Using aerial photographs to assess possible impact of changes in land use and landscape functionality on Ortolan Bunting (Emberiza hortulana) population in SE Moravia

Ortolan Bunting (Emberiza hortulana) belongs to threatened bird species listed in Annex I of the Birds Directive due to massive decline of its population in many countries in Europe.  The main reasons for the decline are changes in agriculture and landscape structure but also in overhunting (Cramp and Perrins 1994, Zaňát and Šimeček 1999). In the Czech Republic, it was recorded in higher numbers in north-western Bohemia, northern Moravia and south-eastern (SE) Moravia.

Population in SE Moravia was present during the first half of the 20th Century and peaked between 1950s-1960s. It wasn’t recorded nesting during 1980s and only sporadic observations were noted (Zaňát and Šimeček 1999). The population was rediscovered after 1992 and peaked in 1997-1998. After this year its decline was recorded (Šimeček and Hora 2006).

We used aerial photographs from five periods (1976, 1986, 1990, 2001 and 2009) to assess whether changes in land use and landscape functionality might have impact on the decline of Ortolan bunting population in SE Moravia localities belonging to a Special Protected Area (SPA) Hovoransko-Čejkovicko.

The aerial photographs were manually vectorized in ArcGIS 9.3 software (ESRI 2008) and delimitated landscape elements were assigned a code that reflected land use categories. Data from 2009 were revised in the field (2012). Older data were revised on the basis of interviews with local stakeholders. Landscape elements from all data sets were divided in two groups – landscape elements favourable for Ortolan bunting, such as small-scale arable fields, small scale vineyards on arable land, fields with scattered trees, vineyards with scattered trees, small extensive orchards, groups of trees, baulks and other strips of grassland, gardens etc., and less favourite/unsuitable landscape elements (e.g. forests, large-scale intensive fields, vineyards and orchards, settlements, grassed vineyards).

Landscape functionality was assessed in terms of corridors connectivity (Skokanová and Eremiášová 2013) and reflected relationship between landscape metrics and landscape functionality (for details see Kuttner et al. 2012, Skokanová and Eremiášová 2013).

Our results show decline in area of favourable landscape elements in 1986 followed by its increase in 1990 (Figure 1). Since 2001, area of favourable landscape elements steadily decreased while area of unsuitable landscape elements increased. These findings correspond with findings from other countries and confirm general theory of decrease in biotopes favourable for Ortolan Bunting. They are results of changes in agricultural practices, especially in mechanization that caused increase in the size of fields and drastic reduction of scattered trees. Also massive grassing of vineyards and other plots might have impact on the Ortolan Bunting population.

Results from landscape functionality did not show any clear pattern as was the case of changes in the landscape elements area (Figure 2). On the other hand, mean functionality tended to be higher (with the exception of 1986) in favourable landscape elements rather than in unsuitable landscape elements.