How do crop types influence breeding success in lesser kestrels through prey quality and availability? A modelling approach
Authored by C Rodriguez, K Johst, J Bustamante
Date Published: 2006
DOI: 10.1111/j.1365-2664.2006.01152.x
Sponsors:
FEDER/POCTI
European Union
Spanish Ministries
Platforms:
Delphi
Model Documentation:
Other Narrative
Flow charts
Mathematical description
Model Code URLs:
Model code not found
Abstract
1. In the middle of the 20th century the colonial lesser kestrel Falco
naumanni experienced a marked decline in its western palaearctic
breeding range. Although this decline has been attributed to changes in
land use influencing breeding success through lowering the abundance and
quality of prey, a quantification of these effects has not yet been
undertaken.
2. To study how these two key factors influence breeding success, we
developed an individual-based model, which translates the hunting
performance of each adult foraging trip into nestling growth and enables
the effect of crop types on the breeding success of the lesser kestrel
to be quantified. Both the authors' own field data and published
inferential and experimental studies were used to parameterize and
validate the growth model.
3. Model results demonstrated that adult provisioning rates provide very
little information on the relation between prey availability and
breeding success.
4. On the other hand, the model indicated that small differences in prey
abundance among crop types cause large differences in breeding success, highlighting the importance of crop composition in the vicinity of
lesser kestrel colonies.
5. Mean prey biomass is an even more important influence on breeding
success. Our results indicated a minimum mean prey size of 0.6 g, below
which colonies become population sinks.
6. Synthesis and applications. We developed an individual-based model
that simulates the growth in body mass of a lesser kestrel brood as a
function of prey abundance and prey size. These two key factors define a
parameter space in which the conservation status of breeding colonies
can be evaluated. We applied the model to six lesser kestrel breeding
colonies with different mean prey size and different agricultural land
use influencing prey abundance. Our model suggests that the habitat
quality of two of these colonies is sufficient for population
persistence, while management actions to increase habitat quality are
required in the remaining four colonies. An increase in the availability
of prey-rich habitats such as field margins would achieve this goal
without imposing too great a cost on the local farming community.
Tags
Land-use
Conservation
birds
growth
Population declines
European agricultural policies
Foraging habitat selection
Falco-naumanni
Editors introduction
American kestrels