The finches are a type of birds that have lot of variations among them, or rather high speciation. The speciation has been the result of the free niches in the food chains and their adaptations to exploit a particular type of food source. Some finches feed on insects, some on fruits, some on seeds, and that has contributed to different types of beaks among them so that they can be more efficient when it comes to obtaining food. If there are equal amounts of insects, seeds, and fruits in a particular environment, than the numbers of finches that feed upon them will also be roughly the same if there isn't any changes in their food sources. The finches that feed upon the fruits and seeds though will be in higher numbers than the finches that feed upon insects, and the primary reason for this is that the plants are producers, thus they provide more energy, while the insects are consumers, so they provide less energy.
It can be stated that the finches, their numbers, and amount of species, directly depend on the environment and the food sources available in it. As this is a highly adaptable type of bird that often is able to out-compete the other species feeding on the food sources, if there is the slightest gap in the food chain, it will occupy it. The more food sources there are, the larger the population of the finches, and the more different types of food sources there are, the higher the speciation among the finches. The population size though will directly be dependent on the type of food source and the amount of energy it provides for the birds.
