Habitat preferences of great bustard Otistarda flocks in the arable steppes of central Spain: are potentially suitable areas unoccupied?

Abstract

Summary 1.Great bustards Otis tarda are globally endangered and 50% of the world population now occurs in agro-steppe habitats in Spain. An understanding of the relationship between land use and the species' habitat requirements is necessary to predict the consequences of land-use change on this declining species. 2. A 2-year study of great bustard substrate preferences was conducted in a large region in central Spain where most cereals are still cultivated in a traditional 2-year rotation. 3. Great bustards showed year-round selection of stubble fields, but avoided ploughed and uncultivated areas. Other substrate types were variously selected, avoided or used in proportion to availability depending on season. Patterns were consistent over 2 years. 4. Human artefacts such as roads, tracks and powerlines were avoided. 5. Variables correlating with flock locations could not discriminate between occupied and unoccupied but apparently suitable areas of traditionally managed cereal steppe. This suggests that great bustard distribution in central Spain is not limited by inappropriate land use in steppe areas. 6. The evidence suggests that great bustards show fidelity to sites regardless of the availability of suitable habitat elsewhere. Settlement patterns are probably determined by the presence of conspecifics rather than habitat cues. This result demonstrates the value of integrating observations of habitat use with knowledge of species' behaviour in order to understand distribution more fully. 7. We propose that conservation efforts should be directed towards securing traditional lek sites and we make three recommendations: first all great bustard lek sites should be identified; secondly, existing European Union legislation should be used to protect these and to ensure that compatible land management practices are applied or maintained; and finally, research programmes should be conducted that aim to enhance the conservation value of stubble fields rather than simply demonstrate their selection.

The benefits of extensive agriculture to birds: the case of the little bustard

“…There are extensive agricultural landscapes similar to the Crau in several regions of Spain and Portugal where many lowland grassland birds with unfavourable conservation status are still abundant (De Juana & Martínez 1996;Delgado & Moreira 2000;Lane, Alonso & Martín 2001). However, irrigation schemes in these regions are currently reducing the availability of extensive agricultural habitats (Donazar, Negro & Hiraldo 1993;Bignal & McCracken 1996), affecting many grassland species (Suárez, Naveso & De Juana 1997;Lane, Alonso & Martín 2001) including little bustards (De Juana & Martínez 1996).…”

“…However, irrigation schemes in these regions are currently reducing the availability of extensive agricultural habitats (Donazar, Negro & Hiraldo 1993;Bignal & McCracken 1996), affecting many grassland species (Suárez, Naveso & De Juana 1997;Lane, Alonso & Martín 2001) including little bustards (De Juana & Martínez 1996).…”

Density and habitat preferences of male little bustard across contrasting agro-pastoral landscapes in Sardinia (Italy)

“…We also compared density estimates for displaying males among three contrasting landscapes of western Sardinia that differ in land-use composition and structure, recent land-use trends and disturbance levels. From available knowledge of habitat preference of the species, we predicted that males' occurrence would be determined by both large-scale landscape features and small-scale habitat characteristics, with densities higher in the landscape with a balance of pasture and cropland cover and low disturbance levels (Lane et al 2001;Suarez-Seoane et al 2002), and predicted lower densities in the more homogeneous landscapes exposed to greater levels of disturbance.…”

Habitat- and density-dependent demography of a colonial raptor in Mediterranean agro-ecosystems

“…It has been suggested that avian species breeding in pseudo-steppes and aggregating in breeding colonies would suffer the most from the current intensification of farming practices (Lane et al, 2001;Catry et al, 2012). The causal link between the decline of such avian species and agricultural changes has been proposed to operate via density-dependent mechanisms, where colony size plays a crucial role (Rodrıguez et al, 2006).…”