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ACTA ZOOLOGICA BULGARICA
Acta zool. bulg., 67 (2), 2015: 223-234
*Corresponding author
Terrestrial Ecology and Behaviour
Research Article
Introduction
Over the last 30 years, most of the farmland birds
have declined in Europe (PECBMS 2013). Land
abandonment and agricultural intensication are
considered the main drivers for the negative trends
in the farmland bird populations (He n l e et al. 2008,
St o a t e et al. 2009, Bu t l e r et al. 2010). While ag-
ricultural intensication is considered a more seri-
ous problem in Western Europe (Do n a l D et al. 2001,
2006, Be n t o n et al. 2002, Bá l D i , Ba t á r y 2011a),
land abandonment is of main concern in Central
and Eastern Europe (re i f et al. 2008, ni k o l o v
2010, Sa n D e r S o n et al. 2013, Ra d o v i ć et al. 2013,
Za k k a k et al. 2014). After the fall of the communist
regimes in 1990, most of the countries in the region
passed through a period of major market reforms.
In Bulgaria, this process caused economic and ag-
ricultural crisis, which in turn led to high levels of
depopulation and agricultural land abandonment in
the regions, where agriculture was the main occu-
pation. Both livestock breeding and crop production
were affected, especially in the mountain regions,
where the abandonment process locally began even
earlier (in the 1970s). This affected farmland bird
populations, which were reported to decline, even
Farmland Birds and Agricultural Land Abandonment:
Evidences from Bulgaria
Sylvia Dyulgerova1, Mladen Gramatikov2, Hristo Pedashenko1, Kiril Vassilev1, Vassiliki Kati3,
Stoyan C. Nikolov4*
1 Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, 2 Gagarin Street, 1113 Soa, Bulgaria
2 GeoMarine Centre Ltd., 45 Solun Street, Soa 1680, Bulgaria
3 Department of Environmental and Natural Resources Management, University of Patras, Seferi 2, 30100 Agrinio, Greece
4Bulgarian Society for Protection of Birds / BirdLife Bulgaria, Yavorov Complex, Bl. 71, Ent. 4, P.O. Box 50, 1111 Soa,
Bulgaria; E-mail: stoyan.nikolov@bspb.org
Abstract: Farmland birds are reported to decrease strongly in numbers throughout Europe over the last 30 years.
Agricultural land abandonment is considered amongst the main drivers for the negative population trends.
This process has been studied widely in Western Europe but the evidence for Central and Eastern Europe
is limited. We examined the differences in the bird community structure among several secondary suc-
cession stages after land abandonment (since the 1940s) in central Bulgaria. Our results demonstrated
that avian species richness and diversity decreased with the secondary succession, while no signicant
difference in the overall bird abundance was observed. The shifts in bird community pattern were mainly
related to grassland specialists, which decreased in species richness, diversity and abundance along the
succession gradient. Birds of European Conservation Concern were also negatively affected by the woody
vegetation overgrowth. We think that in order to stop and reverse the loss of farmland bird diversity in the
low-productive mountainous regions of Bulgaria, the rural sustainable development should be reinforced
by implementation of agri-environmental and other policy measures that encourage effectively small-
scale extensive farming.
Keywords: Agricultural management, common agricultural policy, farmland biodiversity, secondary succession
224
Dyulgerova S., M. Gramatikov, H. Pedashenko, K. Vassilev, V. Kati, S. C. Nikolov
when some of the Eastern European countries joined
the European Union (EU) and implemented agricul-
tural eco-friendly reforms (re i f et al. 2008, Bá l D i ,
Ba t á r y 2011b, Sa n D e r S o n et al. 2013).
