A wise choice
Wise choice
Researchers have done calculations which show that the oystercatcher is wise to choose medium-size cockles. How can birds be clever enough to make such a wise choice?
Natural variation
The explanation is fairly simple: It is believed that, in the distant past, there were individuals which selected their food in different ways. Some took the smallest cockles, others those of medium size, and still others preferred the largest specimens or perhaps a mixture of all sizes.
Costs and benefits
The individuals which tended to select the medium-size cockles got more energy from their food in relation to the cost of gaining access to it. This led to better health, and thus to higher rates of survival and reproduction. As a result, these individuals contributed a proportionately greater number of offspring to the next generation.
