Species reduced to fewer than 50 individuals in the wild can recover if given active conservation support, according to a study published in Proceedings of the Royal Society B. Researchers at the Zoological Society of London and Monash University reviewed every bird and mammal species known to have fallen below 50 wild individuals since 1950.
The findings challenge the assumption that severely bottlenecked populations inevitably collapse due to inbreeding and loss of genetic diversity. Of 51 species that received direct conservation action such as invasive predator control, habitat restoration, captive breeding, or translocations, 61% recovered to at least 100 individuals. In contrast, 37% of species that received no direct support went extinct, and only 2% recovered to at least 100 individuals.
Lead author Dr. Donal Smith from Monash University School of Biological Sciences said the results offer "an empirically grounded note of hope for global biodiversity." He noted that "population size alone shouldn't determine whether we give up on a species. When we actively tackle the external pressures driving their decline and directly support their numbers, small populations show a striking capability to recover."
The study evaluated 141 bird and mammal species with sufficiently documented histories. Combining threat mitigation with direct population management yielded the highest success rates, as demonstrated by Australia's Lord Howe woodhen, which rebounded from 23 birds in the late 1970s to more than 1,600 today. Co-author Rohan Clarke from the same institution stated that "abandoning critically endangered species because their numbers look too low is a mistake" and that "investing in active, science-backed management isn't futile; rather, it's the very thing that saves a species from disappearing forever."