Land abandonment fosters secondary succes-
sion and allows regeneration of the native shrubland
and woodland vegetation, which results in loss and
fragmentation of the open habitats at the landscape
scale (fa r i n a 1997, Si r a m i et al. 2007, 2008). These
changes in vegetation structure lead to alterations
in the availability of breeding sites and food supply
for birds as well as in predation pressure (fu l l e r ,
Go u G H 1999). The mentioned changes are bene-
cial for shrubland and woodland birds but negative
for grassland specialists (Po n S et al. 2003, ve r H u l S t
et al. 2004, re i f et al. 2013). However, there is evi-
dence that the biogeographic origin of the avifauna
may determine whether land abandonment brings
conservation benets or detriments (Su á r e Z –Se o a n e
et al. 2002). Some studies in Central Europe dem-
onstrated higher bird species richness in abandoned
habitats compared to managed habitats (la i o l o et
al. 2004, ve r H u l S t et al. 2004, re i f et al. 2013). In
Eastern Europe the processes that occur in bird as-
semblages along the secondary succession gradient
can initially lead to an increase in the species rich-
ness, when shrubland and ecotone species are added
to the species composition of open habitats (ni k o l o v
et al. 2011, Za k k a k et al. 2013). The woody vegeta-
tion overgrowth at late-succession stages gradually
leads to long-term loss of avian diversity, particularly
affecting the grassland birds (Za k k a k et al. 2013,
Mi k u l i ć et al. 2014). In the Balkan region, many
farmland birds of conservation concern are associat-
ed with low intensity farming in mountainous or low
productivity areas (ka t i , Se k e r c i o G l u 2006, ni k o l o v
2010, ni k o l o v et al. 2011), which, in the last few
decades, have been prone to land abandonment due
to the economic depression and rural depopulation.
Bulgaria is a good example of the above sce-
nario. Since 1989, land abandonment has been ob-
served all over the country and according to the Rural
Development Programme of the country for 2007-
2013, the low productivity mountainous regions have
been mostly affected. This trend remained even after
the massive subsidization of agriculture due to the ac-
cession of Bulgaria to the EU in 2007 (via the Common
Agricultural Policy, CAP): only 58.4% of the arable
land in Bulgaria (concentrated in three main regions)
is cultivated (aG r o S t a t i S t i c S , 2011). The results from
the Common Bird Monitoring in the country showed
that the common bird index has a negative trend since
2005, with the most severe decline reported for farm-
land birds (Hr i S t o v , Pe t k o v 2013).
To improve knowledge about the effects of land
abandonment on farmland birds in Eastern Europe,
where deciency of evidence was reported (Bá l D i ,
Ba t á r y 2011a), we tested a hypothesis that the ag-
ricultural land abandonment in Bulgaria leads to
reduction of avian diversity. We also examined the
differences in bird community structure (species
richness, abundance and Shannon diversity) and
composition among gradient secondary successional
stages over a period of 50 years.
Material and Methods
Study area and sampling plots
The study area is part of the Fore-Balkan region
in Central Bulgaria (Fig. 1), where rural depopula-
tion and resulting land abandonment are widespread
(aG r o S t a t i S t i c S 2011). It is located in the Balkan
mixed forest ecoregion of the temperate deciduous
forest vegetation zone (ol S o n et al. 2001) and rang-
es within an altitude of up to 1000 m.
We used sampling plots of 1 x 1 km squares,
based on the European Environmental Agency
(EEA) grid (http://www.eea.europa.eu/data-and-
maps/data/ee a-reference- grids-2#tab-gis-dat a).
The sampling plots, which corresponded to the fol-
lowing criteria, were considered suitable for the
study (Zakkak et al. 2013): (i) 100% covered by
agricultural land used in the 1940s; (ii) currently
with less than 30% of urban area and/or water
bodies (to avoid potential bias due to bird species
tied to settlements or wetlands); (iii) the distance
between centres of two adjacent sampling plots
is more than 4 km (to avoid bird data spatial au-
tocorrelation). We compared the land cover from
orthophoto imagery from 2011 with the land cover
from aerial photographs of the same region from
the past (1945-1946). A total of 64 sampling plots
were found to meet the criteria. Out of those, we
randomly selected 18 sampling plots (Fig. 1) dis-
tributed equally in three vegetation structure (VS)
categories according to the degree of woody vege-
tation (both shrubs and forest) overgrowth, indicat-
ing succession rate (Sirami et al. 2007, vallecillo
et al. 2008, Zakkak et al. 2013): VS1: < 60%; VS2:
60-90%; VS3: >90%. There was no signicant dif-
ferences in the mean altitude among the studied
vegetation structure categories (Kruskal-Wallis
ANOVA, H2,15 = 0.42, p = 0.81).
