Has anyone ever called you a bird brain? Maybe that term is not as nasty as intended. As we will see today, a bird’s brain is remarkably complex.
We know that birds and reptiles are each other’s closest relatives. Let’s compare a lizard brain and a bird brain.
The noses of land vertebrates are at the front of the body so it is no surprise that the olfactory lobes of vertebrates are the most anterior. The olfactory lobes of a reptile are larger than those of a bird. The sense of smell in a bird is pretty poor in most species. Exceptions occur like Turkey Vultures that locate carrion by smell and albatrosses and other tubenoses that smell the oils on the surface of the ocean released by groups of squid or small fish. Homing pigeons use smell for the final leg of a homing flight to find their roost. But smell is about the only function of the brain that is better developed in lizards.
The olfactory lobes make up a small portion of the forebrain; the cerebrum constitutes the majority of the cerebrum. The cerebral hemispheres are involved in complex behavioral instincts as well as learned intelligence. The cerebrum of a bird dwarfs the cerebrum of a lizard of similar size.
Parrots, corvids (crows and their relatives), woodpeckers and owls are regarded as the most intelligent birds. The particularly large size of their cerebrums is not surprising. Chickens and their relatives and pigeons have relatively small cerebrums.
Birds are very good at lab tests of intelligence, particularly the corvids. Birds can be taught to count to seven; researchers required 21,000 trials to teach monkeys to distinguish two from three.
In fairness to lizards, recent work at Duke University has shown that the Puerto Rican anole tested on a food-finding apparatus scored one for the reptile team. These anoles were able to solve problems as fast and sometimes faster than birds. But, the general rule is that birds are smarter than lizards.
The major part of the mid-brain of a bird or lizard is the cerebellum. The cerebellum plays a major role in muscular coordination. The demands of the complex body movements required for flight result in a well-developed cerebrum in birds. Aerial acrobats require complex control of movements to maintain equilibrium. The cerebellum of a land-restricted lizard is smaller.
The optic lobes of a bird or reptile are also part of the midbrain. Again, the optic lobes of a bird are much larger than the optic lobes of a lizard. We know that birds have the best vision of any vertebrates. The large optic lobes of a bird process the complex signals sent from the eye. Birds can certainly resolve colors much better than lizards (or humans), even seeing into the ultraviolet part of the spectrum that we humans cannot see at all. The resolution of images by birds is unrivalled. This stream of data requires a big computer for processing and the optic lobes function superbly in this regard.
The hindbrain of a vertebrate consists mostly of the medulla, the junction between the rest of the brain and the spinal cord. The hindbrain is also the site of the auditory lobes. We expect that the auditory lobes of a bird would be well developed because of the importance of vocal communication in birds. The auditory lobes are better developed in birds compared to lizards but are nowhere near the relative size of the cerebrum, cerebellum and optic lobes. Avian hearing and human hearing are pretty similar and we know that humans have a poor sense of hearing compared to most mammals.
If someone calls me a bird brain, I take that as a compliment: well-developed intelligence, the grace and control of a gymnast or ballet dancer, better vision than we humans can even contemplate and a pretty good sense of hearing. Thanks!
[First published on November 23, 2014]