Animals have astonishing abilities which help them survive difficult circumstances. Many of them, including bears, hibernate. The state is characterized by low body temperature, slow breathing and heart rate, and low metabolic rate. Hibernation most commonly occurs during winter months. Birds develop more feathers to help them remain warm and support their migratory flight. But there is one subspecies, the palm-sized black-capped chickadee, which adds brain tissue instead of feathers when hibernating.
This extra brain power helps the bird remember where it buried the food item for sustenance. The bird returns to these burial sites when it gets hungry in the winter. Some chickadees can grow the brain by nearly one-third by adding new nerve cells, enabling them to recall hundreds of spots where the food is buried.
“The total size of the chickadee hippocampus increases in autumn and winter as does the rate of hippocampal neurogenesis. The hippocampus is necessary for accurate cache retrieval in food-storing birds and is much larger in food-storing birds than in non-storing passerines,” the NLM said on its website.
“To see this happen under natural conditions is truly awe-inspiring. Our hypothesis is that this exaggerated growth occurs when the birds need it the most,” Colin Saldanha, assistant professor of biological sciences at Lehigh University.