Land cover mapping and interpretation
We used data from the orthophoto imagery
from 2011 (Ministry of Regional Development da-
Farmland Birds and Agricultural Land Abandonment: Evidences from Bulgaria
225
tabase – unpublished), with a grain size of 1 m as
the spatio-thematic source for land cover mapping
and interpretation. Only aerial features limited to a
minimal mapping unit of 100 m² were digitalised as
discrete landscape elements and the maximum width
of linear elements, such as hedgerows, was set to 15
m. By applying a standard scale level of 1:1500 we
could clearly identify and delineate landscape ele-
ments from the image data, which we classied by
22 land cover types (i.e. habitats), displaying the
current state of land use, respectively, agricultural
abandonment (Appendix 1).
The habitat type cover changed signicantly
along the land abandonment gradient, with arable
land, grasslands (pastures and meadows), articial
land and orchards signicantly decreasing (down to
0%), while shrubland and woodland signicantly
increasing (up to 100%) across the vegetation suc-
cession classes. The orchards, which did not present
a signicant differentiation along the gradient, and
the wetlands and bare ground, which were present
in less than ve plots (overall cover < 5%), were not
considered in the analysis (Fig. 2).
Bird sampling
Birds were recorded using the point count meth-
od (Gi B B o n S , Gr e G o r y 2006). Initially, nine point
count stations (PCS) were located systematically
in each sampling plot, placed 300 m apart to avoid
double counting of birds. The following PCS were
excluded from the study: the PCS located closer than
150 meters from rivers, busy roads or settlements;
those that are inaccessible due to physical factors of
relief, fences or others; and those, in which activities
disturbing birds (such as logging, hunting or agricul-
tural activities) were present during the bird counts.
As a result, each sampling plot contained at least six
PCS suitable for the study and the total number of
PCS considered in the analysis was143 for 2011 and
145 for 2012.
The PCS were visited during the greatest bird
activity period: in the morning (05:00 – 11:00 a.m.),
during the height of breeding season (June) in 2011
and in 2012. At each PCS, birds were counted within
a radius of 100 m, based on visual and acoustic reg-
istrations of individuals during two consecutive 5
min sessions (ra l f et al. 1995, Bo n t H o u x , Ba l e n t
2012).
Data analyses
We examined the bird communities using the
following parameters (kr e B S 1999): (i) Species
richness – calculated from the means of maximum
number of species recorded in all PCS in each sam-
Fig. 1. Distribution of the sampling plots (N = 18) in the studied area
226
Dyulgerova S., M. Gramatikov, H. Pedashenko, K. Vassilev, V. Kati, S. C. Nikolov
pling plot; (ii) Abundance – calculated from the
means of maximum number of individuals counted in
all PCS in each sampling plot; (iii) Shannon-Wiener
diversity index. For the species richness, data from
10-min count periods were used to avoid overlook-
ing of cryptic and rare species, while for the index
of abundance and Shannon-Wiener diversity index,
data from 5-min intervals were used to avoid double
counting of the same individuals (Gi B B o n S , Gr e G o r y
2006). Raptors, aerial feeders (swallows, swifts and
bee-eaters) and nocturnal species (e.g. Corncrake
Crex crex) were excluded from the analysis because
the point-count method is not appropriate to assess
their abundance (Si r a m i et al. 2007). Moreover,
records of y-overs, as well as data collected in bad
weather conditions (visibility < 200 m; rain; wind >
2 Beaufort) were not considered in the analysis. As
there were no signicant differences of studied bird
community parameters between years (Wilcoxon
Matched Pairs Test: T = 62.5, p = 0.32 and T = 63.0,
p = 0.33, respectively for the species richness and
abundance), data were pooled for the analyses.
