Individual-based models and the management of shorebird populations
Authored by Richard A Stillman, John D Coss-Custard
Date Published: 2008
Sponsors:
United Kingdom Natural Environment Research Council (NERC)
Platforms:
No platforms listed
Model Documentation:
Other Narrative
Model Code URLs:
Model code not found
Abstract
Individual-based models (IBMs) predict how animal populations will be
affected by changes in their environment by modeling the responses of
fitness-maximizing individuals to environmental change and by
calculating how their aggregate responses change the average fitness of
individuals and thus the demographic rates, and therefore size of the
population. This paper describes how the need to develop a new approach
to make such predictions was identified in the mid-1970s following work
done to predict the effect of building a freshwater reservoir on part of
the intertidal feeding areas of the shorebirds Charadrii that overwhiter
on the Wash, a large embayment on the east coast of England. The paper
describes how the approach was developed and tested over 20 years
(1976-1995) on a population of European oystereatchers Haematopus
ostralegus eating mussels Mytilus edulis on the Exe estuary in Devon, England.
The paper goes on to describe how individual-based modeling has been
applied over the last 10 years to a wide range of environmental issues
and to many species of shorebirds and wildfowl in a number of European
countries. Although it took 20 years to develop the approach for I bird
species on I estuary, ways have been found by which it can now be
applied quite rapidly to a wide range of species, at spatial scales
ranging from I estuary to the whole continent of Europe. This can now be
done within the time period typically allotted to environmental impact
assessments involving coastal bird populations in Europe.
The models are being used routinely to predict the impact on the fitness
of coastal shorebirds and wildfowl of habitat loss from (i) development, such as building a port over intertidal flats; (ii) disturbance from
people, raptors, and aircraft; (iii) harvesting shellfish; and (iv)
climate change and any associated rise in sea level. The model has also
been used to evaluate the probable effectiveness of mitigation measures
aimed at ameliorating the impact of such environmental changes on the
birds. The first steps are now being taken to extend the approach to
diving sea ducks and farmland birds during the nonbreeding season.
The models have been successful in predicting the observed behavior and
mortality rates in winter of shorebirds on a number of European
estuaries, and some of the most important of these tests are described.
These successful tests of model predictions raise confidence that the
model can be used to advise policy makers concerned with the management
of the coast and its important bird populations.
Tags
interference
Foraging behavior
Behavior-based model
Mussel mytilus-edulis
Environmental gradients
Intake rates
Oystercatchers
haematopus-ostralegus
Wading birds charadrii
Spatial variations
Exe estuary