At least two major population declines, possibly due to disease epidemics, have occurred in recorded history: in 1909 and 1950.
The data also pointed to two major population declines in mammoth history: one that occurred 250,000 to 300,000 years ago and another that took place around 12,000 years ago, at the end of the last Ice Age.
Though once one of the most common frogs in south-east Australia, the green and golden bell frog has endured major population declines, particularly in highland areas, leading to its current classification as globally vulnerable.
Amphibians epitomise the modern biodiversity crisis, having exhibited major population declines, disease susceptibility, morphological deformities, and well-publicized recent extinctions [1], [2].
The disease has more recently been recognized as the principal cause of major population declines among wild rainbow trout populations in the intermountain region of the U.S.A with serious negative impacts on sportfishing and allied industries [ 5- 7].
Genetic monitoring holds promise for the rapid detection of major population declines [ 41] however, the discrepancy between biologically significant patterns and the conditions where these patterns are genetically detectable should always be considered [ 18, 19].
Major reasons for population decline include habitat destruction, habitat fragmentation and poaching.
Man-induced mortality of birds caused by electrocution with poorly-designed pylons and power lines has been reported to be an important mortality factor that could become a major cause of population decline of one of the world rarest raptors, the Spanish imperial eagle (Aquila adalberti).
In P. chiapensis, small population size, rather than disturbance, appears to be a major factor in population decline, as small populations of both conserved and disturbed habitats displayed low colonization potential.
