Northern rockhopper penguin Northern rockhopper penguin Recent studies show the northern rockhopper penguin, Moseley's rockhopper penguin, or Moseley's penguin ("Eudyptes moseleyi") distinct from the southern rockhopper penguin. A study published in 2009 showed that the population of the northern rockhopper had declined by 90% since the 1950s. For this reason, the northern rockhopper penguin is classified as endangered. The rockhopper penguins have been considered to consist of two species, northern and southern rockhopper penguin, since research published in 2006 demonstrated morphological, vocal, and genetic differences between the two populations. Molecular datings suggest that the genetic divergence with the southern rockhopper penguin may have
Bird-of-paradise lek-type mating system. Others, such as the "Cicinnurus" and "Parotia" species, have highly ritualised mating dances. Males are polygamous in the sexually dimorphic species, but monogamous in at least some of the monomorphic species. Hybridisation is frequent in these birds, suggesting the polygamous species of bird of paradise are very closely related despite being in different genera. Many hybrids have been described as new species, and doubt remains regarding whether some forms, such as Rothschild's lobe-billed bird of paradise, are valid. Birds-of-paradise build their nests from soft materials, such as leaves, ferns, and vine tendrils, typically placed in a tree