PARENT SESSION
Organized Oral Session 28: Ecological processes important in the responses of bird populations to environmental change driven by agriculture
Organizer(s): K Norris, E Chambers, and J Vickery
Wednesday, August 10, 8:00 AM - 11:30 AM, Meeting Room 511a, Level 5, Palais des congrès de Montréal

Impact of changes in agricultural land use in Easter Europe on the globally endangered grassland bird species: Corncrake Crex crex L.

Keiss, Oskars^{*,1, 2}, Mednis, Aivars^*,2, ¹ Department of Zoology and Animal Ecology, Riga, Latvia² Laboratory of Ornithology, Salaspils, Latvia

ABSTRACT- Changes in agricultural policy, land use and management in Eastern Europe after the collapse of the soviet political and economical system in Eastern Europe had a major impact on many bird species, including IUCN red listed Corncrake, which previously experienced dramatic declines over its global range, especially in Western Europe, where the species became almost extinct. The present study demonstrates how Corncrake population in Latvia became viable, experienced increase and possibly is accelerating species recovery in Western Europe. Corncrake population dynamics, habitat selection and changes in agricultural land use were studied in 68 permanent sample plots in Latvia in 1989-2004. Index of Corncrake population size and indices for each habitat category in all sample plots together were calculated using program Trends for Indices and Monitoring (TRIM, Statistics Netherlands). Corncrake population size were best explained by amount of specific habitat types in the sample plots: grasslands (rs.=0.74; p<0.002), abandoned agricultural lands (rs.=0.68; p<0.005) and arable land (rs.=-0.41; p<0.05). Directional changes in habitat selection were observed over the years in some habitat types (e.g. cultivated meadows) indicating on possible changes within the specific habitat type over the period of observations. Population size of Corncrakes in Latvia was calculated using year specific habitat population density data and available land use data in the country. Population structure of the Corncrake were studied by capturing, banding and measuring 706 adult birds, and taking feathers and blood samples for DNA analyses of 170 individuals between 2001 and 2004. Available data indicate on great mobility of Corncrakes during the breeding season (e.g. first and second clutch of the season might be laid in different countries) as well as gene flow between Latvia and Western Europe, suggesting that immigration of birds from Eastern Europe are responsible for increase of Corncrake numbers observed in Western European countries over the last five years.

Key words: Corncrake, Crex crex, population, habitat selection