The best thing I heard today was definitely Galapagos from Radiolab [July 17, 2014, 1 hour, 6 minutes]. I re-listened to this one for a nature-inspired post that's coming your way tomorrow, and it was just as good as I remembered. The islands are rapidly changing and conservationists are faced with tough questions about stepping in to restore the land. The last half is especially fascinating. If you heard it when it aired back in 2014 but don't quite remember all the details, I'd definitely recommend a second listen.