Do Hummingbirds Hum?: Fascinating Answers to Questions about Hummingbirds

TWO: Systems and Senses

TWO Systems and Senses Question 1: Are hummingbirds intelligent? Answer: Hummingbirds are smart enough to have survived for millions of years, and if we take care of the earth, they will survive for millions more. Hummingbirds are well adapted to their environment. They know when to migrate, when to start nesting, and when it is time to return home. They know how to travel from their breeding ground to their wintering quarters and back. And since they are dependent on high energy sources at frequent intervals, they know where the flower patches are to get the sugar they need to survive all along their migration routes. They learn quickly and remember exactly where their food sources are located and when each resource will be available to them. A bird lover in the eastern United States comments that “my hummingbird comes to my feeder location on the same day every spring. If the feeder is not there, he comes to the window and waits for me to hang it up.” We notice that an experienced bird will look for the feeder in the exact position the feeder was in the last time he fed there. If you move the feeder left or right or up or down a few feet, the bird will first come to the feeder’s original position and hover, looking for the feeding port. After a few seconds it will back off, explore, and find the new location. The bird will do this after being away in Mexico for six months. In our monitoring program, where we band hummingbirds 20 DO HUMMINGBIRDS HUM? throughout the spring, summer, and fall, we encounter the same birds from year to year, and we find that they return in spring within days of when we banded them the previous spring. Birds migrating south in the fall that stop at our monitoring stations arrive to replenish their energy supply within days of when we banded them or encountered them in the previous falls. We have followed this for up to nine years, and other banders have done the same. We know that hummingbirds are a visual species, which means that they remember almost all their clues about the environment and other living things in visual terms. They remember enough detail about each habitat they encounter to decide whether to return or not, and if they return they know the exact location of whatever is of interest to them in relation to everything else in the area. They do not navigate by smell as do salmon, or by ultrasonic clicks like bats, but likely depend on sight to see the stars and the position of the sun for long-distance migration. A hummingbird’s fingertip-sized brain contains an amazing spatial atlas—something like Google Earth but in much greater detail. Their brain can accommodate all this visual information as well as the information necessary to keep them breathing, flying, hovering, reproducing, and surviving. One would hypothesize that the visual areas in the occipital lobe and the motor areas in the brain stem and elsewhere are particularly large. Enlarged motor areas could accommodate the complex motor skills a bird needs to simultaneously remain stable while hovering, its wings beating more than eighty times per second, and accurately insert the bill deeply into a flower—all on a windy day. In 2006, Doug Wylie and Andrew Iwaniuk at the University of Alberta compared hummingbird brains with brains from twenty-eight other bird species. They hypothesized that hummingbird brains might be unique because of their wing speed and their ability to hover and fly forward and backward with great precision. The researchers found that the portion of the hummingbird brain that detects movement in the environment SYSTEMS AND SENSES 21 was proportionally two to five times larger than in any other species. This area is probably responsible, at least in part, for their exceptional optomotor response, which controls visionrelated movement and allows them to see clearly enough to make precise feeding movements while hovering. The passerine birds (songbirds like warblers, sparrows, wrens, thrushes, tanagers, finches, and jays) have the largest brains in relation to their body size. Hummingbirds’ brains are relatively large in relation to body size but not as large as passerines’. In comparison, the brain of a chicken is small in relation to body size. The thinking about avian intelligence is summed up by neurobiologist Anton Reiner at the University of...