Document ID: chunk:federal_register_of_legislation:F2022L00775:reg:18:p7
Version: federal_register_of_legislation:F2022L00775
Segment Type: reg
Provision Reference: reg 18 (pt 7/152)
Character Range: 58281–61341

Tree Island. In 1989 it was the sole Australian breeding site with just 250 breeding pairs. Adults were being killed by native Pied Currawongs (Strepera graculina) because rabbits had eaten out the understorey. Chicks were also becoming entangled in the sticky fruits of Pisonia trees (Pisonia umbellifera). Since eradication of rabbits, the removal of Pisonia trees, and establishment of additional breeding populations on other islands, numbers are continuing to grow.
Australian seabird islands facing invasive species issues include Ashmore Reef, Norfolk Island, Christmas Island and Cocos (Keeling) Island. These important seabird islands may benefit from pest eradication programs, provided the impacts of these invasive species and role with ecosystems is understood.
Control of pest plants on offshore islands can be challenging, particularly where freshwater is scarce, and carting of water (required for mixing herbicide) to islands is problematic. Integrated methods of spraying, burning and revegetating have proved effective on some New South Wales islands. Research and field trials into more effective control methods for weeds that impact seabird islands are a worthwhile priority, particularly species like Tree Mallow (Malva arborea) which require seasonal slashing.
Some weed species may provide important habitat, or be stabilising beaches, dunes or sand islands, and weed control around seabird colonies must be carefully planned. Species such as Little Penguin burrow under woody weeds, such as Boxthorn, and weed removal can alter burrow conditions like humidity or temperature. Removal of native vegetation and weeds may result in erosion that impacts available habitat, or in some cases, total loss of sand spits islands.

24 Wildlife Conservation Plan for Seabirds

Threats

Native wildlife
The influence of native species on the breeding success of seabirds should not be over-looked. Prior to the Macquarie Island Pest Eradication Project, it was believed that the population of Brown Skuas (Stercorarius antarcticus) on the island were being kept artificially high as a result of the availability of introduced rabbits as prey (Ross et al. 1996). Following the eradication of introduced rabbits, there was increased predation pressure by Brown Skua on native seabird colonies (i.e. prey switching from rabbits to seabirds).
Silver Gulls (Chroicocephalus novaehollandiae) can pose a threat to seabirds, particularly around tourist developments and human refuse (Smith 1991, 1992; Egan and Smith 1994). Kelp and Silver Gulls are known to raid tern colonies for eggs and young chicks and in large numbers have the ability to inflict a heavy toll on nesting seabirds (Serventy et al 1971; Ross et al. 1996). Increased abundance of gull species has been related to poor management of waste disposal (Coulson and Coulson 1983) and poor feed management at aquaculture facilities (Harrison 2010). Maintaining and improving good management practices at waste and aquaculture facilities may be important