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

The Ortolan Bunting Emberiza hortulana as the key indicator for monitoring the ecological quality of agricultural landscapes: A study with multi-scale approach.

Vepsäläinen, Ville^*,1, Pakkala, Timo², Piha, Markus², Tiainen, Juha³, ¹ Finnish Museum of Natural History, Helsinki, Finland² Finnish Museum of Natural History, Helsinki, Finland³ Finnish Game and Fisheries Research Institute, Helsinki, Finland

ABSTRACT- During the recent decades, farmland birds have declined all over the world due to the agricultural intensification. In order to observe biodiversity changes in farmland habitats as effectively and at as early stages as possible, knowledge on species that may be especially sensitive to environmental changes has to be obtained. The Ortolan Bunting is one of the most declined bird species of agricultural areas in Europe. We have studied breeding populations of the Ortolan Bunting in large areas of agricultural landscapes in southern Finland in 1984–2002. Spatial scales of the study range from territory to landscape scale. A crash of the Ortolan Bunting population took place synchronously in all subpopulations in the early 1990s, resulting a total decrease of 72% (i.e. from 78 pairs to 22 pairs) during the study period. We found associations with the decline and the amount of environmental heterogeneity, agricultural practices, species density and territory group structure. The species was found to be associated with bush- and tree-growing ditches and other vegetated landscape elements, which are important for structural and biological diversity in otherwise relatively open field areas. Our results show that there was also a connection between a decrease in the amount of bush- and tree-growing ditches and the decline of the Ortolan Bunting. The species was also found to be dependent on the field area not covered by vegetation in springtime. Our results suggest that the Ortolan Bunting might be an appropriate candidate for an indicator species for the general quality of farmland habitats, since the species seems to respond dramatically strongly to deterioration of habitats at multiple spatial scales — even when the changes in the environment may seem to be rather small from the humans' point of view. Future threats on many other farmland bird species may be probably expected if local Ortolan Bunting populations are observed to be in strong decline. The European-wide decrease of the Ortolan Bunting indicates also changes in migrating and wintering areas, especially in sub-Saharan Africa.

Key words: Emberiza hortulana, farmland birds, agricultural landscapes, indicator species