passerines resulted primarily from the selection on males in attracting mates or deterring rivals. However, a study found that females also produced mimetic vocalisations while foraging and during nest defence, suggesting that mimicry has a function in deterring predators and conspecific rivals. Mimicry of anthropogenic sounds In David Attenborough's Life of Birds (ep. 6), the superb lyrebird is described as able to imitate twenty bird species' calls, and a male is shown mimicking a car alarm, chainsaw, and various camera shutters. However, two of the three lyrebirds featured were captive birds. One of the three was observed imitating a laughing kookaburra with such close similarity that a nearby kookaburra began responding to the lyrebird and calling back. A recording of a superb lyrebird mimicking sounds of an electronic shooting game, workmen, and chainsaws was added to the National Film and Sound Archive's Sounds of Australia registry in 2013. The vocalizations of some superb lyrebirds in the New England area of New South Wales are said to possess a flute-like timbre. Ecosystem engineers The foraging behaviour of the superb lyrebird has a major effect on the structure of the forest floor. A lyrebird can move and bury up to 200 tonnes per hectare of leaf litter and soil every year, disturbing the soil to a greater extent than virtually any other animal. This soil disturbance hastens the decomposition of the leaf litter, and increases the rate of nutrient cycling in the ecosystem. The lyrebirds’ clearing of bare patches also reduces the amount of fuel available for forest fires, which in turn reduces the extent and intensity of wildfires. Threats and predators Superb lyrebirds are vulnerable to native predatory birds such as the collared sparrowhawk, gray goshawk, and currawongs. Nests are particularly vulnerable to predation, but adults are also vulnerable due to their loud calls. It has been observed that males suffer higher degrees of mortality, suggesting that their courtship displays render them highly vulnerable. Methods utilised by superb lyrebirds to reduce predation risk include selection of protected areas for nest sites, mimicking calls of other predatory birds, and adopting solitary and timid behaviours. As the superb lyrebird is a poor flyer, when alarmed it will tend to run away, sometimes incorporating short gliding flights to lower perches or downhill. Human factors also pose threats to superb lyrebirds. Because they are ground-dwelling, superb lyrebirds are particularly threatened by vehicle collisions. The presence