Did you know that February 3 is the “Feed the Birds Day”?
While it may not be a widely recognized holiday, it serves as a reminder of the importance of preserving bird habitats and providing them with food and shelter.
One interesting fact about birds is that they are insensitive to “hot” chili peppers. Birds are just indifferent to the pain-producing effects of capsaicin and enjoy eating pepper seeds.
In 2002, Sven-Eric Jordt and David Julius cloned an avian vanilloid receptor (TRPV1) from chicken sensory neurons and found that the avian TRPV1 channel fails to be activated by capsaicin. The Chicken TRPV1 responded to noxious heat or protons, but not to capsaicin (see here).
The sequences of the avian TRPV1 and its mammalian counterparts exhibit an unusually high level of divergence – only 68% amino acid identity. And these structural differences between avian and mammalian TRPV1 orthologs have important consequences for both plants and animals.
For the pepper plant, these differences appear to underlie the phenomenon of directed deterrence, whereby mammalian predators (that would destroy the seeds) are repelled, whereas birds are favored as carriers for seed dispersal.