Foraging Animals PDF
Optimal Foraging
All animals face the problem of finding resources for growth, maintenance and reproduction. It is assumed that natural selection should tend to produce animals that are very efficient at propagating their genes, and hence at doing everything else, including finding food and mates. At some point in an animal’s life it may experience starvation, and prolonged starvation can lead to death. By natural selection, the animals that survive are able to pass their genes to the next generation, while the genes from animals that die are eliminated along with their unsuccessful foraging behaviour. Foraging (food seeking) in a patchy environment requires complex decisions, such as where to forage and for how long. To make these decisions animals should acquire information from the environment. The questions we may ask include: Should a predator eat only the most nutritious prey? What other factors should be taken into account in its choice of prey?
To optimise a diet
Different foods have different values. In order to optimise a diet, a forager must be able to distinguish between different food items and select the most profitable. This holds for all predators, insects, parasitoids, etc… Many studies have shown that foragers prefer the most profitable food, eg: the size of mussels preferred by crabs was calculated by being the most profitable. Mussels that are too small have a very low energy content while very large ones require a lot of effort (time and energy) to open. So, should the forager only eat the most profitable food items? To what extent should it include less profitable food in its diet? This depends on how long it takes to find the most profitable ones, i.e. how abundant they are both in general and in relation to other food items. The longer the forager has to spend looking for each food item, the more energy it uses, therefore the lower the net gain in energy. To calculate how many food types the forager should accept in its diet, travel
All animals face the problem of finding resources for growth, maintenance and reproduction. It is assumed that natural selection should tend to produce animals that are very efficient at propagating their genes, and hence at doing everything else, including finding food and mates. At some point in an animal’s life it may experience starvation, and prolonged starvation can lead to death. By natural selection, the animals that survive are able to pass their genes to the next generation, while the genes from animals that die are eliminated along with their unsuccessful foraging behaviour. Foraging (food seeking) in a patchy environment requires complex decisions, such as where to forage and for how long. To make these decisions animals should acquire information from the environment. The questions we may ask include: Should a predator eat only the most nutritious prey? What other factors should be taken into account in its choice of prey?
To optimise a diet
Different foods have different values. In order to optimise a diet, a forager must be able to distinguish between different food items and select the most profitable. This holds for all predators, insects, parasitoids, etc… Many studies have shown that foragers prefer the most profitable food, eg: the size of mussels preferred by crabs was calculated by being the most profitable. Mussels that are too small have a very low energy content while very large ones require a lot of effort (time and energy) to open. So, should the forager only eat the most profitable food items? To what extent should it include less profitable food in its diet? This depends on how long it takes to find the most profitable ones, i.e. how abundant they are both in general and in relation to other food items. The longer the forager has to spend looking for each food item, the more energy it uses, therefore the lower the net gain in energy. To calculate how many food types the forager should accept in its diet, travel