The brush turkey mound
HEAT TO INCUBATE brush turkey eggs is supplied by microbial action from the decomposition of organic matter. By adding or removing compostable material, the male bird carefully maintains an incubating temperature of 33°C to 35°C within the mound. As with some reptiles, incubation temperatures affect the sex ratio of brush turkey chicks. At 34°C the sex ratio is equal, but with cooler temperatures there is a greater mortality among the female embryos than the male ones. Conversely, at higher temperatures mortality among male embryos is greater.
To achieve this, he first uses his beak as a probe and inserts it into the mound as far down as the level of the eggs. His palate acts as a thermometer, and, depending on the temperature he senses, he removes or adds leaf-litter as needed.
But exactly why have these tenacious builders and fussy housekeepers successfully reclaimed significant parts of their range in such an altered environment as Sydney? Slow moving and not particularly agile flyers, brush turkeys might easily be caught. They are said to be a good food source, just like their commercially reared namesake, and would certainly have been part of many an Aboriginal meal in pre-European times. Brush turkeys were also on the colonial menu and featured in cookbooks. During the Great Depression in the 1930s they became welcome fare on meagre dinner tables, but legislative protection of fauna and flora after World War II effectively saw hunting cease.
As with so much wildlife, predation of chicks by foxes and cats remains a silent scourge. Sustained fox baiting in recent years has helped, yet, according to Dr Ann Goeth, a Sydney-based wildlife behaviourist, brush turkey expert and educational consultant, the easing of predation is only part of the answer.
A number of changes in the urban environment have helped the turkey resurgence gain momentum, she says, such as the spread of introduced lantana in bush gullies. Newly hatched chicks without any parental protection are vulnerable to predation, so dense thickets provide a perfect haven. This is perhaps a factor in the survival of brush turkeys in my suburb, with a steep, remnant bush gully and patches of lantana several streets away.
“People often feed brush turkeys…directly or unwittingly by leaving their pet’s bowl sitting about outside,” she says. “They are total omnivores and will eat anything.” Uncovered compost heaps are an additional source of profitable pickings, with scraps, and the worms and insect larvae they encourage, eagerly devoured.
On a broader scale, the fashioning of leafy gardens in the more affluent suburbs has unwittingly mimicked the brush turkey’s preferred habitat. As wide lawns have given way to dense plantings and bush gardens, and as garden gurus have exhorted gardeners to mulch well in the crusade to conserve water, the male turkey has decided it is Christmas every day. And this time he is definitely not on the menu.
Loose, moist mulch with which to construct a magnificent edifice is every male’s fantasy.The more plentiful his raw materials, the more palatial his mound, and the more females he is likely to attract.The more females he attracts, the more eggs will be produced. With ample supplies of home-delivered mulch, and an abundance of food and suitable trees and shrubs to roost in safe from predators, brush turkeys moved right into the suburbs and made themselves at home.
Of course, most gardeners do not share a turkey’s view of landscape heaven. Male brush turkeys have been known to demolish a freshly planted and mulched garden in a day, stripping young plants from the ground with seemingly malicious intent. Shocked gardeners, despairing of their ruined investment, have contemplated murder, but instead resort to what they mistakenly consider a more sensitive and less drastic remedy – relocation. “You might as well kill them straight away,” says Ann. Brush turkeys are territorial, and moving them only leads to conflict with other turkeys. Not-so-lucky ones either starve, or end up as road kill.
Whatever the future population dynamics of the species, it seems they are here to stay in urban environments up and down the east coast. Strategies such as using pebbles or gravel as mulch, and protecting young seedlings, might sooth the nerves of anxious gardeners, but I for one can only admire the tenacious bird that came one night to roost on my inner city balcony. A wildlife success story indeed.
Brush turkeys have been known to demolish a freshly planted and mulched garden in a day.