This week was for the birds — in a good way: Two previously endangered species seem to be enjoying a rebound. The population of the once desperately rare Polynesian Megapode has doubled and the bird could soon be removed from the list of critically endangered species maintained by the World Conservation Union. The species is the Pacific’s last megapode — a large-footed bird that uses hot volcanic ash to incubate its eggs. The successful rebound of the Polynesian Megapode is due to a concerted conservation effort begun in 1993. Meanwhile, scientists in Guyana have discovered a previously unknown population of red siskins, which were thought to be approaching extinction in the wild. The species was once common in the coastal mountains of Venezuela and Colombia, but was decimated by trapping in the 1800s. The Guyana population of red siskins numbers in the thousands — several times the known population of the birds elsewhere in the wild.