Published as: Davey,Fullagar & Slater 2005. Lyrebirds and Bushfire. Wingspan 15: 16-17.
LYREBIRDS AND BUSHFIRE
How did Superb Lyrebirds rise from the ashes of the devastating 2003 bushfires?
The devastating bushfire that culminated in loss of life and housing in Canberra on 18 January 2003 burnt two-thirds of the Australian Capital Territory and 88 per cent of the Territory’s reserve system. The fires were extensive and extremely hot, destroying both understorey and upper canopy. The intensive heat greatly affected the microfauna of the soil and destroyed the leaf litter, both elements critical to the re-establishment of the forest ecosystem and, in particular, the pace at which ground-feeding fauna can recover.
In the 1960s, Norman Robinson and Harry Frith studied the ground-feeding Superb Lyrebirds of Tidbinbilla Nature Reserve. Their intensive study, conducted two decades after the last major fire, in 1939, covered 37 ha, within which there were nine male territories. Since then the Reserve has become renowned for its Lyrebirds.
The fires of January 2003 were exceptionally hot and widespread. Amazingly, just two months after the inferno, in charred Namadgi National Park, close to 20 lyrebirds were observed. But, a visitor to the Brindabella Ranges three weeks after the fire found five dead lyrebirds. Interestingly, none had been burnt and must have died subsequent to the fire. Thus, it was clear that some birds had survived the fire but not its aftermath.
In the Tidbinbilla Valley virtually all food resources for Superb Lyrebirds appeared to have been destroyed. No significant areas of unburnt or lightly burnt refugia persisted anywhere near the Robinson and Frith study area. How had the Tidbinbilla Lyrebirds fared?
We decided to resurvey Robinson and Frith’s wider study area, of 60 ha, to see whether any Lyrebirds had survived and how they have been recovering in the years since. We combined three techniques: counting display mounds, observing lyrebirds on walking surveys, and recording vocalisations. Initially, the area was so devoid of vegetation that there was little possibility of lyrebirds not being detected. With increasing density of ground cover it was noticeable that lyrebirds would be visible as they checked out the source of disturbance and only then flee. But, by January 2005 the vegetation had become so dense that replay of lyrebird calls was used as an aid to locate birds.
Every three months starting October 2003 the study area was covered on foot to locate and count the number of display mounds and the number of individual lyrebirds present. We also set up an automatic listening station close to the centre of the intensive study area. A cassette recorder with an omnidirectional microphone sampled for c.10 seconds, day and night, at half-hourly intervals. The station collected data continuously from 1 August to 8 October 2003 and again for approximately one week a month from April to October 2004.
The automatic sound recording station used at Tidbinbilla. The lid of the waterproof box has been removed to show some of the contents, including the tape recorder and timing device. The two rechargeable 6-volt dry cell batteries used to power the system are housed under the false floor and the microphone is connected by a c. 5m insulated lead to one end of this box.
Our first access to the site was on 8 May 2003, 14 weeks after the fire. Epicormic growth was only modest by the time of this visit and ground cover non-existent. Treeferns clustered in the deepest gullies were beginning to sprout new fronds but the area was devastated and dusty.
The study area near the automatic recording station, at the site of the field hut used by Robinson and Frith in the 1960s: Taken on 8th May 2003, four months after the fire, showing the total loss of groundcover, understorey and canopy, with some slight regrowth beginning; Photo by Peter Fullagar
Two views of the same area. The upper picture taken May 2003 and the lower in January 2005.
An observation of footprints and scratchings of a single lyrebird on the 29 July was the first indication of the presence of lyrebirds within the study site. The first call was detected by automatic sound recording station 9 September; 40 days after the beginning of continuous sound sampling. From the end of September until 8 October 2003 calls were detected daily, and again frequently throughout the recording period April to October 2004 (see graph).
Relative frequency of Superb Lyrebird calls recorded at a listening station at Tidbinbilla Nature Reserve. For ease of comparison, the blue columns represent the same months surveyed in 2003 and again in 2004. Vertical scale represents 'calls per hundred daytime samples'
During the first five-hour walking survey in October 2003 three lyrebirds were encountered. All were found where soil had accumulated, creating flat moist areas at creek junctions or at the head of a waterfall; places where tree ferns were regenerating fronds. At this time most of the creek beds were filled with eroded soil causing water to flow underground and these flat areas were the few spots where surface water was available. These locations appear to have formed the core areas for subsequent sightings (see map).
Locations of the accumulated sightings of Superb Lyrebirds between October 2003 and January 2005 within the Lyrebird study area (clouded area) at Tidbinbilla Nature Reserve (creeklines are highlighted in blue).
Like the Lyrebirds, most species have returned to the site but are in very low numbers. In two years since the fires 36 species were recorded and most species expected at the site were seen or heard, although in many cases only a few individuals were involved. However, no Pilotbirds or Spotted Quail-thrush were heard or seen although the latter species was found elsewhere in the reserve. Other ground-feeding birds were slow to reappear on the study site. The Wonga Pigeon was not heard or seen until April 2004 and has rarely been detected since then. Satin Bowerbirds were neither seen nor heard until September 2004.
The accumulation of species records for birds at the Tidbinbilla study site from May 2003 to January 2005*.
*Extracted either from field observations or from the identified calls detected in the sound samples collected at the automatic recording station: y = seen; * = tape recorded; (y) = tracks seenTwo years after the bushfire of January 2003 the number of Superb Lyrebirds within the Reserve is very low; few display mounds have been found and there has been no evidence of breeding. On the study site a maximum of three birds had been seen at any one time. By extrapolation from Robinson and Frith’s results, the same 60 ha would have supported about 15 male territories in the 1960s, and females and juveniles would have added to the tally.
Lyrebirds are sedentary by nature and the January 2003 wildfires were so widespread that it might be expected that recovery of the Lyrebird population would depend on those individuals that actually survived in an area. Colonization from outside the fire-affected area would require long distance immigration, which seems unlikely. How could even just a few Lyrebirds survive such an intense, all-destroying fire?
During our surveys Lyrebirds were seen disappearing down wombat burrows and Common Wombats certainly survived the fires—by May 2003 their distinctive faeces and scratchings were observed frequently. Hence, we believe that the most likely way that any Lyrebirds survived at the study site was by seeking safety within wombat burrows and other holes.
"When the fire descended, Mitchell [the surveyor-explorer of the mid 1800s] took refuge in the river and waited for it to pass. He was, however, not alone; because, from eight o'clock in the morning, three hours before the fire reached him, 'the lyrebirds began to flock from the higher country to take shelter in the river and, moreover, they could not be made to move from the positions taken up immediately on reaching the water'." L.H. Smith (1988)AcknowledgementsWe would like to thank Environment ACT for allowing us access to the area so soon after the fire and in particular Wildlife Research and Monitoring and staff from the Tidbinbilla Nature Reserve.
Further ReadingFraser, I (2003) Burning and learning: the aftermath of the January 2003 fires in Namadgi and Tidbinbilla.
Canberra Bird Notes 28: 10–16.
Robinson, FN & Frith, HJ (1981) The superb lyrebird
Menura novaehollandiae at Tidbinbilla (ACT). Emu 81: 145–57.
Smith, LH (1988)
The Life of the Lyrebird. William Heinemann Australia: Melbourne.
