Land use and the conservation of farmland birds
Jules Bos, Plant Research International & Walter Rossing, Wageningen University Biological Farming
Systems
With the expansion of agriculture in Europe over the past centuries, an important part of European
biodiversity is now linked to farming. This includes bird populations linked to farming activities. During
the last three decades there have been widespread and severe declines in populations of farmland birds
and other wildlife. These declines have been attributed to the general process of agricultural
intensification (e.g. Herzon et al., 2008; Donald et al., 2006). With farmland constituting the single
largest habitat in Europe, the continental-scale effects of agricultural intensification on biodiversity may
be comparable with potential effects of climate change. Addressing biodiversity loss on European
farmland therefore is a major societal issue.
Agricultural intensification encompasses a wide range of interrelated components that may have
occurred simultaneously. Each component may impact on reproduction and mortality rates of single
species in different ways. The multifaceted character of agricultural intensification complicates the
identification of specific causes of farmland bird population declines. However, there is broad agreement
that following components of agricultural intensification have played a major role (Wilson et al., 2009;
Newton, 2004):
 Increased use of pesticides and fertilisers. Pesticide use affects reproduction and mortality both directly
and indirectly. Direct effects occur instantly via failed reproduction or immediate mortality. Indirect
effects impact via reduced food supplies. For example, the use of herbicides decreases weed
populations and hence also weed seed availability in agricultural areas, reducing food supply in both
the short and long term. Weeds also support insects, another important component in the diet of birds.
The use of fertilizers benefits the growth of improved agricultural crops at the expense of wild plants,
resulting in uniform fields with dense crop canopies that are less accessible to farmland birds for use as
foraging or breeding habitat (Kragten et al., 2008; Eraud & Boutin, 2002; Chamberlain et al., 2000).
 The removal of hedges, shrubs, ditches, wooded banks and other landscape elements, resulting in a
strong reduction of semi-natural, often insect-rich habitats within the agricultural matrix. Semi-natural
habitats are both important as nesting habitat and as a source of food.
 Decrease of the area planted to summer cereals and dominance of winter cereals or maize in regional
crop rotations. The decreased summer cereal area has resulted in a reduced availability of cereal
stubbles in winter, which constitute an important food source (Gillings et al., 2005). The dominance of
winter cereals or maize in regional crop rotations implies that farmland birds in the breeding season
have fewer opportunities to take advantage of different crops in different stages of development within
their territories, adding to the problem of the general lack of insect-rich vegetations where youngfeeding parent birds can forage efficiently .
 Loss of mosaics in space and time, resulting from the spatial separation of arable land and grassland,
increases in the scale of farming and uniformization of farmland. These developments have reduced
the supply of different habitats at multiple spatial scales (Benton et al, 2003). Increases in the scale of
farming have also reduced the supply of field margins and field boundary structures, which are often
valuable to farmland birds. For safe nesting sites, efficiently foraging sites and sufficiently high
reproduction rates in the breeding season, the presence of different crop and non-crop habitats within
short flight distances is important.
Relative immigration and emigration rates being equal, changes in population size are determined by the
balance between reproduction and mortality. A decreasing population size means that long-term
mortality rate exceeds long-term reproductive rate. Whether the dominant cause of population decline is
increased mortality, reduced reproduction or both combined, is not easily determined. Moreover, the net
balance between mortality and reproduction may vary in space and time. Primary demographic causes
may reflect a whole range of secondary causes, such as reduced chick survival or increased mortality
during the late winter months.
To stem further declines of farmland birds and other biodiversity taxa, agri-environment schemes have
been designed and implemented since 1992. They have been shown to enhance local species richness
and abundances of some species groups and to provide various food sources for farmland birds (e.g.
Perkins et al., 2008; Peach et al., 2001). However, their effectiveness in reversing population declines
has so far been limited. There are several reasons why agri-environment schemes generally have failed
to deliver, including low spatial coverage, poor spatial targeting and poor monitoring (Geiger, 2011;
Kleijn & Sutherland, 2003). Recently, there is a growing amount of literature suggesting that the
effectiveness of agri-environment schemes strongly depends on landscape composition (Geiger, 2011,
Concepción et al., 2008; Sabatier et al., 2010; Smith et al., 2010).
