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Possible cooperative feeding by Grey Butcherbirds Cracticus torquatus.

I knew Grey Butcherbirds Cracticus torquatus (Fig. 1) occurred in the Croydon area of Victoria, but had not seen one in the vicinity of my home until May 2018. They frequently skewer uneaten food on twigs or hang it in forks of tree branches, thus their common name. I had just provided a tiny piece of low fat, hard cheese to my 'co-owners' of the back and front yards, four Australian Magpies Cracticus tibicen. These tiny snacks are provided irregularly and the Magpies are not dependent on the human residents of the property, although the male, in particular, makes good use of my activities. When I garden, this Magpie is usually there, and snatches any worm I may disturb. When I chop wood, he stands by my feet and pounces on any grub revealed by the splitting of wood. On this particular occasion, I was turning to go inside after giving the Magpies a snack when I saw a Grey Butcherbird alight on the nearby side fence. I offered a snack, but the bird was very timid and flew away. This was my first encounter with the Butcherbird.

Some days later, I again gave the Magpies a snack and saw the Butcherbird on the side fence. Not wishing to frighten it, I turned to go inside, but it flew to a hanging basket on my back verandah, where it stared at me until I threw a tiny piece of cheese onto the ground. It then scanned the area carefully, I presumed for danger, before it darted down and flew off with the cheese.

This Butcherbird visited rarely, always following a visit by the Magpies, and it always flew off with the cheese. However, in late July, it went to the oak tree beside the back verandah and ate its snack on a low branch while I was watching. It then looked at me as if seeking another piece. I considered this behaviour unusual and gave it a second piece, using the coldness of the morning to salve my conscience. After again scanning the area in all directions, it dived down, took the cheese and flew off. I wondered whether it was feeding its young, or mate as the species is known to do (Burt 1996; Johnson 2003; Ligon and Burt 2004). It always flew off in the direction of a tall Eucalyptus tree about 250 m away and close to a strip of trees alongside the railway and Silcock Reserve. This became its usual behaviour during its infrequent visits.

Another time, I had gone inside after giving the resident Magpies a snack in response to their carolling to let me know they were there. I heard what I at first thought was a Magpie singing so ignored it, as I thought it was being greedy, but, as the singing continued I realised there was something different about it and went out to investigate. I was pleasantly surprised to find it was my Butcherbird singing a most beautiful song while sitting on his usual perch on the oak tree (I was now able to sex it. Both sexes have a white loral spot but, in the female, a white line extends backwards from the spot under the eye. The male also tends to be a little larger and its colouration slightly brighter [Johnson 2003]). Upon sighting me, he flew to the hanging basket and waited for food. I had to go back inside for this and feared he might leave, but he waited, and when I threw the morsel of cheese on the ground, he carefully looked in all directions, dived to take the cheese back to his perch, ate it and then 'requested' a second piece, which he took before flying off in the usual direction. I wondered whether the Butcherbird had learnt from the Magpies to sing for a breakfast snack.

Yet another time, late in the breeding season, I came out of the back doorway and the Butcherbird flew from the oak to the hanging basket, stared at me and waited for his snack. This was mid-morning and the Magpies were not present. The Magpies normally came early in the morning, if they visited. We went through the usual routine, but instead of darting down for his snack the Butcherbird checked for danger, turned its whole body 180 degrees, looked up into the oak tree and made three short, soft, throaty calls, the last a fraction longer than the first two. A female Butcherbird darted down from higher in the oak, took the cheese and flew towards the eucalypt that the male always flew to. The male then turned again, looked at me and waited for another piece of cheese. When I threw it down, he again carefully looked in all directions, dived down, picked it up and flew off after the female. This occurred on three more occasions; however, I heard calling only the first time. The other times he turned and looked at the female, which responded by diving down and carrying the snack away, i.e. it appeared to me he was signalling the female to let her know it was safe. I have not seen a record of this behaviour in the literature. Grey Butcherbirds display cooperative breeding (Burt 1996; Johnson 2003; Ligon and Burt 2004), where the mate and/or one or more of the previous season's young feed the chicks and, in some instances, the bird sitting on the eggs (Johnson 2003). I wondered whether this signalling to let the female bird know it was safe was another form of cooperative behaviour.

After the end of November 2018, I saw neither the pair nor the male Butcherbird on its own until, late in June 2019, the male came back. I have seen it only once this year. However, another male Grey Butcherbird now visits the front yard infrequently, and has done so since May. He too comes and goes to a large Eucalyptus tree but always from the opposite direction to my first Butcherbird. This second Butcherbird is slightly larger and the two behave quite differently. The first male never ventured into the front yard and stayed a greater distance from me than the second, which would allow me to walk past it.

The second male first came on his own, but then brought a female. Three times I have seen the same behaviour that occurred with the first pair of Butcherbirds, where the male waits for a piece of cheese to be thrown down and then alerts the female. With the second pair, I have heard the male call the female from her higher branch to collect the cheese, but it gave only a single short, soft, throaty call in each of the three instances. Again, the male always carefully examined the immediate area before calling the female.

This pair visits more frequently, both together and individually, but not regularly. At first they came only following the Magpies' chorusing, but now come either tailing the Magpies or during mid morning. At the time of writing (the end of June, 2019), I have yet to see whether this male will take the cheese back to what I presume is their nesting tree when, again presumably, there will be eggs in the nest.

