Jg. Ollason et al., PREDICTED SEABIRD DISTRIBUTIONS IN THE NORTH-SEA - THE CONSEQUENCES OF BEING HUNGRY, ICES journal of marine science, 54(4), 1997, pp. 507-517
This paper describes a model of the physiology of feeding of a generic
seabird. The bird is represented as two types of tissue - structural
tissue and reserve tissue - and the ingestion of the food is controlle
d by a Holling type II functional response. The food passes into the g
ut, from where it is cleared by a process of exponential decay and is
incorporated into the reserve tissue. The reserve tissue supplies the
energy required for maintenance and movement, modelled as a power func
tion of the total body mass, with parameters appropriate to the curren
t activity such as flying or surface feeding. A behavioural rule is ad
ded to the physiological model. This causes the bird to remain feeding
as long as the mass of reserve tissue is increasing. When the bird ce
ases to feed, it chooses an adjacent feeding area at random and moves
to it. This rule can be shown formally to generate foraging behaviour
that converges to that predicted by optimal foraging theory. Currently
, the model represents the behaviour of an adult seabird in the phase
of life before it begins to breed. This paper presents the model param
eterized for the kittiwake, foraging over the North Sea, the matrix of
patches of potential food being represented by 220 cells, the ICES st
atistical rectangles, and describes the expected distribution of kitti
wakes that would arise if the population fed exclusively on sandeels,
Ammodytes spp. The main difference between the predicted distributions
and the observed distributions is that the observed kittiwakes are mo
re closely associated with the coast during the breeding season. (C) 1
997 International Council for the Exploration of the Sea.