ABSTRACT
Farmland habitats are witnessing
steep declines in biodiversity. One rapidly declining farmland species
is the Ortolan Bunting. In Finland, a staggering 99% of the population
has been lost during the past 30 years. Changes in the breeding habitats
have been proposed as a reason for the decline, although hazards during
migration and wintering may also play a role.
We gathered a 19-year data set of Finnish Ortolan Buntings and studied
which spatial characteristics, habitat features, and climate factors
might explain the population growth rate at the singing-group level. As
explanatory variables we used region, density of small-scale landscape
structures, proportion of agricultural area in the landscape, diversity
of crop types, proportion of bare ground, and temperature and
precipitation of previous breeding season.
The only region with a marginally positive growth rate was North
Ostrobothnia, where the species often occupies newly established fields.
High crop type diversity mitigated the declines by perhaps providing a
wide array of feeding, hiding and nesting places. Bare ground benefited
Ortolan Buntings by perhaps providing an easy access to food. The last
Ortolan Buntings occurred in landscapes dominated by interconnected
agricultural land which, we think, reflects the species’ sociability and
avoidance of forested areas.
We suggest that agricultural intensification and the following potential
reduction in food availability may be a cause of the decline of Ortolan
Bunting. As general conservation measures, such as promoting set-aside
land or field margins, have been inadequate, either in effect or in
extent of application, it is evident that work remains. Northern
populations of Ortolan Bunting should be targeted for further studies on
feeding and breeding ecology as well as for urgent conservation actions,
such as increasing crop type diversity and bare ground. Promoting more
multi-functional and agro-ecologically managed agricultural landscapes
would benefit a wider range of farmland species as well.