Single species have specific requirements and preferences in terms of nest sites and availability of
summer food and winter food. Based on extensive, multi-annual research programmes, the demands of
some farmland bird species are well known, including Grey partridge (Peridix perdix) and Skylark
(Alauda arvensis). The relatively comprehensive knowledge base for these and other species allows the
modelling of (regional) population density as a function of landscape composition and/or land use in
terms of e.g. cultivated crops, field size, agricultural management and supply of semi-natural habitats,
both at landscape scale (e.g. Boatman et al., 2009; Swetnam et al., 2005) as well as at larger spatial
scales (e.g. Scholefield et al., 2011; Butler et al., 2010). In turn, this progress in quantitative knowledge
on bird ecology allows evaluation of alternative landscape configurations in terms of bird conservation
relative to other objectives of land use, for instance those related to carbon sequestration, excess
surface water storage and agricultural production. Such integrated analyses are rare due to
fragmentation of knowledge along disciplinary divides and limited interest among scientists in designoriented approaches. At the same time integration of information and demonstration of trade-offs and
synergies can support learning and negotiation processes which by many are deemed essential to
develop new perspectives for systems management (Folke et al., 2005; Gunderson et al., 1995).
Thinking about alternative landscapes often results in a number of ‘sketch designs’ – scenarios
developed by experts or in participatory settings with stakeholders. A more effective approach is to
generate a large set of alternatives that perform differently in terms of the land use objectives at stake.
Such approach has three advantages over a sketch design approach. Firstly, interactions among
objectives can be explored and trade-offs made apparent (Groot et al., 2007; Tittonell et al., 2007). This
gives insight in the space for manoeuvre given the various and often conflicting objectives of stakeholder
groups involved. Secondly, insights from psychology on self-determination and motivation (Ryan and
Deci, 2000) show that acceptance and internalization of policy solutions is enhanced if decision makers
are offered a choice from a broad portfolio of alternatives as opposed to policy prescription (Moller at al.,
2006). Thirdly, exploration of the full set of possible landscapes can yield radically different alternatives
that break path dependency and avoid lock-in often associated with small incremental changes.
Objectives of land use may act at different levels, further adding to complexity. For instance, the degree
of bird reproduction success acts at the landscape level, C-sequestration is relevant at the field level and
profit is considered at the farm level. Field-farm-landscape modelling techniques developed over the
past decade can assist in creating and learning from a salient diversity of landscape alternatives. In the
past decade major progress has been made in integrated assessment methods that enable systematic
generation and evaluation of landscapes in a spatially explicit manner (Groot and Rossing, Methods in
Ecology and Evolution accepted). The Landscape IMAGES model (Groot et al., 2010) provides a
framework for such assessments, demonstrates relations between objectives and shows the spatial
landscape implications.
Conservation of farmland birds can thus be considered a multi-objective optimization problem. Land use
activities constitute the decision variables which determine the provision of the objectives (Figure 1a). In
contrast to global, single-objective optimization, multi-objective problems do not have a single optimal
solution, but are solved by a set of alternative solutions that reveal synergies or trade-offs among the
objectives (Coello Coello et al. 2007). A considerable part of multi-objective optimization procedures rely
on aggregating the various objectives into one by weighing and normalization and then optimizing a
single objective problem. Weighing procedures introduce technical complexity and arbitrary choices that
are not conducive to the transparency of design processes where conflict and negotiation usually prevail.