Birds were classied in functional groups ac-
cording to their main habitat: grassland, shrubland,
woodland or other type of habitat (ia n k o v 2007),
as well as species from the European Conservation
Concern (SPEC) list (Bi r D li f e in t e r n a t i o n a l 2004;
see Appendix 2). Separately, we analysed the bird-
habitat associations of all the species (n = 21) re-
corded in both years of the study, in more than ve
sampling plots per year and with total abundance of
20 or more individuals.
Because data were not normally distributed
and did not approach the normal distribution even
after transformation, non-parametric tests (Kruskal-
Wallis ANOVA and Spearman-Rank Correlation test)
were used. The statistical analysis was conducted
by STATISTICA 7.0 (St a t So f t 2004). The ordina-
tion analysis was applied using CANOCO 4.5 (t e r -
Br a a k , Sm i l a u e r 2002). The length of gradient in a
dataset was checked by Detrended Correspondence
Analysis (DCA). The bird associations along the
studied landscape gradients were determined by
Canonical Correspondence Analysis (CCA). The
signicance of canonical axes was assessed by the
Monte Carlo Permutation test.
Results
Bird community structure along the secondary
succession gradient
We recorded 61 bird species (3587 individuals), of
which an important proportion of 30% was SPEC
(Appendix 2). The dominant group was woodland
Fig. 2. Habitat cover across the three vegetation succession classes (VS1 : <60%, VS2: 60-90%, VS3: >90% of woody
vegetation cover)
Farmland Birds and Agricultural Land Abandonment: Evidences from Bulgaria
227
birds (66%), including a small proportion of SPEC
species (23%). Grassland birds accounted for a small
proportion of species richness (11%), but included
the largest proportion of SPEC species (56%).
Shrubland (16%) and other birds (7%) included also
quite an important number of SPEC species (30%
and 50%, respectively).
Bird species richness and Shannon-Wiener di-
versity index signicantly decreased along the veg-
etation succession gradient (VS1 to VS3), when all
bird species were considered; however, the overall
abundance did not differ signicantly among the
vegetation succession classes (Table 1). The diversi-
ty of grassland and SPEC species (species richness,
Shannon-Wiener diversity index, and abundance)
also signicantly and strongly decreased along the
vegetation succession gradient. There were no sig-
nicant differences in the shrubland and woodland
bird diversity among the three vegetation succession
classes (Table 1).
Bird-habitat associations
The main gradients in the landscape, which in-
uenced the bird species composition, were related to
secondary succession (transition from semi-natural
grasslands and arable lands to woody vegetation) and
the structure of farmlands (from arable lands to rural
mosaics; Fig. 3). Accordingly, there were two main
bird assemblages: (i) related to open landscapes (ara-
ble lands and semi-natural grasslands) and (ii) woody
vegetation and rural mosaics. The early-successional
stages were dominated by grassland (Corn Bunting
Emberiza calandra and Skylark Alauda arvensis) and
shrubland specialists (Blackbird Turdus merula, Red-
backed Shrike Lanius collurio, Common Whitethroat
Sylvia communis; Fig. 4a,b), while the latest suc-
cessional stage was dominated by woodland birds
(Common Chafnch Fringilla coelebes, Common
Chiffchaff Phylloscopus collybita, Great tit Parus ma-
jor, Robin Erithacus rubecula, etc.; Fig.4c).
Discussion
Shifts in bird community structure
Our results demonstrated that the overall species rich-
ness and Shannon-Wiener diversity index decreased
along the succession gradient, while the overall bird
abundance remained stable. Similar results were re-
ported for the extensively grazed and abandoned up-
land pastures in Western Bulgaria (ni k o l o v 2010).
