S. Stocker et D. Weihs, BIRD MIGRATION - AN ENERGY-BASED ANALYSIS OF COSTS AND BENEFITS, IMA journal of mathematics applied in medicine and biology, 15(1), 1998, pp. 65-85
We look at a model of migration as part of a whole ecological system.
The purpose is to investigate the mutual relationship of population dy
namics and migration strategies. In particular, we deal with the quest
ion of justifying the cost and danger of migration. We evaluate the fl
ight costs in terms of energy and try to model annual events that infl
uence migration rather than emphasizing single aspects. We apply estim
ates of the total annual energy budget to assess the motivation for mi
gration. We give simulation runs of our model for the migration behavi
our of one bird-of-prey species (Houbara bustard, Chlamydotis undulata
macqueenii) and of one passerine species (stonechat, Saxicola torquat
a). In our model the most important factors determining migration succ
ess are overwinter survival and reproductive success. This is in agree
ment with experimental studies. The model allows strategies to be chec
ked with respect to evolutionary stability in simulating species with
very small initial values for the population size. During a period of
warm winters a nonmigratory behaviour can be an evolutionary-stable st
rategy (ESS), but species which do not migrate are endangered and they
can easily be extinguished during seasons with food supply below the
average minimum (strong winters), even if such seasons are rare.