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Callocephalon fimbriatum

Gang-gang Cockatoo

Update on  Gang-gang research

 

Citizen Science rescues Gang-gang chicks

One of the advantages of citizens monitoring the activity at Gang-gang nest hollows is that chicks that fall out of the hollow can be placed back before they are predated by cats, foxes or birds like the Australian Raven. About a week prior to fledging gang-gang parents will entice chicks to the entrance of their usually 50cm deep hollow by only feeding them there. Sometimes the structure of the hollow entrance make it precarious for the Gang-gang chicks to perch there. This is exacerbated at feeding times where beak to beak contact by a parent can be quite forceful. Thus chicks occasionally fall or are knocked off their hollow rim perch prior to their wings being fully developed. We also suspect that extreme heat and/or smoke leads to a greater number of premature nest departures. On four occasions tree hollow watchers have discovered fallen chicks at the base of nest trees. At one site Government authorities didn’t allow a tree to be climbed but at the three locations where chicks could be replaced they have been quickly cared for by parent birds and successfully fledged. This includes one chick that spent a night at a local vets, separated from parents, but on reunion was immediately cared for by the parents. An added bonus of our study, and also guidance as to what to do if you come across a fallen chick. 

 

To recap if you find a chick on the ground, best to try and arrange to have it put back into the hollow as soon as possible. If it can’t be put in the hollow have it placed up as high as you can away from predators and with some leaf or branch protection from the elements. Don’t remove unless you absolutely have to.

 

 

Thank-you to the hundreds of you that have contributed to this year's research. We have unearthed new and important information on the Gang-gang and how to better look after this beautiful bird. Please keep your feeding and nest activity sightings flowing in - it has been fantastic and thankyou. Some of what we are learning is detailed below.

 

Hollow occupancy - what have we found in the hollows you have reported?

Over the last three years you have made over 500 image based reports of Gang-gang activity at tree hollows. Thank you, to all those who reported sightings. Trees with multiple records or where Gang-gangs were observed entering or leaving hollows were prioritised for checking. The occupancy of hollows during this Gang-gang breeding season was initially checked by visible observation and if no activity was observed then with a pole camera. To date, one Hundred and ninety hollows of known Gang-gang interest were checked in the Canberra area, fifteen at Cooma and four at Tumbarumba.

The following are the initial results

1 Hollows empty – 109 (52%)

2. Gang-gang nest hollow – 22 (11%) note two nests seem to be no longer active

3. Flooded (hollow a likely water source) - 19 (9%)

4. Brushtail Possum in hollow - 18 (9%)

6. Hollow lined with many gum-leaves suggesting possum use  - 12 (6%)

7. Now a bee-hive -6 (3%)

8. Galah nest hollow – 6(3%)

9. Wood-duck eggs or eggshell in hollow 5 (2%) – woodducks have an earlier breeding season and sometimes woodducks and Gang-gangs can use the same hollow within a year

10. Sulphur-crested Cockatoo nest hollow 4 (2%)

11. Crimson Rosella nest hollow 1

12. Rainbow Lorikeet nest hollow 1

13. Kookaburra nest hollow 1

14. Boobook Owl roost/nest hollow 1

 

At least eight of the empty hollows were known Gang-gang nest hollows in previous years. At least three previous nest hollows were flooded this season. Over half of the hollows in which Gang-gangs were observed entering, leaving, chewing bark around or looking into, were empty. Galahs, Sulphur Crested Cockatoos, Rainbow lorikeets and Corellas have all been suspected as being significant competitors of Gang-gangs for nesting hollows, but between them they only occupied 5% of the inspected hollows.

Brushtail possums were observed in 9% of the hollows, with evidence of possum use found in a further 6% of hollows. No Gang-gang nests were found in trees in which Brush-tail Possums were observed but on a few occasions Gangs-gangs were found nesting in the same tree as Sulphur Crested Cockatoos.

Once completed and nest images checked the results will be subject to further analysis, but your work is already providing valuable insights. 

