Hummingbird Greed

When I was in Haines recently (a small town north of Juneau), I watched hummingbirds swarm around a feeder for a long time. At first I sat inside the cabin and every time I raised my camera, they would notice the movement and fly away. A friend took this picture by standing still ready to shoot until they all flew back. Eventually I sat outside on the deck watching them and it was the first time I had ever heard the sound of their speech. I was familiar with the whirring sound their little wings make, but not with the angry chirps they use with each other when fighting over the nectar. One hummingbird kept others away by flying at them when they came near and making sharp sounds. At first, as you can see in the picture, they fed together. And then, one of them began guarding the red globe zealously, expending precious energy in fighting off the other birds. It would dip its beak into the tiny hole and sip, and as soon as another showed up, would charge it, and then go back to the feeder and drink again before another bird came to feed. It seemed like such senseless behavior. The feeder was an abundant public resource, filled up every morning, always more than enough for all of the birds. Yet this one bird began treating the feeder as a private resource, allowing only a few to drink from it. I felt uncomfortable watching it as the behavior was so very familiar. History tells us this story over and over. Which part of our brains tells us that there won't be enough for everyone?