Pigeons were the first birds to have their brains fully “mapped.” Published in a 200-page opus called A Stereotaxic Atlas of the Brain of the Pigeon by Harvey J. Karten and William Hodos working at the Walter Reed Army Institute of Research. They built on earlier work in the stereotaxic method in both mammals, but previous approaches to bird brains had been partial. I have no idea what stereotaxic means to this day except that it was the preferred method of imaging a brain along a particular axis at that time. The pigeon was selected because its behavior had previously been studied and because of the existence of standardized breeds, which would hopefully mean less variation and therefore a more accurate atlas. Previous studies of pigeons included B.F. Skinner’s, in which he tricked pigeons into being superstitious in a similar way to superstitious human bowlers; in general, the pigeon’s overall proximity and breeding by humans has made it an easily accessible object of study.
The Introduction to the Atlas delves more into the methods of slicing open pigeon brains than it does to the history and conception of the project, however. The text itself unfolds like an extensive and complicated abstract coloring book or a series of Rorschach ink blots that have been somehow dissected. To open up these pages and read some sort of intelligence into these cross-sections requires a specialty training well beyond me. What we have ultimately gathered from bird brain studies in general is that there exists an entirely different pattern of brain evolution, an alternative pattern of meaningful nerve networks which still somehow resulted in tool-making, complex social arrangements, and, of course, song.
The irony of pigeons being the first birds to have their brains mapped is that pigeons are the birds whose “brain maps” (meaning, now, their mental maps of space and laction) have been most thoroughly used by human society. Homing pigeons were bred to carry messages from station to station with the expectation that they would find their way home. Though homing pigeons were domesticated animals bred deliberately, the ability of many birds to remember where they came from and go back to it is one of the most common signs of an intelligence that doesn’t quite fit into the readings of animal intelligence based on human ideas about intelligent abilities. Instead, it is read more along the lines of instinct and group behavior in migration patterns. What is in humans a good skill some have (sense of direction) is, in birds, often a species-level ability that determines yearly patterns and socialization. Humans only have horizontal movement open to us, most of the time; if you live in a space where vertical and horizontal movement are equally open and the only visual markers available are on the Earth far below, your brain does, it turn out, develop an uncanny ability to remember where you live.