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
The Annual Lyrebird Survey at Tarra-Bulga National Park has been carried out for the last 20 years as a means of detecting any changes of the population of the birds, within an area of the park covering from around the visitors centre area to the rainforest gully at the headwaters of Macks Ck. Although Lyrebirds are not considered endangered, they are at risk from natural disasters such as bushfires, habitat decline and attack from foxes, feral animals and domestic cats and dogs. The annual survey contributes to long term data on the density of the local population and helps park management plan their future management actions.
The Lyrebirds are counted not by attempting to spot them visually, but by listening out for their song. (Sometimes you may be lucky enough to see a bird but often they are out of sight perched in a tree canopy or in ferny understorey). The survey is undertaken during the Lyrebirds’ breeding season. At this time mature male Lyrebirds are all actively searching for females to mate with and it is during this time when they are reliably singing for much of the day. The survey is consistently undertaken at dawn (when the wind is often calmer and the Lyrebirds begin their morning calls, usually while perched up in a tree).
The count is carried out by distributing groups of volunteers across the survey area at
established monitoring points. Each of these points is marked with a numbered sign so that they can be found in the pre-dawn light. As the sun rises and the Lyrebirds start singing their varied repertoire, the volunteers use a compass to establish the direction the calls are coming from and estimate the distance (close, medium or far) that the call is coming from. The survey lasts for approximately 30 minutes, after which the volunteers generally go off and enjoy breakfast at the aptly named Lyrebird Cafe.
Once the survey is completed survey sheets are collected and the direction the calls were coming from are plotted as lines onto a map, where lines coming from several surrounding monitoring points meet, we can be confident that it is a location where a male Lyrebird was calling from.
Friends of Tarra-Bulga are looking for volunteers to assist with a planting day on Saturday August the 29th.
The planting site is on a north facing slope along the Grand Ridge Rd, it had been originally successfully planted with Mountain Ash in the early 1990’s. Unfortunately the fires in 2009 killed them all and there was no natural regeneration of new overstorey because they had not yet started to flower and produce seed. This is the second year we have done planting at this site and with the aid of strong wire-mesh wallaby guards progress towards restoring the site is going fantastically well.
If you can’t make it along for the Saturday we do need volunteers to help make up tree guards before the event and may need to do some more planting later on if we don’t finish the job on the 29th, so let us know if you are available.
The meeting point on Saturday the 29th will be at the park visitors centre at 9.00am.
Friends of Tarra Bulga recently held its AGM, where the diverse activities carried out by the group were highlighted. A major activity of the group is to staff the Parks Visitor’s centre, in the past year 29 Volunteers contributed to opening the centre on Weekends and School and Public Holidays (a total of 182 days).
The Friends also have plenty of hands on activities throughout the year aimed at helping to learn more about the park and enhance it. This includes walks along some of the more remote tracks, Lyrebird surveys and working bees involving both weed control and tree planting. The group undertakes photo-monitoring of various sites to monitor vegetation change and has a network of remote cameras that are helping to gain a better picture of what is happening with both native and feral animals in the park. A device that can be left out in the park to record frog, bird and bat calls is a recent acquisition.
To let everyone know what is happening in Tarra Bulga and more about its plants animals and fungi they have a Blog http://www.tarrabulga.wordpress.com which is packed full of photos and information. They are also on Facebook and Twitter and are very keen for the public to share their own Tarra Bulga experience via these sites. You can also find more information about getting involved with the group by contacting the Ranger, Craig Campbell on 5172-2508.