Feeding of birds in Australia, generally, is not recommended and a number of websites provide lists/factsheets of the detrimental effects this practice has on birds; e.g. Birdlife Australia; City of Monash; Knox City Council; Wildlife Information, Rescue and Education Service (WIRES). This, generally, is supported by veterinarians, e.g. Brisbane bird and exotic animal vet Deborah Monks (Renault 2018). However, the growing scientific literature on the effects of feeding wild birds, (e.g. Ishigame et al. 2006; Jones and Reynolds 2007; O'Leary and Jones 2005; Reynolds et al. 2017; Wilcoxen et al. 2015) demonstrates both positive and negative effects, and that birds do not become dependent except in extreme situations (O'Leary and Jones 2005; Wilcoxen et al. 2015). Chapman (2015) reports that 63% of Australian households feed wild birds. It is becoming accepted that people will continue to feed wild birds and there are calls that we should be discussing rather than demonising the practice (Jones 2016; Convery 2017) and that advice on feeding should be based on scientific rigour (Ishigame et al. 2006; Jones and Reynolds 2007; Wilcoxen et al. 2015). People feeding birds could participate in Citizen Science projects and contribute to large-scale, multi-faceted projects in this field (Jones and Reynolds 2007).

I hesitated in writing this article, due to a possible backlash for succumbing to the overtures of 'my' Magpies and Butcherbirds. I am not supporting bird feeding with this article, and have warned people of the possible dangers, yet I am one of the 63% of Australians who do so. Neither should publication of this Naturalist Note suggest The Victorian Naturalist or Field Naturalists Club of Victoria support feeding wild birds. The Note was written simply to share with others a possible form of cooperative feeding by the Grey Butcherbird.

References

Birdlife Australia (2019) Attracting birds to your garden. <http://www.birdlife.org.au/images/uploads/education_ sheets/INFO-Attracting-birds-to-garden.pdf> (accessed 25 June 2019).

Burt DB (1996) Habitat-use patterns in co-operative and non-co-operative breeding birds: testing predictions with Western Scrub Jays. The Wilson Bulletin 108, 712-727.

City of Monash (2019) Impacts of feeding birds. <https://www.monash.vic.gov.au/Services/Pets-amp-Pests/Wild-life-and-Pests/Impacts-of-feeding-birds> (accessed 25 June 2019).

Chapman RA (2015) Why Do People Feed Wildlife? An International Comparison. (Unpublished Ph.D. thesis, Griffith University). In Reynolds SJ, Galbraith JA, Smith JA and Jones DN (2017) Garden bird feeding: insights and prospects from a North-South Comparison of this global urban phenomenon. Frontiers in Ecology and Evolution 5. <https://doi.org/10.3389/fevo.2017.00024>.

Convery S (2017) Feed the birds: stop the demonising and tell us how to do it properly. <https://www.theguardian.com/environment/2017/dec/09/feed-the-birds-stop-the-demonising-and-tell-us-how-to-do-it-properly> (accessed 25 June 2019).

Ishigame G, Baxter GS and Lisle AT (2006) Effects of artificial foods on the blood chemistry of the Australia Magpie. Austral Ecology 31, 199-207.

Johnson G (2003) Vocalisations in the Grey Butcherbird Cracticus torquatus with emphasis on structure in male breeding song: implications for the function and evolution of song from a study of a southern hemisphere species. (Unpublished PhD thesis. Griffith University).

Jones DN and Reynolds SJ (2007) Feeding birds in our towns and cities: a global research opportunity. Journal of Avian Biology. 39, 265-271.

Jones DN (2016) It's time to talk about feeding. <https://www.birdlife.org.au/australian-birdlife/detail/its-time-to-talk-about-feeding> (accessed 21 August 2019).

Knox City Council: Impacts of feeding birds. https://www.knox.vic.gov.au/Page/page.aspx?page_Id=169&h=0

Ligon JD and Burt DB (2004) Evolutionary origens. In Ecology and Evolution of Cooperative Breeding in Birds. Eds WD Koenig and JL Dickinson. (Cambridge University Press: Cambridge, UK).

O'Leary and Jones (2005) The use of supplementary foods by Australian Magpies Gymnorhina tibicen: Implications for wildlife feeding in suburban environments. Austral Ecology 31, 208-216.

Renault H (2018) If you love feeding magpies, your kindness could be killing them. ABC Radio. <https://www.abc.net.au/news/2018-10-18/these-foods-could-be-hurting-your-backyard-magpies/10365712>. [accessed 21 August 2019].

Reynolds SJ, Galbraith JA, Smith JA and Jones DN (2017) Garden bird feeding: insights and prospects from a north-south comparison of this global phenomenon. Frontiers in Ecology and Evolution <https://doi.org/10.3389/fevo.2017.00024> (accessed 21 August 2019).

Wilcoxen TE, Horn DJ, Hogan BM, Hubble CN, Huber SJ, Flamm J, Knott M, Lundstrom L, Salik F, Wassenhove SJ and Wrobel R (2015) Effects of bird-feeding activities on the health of wild birds. Conservation Physiology 3. <https://doi.org/10.1093/ conphys/cov058>.

Wildlife Information, Rescue and Education Service (WIRES) (2019) Feeding Birds. <https://www.wires.org. au/wildlife-info/wildlife-factsheets/feeding-birds?gclid=C jwKCAjwtuLrBRAlEiwAPVcZBms3foKHLBILJ2XGeFLB k8dIplFaB21DLcnQjS8Ym97srsrIF1VM-RoC2qIQAvD_ BwE> (accessed 25 June 2019).

Maria Gibson

Field Naturalists Club of Victoria PO Box 13 Blackburn, Victoria 3130
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Title Annotation:Naturalist Note
Author:Gibson, Maria
Publication:The Victorian Naturalist
Geographic Code:8AUST
Date:Dec 1, 2019
Words:1996
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