Pareto-optimality represents a powerful criterion to combine objectives without a priori weighing and has
been scarcely used thus far. The Pareto-optimal solution set is a collection of alternatives that cannot be
improved for one of the objectives without compromising any of the other objectives involved (Figure
1a). Put differently, the alternatives in the Pareto-optimal set are not ‘dominated’ by solutions that
perform better for all the objectives (Figure 1b). In a set of alternatives comprising both optimal and
non-optimal solutions, the dominance concept can be used to rank the alternatives in terms of Pareto-
optimality in different ways (Coello Coello et al. 2007). For example, after removal of the non-dominated
alternatives (rank 1) from the set, a new collection of non-dominated alternatives can be identified that
will receive rank 2 (Figure 1b). This can be repeated until all alternatives have been ranked (Goldberg
1989). In this way, the initial n-dimensional optimization problem is reduced to a one dimensional
problem without a priori weighing (Fig. 1c).
Here we propose to evaluate opportunities and trade-offs for conservation of Grey partridge and Skylark
by bringing together information on bird ecology and agronomy for selected case study landscapes.
Figure 1. a. Stylized illustration of a trade-off between farm gross margin and nature value in an agro-ecosystem, and the
associated landscape for the alternatives. The closed symbols represent landscape alternatives belonging to the Pareto-optimal
set (rank 1). The ranking scheme is demonstrated in b., where the shaded areas indicate the region of the solution space that
is dominated by a particular solution (the solution performs better for all the objectives than any other solution within the
shaded area; for further explanation see text). c. Conceptual outline of the optimization process employing the iterative steps
of generating, evaluating and selecting. The pressures exerted by the optimization algorithm through Pareto ranking (solid
arrow) and the search for less crowded areas (dashed arrows) are indicated. The encircled solution can represent the original
situation. The dotted line in a. and c. indicates the Pareto frontier, which is approached by the optimization (from Groot &
Rossing, 2011).
a.
b.
c.
References
Benton T.G., J.A. Vickery & J.D. Wilson, 2003. Farmland biodiversity: is habitat heterogeneity the key?
Trends in Ecology and Evolution 18: 182-188
Boatman, N.D., S. Pietravalle, H.R. Parry, J. Crocker, P.V. Irving, D.B. Turley, J. Mills & J.C. Dwyer,
2010. Agricultural land use and Skylark Alauda arvensis: a case study linking a habitat association
model to spatially explicit change scenarios. Ibis 152: 63-76
Butler, S.J., L. Boccaccio, R.D. Gregory, P. Vorisek & K. Norris, 2010. Quantifying the impact of land-use
change to European farmland bird populations. Agriculture, Ecosystems & Environment 137: 348-357
Chamberlain, D.E., J.A. Vickery & S Gough, 2000. Spatial and temporal distribution of breeding skylarks
Alauda arvensis in relation to crop type in periods of population increase and decrease. Ardea 88: 61-73
Coello Coello, C.A., G.B. Lamont, & D.A. Van Veldhuizen, 2007. Evolutionary algorithms for solving
multi-objective problems. Springer, New York, 2007.
Concepción, E.D., M. Diaz & R. A. Baquero, 2008. Effects of landscape complexity on the ecological
effectiveness of agri-environment schemes. Landscape Ecology 23: 135-148
Donald, P.F., F.J. Sanderson, I.J. Burfield & F.P.J. van Bommel, 2006. Further evidence of continentwide impacts of agricultural intensification on European farmland birds, 1990-2000. Agriculture,
Ecosystems and Environment 116: 189-196
Eraud, C. & J.-M. Boutin, 2002. Density and productivity of breeding Skylarks Alauda arvensis in relation
to crop type on agricultural lands in western France. Bird Study 49: 287-296
Folke, C., Hahn, T., Olsson, P. & Norberg, J., 2005. Adaptive Governance of Social-Ecological Systems.
Annual Review of Environment and Resources 30: 441–473.
Geiger, F., 2011. Agricultural intensification and farmland birds. Thesis Wageningen University, 184 p.
Gillings, S., S.E. Newson, D.G. Noble & J.A. Vickery, 2005. Winter availability of cereal stubbles attracts
declining farmland birds and positively influences breeding population trends. Proceedings of the Royal
Society B – Biological Sciences 272: 733-739.
Groot, J.C.J, A. Jellema & W.A.H. Rossing, 2010. Designing a hedgerow network in a multifunctional
agricultural landscape: balancing trade-offs among ecological quality, landscape character and
implementation costs. European Journal of Agronomy 32: 112–119.
