Threats to wildlife
Threatening processes are practices that are reducing or will reduce the biodiversity and ecological integrity of a regional ecosystem and our threatened wildlife. Process that are threats in Queensland include:
Loss of natural habitat through land clearing for pastoral purposes, urban development and agriculture can threaten native wildlife and their habitat.
Inappropriate grazing and fire regimes
Grazing pressure from domestic stock and introduced animals (such as rabbits) can have a negative impact on habitat of native animals. Changes in the frequency and intensity of fire can cause wildlife populations to decline. Some species depend on a suitable fire regime for successful regeneration and survival.
Invasive plants and animals
Salvinia Photo: EHP
The global movement of goods and people are directly contributing to the introduction of plants and animals to areas where they do not naturally occur. These species taken to new environments may fail to survive but some thrive, and become invasive. This process, together with habitat destruction, has been a major cause of extinction of Australian native species in the past few hundred years. Invasive species causing harm to the environment, biodiversity, human health or productivity are declared under Queensland legislation and are subject to a range of control actions, from preventing spread to eradication.
Invasive species include:
- introduced marine pests
- diseases, fungi and parasites
Introduced pest animals place considerable pressure on native plants and animals. While some impacts have been well documented, the true impact of pest animals on Queensland's environment is unknown and difficult to quantify. Foxes and feral cats, which prey on native fauna, have been implicated in the decline or extinction of at least 17 native species.
Examples of invasive animals include:
- cane toad - Introduction of amphibians from overseas brings a high risk of introducing diseases, which would devastate native populations. Examples of pathogens (disease-producing organisms) that have been brought in include the amphibian chytrid fungus. Other potential pathogens include ranaviruses.
- feral fish – - Queensland has the highest diversity of freshwater fish in Australia. Unfortunately this diversity is threatened by the presence of exotic fish (such as tilapia and carp) which can compete for resources, degrade fish habitat, predate native fish species and introduce and spread diseases and parasites. For example, feral fish such as gambusia (mosquito fish) eat eggs and larvae of native fishes and amphibians and there is evidence that they may threaten the survival of populations of red finned blue eye, Edgbaston goby and several endangered frog species.
- feral bee - competition with glossy-black cockatoo and yellow-bellied glider for tree hollows.
- feral ants – (red fire ant, electric ant & yellow crazy ant) - predate upon and compete with native animals, or indirectly impact them by modifying habitat structure and altering ecosystem processes.
Weeds (introduced plants) can degrade native vegetation and have a detrimental impact on biodiversity.
- Rubber vine Cryptostegia grandiflora has the potential to completely destroy all deciduous vine thickets in northern Queensland, which would lead to the loss of entire unique ecosystems and the extinction of many native plant and animal species.
- Dutchman's pipe, Aristolochia elegans, is an introduced ornamental vine that has become a weed in southeast Queensland and northern NSW. The Richmond birdwing butterfly, a feature of the subtropics, lays its eggs on a related native plant species. Female birdwings lay their eggs by preference on Dutchman's pipe, but when the larvae hatch and start to feed on the plant they die, as the introduced species is toxic to them. As Dutchman's pipe becomes more common, the Richmond birdwing may become even rarer.
- Lantana, asparagus fern, mother of millions and guinea grass compete with the native Isis tamarind Alectryon ramiflorus.
Aquarium and other aquatic plants can carry pathogens that can devastate native populations of plants and animals.
There are a number of non-native marine organisms reported in Australian waters most of which were introduced accidentally by shipping and aquaculture activities. Some including several crabs, mussels, seastars and seaweeds have been found to be aggressive and threaten native biodiversity.
Pests and diseases
Diseases, fungi and parasites can reduce the ability of native species to reproduce or survive. Due to the reduced or restricted populations of and the impacts of other threatening processes threatened species can be particularly vulnerable to introduced diseases, fungi and parasites. Some of the diseases, fungi and parasites currently of concern because of their impact on native species include:
- Phytophthora cinnamomi disease affecting many native plants
- Psittacine beak and feather disease (psittacine circoviral disease) impacting on native parrots
- Chytrid amphibian fungus – Chytridiomycosis impacting on native frogs.
Collecting native plants and plant parts is another threat to some of our native plants. Under the Nature Conservation Act 1992and Nature Conservation (Wildlife) Regulation 1994, the harvesting and sale of native plants and plant parts are closely regulated.
Some ferns, tree ferns, cycads and orchids are seriously threatened by collecting. Even common plants like grasstrees and staghorns are at risk. Individual plants can be damaged when stems, fruits and flowers are removed. Collecting a plant's seeds reduces the prospects for successful regeneration.