Birds of the Ginninderra Gorge and Murrumbidgee River Corridor
Presentation by Chris Davey, President, Canberra Ornithologists Group, given at the inaugural meeting of the Ginninderra Falls Association.
As I understand it the meeting this evening is to initiate the formation of the Ginninderra Gorge Association with the aim of setting in motion the creation of the Murrumbidgee River and Ginninderra Gorge National Park. To date no boundaries have been discussed but I would like to think that the area would include not only the Ginninderra Gorge but a section upstream and downstream where the Ginninderra Creek meets the river. I envisage the corridor to not only extend on either side of the river up to the corridor ridge line but also extend out in places to encompass those areas of native grasslands and woodlands that abut the corridor ridge. In this way all of the major habitats except for wetlands and the high country vegetation that occurs in the ACT and surrounding region would be included.
I have been asked this evening to talk on the birds of the Ginninderra Gorge and Murrumbidgee River corridor but I would also like to include those species that could be found in the surrounding grasslands and woodlands. The possibility of a Murrumbidgee-Ginninderra Gorges National Park would be of enormous value to the conservation of birds in the local region. As the urban fringe within the ACT spreads ever closer to the riverine habitats there is an urgent need to conserve habitats associated with the local river systems.
The Canberra Ornithologists group is a club of some 320 members and has been going since 1963 so we are coming up to our 50th year. Our area of interest includes not only the ACT but also the surrounding district from Yass, Goulburn, Lake Bathurst and to Bredbo in the south.
Each year the Group produces a Bird Report with the aim of providing a summary of COG’s entire database records of birds recorded in the region during the year and draws attention to significant changes or trends in the distribution or abundance of species. It is this report and my own experiences of 40 years of bird watching in the local region that I will draw on.
Depending on the chances of seeing a bird and of its distribution with the region we can rate each bird species by its abundance, whether it is a resident and whether it breed here or not. All States and Territories have legislation that allows for the declaration of species to be threatened. In the ACT threatened species can be classifies as Endangered or Vulnerable whilst New South Wales and Federal legislation also allows for Critically Endangered. I should point out that a species is not classified by its abundance but rather by its rate of decline. Some species naturally occur in large numbers and many occur in small numbers so a rare species, that is one that one does not often see, is not necessarily threatened. This highlights the importance of long-term observations over a species range to determine whether numbers are increasing or decreasing. Bird watching and associated activities is now well recognised as a major attraction as demonstrated by the ever increasing number of regional Bird Route brochures produced by local councils and obvious to anyone perusing the local tourist information centre. With its proximity to the large urban population of the ACT the proposed area with its mix of unusual habitat types would soon become a major tourist attraction for those interested in the region’s flora and fauna.
In summary, with the ever increasing expansion of suburbia in the ACT and increasing push for the government to use Nature Reserves for uses such as horse riding, mountain bike and motor cycle riding and $X driving, in other words the more active pursuits, an area of conservation within New South wales yet close to the ACT boarder would be of considerable importance to the avifauna of the local region.
The possibility of a Murrumbidgee River Corridor/Ginninderra Gorge park would allow for the conservation of much of the local habitat types, in particular the riverine habitat that in the ACT is now under increasing developmental and recreational pressure. The creation of such a reserve in association with the possibility of conservation agreements on private lands would go along way to ensure that the services that birds provide will continue into the future.
Notes for individual slides
According to the 2009-10 Annual Bird Report there were 234 species reported during the 12 month period starting July 2009 within the Canberra Ornithologists area of interest. I have examined these records and from my experience I estimate that the possible number of species that could use an area such as the Murrumbidgee Corridor and the Ginninderra Gorge would be around 190, that is 80% of the species recorded in 2009-10. If I exclude those species restricted to grasslands and woodlands then the number is reduced to 160 or 68% of the total.
Grouped according to their abundance and distribution 50% of the 190 could be regarded as common in the local region, 30 as uncommon and 20% as rare. Seventy-four percent of the species are regarded as breeding within the region and 60% of the species are resident with 20% as either summer or winte migrants and the remaining 20% regarded as vagrants to the area.
Of the 28 species listed as threatened within the region there are 18 that could occur within the proposed area. In addition, there are 4 listed by the ACT Flora and Fauna Committee on a Watching Brief. These are species that we have so little data on that we cannot determine whether numbers are increasing or decreasing.
