I've been familiar with the Cornell Lab of Ornithology's online resources for a number of years but just ran across their Birds of North America site, which app

I've been familiar with the Cornell Lab of Ornithology's online resources for a number of years but just ran across their Birds of North America site, which appears to have been (relatively) recently updated. There are so many thoughtful details to the design that make it beautiful to interact with, including a spectrogram that appears when the user clicks to listen to a birdsong on the front page. I feel like my bird knowledge has been enriched after just a few minutes of poking around!