ed to the factory so that they can be sent to a store made from still more machinery built and maintained using still more energy, and so on through a long chain that must occur before the cook ever enters the picture. Even when the can of soup is bought and transported to the kitchen it must be heated on a manufactured stove run on still more energy, additional to what went into the metal from which it is made being taken from the ground, shipped and turned into a stove that is shipped to a store and then to the kitchen, the soup is poured into a bowl and eaten with a spoon that have consumed more energy to be built and shipped, all so a simple lunch can be served. Of course to dump the soup into a pot, and, once heated, into a bowl, and to lift the spoon from bowl to mouth does require metabolic energy, but it is a fraction of the amount of energy from non-metabolic sources that allowed the soup to be there in the first place. And we won’t discuss the dishwashing that follows, or the disposal of the tin can or the manufacture of the soup bowl.
No other species has that option to access energies derived mostly from fossil fuels, but also, to varying degrees, from atomic power, wind and solar power, water-driven turbines, battery power or even tidal or geothermal power. The late John A. Livingston, Canadian naturalist-author, referred to technology as a “prosthesis,” a contrivance that humans have come to depend upon for their survival. He provocatively argued that humans were the first species to domesticate themselves. Most people are not really aware of just how much they depend on technology, and the expenditure of energies that do not derive from their own bodies. It is all taken for granted.
Now consider the cormorant. The energy that she needs to expend in order to survive must be balanced by the energy derived by the food consumed. That is true of every species but humans. Compared to humans, the chain of energy expenditure is relatively simple. The cormorant must swim underwater, pushing against the inertia of the water to drive her body with enough speed to overcome the fish, while holding her breath (oxygen being essential for metabolism to occur and birds, like us, get their oxygen from air) and maintaining all bodily functions. During the nesting season the amount of fish captured must meet her increased needs to produce eggs, and later to feed her young. Not all of the fish is converted into what the body needs, with the remainder ejected as excreta that contains concentrated nutrients often transferred from water to land.
Let us imagine a situation where cormorants really could eat all the fish. Visualize a swimming pool, stocked with 200 or so fish, each maybe 4 to 5 inches long, thus a perfect size for cormorants to swallow. Let us further pretend that these fish are sluggish in movement, thus easy to catch.
Now let us imagine two hungry cormorants placed in the pool. They must eat to survive, obviously, but what would happen if the only place they could eat was in the pool? At first the cormorants would do well, there being 200 fish distributed in the pool. It would be relatively easy to catch the first ones as none would be too far away if they were evenly distributed. If concentrated in one part of the pool they’d also be easy to catch. As the number of fish went down the cormorants would have to expend still more energy to catch each fish because each fish would have more space to flee.
Eventually one of two things would happen: In Scenario One the cormorants would eventually catch all the fish and then starve, because that was the only place where they could eat (and we are imagining fish who are conveniently sluggish in movement, so ultimately all could be caught). That would mean no fish and thus, soon after, no cormorants.
Scenario Two requires that we imagine the fish not to be so sluggish and the pool larger. The fish are fast-moving, and whoever owns the pool makes sure that they have lots to eat so that they maintain high energy levels.
In this state of affairs as the number of fish decreases