These results could be explained with the similarity
in the ecological capacity of the natural habitats to
host as much avian diversity as farmland environ-
ment (na v a r r o , Pe r e i r a 2012, Gu i l H e r m e , mi G u e l
Pe r e i r a 2013). Previous works (e.g. Sa n t o S 2000,
la i o l o et al. 2004, Si r a m i et al. 2008, ni k o l o v et al.,
2011, Za k k a k et al. 2013) reported an increase in spe-
cies richness and diversity in the successional stages
just after abandonment due to an inux of shrubland
and ecotone species to the community, while open
habitat species still persist there. A gradual decrease
in the species richness and Shannon-Wiener diver-
sity index with vegetation succession in this study
could be explained by the fact, that the study did not
include the intensively managed farmland as start-
ing point of the succession. Such intensive agricul-
tural land use (on one extreme end of the gradient) is
considered the main driver of the widespread farm-
land bird declines observed in Europe (Do n a l D et al.
2001, 2006). At the same time, the late-successional
habitats as scrubland and woodland (on the other
extremity of the gradient) were reported to support
high avian species richness in Central and Western
Europe (Gu i l H e r m e , mi G u e l Pe r e i r a 2013, re i f et
al. 2013).
We found that the diversity of grassland birds
and SPEC birds was affected negatively by the post-
abandonment vegetation succession. This result sup-
ports the view that the secondary succession through
the agricultural land abandonment is the reason for
the grassland bird diversity loss, as it is already
Table 1.Differences in bird community structure among three-scale vegetation succession gradient (VS1 : <60%, VS2:
60-90%, VS3: >90% of woody vegetation cover), based on Kruskal-Wallis ANOVA test (K-W), and relation between
studied bird community parameters and woody vegetation cover, based on Spearman correlation coefcient (rho).*:
p<0.05, **:p<0.01, ***:p<0.001, ns: p>0.05.
Bird group Species richness Shannon index Abundance
K-W rho K-W rho K-W rho
All species 6.25* - 0.36* 13.34** - 0.54* 5.71 ns -
SPEC species 18.77*** - 0.77* 16.74*** -0.75* 16.74*** -0.73*
Grassland birds 20.87*** - 0.81* 9.98** - 0.59* 17.87*** - 0.77*
Shrubland birds 3.36 ns - 4.27 ns - 0.36 ns -
Woodland birds 3.38 ns - 1.96 ns - 0.83 ns -
228
Dyulgerova S., M. Gramatikov, H. Pedashenko, K. Vassilev, V. Kati, S. C. Nikolov
known for the Mediterranean region (Pr e i S S et al.
1997, fa r i n a 1997, Sa n t o S 2000) and recently de-
scribed for the Balkans (ni k o l o v 2010, Za k k a k et
al. 2013, Mi k u l i ć et al. 2014). Actually, the early-
successional stages in the present study, with which
these groups of birds were associated, were similar
to the heterogeneous agricultural landscape under
traditional extensive farming, known to be benecial
for farmland biodiversity (ka t i , Se k e r c i o G l u 2006,
ka t i et al. 2009, ni k o l o v et al. 2011).
Effects of secondary succession at species level
The common bird species composition along
the succession gradient showed the expected initial
prevailing of open habitat species (e.g. Corn Bunting,
Red-backed Shrike and Skylark), displaced at late-
successional stages by shrubland (e.g. Blackbird
and Common Whitethroat) and ecotone species
(e.g. Common Chiffchaff and Robin), and nally,
predominated by woodland species (e.g. Common
Chafnch, Great Tit and Song Thrush).
Species respond in an idiosyncratic way to the
habitat types analysed, given their different degree of
specialisation (fu l l e r et al. 2004). Some open habi-
tat species (e.g. Skylark, Corn and Ortolan Buntings)
respond negatively to land abandonment due to
habitat loss through the turnover in late-successional
stages (va l l e c i l l o et al. 2008), and negative for-
est edge effects (fo n D e r f l i c k et al. 2013). Others
(e.g. Woodlark, Red-backed Shrike and Common
Whitethroat) are more tolerant to secondary suc-
cession due to ‘complementation’ type response,
being favored by the coexistence of both farmland
and shrubland landscapes (ka t i , Se k e r c i o G l u 2006,
tS i a k i r i S et al. 2009, Za k k a k et al. 2013) and should
be expected to persist longer in the changing habitat.
