In the late 1990s, a group of scientists were birdwatching in a remote forest in Ecuador when they heard a call like no other.
Running from July to September, the associated fundraiser raked in $480,000 for the over 1,000 animal shelters participating.
This delicate, rather dainty work, has nevertheless been popular among the inmates, and this year the program oversaw 100 caterpillars.