RIDGE Group Research
Following are details of areas of deer research conducted by RIDGE to date.
Initial research programs were conducted only on the red deer population but subsequent programs have been initiated on both the chital herds of Charters Towers and the rusa deer within the Torres Strait.
Landowner and Hunter Data
RIDGE has sourced information from landowners and hunters over the past 24 years, on properties across the Brisbane, Mary and Burnett river systems.
The aim has been to accurately estimate:
A historic growth rate
The overall herd size
Some families have lived on or around their present properties since deer were first released and their notes and recollections give a good basis for estimations.
This data was collated by Dr Graham Hall, taking into consideration inherent problems with anecdotal opinions.
It appears certain that red deer populations expanded across these watersheds in what is commonly called a “Wave”.
Populations would build up in a certain area, usually around a creek system, before moving reasonably rapidly into another, leaving behind a resident population. This would continue until a natural or man-made barrier was reached.
It would appear all the historic deer herds within Queensland reached these barriers within the first 100 years of liberation and little movement has been achieved by these herds since then. (with the exception of new releases)
Which animals are more likely to move, what age group and which sex are questions RIDGE research aims to provide.
Red deer populations appear to have reached a peak between 1960 and 1970, before dropping back in the face of escalating pressure from trapping and hunting.
Once deer trapping stopped, pressure from hunting continued to increase especially since deer were rejected from the Nature Conservation Act 1992.
RIDGE estimates put wild red deer numbers close to or slightly above the 1970 peak at 10 – 15,000 animals across a total range of less than 1.5 million hectares.
It is estimated that over 95% of the total wild red deer population live in an area less than 750,000 hectares.
It is also recognised that there are clear differences in herd densities within this area caused by towns, heavily cleared areas, major dams and also areas which can remain without good feed or water reserves for extended periods.
This suggests a realistic core area of around 500,000 hectares and an overall population density of between 1:30 – 1:40 / ha, within the core area.
A Robinson R44 helicopter has been used to verify ground based data collected from hunters and landowners. Deer density estimations are made on selected quadrats of approximately 1000 ha by an independent assessor.
The estimates are based on existing data and kept confidential from the helicopter pilot and observers. These quadrats are then flown using successful aerial capture methods developed over these same areas between 1980 and 1991.
All animals seen were videotaped and left undisturbed, giving a very high success rate on sightings.
Presently, RIDGE is compiling this data on an overall G.I.S mapping program, which will eventually give the most accurate estimation of wild red deer numbers ever made.