Fallow management for steppe bird conservation: the impact of cultural practices on vegetation structure and food resources

The potential of fallow lands to favor farmland bird conservation is widely recognized. Since fallows provide key resources for birds within the agricultural matrix, such as nesting sites, shelter and forage, complete understanding of the effect of field-management strategies on vegetation structure and food is essential to fulfill bird requirements and improve habitat management. In this study we experimentally compare the most common field practices (ploughing, shredding, herbicide application and cover cropping) on fallow lands by assessing the resources they provide for birds in terms of vegetation structure and food resources (leaf and seed availability), as well as the economic costs of their implementation. Fallow management treatments are ranked for six target species in a lowland area of the north-eastern Iberian Peninsula, according to the available information on their requirements. The different agronomic practices offer various quantities and types of resources, highlighting the importance of fallow management in bird conservation. Shredding and early herbicide application (February) are estimated to be good practices for Little Bustard (Tetrax tetrax) and Calandra Lark (Melanocorypha calandra), providing both favorable habitat and foraging conditions, while being economical. Meanwhile, superficial tillage in spring is found to be optimum for the rest of the species tested, despite being among the poorest food providers. Alternating patches of the best treatments would improve the effectiveness of agri-environmental schemes by maximizing the harboring habitat for the endangered species.

The present work has been financed by the Spanish National Program (proyect: AGL2010-22084-C02-01, BES-2011 047518). We gratefully acknowledge the field assistance of B. Bar- aibar, JA. Conesa, N. Moix, J Rey, A. Royo, X. Sole ́ -Senan and J. Torra. Thank are also due to J. Caus, P. Forns, J. Messegue and JM Montull for allowing us to use their fields and for their patience and hospitality. Field work permits were issued by the ‘Departament de Medi Ambient de la Generalitat de Catalunya’. We appreciate the comments of J. Traba to improve the final draft and S. Lade for the English correction. A pre- doctoral FPI scholarship was provided by the Spanish Ministry of Science and Education for I. Roblen ̃ o.