29.10: Conservation of Declining Populations
Conservation of declining population focuses on ways of detecting, diagnosing, and halting a population decline. The approach uses methods to prevent populations from going extinct.
Conservation efforts often utilize scientific approaches to identify the reasons, or the agents, causing the population to decline. This approach then devises steps to remove, oppose, or neutralize the agents.
Conservation efforts may also introduce a test group to determine the probable cause of the decline. The translocation of the remaining population to unaffected areas follows if the cause is confirmed. In cases where the remaining population is too low, or at risk of further reduction, a protected stock is bred rapidly and released to bolster the population. Subsequent monitoring confirms the success of population re-establishment.
The conservation approach has successfully restored the population of an endangered Australian bird—the Lord Howe Woodhen. These flightless birds are endemic to Lord Howe Island off the Australian coast. The population of these birds began dwindling since the beginning of human inhabitation within the island. The population had reached a state of extinction when an ornithologist, Dr. Ben Miller, identified the situation.
Methodical testing and rejection of several hypotheses identified the feral pigs as responsible for the contraction of the population size of these birds. These pigs, introduced into the island with human settlement, killed and ate the incubating birds and also destroyed their nests and eggs.
Miller’s finding resulted in the elimination of the pigs and instituting a breeding program to rear these endangered birds within an enclosed facility. The progeny from the breeding program was released into the wild in batches and monitored closely. Subsequently, the released birds started breeding, and stabilizing their population and saturating all the suitable habitat on the island.