What is a Threatened Bird?

In a general sense a threatened bird species is one which is declining in abundance or occurrence and is headed towards extinction.  However, just as ‘oils ain’t oils’, threatened birds aren’t just threatened birds.

There are different categories of threat, or status, for species based on the factors which are affecting them and the speed or dimension of their decline.  These threat categories are determined mainly by the International Union for Conservation of Nature (IUCN).  As a general guide species are sorted into one of the following categories:

•    Extinct
•    Extinct in the Wild
•    Critically Endangered
•    Endangered
•    Vulnerable
•    Near Threatened
•    Least Concern

These criteria are used by governments on local, state, national and international levels to evaluate the health of populations of species, and to determine where to direct valuable conservation resources.  One thing of note is that in these lists the conservation ‘currency’ is taxa, not species.  What this means is that organisms below species level (such as sub-species) can also be listed and be subject to conservation effort.  This allows for the greatest diversity possible to be conserved, such that future generations of organisms can evolve. 

One thing to bear in mind is that there are a number of threatened taxa lists around the world, and a taxon in one particular region may have differing status on different lists.  For example, in Australia the Federal Environmental Protection and Biodiversity Protection (EPBC) Act was established in 1999 to protect species and environmental issues of national importance.  Accordingly, as part of that, there are lists of threatened taxa.  The same applies for each state, such as the Victorian Flora and Fauna Guarantee (FFG) Act 1988.  If we consider the Grey-crowned Babbler we can see the difference in the way a taxon or species is treated depending upon the jurisdiction it falls under.  Within Victoria, the FFG Act recognises this species as Vulnerable due to declines in population size as a result of land clearance, habitat fragmentation, and a reduction of habitat quality.  However, this species is not listed under the Federal EPBC Act as requiring protection, as the species is still common in other parts of Australia (e.g. New South Wales, Queensland, Northern Territory).  This allows species of greater concern nationally to receive more conservation attention, with the knowledge that Victoria is working to reverse the declines.  So the system is designed to work on a complimentary basis, such that conservation resources are allocated to minimise threats to species survival as best as possible.

What are the Threats?

There are a whole host of reasons which can cause declines of species to the point where they are recognised as being threatened.  The most obvious threat is habitat loss.  Since European settlement in Australia vast swathes of habitat have been cleared for agriculture, industrialisation, and establishment of towns and cities.  For example, one-third of Australia’s woodlands and over 80% of temperate woodlands are cleared, and in some areas less than 5% of the remnant vegetation remains.  Coupled with loss of habitat is fragmentation.  As areas are cleared for various purposes the remaining remnants of vegetation are increasing isolated from one another.  This leads to populations of species being separated, and causes a cascade of other problems to develop. 

Many of these remaining remnants are also degraded by grazing or weed invasion, and many species suffer from increased competition with introduced animals (for example, the introduced Common Myna is known to kill nestling parrots in hollows and then take over the site for breeding).  These issues can lead to further problems such as decreased dispersal ability for the birds (as they cannot cover the distances between remnants), genetic inbreeding, and an overall decrease in the viability of populations.

However as we know, not all birds use woodlands.  Many species, such as waders and other waterbirds, are threatened by changes to wetlands and coastal environments.  These can be in the form of altered environmental flows, drainage of wetlands, and reduced water quality through salinisation.  Coastal species also suffer increased pressure from beach recreationists, and many species such as the Hooded Plover have reduced breeding success as a result of this disturbance.

Species also suffer from predation by feral predators (such as cats and foxes), and in the past a number of species suffered extensive persecution.  For example, Peregrine Falcons were once hunted in large numbers due to the impact they were having on pigeon racing.  Whilst this awful practice is still not completely gone, legislative protection of the species and a change in attitude has seen a return of these majestic hunters to a number of former haunts.