3 September 1998

Low flying surveys for kangaroos notch up record

University of Queensland senior scientific officer Lyn Beard knew she had mastered her job as an aerial observer when she stopped counting kangaroos in her sleep.

She is one of three University of Queensland staff - with Zoology Department head Professor Gordon Grigg and researcher Dr Tony Pople - to participate in one of the world's longest running aerial surveys of wildlife using the same methodology.

Professor Grigg has just completed the 21st annual survey of kangaroos in the South Australian Pastoral Zone for the South Australian National Parks and Wildlife Service (SANPWS). Each survey covers nearly one quarter of a million square kilometres - about half the state of South Australia.

Aerial surveys are used to build up research information for wildlife management, including animals in African game parks, Australian dugongs and even Antarctic marine mammals. However, few if any, aerial surveys anywhere in the world are so extensive in their geographic cover and over such a long time frame.

From 1978 to 1998, Professor Grigg has flown an estimated 370,000 kilometres in a fixed wing Cessna 182 for the South Australian kangaroo survey. In each annual two-three week survey he and the crew of observers travel a distance equivalent to more than two-thirds around the globe.

"The work takes a lot of concentration for both pilot and observers," Ms Beard said.

"The pilot needs to maintain a constant ground speed of 185km an hour (100 knots) and fly at a constant height of 250 feet (76 metres) above the ground along the predetermined 200 metre-wide transects.

"Nowadays Gordon has a Global Positioning System to give a constant readout of both position and ground speed, but for most surveys he had only visual reckoning to navigate and maintain a constant speed over the ground, regardless of drift, tailwind or headwind. Even with that, it's very ?hands-on' flying.

"Height above ground is maintained using a radar altimeter, to ensure that observers are scanning a transect of the correct width, 200 metres, which is demarcated by a rope tied to the strut and streaming back horizontally in the slipstream to mark the outer edge.

"It requires reasonable concentration to fly so close to the ground because if something goes wrong there is only a small margin for error."

Hazards of low flying include power lines and errant birds. An eagle once hit the tail fin and carried away their HF (high frequency) radio antenna, resulting in 60ft of wire trailing from a wing tip.

Observers also require great skill. Two observers in the rear seats count kangaroos spotted on either side of the aircraft.

New observers take about 50 hours to get used to the discomfort of the noisy and often bumpy environment, and to maintain a steady high level of concentration and identify and record the three most abundant species in the survey area - red kangaroos, grey kangaroos and wallaroos. Novice observers are trained against an experienced hand, sitting in the front right seat next to the pilot and counting the same transect as the fully trained observer sitting behind them. Typically, a trainee sees about 50 percent of the trained observer's tally on the first session. Improvement over time can be measured as an increasing percentage until both trainee and trained observers see similar numbers in a session. It takes great concentration and self-discipline, especially to keep watching only the ground no matter what the aircraft is doing. Observers soon learn to catnap in the 10-minute breaks between one transect and the next to give their eyes a rest.

But not everyone is suitable for the job. The success rate is about 67 percent and, according to Professor Grigg, a trained observer is worth his or her weight in gold. Because it takes such a lot of training, they aim to keep the same observers for a number of years. Ms Beard has been on 17 surveys; Peter Alexander of SANPWS, 16 surveys; Tom Gerschwitz of SANPWS, 9 surveys; and Dr Pople (UQ), 7 surveys.

"It is a symbiotic association with the South Australian National Parks and Wildlife Service", Professor Grigg said. "They want accurate annual assessments so they can set harvest quotas for the following year. We are interested in the data for research, so we can build mathematical models of population trends, based on rainfall and plant growth. In the long run, we may be conducting the surveys more to confirm predicted trends than for direct quota-setting." That part of the work is collaborative with another long-term associate, Dr Stuart Cairns of the University of New England's Zoology Department.

A qualified pilot since 1974 with a command instrument rating and subsequent endorsement for ultralights, Professor Grigg was approached by the late Dr Graeme Caughley to try aerial survey flying in 1975 when both were at the University of Sydney. This association began with surveys in NSW and in Queensland culminating in an "all Australia" survey in 1981-1982, with surveys conducted in an aircraft fitted with long range fuel tanks in the Great Victoria and Great Sandy Deserts in Western Australia.

They thought the 1978 South Australian kangaroo survey (SAKS) would be just a "one-off", but it has turned into something of an institution. Dr Caughley discontinued his direct involvement when he joined CSIRO in 1979, but he and Professor Grigg continued collaborative work for several more years, an association which lives on in the current participation of David Grice, a CSIRO observer trained by Dr Caughley.

Despite harvesting, grey kangaroo and red kangaroo numbers have tended to increase in the survey area over the past 20 years, and the range of greys seems to be expanding northwards. Annual harvest quotas are rarely met, as prices for kangaroo meat and leather are not high enough to permit economic harvesting except where densities are very high. Prices are rising, however, and Professor Grigg thinks it is only a matter of time before the kangaroo industry becomes a much larger component of Australia's primary production.

Professor Grigg estimates that nationally, Australia has 25-35 million kangaroos, implying the capacity for an annual harvest of at least five million. Present harvests are about three million, with the meat from about half of them going to waste. He would like to see the meat exported for much better prices to the specialty game meat market, and both the skins and the meat used fully. With dingoes under control throughout the sheep rangelands, man is really the only predator nowadays.

Five of Australia's 50 macropod species are currently under management programs. The red kangaroo, eastern grey kangaroo and western grey kangaroo make up almost all the take, with smaller numbers of euros (also called wallaroos) and a very small number of whiptail wallabies.

"There is a definite relationship between good seasons and kangaroo population increases," Professor Grigg said. "Ultimately we want to use remote sensing satellite data to look at the greenness of properties measured by satellites, as an indication of rainfall and subsequent grass growth as a way of predicting kangaroo populations."

Professor Grigg said a valuable outcome of the public scrutiny and debate over kangaroo harvesting had been that Australians had given very close attention to the philosophy and operational aspects of kangaroo management.

Accordingly, annual harvests, limited by quota, are conducted under formal management programs based on extensive scientific research and monitoring.

Professor Grigg said kangaroo harvesting was mainly undertaken for pest control and to mitigate damage to crops, pasture and fences. However, there was increasing recognition that kangaroos were a valuable resource whose commercial use was in tune with ideas about gaining conservation benefit from sustainable wildlife use.

Ms Beard said 20 years ago the scientific community had been reluctant to accept aerial surveying as a valid method for estimating kangaroo populations.

"The scientific technique was challenged by overseas activists opposed to kangaroo culling, who thought our estimates of kangaroo populations must be too high," she said. "In fact we now know that, if anything, they are too low. The validity of the technique has become accepted over the past 10 years."

Aerial surveying has spread from fixed wing aircraft for surveys in arid areas to helicopters and ultralights - more suitable for counting species like the eastern grey kangaroo in dense scrub. Professor Grigg, Ms Beard and Dr Pople developed and validated the use of a Drifter ultralight aircraft, cheaper than a helicopter but with the same low speed advantages, in a study conducted in 1992-1993.

Earlier this year the University of Queensland Zoology Department hosted a workshop for the small pool of researchers engaged in aerial wildlife surveying in Australia, to discuss methodologies and to agree on standardisation procedures so that comparability of data gained in different surveys would be assured. Those discussion papers, edited by Dr Pople, will be published in a forthcoming issue of the Royal Zoological Society's Australian Zoologist.

For further information, contact Professor Grigg, telephone 07 3365 2471, Ms Beard, telephone 07 3365 2959 or Dr Pople, telephone 07 3365 7386.