The other day my local newspaper ran a letter from a realtor who is supporting a proposed housing development of 1400 acres. He dismissed the effect on wildlife due to the destruction of habitat that will ensue by saying that the animals will just move. “The hawks will just move elsewhere to find food.” This rather ignorant remark ignores the reality of what ecologists call “niches.” A niche, or ecological niche, is both a habitat supplying the factors necessary for the existence of an organism and the ecological role of an organism in a community especially in regard to food consumption. Every organism occupies a niche specific to their needs. A squirrel can’t live in a stream and earthworms don’t inhabit live trees.
So if a hawk is displaced from its home, it needs to find another place to serve as its niche. Problem is, if it does find a new geographical location that will serve its needs – food, water, nest sites – it is likely that another hawk already occupies that niche. Hawks (or other creatures) are not going to share resources willingly and it’s not likely that this new habitat has enough resources for both hawks. So what happens? One outcompetes the other and one dies or at least is unable to reproduce. There is no reason to expect organisms that occupy the same niche to share; that’s not how nature works. In this parable from Dr. Seuss:
And Nuh is the letter I use to spell Nutches
Who live in small caves, known as Nitches, for hutches.
These Nutches have troubles, the biggest of which is
The fact there are many more Nutches than Nitches.
Each Nutch in a Nitch knows that some other Nutch
Would like to move into his Nitch very much.
So each Nutch in a Nitch has to watch that small Nitch
Or Nutches who haven’t got Nitches will snitch.
I don’t know about snitching, but you get the idea. The competitive exclusion principle states that no two species can occupy the same niche. They both need the same resources and one will outcompete the other. For two individuals of the same species, it’s the same idea. Unless there are sufficient resources, two hawks of the same species cannot survive in the same habitat. So forcing one hawk out of its habitat and saying that the hawk will just find food elsewhere is just ignoring reality. Unfortunately, that’s what often happens.
In limited ways we can mitigate the loss of habitat except to create new habitat. Not to create new land, that’s impossible, but to create new habitat out of what is minimal habitat. We can convert strip mines, minimally or nonproductive agricultural fields, clear cut forests, and land destroyed by natural disasters into useable wildlife habitat once more. Many conservation organizations do just that.
What we need is a system, or legislation, to create new habitat acre for acre for all that we destroy.