In the present study, most of the predominant
species at late-successional stages (e.g. Blackbird,
Common Chafnch, Great Tit, and Robin) were
generalists (ka t i , Se k e r c i o G l u 2006, ia n k o v 2007),
while relatively more SPEC species were tied to
early-successional stages and responded negatively
to agricultural land abandonment. The results are in
agreement with the work of re i f et al. (2013) and
Za k k a k et al. (2013), showing that early-successional
stages host bird communities with the highest habitat
specialisation and threat level (but see Ra d o v i ć et al.
2013, Mi k u l i ć et al. 2014). Therefore, the popula-
tion declines of the common bird species in Bulgaria
(Hr i S t o v , Pe t k o v 2013) tied to open habitats (arable
lands and grasslands) and found to respond nega-
tively to secondary succession (e.g. Skylark, Red-
backed Shrike, Ortolan and Corn Buntings), should
be further investigated in relation to the nationwide
abandonment of arable lands in the low-productivity
mountainous regions, besides the other operating
factors.
Conservation implications
Conservation implications for biodiversity vary
since the arable land abandonment results from mul-
tiple drivers and is not per se a positive or negative
process (Be i l i n et al. 2014). Extensive grazing in the
former hilly and mountainous cultivations has been
proposed by some authors (ni k o l o v 2010, ni k o l o v
et al. 2011, Za k k a k et al. 2013) as an alternative
solution to maintain open landscape structure and
open-land farmland birds. Under appropriate zona-
tion regime, this type of management has been sug-
gested as an efcient measure also for sustaining
vegetation diversity in open-grassland and mid-suc-
cessional grassland communities in the Balkan up-
lands (va S S i l e v et al. 2012). Nevertheless, grazing is
not an adequate solution in all cases, as many of the
farmland bird species are tied to arable land rather
Fig. 3. CCA biplot graph of bird species and main habi-
tat types. Canonical axes were statistically signicant
(Monte Carlo permutation test, F = 1.48, p = 0.03) and the
model explained 89.6% of data variability. Bird species
are indicated as triangles (see Appendix 2 for acronyms).
Habitat variables are indicated as arrows: Woody – forests
and shrubs; Arable – arable lands; HedgeOR – rural mo-
saics (hedges and orchards); Urban – roads and articial
structures; Grassland – meadows and pastures
Farmland Birds and Agricultural Land Abandonment: Evidences from Bulgaria
229
than to pastures only (ni k o l o v et al. 2011, Za k k a k
et al. 2013). Shrub-clearing (Bo c c a c c i o et al. 2009)
and logging in former agricultural land (Za k k a k
et al. 2013) have been also promoted to maintain
open spaces in the Balkan context. Based on the as-
sumption that bird communities can adapt to land-
use changes derived from farmland abandonment,
Gu i l H e r m e , mi G u e l Pe r e i r a (2013) argued that rewil-
ding may be a suitable management option for many
European mountain areas. Indeed, at metapopulation
level, an animal species can temporarily persist (i.e.
can have a low local extinction rate) even after se-
vere habitat fragmentation or after a sharp decrease
in habitat quality (Si r a m i et al. 2008). However,
the results from the present study clearly indicated
a decrease in the species richness, abundance and
diversity of grassland birds, while a simultaneous
opposite trend in the shrubland and woodland birds
was not observed. Therefore, at least for the studied
region, rewilding cannot be considered an appropri-
ate compensation method for the farmland bird di-
versity loss. Most of the conservation implications
Fig. 4. Dominant structure of bird communities in the studied successional stages (a) VS1: <60%, (b) VS2: 60-90%,
and (c) VS3: >90% of woody vegetation cover (see Appendix 2 for bird species acronyms)
230
Dyulgerova S., M. Gramatikov, H. Pedashenko, K. Vassilev, V. Kati, S. C. Nikolov
for reversing the negative effects of agricultural land
abandonment on birds are related to maintenance of
extensive traditional farming and livestock rearing
within rural mosaics (ka t i et al. 2009, ni k o l o v et
al. 2011, Za k k a k et al. 2013, He r Z o n et al. 2014),
which fully corresponds to the agricultural manage-
ment and habitat conguration of the studied area
in the past (unpublished data from questionnaires of
old people and aerial photographs from 1945-1946,
collected during the present study).
