK Biodiversity Action Plan. One of the recommendations of the UK Species Population trends in Britain and Europe Action Plan for the Turtle Dove is to undertake Survey and census work organised by the BTO an autecological research project to identify the suggests that numbers of Turtle Doves in cause of the recent decline, in order to form a Britain declined by 70% between 1968 and 1999 recovery plan (Anon 1998). (Baillie et al. 2002), with a 25% contraction in This pattern of range expansion followed by range between the 1968-1972 and 1988-1991 recent decline has been repeated elsewhere in breeding Atlases (Gibbons et al. 1993). This Europe, with evidence of local downturns being sharp decline commenced in 1979, following a noted from the 1950s onwards (Holzwarth lengthy period of apparent increase and range 1971; Kraus et al. 1972; Cederwell 1978; expansion from at least the mid nineteenth Hongell & Saari 1983; Bijlsma 1985; Yeatman- century (Spencer 1965; Duckworth 1992; Hol- Berthelot & Jarry 1995). Although census and 60 British Birds 98 • February 2005 • 58-72 Studies of West Palearctic birds: Turtle Dove migration data are often rudimentary or non- (Nankinov 1994a, Nankinov 1994b), (the existent, it is believed that, on a European scale, former) Czechoslovakia (Pikula & Beklova the decline of the Turtle Dove occurred from 1984), France (Genard 1989), Germany the mid 1980s onwards, particularly in western (Holzwarth 1971; Kraus et al. 1972), The Europe (Tucker & Heath 1994; Heath et al. Netherlands (Bijlsma 1985), Portugal (Dias & 2000). Turtle Dove is now a Category 3 species Fontoura 1996; Dias et al. 1996), Spain (Peiró of European conservation concern (SPECs): a 1990), Sweden (Cederwell 1978), and in the ‘species whose global populations are not con- southern Urals (Kotov 1974). Other studies centrated in Europe, but have an Unfavourable have looked at specific aspects of Turtle Dove Conservation Status in Europe’ (Heath et al. biology, including diet (Garzón 1974; Kiss et al. 2000). 1978; Jimenez et al. 1992; Dias & Fontoura 1996) and habitat requirements (Aubineau & Previous research on the Turtle Dove Boutin 1998). Turtle Dove migration was docu- Until recently, the only major ecological study mented by, for example, Ash 1956, Rappe 1965, of the Turtle Dove in Britain was completed in Marchant 1969, Bourne & Beaman 1980, the early 1960s (Murton et al. 1964; Murton Mountfort 1981, Genard 1989, Nankinov 1994b 1968). In 1996, a pilot study was undertaken (by and Aebischer 2002, and the biology of the The Game Conservancy Trust, funded by species on its wintering grounds in Africa by English Nature) to collect basic information on Morel & Morel 1979, Morel 1985 and Morel the ecology of the Turtle Dove and to test the 1987. methodology for a more detailed study (Calla- dine et al. 1997). The factors causing its recent Migration decline, in a modern agricultural environment The Turtle Dove is the only British member of which has changed considerably since the 1960s the pigeon family to undertake a long-distance (Grigg 1989), and the stages of its life history at migration, travelling up to 4,000 km twice a which those factors operate, were therefore year between breeding and wintering grounds.