Project
title:
Assessment of the effectiveness of agri-environment measures in
conserving great bustards and other steppe birds in the IBA Talamanca-Camarma
Financed by:
Dirección General de Investigación (Projet CGL2005-04893/BOS)
December 2005-December 2008
Principal
researcher: Juan C. Alonso
Summary:
Agri-environment
schemes compensate farmers for income losses associated with measures that aim
to benefit biodiversity. These schemes have been applied in Europe
throughout the last decade, yet without appropriate testing of their
effectiveness. In a recent review, Kleijn & Sutherland (2003) concluded
that most studies used inadequate research designs, which limited the validity
of their conclusions. We aim to do a rigorous assessment of the effectiveness
of an agri-environment scheme currently being applied at the IBA Talamanca-Camarma in central Spain. This area hosts important
populations of great bustards Otis tarda
and other threatened steppe birds. The methodological design includes an
historical comparison (before vs after agri-environment scheme application), as
well as a spatial comparison (agri-environment scheme areas vs control areas),
of demographic parameters –bird densities, productivity, survival- and
behavioural parameters –habitat selection, diet- of great bustards, with
complementary data from other pseudo-steppe birds. The series of data on
demography, distribution and behaviour we have collected during our long-term
study of the great bustard population of the region guarantee the success of
the research project proposed.
Objectives:
Our objective is to determine
if agri-environmental measures currently being applied in the IBA Talamanca-Camarma
to favour great bustards and other steppe birds are really efficient. The measures are: (a) enhancement of the
traditional two-year cereal rotation cycle (keeping stubbles until January, no
ploughing between 1st April and 15th June, no use of
pesticides, herbicides, no burning of stubblles); (b) fields sown with vetch as
winter food for the birds; and (c) some fields left as fallow fields for 4
years. These measures are being applied since season 2003-2004 in the six
sectors of the IBA Talamanca-Camarma holding the largest populations of steppe
birds, with a favourable acceptance by local farmers. For example, during the
2004-05 season measures were applied in 704 ha, with a total investment of 164328 euros.
The hypothesis is that such
measures benefit these species as they provide supplementary feeding, nesting
and refuge areas, but recent evidences have questioned the efficiency of such
measures (Kleijn et al. 2001).
We will examine the following
predictions: in the short term we expect some changes in the behaviour of the
great bustards in the study area:
1.a) a shorter time spent feeding,
and a corresponding longer time available for resting;
1.b) a higher use of the zones where
agri-environmental measures are being implemented, as birds have to move
shorter distances to search for food:
1.b.1) a
higher presence of birds in fields subject to measures,
1.b.2) smaller
home ranges of birds in areas with measures,
1.b.3) a lower winter migration rate
of marked birds from areas with measures to wintering sites;
in the long-term, as a consequence
of the above mentioned patterns, we expect a change in demographic parameters:
2.a) an increase in the numbers of
birds in the study area,
2.b) a higher young productivity, and
2.c) a higher survival rate of birds
living in the study area.
As for other bird species we expect
3) higher bird densities in fields
with agri-environmental measures.
Our
own studies (Alonso & Alonso 1990: Paramétros
demográficos, selección de hábitat y distribución de la avutarda en tres regiones
españolas. ICONA, Lane et al. 1999: Journal of Zoology Lond. 247, 2001: J. Appl. Ecol. 38) have
shown the importance of cereal stubbles,
alfalfa, vetch, and fallow fields as feeding areas, and also as nesting
and refuge sites for bustards. We have also observed the bustards tend to
aggregate in area with higher numbers of conspecifics and higher average
productivity, probably due to the higher habitat quality in these areas (Alonso
et al. 2004: Biod. & Conserv. 13).
However, it is still unknown to what
extent the current agri-environmental program is successful, particularly in
relation to the high investment devoted to this program in compensations to
farmers.
Previous results from other research
projects, such as those from the recent European project EASY (http://www.dow.wau.nl/natcons/NP/EASY/), underline the importance of
experimentally testing the validity of our working hypothesis, and identifying
possible factors that might limit its applicability.
Our specific objectives
were:
- To
compare demographic (bird density, productivity and survival) and
behavioural parameters (habitat
selection, time budget) of birds prior to (1995-2002, with partial data
from 1988, 1989, 1993) and after (2003-2008) application of
agri-environmental measures (this objective will only be studied with
great bustards, the only species for which data are available)
- To compare demographic parameters (those mentioned above for great
bustards; relative densities in other bird species like little bustards
and some passerines) and behavioural parameters (including those of the
previous paragraph and also a study of the diet in great bustards) in
areas of application of agri-environmental measures and control areas
without such measures
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