Biodiversity Strategy - Gosford City Council - NSW Government

connections but may provide “stepping stones” in an otherwise modified urban environment.
Corridors enable movement and interaction of plants and animals – both on a physical and
genetic level. Without these corridors some species, such as small ground dwelling mammals
would be unable to move between habitat areas, particularly in the event of natural disasters
such as through bushfire or flood and human disturbances.
Corridors are vital to species being able to maintain viable populations, enabling species to
cross pollinate or interbreed and maintain genetic diversity. Without adequate linkages species
evolve in isolation, perhaps unable to breed and in the longer term are likely to become extinct
in isolated areas. The long term result of not protecting linkages is that isolated patches of
vegetation become ‘sink habitats’. These are areas where the death rate of native species
exceeds the birth rate, ultimately resulting in declining species abundance and the risk of
extinction for these populations. One example of an island or sink habitat is Blackwall Mountain
Reserve, which is isolated by roads and lack of connectivity to other reserves in the area.
A considerable amount has been written about the value of corridors for native animals
(Saunders and Hobbs 1993, Saunders and Hobbs 1991 Hussey et al 1991, Lindemayer 1994)
including debate about their value (Bonner 1994 etc).
Not all areas of native vegetation may function as a wildlife corridor and not all species will
utilise the corridor in the same way. For example, Yellow-bellied Gliders (Petaurus australis) are
likely to require a minimum of 100 metre corridors plus tall trees to enable gliding as well as
adequate numbers of hollow bearing and feed trees. Studies done on invertebrates by Mader
indicate that < 6 metre roads can pose a total barrier which insects and spiders will not cross
(Bennett 1990). This needs careful consideration as invertebrates are an important food source
for small mammals and permanently limiting their range can limit the range of other species
which depend on it.
Condition may also be a disincentive or barrier to animal movement. Small mammals may
require good coverage such as a dense shrub layer before they will move across areas. A study
on radiotelemetry of tagged mice (Bennett 1990) demonstrated that they preferred to move in
fencerows rather than in more open landscape elements. Other studies have indicated that
gaps < 10 metres can inhibit their movement. (Bennett 1990). Barnett et al. (1978) showed that
gaps of more than 3 metres appeared to inhibit movements of Brown Antechinus and Bush Rat
(Bennett 1990).
A - 5.6.3
Regional Corridor Planning
Payne (2001) undertook field surveys on behalf of the CCCEN to investigate wildlife corridors in
the Gosford, Wyong and Lake Macquarie local government areas. Payne identified “keystone
habitats” that comprise resources that are essential to the survival of particular species. These
were sites that contained Swamp Mahogany forest (MU 37) that may support a suite of fauna
species including 10 threatened species; and Scribbly Gum Forest (MU 15) where a Banksia sp.
understorey is present and occurs in close proximity to Swamp Mahogany forest as a crucial
habitat for the Squirrel Glider (Smith 2000) and also for woodland. Bluegum Gully Forests and
Gully Rainforests that have a specialised understorey frugivorous component were considered
to be important for fruit eating pigeons. Sydney Bluegum and Swamp Mahogany are considered
important resources for the Yellow-bellied Glider.
Payne (2001) provides recommendations for where major regional corridors should occur noting
that Gosford was fortunate to have some of these areas protected as National Park and COSS
areas. It was observed that as the COSS lands are primarily on ridgelands that connectivity has
been lost with few connections along the valley floors such as Erina Creek to connect the major
ridges of Mount Kincumba, Rumbalara and Bouddi. Payne noted that it is important that the two
councils work together to maintain a connection over the Ridgeway from the Gosford LGA to the
Wyong LGA. Specific recommendations for connectivity are to link Rumbalara to the Ridgeway,
Biodiversity - Technical Report Page 123