A nasty dose of the flu put a big crimp in my outdoor activities this week, so apart from one smokey sunset session most of this post’s images date back a year or so.
The previous post touched upon wildlife that makes a home in Sydney’s CBD. This week I want to focus on the wildlife of the largest areas of ‘artificial’ habitat we’ve created around Sydney, the various forms of modified grassland.
Sydney contain natural grassland prior to the arrival of Europeans, especially amongst the open forest and woodlands of the Cumberland Plain. Regular burning by the Dharawal probably kept coastal vegetation in a much more open form than at present, promoting new growth to attract kangaroos and wallabies. Nonetheless, even if the landscape was more much open than present coastal bushland, Sydney had nothing like the vast areas of open grassland that now exists in the form of paddocks, playing fields, flood basins, golf courses, parklands and community open space.
At first sight these artificial grasslands might seem to offer little to wildlife. They tend to be slashed or mown and heavily used for activities like weekend sport. Much of the grass never gets to set seed. Conversely, human disturbance is mostly concentrated into just a few hours each week, and much of the grassland is well watered and even fertilised. The result is that species that can take advantage of the non seeding grasses or associated invertebrates have access to an immense food source.
The thing I find most fascinating about the wildlife of Sydney new grasslands is that it includes several grassland specialists whose natural range is to the west of the Great Divide. These include some of the most familiar wildlife sights around Sydney, white cockatoos.
There are three different species of white cockatoo in Sydney. Most common are Sulphur Crested Cockatoos, the largest of the trio and the only one that is a native inhabitant of the Sydney basin.
The numbers of Sulphur Crested Cockatoo in Sydney have increased hugely over the last two centuries. They naturally inhabit coastal forests and woodlands, but are equally happy in the new grasslands, crops, gardens and anywhere they can pry open a garbage bin. Their curiosity and behavioural flexibility makes them the one of the most successful occupants of modified habitats in Sydney. I suspect that a big contributor to the success of all the large parrots are the hollows produced by one of our most abundant trees, the Sydney Pink Gum or Angophora costata. This provides lots of potential nesting sites, usually a major constraint on hollow nesting species.
The two ‘out of range’ species of white cockatoos in Sydney are Little and Long Billed Corellas. The Little Corella is the smallest and plainest of the group. Their natural range is the arid woodlands west of the Great Divide. In Sydney they are concentrated along the coastal strip. They forage on grasses, pulling them out of the ground to eat the starchy base of the plant. I’ve seen them feeding on spinifex grass in the sand dunes and even amongst the drifts of seaweed. Very novel habitats for a bird of the arid inland!
Long Billed Corellas are more colourful than their smaller relative and have a flush of red feathers around the neck. Their normal range is in the northwest of Victoria,. That long bill allows them to extract grass roots from deep in the soil. Long Billed Corellas are most common in the western parts of Sydney, including Parramatta Park and the Mount Annan Botanic Gardens.
Galahs are another species of cockatoo commonly seen on Sydney grasslands. Instead of white they are a subdued but beautiful mix of white, pinks and greys. They are typically an arid country species but are very widely distributed and may have found their own way to Sydney. Galahs don’t seem to occur in the same numbers as the other white cockatoos but are distributed right across the city.
So why did these western cockatoos take up residence in Sydney? The most probable explanation is that the Corellas and Galahs are the descendants of aviary escapees. Another suggestion is that large numbers were released by commercial trappers when the large scale export of Australian parrots was banned. A third, least likely option, is that one or both species arrived in Sydney as part of large scale dispersions during major drought events.
Red Rumped Parrots are much smaller than the cockatoos and the parrot most associated with grassland habitats, to the extent that they are often called Grass Parrots. Their natural range does include the coastal side of the Great Divide but their numbers have clearly benefited from the expansion of urban grasslands. They are particularly fond of well watered grasses such as golf courses. They have a high level of sexual dimorphism, the girls in mottled shades of green and brown while the boys are emerald green with a bright red patch on the rump. They are always on the lookout for raptors and other predators.
Moving away from the parrots another characteristic group of grassland birds are the finches. The commonest finches around Sydney are Red Browed Finches. They are a bit unusual in that they prefer dense vegetation and only forage in the open where they have an easy retreat back into the shrubs.
A more typically grassland species is the Chestnut Breasted Finch. They are found in tall rank grasses on the edge of wetlands on the Cumberland Plain.
Double Barred Finches are the most abundant finch in paddocks or planted fields. They have a wonderfully distinctive call that announces their arrival long before you spot them.
The final set of images in this week’s have nothing to do with grasslands. Flying birds silhouetted against the sunset. is a subject I find endlessly appealing so here’s a few more.