Mathematical models of kleptoparasitism
The phenomenon of kleptoparasitism - "food-stealing" - has frequently
been observed, in a wide range of animal species. In this thesis, I extend the
game-theoretic model of kleptoparasitism, proposed by Broom and Ruxton
1998, in a number of ways.
Firstly, using their model, I investigate how quickly the equilibrium state of a
kleptoparasitic population is reached. This work has been published (Luther
and Broom 2004).
I then investigate the case of a single homogenous population of kleptoparasites,
finding which behaviours are Evolutionarily Stable Strategies. This is
done with a variable probability that a challenger succeeds when attempting
to steal food from a handler, and also allowing the possibility that the handler
does not resist the attack. This work has been published (Broom et al
I then consider populations of two groups, one stealing and the other only
foraging, to find ESS's, particularly looking at situations where a mixed population
can be an ESS, and other cases where pure populations are an ESS.
I do this for indistinguishable groups, and then distinguishable groups.
I show that a homogenous facultative population behaving in the Broom and
Ruxton 1998 ESS has the same handling ratio as a mixed obligate population
of kleptoparasites and foragers.
Finally, I discuss some ornithological data on kleptoparasitism, and make a
simple comparison with our models, to see if they are an accurate representation
of the actual phenomenon