Land abandonment is more strongly inuenced
by socio-economic factors, such as farming subsi-
dies and land reforms, than the characteristics of
the land itself (al c a n t a r a et al. 2013). Therefore,
the low productive mountainous regions in Bulgaria
need appropriate management, not only for the ben-
et of biological diversity, but also for the sake of
quality of life of the rural communities. The latter
is particularly important, as the rural poverty and
low standard of living tied to small scale extensive
farming cannot be promoted only on the grounds of
their association with high nature conservation-val-
ue farmland (mccr a c k e n et al. 1997). An integrated
approach to agricultural, environmental and social
policies for such areas is, therefore, highly recom-
mended (la i o l o et al. 2004). Similarly to the results
from Greece (Za k k a k et al. 2013) and from Croatia
(Mi k u l i ć et al. 2014), this study suggests that these
policies could be developed and implemented at
the Balkan rather than national level, at least for
the EU member states or candidate member states.
They may include promotion of extensive farming,
establishment of an adequate market system for lo-
cal products, and subsidies for both extensive culti-
vation and grazing in order to enhance the income
of agricultural activities in remote mountain areas
(Za k k a k et al. 2013).
Acknowledgements: This study was conducted under the
AGRALE project (Sub-project ERA 164/04) funded by SEE-
ERA.NET PLUS scheme. We would like to thank Thomas Wrb-
ka, Andreja Radović, Spase Shumka, Michael Kuttner, Stefan
Schindler, and Mirjan Topi, for their expertise and fruitful dis-
cussions, as well as Dimitar Zarev and Vladimir Petrov for their
assistance in bird data collection. Irina Herzon, Riho Marja and
Pavel Zehtindzhiev provided valuable comments on an earlier
draft of the manuscript. Penka Tzekova proofread the paper and
improved the English.
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Appendix 1. Land cover types (i.e. habitats) description
Land Cover Type Description
Arable Land (AL) Grain, forage crops, root crops
Meadow (ME) No bare soil, uniform texture, traces of mowing
Pasture (PA) Obvious signs of pastoral use like trampling
Orchard (OR) Fruit tree plantation
Vineyard (VY) Vineyards
Coarse grassland (CGR) Extensively used grasslands (including fallow lands), showing a coarse texture
Heterogeneous grassland (HGR) Extensively used grasslands (including fallow lands), showing a heterogeneous structure
Shrublands (SHR) Shrubby vegetation (> 75 % shrub cover)
Broad-leaved forest (BLFO) Forest with < 20 % coniferous trees
Coniferous forest (CFO) Forest with < 20 % broad-leaved trees
Mixed forest (MFO) Forest with > 20 % broad-leaved and coniferous trees
Open forest (OFO) 30 - 50 % tree cover
Farmland Birds and Agricultural Land Abandonment: Evidences from Bulgaria
233
Land Cover Type Description
Small woodlot (WL) All forest types < 1,500 m²
Articial surface (AS) Built up areas, incl. settlements, parking spaces, extraction sites, etc.
Bare surface (BAR) Bare rock or soil, eroded areas
Baulk (BA) Field margins, ridges, embankments
Burnt surface (BUR) Burnt areas, especially forests and shrublands
Hedge (HD) Hedgerows of shrubs and/or trees
Road (RO) Sealed, gravel or dirt roads
Sparsely vegetated areas (SVA) < 50 % vegetation cover (all types)
Standing waterbody (WBSN) Lakes, ponds, water reservoirs
Streaming waterbody (WBSR) Rivers, streams, channels
Appendix 2. Bird species, overall abundance, habitat preference, and conservation status.