Groot, J.C.J. and W.A.H. Rossing, 2011. Model-aided learning for adaptive management of natural
resources – An evolutionary design perspective. Methods in Ecology and Evolution, accepted.
Groot, J.C.J., W.A.H. Rossing, A. Jellema, D.J. Stobbelaar, H. Renting & M.K. Van Ittersum, 2007.
Exploring multi-scale trade-offs between nature conservation, agricultural profits and landscape quality –
a methodology to support discussions on land-use perspectives. Agriculture, Ecosystems Environment
120: 58–69.
Gundersson, L.H., C.S. Holling & S.S. Light, 1995. Barriers and bridges to the renewal of ecosystems
and institutions. Columbia University Press, New York.
Herzon, I., A. Aunins, J. Elts & Z. Preiksa, 2008. Intensity of agricultural land-use and farmland birds in
the Baltic States. Agriculture, Ecosystems and Environment 125: 93-100
Kleijn, D. & W.J. Sutherland, 2003. How effective are European agri-environment schemes on
conserving and promoting biodiversity? Journal of Applied Ecology 40: 947-970.
Kragten, S., K.B. Trimbos & G.R. de Snoo, 2008. Breeding skylarks (Alauda arvensis) on organic and
conventional arable farms in The Netherlands. Agriculture, Ecosystems and Environment 126: 163-167
Moller, A.C., Ryan, R.M. & Deci, E.L., 2006. Self-determination theory and public policy: improving the
quality of consumer decisions without using coercion. Journal of Public Policy & Marketing 25: 104–116.
Newton, I., 2004. The recent declines of farmland bird populations in Britain: an appraisal of causal
factors and conservation actions. Ibis 146: 579-600
Ostrom, E., Burger, J., Field, C.B., Norgaard, R.B. & Policansky, D., 1999. Revisiting the Commons:
Local Lessons, Global Challenges. Science 284: 278–282.
Peach, W.J., L.J. Lovett, S.R. Wotton & C. Jeffs, 2001. Countryside stewardship delivers cirl buntings
(Emberiza cirlus) in Devon, UK. Biological Conservation 101: 361-373.
Perkins, A.J., H.E. Maggs, J.D. Wilson, A. Watson & C. Smout, 2008. Targeted management intervention
reduces rate of population decline of Corn Buntings Emberiza calandra in eastern Scotland. Bird Study
55: 52-58
Ryan, R.M. & E.L. Deci, 2000. Self-determination theory and the facilitation of intrinsic motivation, social
development, and well-being. American Psychologist 55: 68–78.
Sabatier, R., L. Doyen & M. Tichit, 2010. Modelling trade-offs between livestock grazing and wader
conservation in a grassland agroecosystem. Ecological Modelling 221: 1292-1300
Scholefield, P., L. Firbank, S. Butler, K. Norris, L.M. Jones & S. Petit, 2011. Modelling the European
Farmland Bird Indicator in response to forecast land-use change in Europe. Ecological Indicators 11: 4651
Smith, H.G., J. Dänhardt, A. Lindström & M. Rudlöf, 2010. Consequences of organic farming and
landscape heterogeneity for species richness and abundance of farmland birds. Oecologia 162: 10711079
Swetnam, R.D., J.D. Wilson, M.J. Whititngham & P.V. Grice, 2005. Designing lowland landscapes for
farmland birds: scenario testing with GIS. Computers, Environment and Urban Systems 29: 275-296
Tittonell, P., van Wijk, M.T., Rufino, M.C., Vrugt, J.A. & Giller, K.E., 2007. Analysing trade-offs in
resource and labour allocation by smallholder farmers using inverse modelling techniques: A case-study
from Kakamega district, Western Kenya. Agricultural Systems 95: 76–95.
Wilson, J.D., A.D. Evans & P.V. Grice, 2009. Bird conservation and agriculture. Cambridge University
Press, Cambridge, UK, 394 p.