The COG database, with records from the early 1970’s provides 278 records of observations listed as coming from Ginninderra Falls. These records come from 12 visits to the area between 1984 and 2004. Eighty-one species have been recorded and this really only shows the lack of coverage of the area by bird observers who are prepared to record their observations to the database. This includes one visit I made in October 1988 when I recorded 26 species.
Of the 81 species recorded from the Falls the Flame Robin, Scarlet Robin, Gang-gang, Little Eagle and Varied Sittella are five species listed as threatened either in the ACT or surrounding New South Wales.
Let us now look at some of the species of interest in more detail:
Of particular importance would be the conservation of the rich raptor community that would be severely affected by proposed urban development within the Molonglo Valley and inappropriate development within the Molonglo River Corridor.
|4||The Molonglo Valley is regarded as significant within the ACT for its diversity and abundance of raptors. There are 12 species of raptors within the valley of which 10 are breeding residents and two others may breed there. The proposed developments within the valley are likely to severely impact on all but two of these species (Sparrowhawk and Hobby) and an area such as the proposed Murrumbidgee River-Ginninderra Gorge National park would be of considerable value in offsetting the effects of the proposed development. As an example the Little Eagle – a declare threatened species in the ACT and NSW is now only known to breed in one or possibly two sites in the ACT, both in the Molonglo Valley area. This is down from 11 known nesting sites in the ACT in the last 10 years. This species has been recorded from Ginninderra Falls but its breeding status in the area is unknown. A draft Action Plan for the Little Eagle has been produced for comment by the ACT Government and COG has recommended that this species by up-graded to Endangered in the ACT. Another species that is known to inhabit the Falls area is the Peregrine Falcon and again the nesting sites on cliffs could be severely compromised by any Molonglo Valley development. Of the 12 raptor species six have been recorded from the Ginninderra Falls. Recently whilst at Shephards Lookout looking downstream towards the Gorge area I was surprised to see a White-bellied Sea-Eagle and most unusually an Osprey using the river corridor.|
|5||The Rainbow Bee-eater is a summer migrant to the region. This species breeds in tunnels dug either in the sandy beaches along the river or into erosion gullies. The habitat provided by the Murrumbidgee corridor is of major importance to the breeding success of this species.|
|6||Many species of honeyeaters migrate to the local region to breed, returning to their wintering areas in the autumn. The autumn migration out of the region is particularly spectacular between late March and early June when many thousands of birds pass out of and through the ACT. The river corridors are well known transit routes and overnight refuelling spots where at certain locations thousands of Yellow-faced and White-naped Honeyeaters may pass through in an hour. The migration attracts other moving species and in particular various raptor species. Various exit points along the corridor are well known and can be easily disrupted as has happened with development in the Point Hut area. Again, the conservation of areas such as the Gorge will be of great benefit for the safe migration of these species.|
|7 & 8||In south-eastern Australia there are eight different Robin species, all of which but one (Pink) could occur in the Park. Five of these could well occur in the Gorge with 3 having already been observed. For reasons which we are not sure of four of the seven are listed as Threatened or on the ‘Watching Brief’. These include the Jacky Winter, and the Scarlet, Flame and Hooded Robin. The Eastern Yellow Robin appears to be relative common in the area whilst the Red-capped and Rose Robin are vagrants.|
|9 & 10||One might expect up to 17 species of cockatoos and parrots within the area. Many are common but threatened species would include the Superb Parrot, Gang-gang, Glossy Black-Cockatoo and the Swift and Turquoise Parrot.|
|11||A species that I believe we should be concerned about is the Fairy Martin. This species is a summer migrant and breeds in the area in its unique bottle shaped mud nests. They normally nest under overhangs on cliffs, erosion gullies and road culverts but unfortunately today unused sites are the norm. Although not recorded from the Gorge I see no reason why this should be a good spot for the species to breed.|
|12||Of the eight species of thornbills that occur in the ACT region all but one are relatively common and can be found in the possible Park area. The Little or Yellow Thornbill is classified as an uncommon breeding resident. Although not a species to get one’s pulse racing it is one that is particularly difficult to identify without knowing the call. It tends to be found in vegetation with needle-like or feathery leaves and so the river corridor and gorge with its Casuarina and Callitris tree species is I believe a stronghold in our region.|
|20||Grey-crowned babbled-extinct in region but who knows?|