As if the elephant bird wasn’t strange enough, a new study has shown that these 3-meter-tall (~10 foot) birds that once stomped around Madagascar were most likely nocturnal. Weirder still, they might have even been practically blind.
Using CT scans of skulls from two species of elephant bird, researchers at the University of Texas at Austin built up a clear picture of what the bird’s brain looked like. It showed that the bird’s optic lobe, a bundle of brain nerves that controls and processes eyesight, was tiny. Within some of the specimens, it even appeared to be virtually absent. In other species, especially of birds, this is a clear clue that the animal doesn’t use its sight much and therefore lived a nocturnal lifestyle.
"No one has ever suspected that elephant birds were nocturnal," Christopher Torres, a PhD candidate who led the research, said in a statement. "The few studies that speculated on what their behavior was like explicitly assumed they were active during the day."
"Humans lived alongside, and even hunted, elephant birds for thousands of years," Torres said. "But we still know practically nothing about their lives. We don't even really know exactly when or why they went extinct."
The new study can be found in the journal Proceedings of the Royal Society B. As the researchers note in the study, bird skulls wrap tightly around their brains, so it’s pretty easy to discern the shape and structures of bird brain just from studying their skull shape.
Weighing a whopping 650 kilograms (1,400 pounds), elephant birds were a family of flightless birds on the island of Madagascar that went extinct between 500 and 1,000 years ago. Their closest living relative is the kiwi, the chicken-sized flightless iconic bird of New Zealand, which also just so happens to be practically blind. They have effectively replaced their sense of sight with a super sharp sense of smell and a keen ear.
This doesn’t seem to be the case with elephant birds, however. The larger of the two species of elephant bird had a large olfactory bulb, a bundle of neurons that process smells and odor. This hints that it was most likely a forest dweller that needed to sniff around for food. However, the smaller elephant bird species had a smaller olfactory bulb and relatively average sense of smell but also had keener vision. The researchers think that this could mean the smaller species was a grasslands-dweller that foraged at dusk, rather than the dead of night.
"Studying brain shape is a really useful way of connecting ecology -- the relationship between the bird and the environment -- and anatomy," Torres added. "Discoveries like these give us tremendous insights into the lives of these bizarre and poorly understood birds."