Archivos de Diario para septiembre 2021

10 de septiembre de 2021

Gang-gang research update

Dear Hungry Parrot Project contributor

I have already messaged many of you about the Gang-gang citizen science projects and how your Inaturalist sightings are helping us expand our knowledge on this truly magnificent Cockatoo. I also want to publicly thank Erika Roper for allowing me to utilise the Hungry Parrot team and your sightings. For those for which this is my first contact, hi, please keep up your reporting of all parrot feeding, but of course I would like you to pay particular attention to the Gang-Gang. Within the last three decades there has been a 69% decline in its reporting rate across its range, while the 1999/2000 fires significantly impact about 30% of its habitat.

I write to both thank you for the sightings you have already contributed to Hungry Parrots and to encourage you to keep those sightings coming and to dig out and lodge old images you may have. To date about 350 separate Gang-gang feeding sightings have been lodged. I have combined these with a similar number of sightings recorded via the Naturemapr network and about 600 feeding records from the Canberra Ornithologists Group’s The Gang-gang Cockatoo Citizen Science Survey March 2014 – February 2015. A special thanks if you also contributed to this survey.

There are a tens of records, many of them eucalyptus, that I still have work to do to identify to species level. Where I can, I will also extract feeding events from the records, that is the food item captured in the image x number of birds x number of consecutive days spent feeding. Please, where you can, include this information in the comments section of future sightings .The current “highest scores” are 25 birds feeding together and another records states continuous daily feeding over 3 weeks.

To date we have 1180 feeding sightings and they are telling us that the Gang-gang has wide ranging tastes feeding on 132 different plant taxa across 25 different plant families. They are mainly eating flower buds and seed pods but also eat blossom, leaf buds, fruits and seeds. Mostly they are feeding on trees and shrubs but there are images of them feeding on the fruits and seeds of Devils Twine (Cassytha species) and one image of a male eating the head of a Ribwort (Plantago lanceolata).

The major families from which food is obtained is shown below, together with the genus targeted and the number of species fed on within each genus.

Myrtaceae (Eucalyptus 40, Corymbia 4, Leptospermum 2, Melaleuca 2 and Angophera 1)
Fabaceae (Acacia 25, Cercis 1 and Sophora 1)
Rosaeace (Cotoneaster 3, Pyrus 3, Crataegus 2, Malus 2, Prunus 1 and Sorbus 1)
Cupressaceae (Cupressus 4, Callitris 2, Chamaecyparis 1 and Cryptomeria 1)
Proteaceae (Hakea 4, Persoonia 4 and Banksia 1).

Just over 2% (27 sightings) of all food images are invertebrates, with sawflies making up half of these (13). Acacia (4) and eucalypt galls (2), Lerps (5) and Red-eye Cicada (2) are eaten. There is also one sighting of a pair feeding on Acacia fungal galls.

This catholic omnivorous diet seems to suggest that the Gang-gang would have a large potential food supply and that starvation or poor nutrition is unlikely to be a factor in its dramatic recent national decline. However nearly 70% of all food item sightings are from just four genera. Eucalypts comprise 50% of all sightings, Acacias 8%, Liquidamber styraciflua 6% and Pistacia chinensis 4%. Rosaeace are the food item in 12% of sightings and Cupressaceae are in 4%.

Around 2/3 of all records are from Canberra, but when only sightings from native vegetation away from Canberra, are considered there are more than 50 species fed on, with Eucalypts making up a large majority of the food item sightings. In both the Canberra and wider records certain species and types of both Eucalypts and Acacias are targeted above others. It is hoped that with your further reporting of food items we can have a good understanding of exactly what species are being targeted and build this information into guidelines for re-establishment or enhancement of Gang-gang habitat. The information should also enable use to inform people in cities and rural blocks what species they can plant if they want a Gang-gang garden.

I hope you collectively will report over 3,000 Gang-gang food item sightings by the middle of next year, and it would be fantastic to have the current level of Canberra’s documentation reported in other parts of the Gang-gangs range. But you Canberra people are special and I also want you to keep contributing sightings. You are special because:
• At a local scale the Australian Botanic Gardens is a field experiment fifty years in the making with one of the greatest collections of eucalypts and acacias in the country providing a real test of Gang-gang species preferences for these two key food groups;
• At a wider scale the location and abundance of street trees and public plantings is recorded while the level of private plantings has been researched meaning that it is again possible to test that Gang-gang food preference is not just reflecting the relative abundance of plant species; and
• We know of 35 nest trees in the Canberra area, of which 12-16 will be used each year. If we receive a large number of sightings we can study whether the food items selected close to nest sites is different to that observed in areas where birds are not nesting. This may provide insight in to how breeding success could be enhanced.

Thanks for already contributing to our knowledge on what Gang-gangs are eating and I hope I am not being too pushy in asking you to go out and get more.


Michael Mulvaney

Anotado en 10 de septiembre de 2021 a las 07:52 AM por michaelmulvaney michaelmulvaney | 3 comentarios | Deja un comentario