Nowadays human activity causes loss of biodiversity, mainly by changing diversified
landscapes into homogeneous landscapes. The loss of diversified landscpaes and
intense land cultivation (for example agricultural sector) are causing the loss
of biota. Increased production in nowadays technics of agriculture and ohter
ways of land cultivation have now increased importance of finding solutions how
to maintain biological diversity. The largest biodiversity in landscapes are in
ecotones (or edge habitats), because they are mixture of (two) different habitats.
Due to that, it is very important to concentrate on those areas when practicing
Predatory birds are important indicators for biological diversity because
they are hunting close to ecotones and one of the largest part in their diet consists
of small mammals. Many small mammal spieces live in ecotones. One way to find the
appropriate size of ecotones for preserving the biodiversity in agricultural landscapes
is to study predator-prey relations. In this study we want to find out which species
exactly are living in ecotones and how far they distribute in agricultural landscapes.
Also, we want to study how far are predator birds (mainly lesser spotted eagles
Clanga pomarina) going while hunting
in those landscapes. We would like to give practical suggestions how wide should
edges be in agricultural landscapes so the biodiversity could be maintained.Edge effect occurs when two different
habitats meet and interact. There is higher biodiversity due to mixture of
(two) different habitats – fauna and flora are from both habitats. Ecotones
can be quite similar, for example, when coniferous forest is next to a deciduous
forest or ecotones can be with “sharp” transition, for instance, grassland is
next to a lake or next to a crop field, lumbering pace is next to a forest etc.
(Butet et al. 2006; Masing 1992).
The range of edge effect is considered to
be up to 200 meters from edge to its “neighbor” biotope, but it certainly
differs among different groups of organisms (Hunter & Schmiegelow 2011; Paton
1994). For example, for birds it is considered to be 50-100(200) meters from
the edge (Paton 1994), but for plants it is 10-30 meters (Wilcove et al. 1986).
Habitat fragmentation is a phenomena when
habitat is divided into several smaller patches (Fahrig 2003; Gillespie 2012;
Wilcox & Murphy 1985; White 2013). As a result, there is an increase of
smaller habitat patches and decrease of the total area of the habitat. Smaller
habitat patches will be more vulnerable to extreme conditions (van Apeldoorn et
al. 1992; Butet & Leroux 2001; Haapakoski & Ylönen 2010; Hunter &
Despite the fact that edge habitats are
important, there is lack of information about conservation and management of
edge habitats in Estonia. For instance, Estonian Rural Development Plan (ERDP)
for 2014–2020 mentions the importance of edges of fields (mostly importance of
keeping “lines” of trees and bushes). Yet, there are no quantitative
recommendations for preserving grassland “lines” (Eesti Maaelu Arengukava
Small mammals are living in forests, open
areas and between those habitats – in ecotones. Forest species is for example
Red-backed vole Myodes glareolus (Kozakiewicz
et al. 1999; MacDonald & Barrett 2002; Marsh et al. 2001),
open habitat species are for instance Field vole Microtus agrestis and European (or Common) pine vole Microtus subterraneus. The Eurasian
pygmy Shrew Sorex minutes lives in
edge habitats and grasslands (Butet et al. 2006; Korpimäki 1984).
Yellow-necked mouse Apodemus flavicollis lives
mostly in forest areas which are close to edges (Kozakiewicz
et al. 1999; MacDonald & Barrett 2002; Marsh et al. 2001).
Small mammals have important roles in
ecosystem. They are important part in food chain. Small mammals are on the
second and third place in trophic level. They feed on plants and invertebrates.
While eating different parts of plants (mostly seeds) small mammals are helping
plants to spread (MacDonald & Barrett 2002; Masing 1992).
Small mammals are food for many predators. For
example for many mammals: Red fox Vulpes
vulpes, European badger meles meles, European
pine marten martes martes, European
polecat Mustela putorius and Stoat Mustela erminea. Small mammals are also food for several
birds, for instance, the Common kestrel Falco
tinnunculus, the Rough-legged buzzard Buteo lagopus, the Long-eared owl Asio
otus and the Common buzzard Buteo
buteo (Andersson & Erlinge 1977; Elmeros 2006; Goldyn et al. 2003;
Korpimäki 1984; Lanszki & Heltai 2007; Lanszki et al. 2007; Michel et al.
2006; Šàlek et al. 2010). Several predators which hunt small mammals are either
living or hunting in edge habitats (Heske et al. 1999; Larivière & Messier
2000; Michel et al. 2006; Šàlek et al. 2010; Tattersall et al. 2002). For
example, Lesser spotted eagle prefers to hunt in the edges of large forest
areas (Väli 2003).