In the pre-dawn darkness on Saturday the 18th of June, twenty-five volunteers and one Park Ranger were greeted with perfectly calm conditions for Tarra-Bulga National Park’s Annual Lyrebird Survey. Overnight showers had passed by leaving moist dripping foliage in their wake.
The survey is designed to monitor the density of Lyrebirds living in 60ha comprising of wet sclerophyll and cool temperate rainforest immediately to the east of the Tarra-Bulga National Park Visitors Centre. There are sixteen monitoring points strategically placed throughout the site and volunteers move to each site before adult male Lyrebirds start their morning calls at dawn. Volunteers then use a compass to record the direction and proximity of the Lyrebird calls. This year we had enough volunteers to cover all but one of the monitoring points.
Following the survey, lines representing the direction of the calls are plotted onto a map, and triangulation is used to establish the spots where birds were calling from. This year the results indicate we had at least nine (male) Lyrebirds calling in our 60ha zone. This corresponds to a density of one adult male Lyrebird per 6.7 ha. You can also assume that there will be female lyrebirds and immature males or non-calling males within our target area. To account for this to get our overall population of Lyrebirds we multiply the number of calling males by a factor of 2.5. It is believed that male Lyrebirds do not begin to breed until they are around 6 or 7 years old.
Summary of Tarra-Bulga National Park Lyrebird Surveys