Hummingbirds are small birds that are known for their ability to hover near flowers with precision as they sip nectar. While the flight mechanics of hummingbirds have been well-studied, less is known about how their sense of touch helps them navigate while feeding. A recent study led by UCLA researchers published in Current Biology reveals that when hummingbirds are in flight, neurons in specific areas of their forebrain fire in response to air pressure on their feathers and skin. This allows them to create a 3D map of their bodies and gauge their orientation relative to objects around them.
The research also involved studying zebra finches, which have a similar organization in their brains but with slightly less sensitivity in some areas compared to hummingbirds. This suggests that these specific areas in hummingbirds are crucial for their highly specialized flight dynamics. The findings add to the understanding of how animals perceive and navigate their environments, and could potentially lead to advancements in technology and improvements in animal welfare. By understanding how animals perceive touch, researchers hope to develop practices that are less disturbing to them.
Unlike mammals, birds have brains without a layered cortex structure, making it an unanswered question how touch is represented in their brains. The study found that touch for the head and body is mapped in different regions of the forebrain in hummingbirds. Neurons in these regions are activated by air pressure and play a role in helping the birds adjust their flight in a nuanced way. The feet of hummingbirds were found to be acutely sensitive to touch, likely aiding in perching, and had a large representation in the brain. These areas may be even larger in other birds like parrots that use their feet to grasp and manipulate objects.
The researchers were able to observe neurons firing in real-time by placing electrodes on hummingbirds and finches and gently touching them with cotton swabs or puffs of air. By converting the signals to sound for analysis, they confirmed that touch activates specific clusters of neurons in the forebrain and identified receptive fields on the birds where touch triggers firing of neurons. Hummingbirds showed very small receptive fields, indicating their ability to sense even the lightest touch, while zebra finches had larger receptive fields, suggesting less sensitivity compared to hummingbirds.
The study provides valuable insights into how animals perceive touch and could have implications for advancements in technologies such as prosthetic limbs and autonomous devices. By understanding how animals process tactile information, researchers aim to develop methods that are less disturbing to animals and improve their welfare. This research sheds light on the intricate mechanisms that allow hummingbirds to navigate their environment with remarkable precision and offers a deeper understanding of the sensory capabilities of these tiny, energetic birds.