 

Differing breeding times across the Gang-gang range

The methodology of the Canberra survey techniques is being applied elsewhere with nests located at Campbelltown and Moruya, where Gang-gang chicks have already fledged. This is about 4-6 weeks ahead of the nesting occurring in the twenty observed nests in the Canberra area and one in Cooma. In terms of the Gang-Gangs total range, Campbelltown and Moruya are at the higher latitude and or lower altitude parts of this range. Thus they achieve higher temperatures than most areas in which Gang-gangs occur.

Peter and Judy Smith in their 2018 Gang-gang survey of Hornsby Shire, (https://www.researchgate.net/publication/340599663), failed to record any Gang-gangs in areas where from 1970-2010 they were commonly sighted. They concluded that Gang-gangs in the Hornsby and Ku-ring-gai Local Government Areas are certainly very close to extinction if not already extinct. They noted that a similar decline had occurred within a 20km radius of their study area and at the lower elevations of the Blue Mountains. They proposed that this pattern of decline suggests a climate change effect. They noted that the Gang-gang is adapted to cooler conditions and has always been more common at higher elevations and more southern latitudes. They hypothesized that as the climate warms up, Gang-gang Cockatoos can be expected to decline at lower elevations in the northern parts of their distribution.

A result of our citizen science study suggests that Gangs-gangs in at least part of the northern lower elevation range may be able to avoid the higher summer temperatures by breeding earlier than more elevated or southern birds. This is a hopeful finding, that will need further investigation.

Probable nests are also being watched in Tumbarumba, on the outskirts of Melbourne and in western Victoria – none of which appear yet to have produced fledglings. 

 

What are Gang-gangs eating?

I recently did an analysis of the 1800 feeding records I have so far received for Birdlife Australia as part of their preparation of a program to encourage residents and schools to plant Gang-gang friendly plants in their gardens and grounds. About 50% of the records have come from Canberra Nature Map or the earlier Canberra Ornithological Group study. Thank you to all that have contributed - please keep those records coming. The 1800 sightings included 181 food items and recorded 7230 feeding events. (The number of Gang-gangs recorded by a sighting, multiplied by the number of days over which the feeding occurred.).

About 30% of the feeding is on exotic plants. 

Gang-gangs seem to feed from five main food groups. The current data provides the following information

1. Eucalyptus and other Myrtaceae buds, fruit and flowers (56 Eucalypts, 2 Angophora, 5 corymbia, 1 leptospermum and 2 Melaleucas) - 44% of sightings, 50% of events

The top ten species are

Eucalyptus globulus asp bicostata

Eucalyptus globulus spp maidenii

Eucalyptus bridgesiana

Eucalyptus macrorhyncha

Eucalyptus viminalis

Eucalyptus globulus sip globulus

Eucalyptus pauciflora

Eucalyptus sieberi

Eucalyptus mannifera 

Corymbia gummifera

Eucalyptus sideroxylon

 

2. Wattles (35 species recorded) 9% of sightings or 5% of events the top 3 are all bipinnate species

Acacia dealbata

Acacia baileyana

Acacia mearnsii

 

3. Cones and Pods (32 species) 16% of sightings and 20% of events. the top five are 

Liquidambar styraciflua

Cupressus sempervirens

Callitris enlicheri

Cupressus arizonica

Cupressus macrocarpa


4. Relatively small berries with relatively large seeds (31 species) 26% of sightings and 21% of events, the top six are

Crataegus monogyna/laevigata

Cotoneaster glaucophyllus

Pistacia chinensis

Melia azerderach

Persoonia linearis

Persoonia pinifolia

 

5. There are eight Insects and Acacia Fungal galls as food items they only make up 2% of sightings and 1% of events. The majority of records are of sawfly larvae

Thanks again for being part of this research. there is so much more that we are unearthing -so please keep up your magnificent contributions

 

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Species information

  • Callocephalon fimbriatum Scientific name
  • Gang-gang Cockatoo Common name
  • Sensitive
  • Very Rare / Threatened
  • Non-Invasive

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