G: Grassland birds, S: Shrubland birds, W: Woodland birds, O: Other birds (ia n k o v 2007). SPEC 1: Species in Europe
of global conservation concern, SPEC2: Species, whose global population is concentrated in Europe, with unfavour-
able conservation status in Europe, SPEC3: Species, whose population is not concentrated in Europe, with unfavour-
able conservation status in Europe (Bi r D l i f e in t e r n a t i o n a l 2004)
Bird species Code Abundance Habitat Conservation status
Aegithalos caudatus Aegcau 7 W -
Alauda arvensis Alaarv 134 G SPEC 3
Anthus trivialis Anttri 19 W -
Carduelis cannabina Carcan 3 G SPEC 2
Carduelis carduelis Carcar 4 W -
Carduelis chloris Carchl 10 W -
Certhia brachydactyla Cerbra 8 W -
Coccothraustes coccothraustes Coccoc 40 W -
Columba palumbus Colpal 17 W -
Corvus corone Corcor 2 W -
Coturnix coturnix Cotcot 13 G -
Crex crex Crecre 5 G SPEC 1
Cuculus canorus Cuccan 59 W -
Cyanistes caeruleus Cyacae 40 W -
Dendrocopos major Denmaj 28 W -
Dendrocopos minor Denmin 5 W -
Dendrocopos syriacus Densyr 1 W -
Dryocopus martius Drymar 7 W -
Emberiza calandra Embcal 376 G -
Emberiza citrinella Embcit 125 W -
Emberiza hortulana Embhor 115 S -
Emberiza melanocephala Embmel 2 S -
Erithacus rubecula Erirub 173 W -
Ficedula semitorquata Ficsem 1 W SPEC 2
Fringilla coelebs Fricoe 293 W -
Garrulus glandarius Gargla 78 W -
Hippolais pallida Hippal 4 S SPEC 3
Jynx torquilla Jyntor 10 W SPEC 3
Appendix 1. Continued
234
Dyulgerova S., M. Gramatikov, H. Pedashenko, K. Vassilev, V. Kati, S. C. Nikolov
Bird species Code Abundance Habitat Conservation status
Lanius collurio Lancol 209 S SPEC 3
Lanius senator Lansen 1 S SPEC 2
Lullula arborea Lularb 24 G SPEC 2
Luscinia megarhynchos Lusmeg 117 W -
Motacilla ava Mota 9 G -
Muscicapa striata Musstr 3 W SPEC 3
Oriolus oriolus Oriori 28 W -
Parus lugubris Parlug 4 W -
Parus major Parmaj 187 W -
Parus montanus Parmon 3 O -
Passer domesticus Pasdom 42 O SPEC 3
Passer montanus Pasmon 2 O SPEC 3
Phasianus colchicus Phacol 5 O -
Phoenicurus ochruros Phooch 1 S -
Phylloscopus collybita Phycol 283 W -
Phylloscopus sibilatrix Physib 12 W SPEC 2
Phylloscopus trochilus Phytro 5 W -
Picus canus Piccan 3 W SPEC 3
Picus viridis Picvir 18 W SPEC 2
Poecile palustris Poepal 9 W -
Sitta europaea Siteur 30 W -
Streptopelia turtur Strtur 21 W SPEC 3
Sturnus vulgaris Stuvul 18 W SPEC 3
Sylvia atricapilla Sylatr 124 W -
Sylvia borin Sylbor 2 W -
Sylvia communis Sylcom 140 S -
Sylvia curruca Sylcur 3 S -
Sylvia nisoria Sylnis 16 S -
Troglodytes troglodytes Trotro 9 W -
Tudus merula Turmer 498 S -
Turdus philomelos Turphi 158 W -
Turdus viscivorus Turvis 12 W -
Upupa epops Upuepo 12 W SPEC 3
Total 61 3587
Appendix 2. Continued