According to the International Union for the Conservation of Nature's latest 'Red List of Threatened Species', "17,291 species out of the 47,677 assessed species are threatened with extinction", including "21 percent of all known mammals, 30 percent of all known amphibians, 12 percent of all known birds, and 28 percent of reptiles, 37 percent of freshwater fishes, 70 percent of plants, 35 percent of invertebrates assessed so far".
Meanwhile, in our garden in Gippsland we've recently added more rocks and installed 6 nesting-boxes, two for King Parrots and Crimson Rosellas, one for Tree-creepers, one for Grey Shrike-Thrushes and two for bats. Pictures coming soon, but it will take some time before the birds become interested in them, so they might not get used until next season, unfortunately. However, most native birds breed from about September to late summer, so there is time yet. The bat nesting-boxes are for sleeping in during the day as well as breeding, so hopefully they will be used before too long. Fortunately none of these species are rare, but they need hollows in trees to nest in, so the bushfires of last summer have probably put them at a disadvantage. However, one rare and endangered Victorian bird is the Powerful Owl (Ninox strenua), which are threatened because they have trouble finding hollows large enough to breed in now that many large old trees are logged or destroyed in fires, so I'll be making a large nesting-box for these birds soon.