Far North 1st Rabbit Survey report October 2007 Michael Brennan: Robert Wicks Pest Animal Research Centre, Biosecurity QLD, DPI&F

Background A rabbit monitoring program was established in FNQ in the shires of , Atherton, Herberton and Eacham. The monitoring was in response to an increase in reported rabbit sightings in the tablelands area. A decision was made by the involved councils to gather some baseline density data to help determine: a) the location and density of the rabbit populations, and b) the scope and size of the problem.

Who is involved? Eacham Shire, Mareeba Shire, Atherton Shire, Herberton Shire FNQROC Pest Project Officer DPI&F Biosecurity QLD CSIRO

Figure 1: Rabbit habitat at a shed in the Mareeba Shire

Methods The most efficient method for determining rabbit densities is to spotlight. It is a quick and relatively simple way of learning how active rabbits are in an area. The main benefit of spotlighting is that if the method is consistent (same time of day, location, and speed) it gives reliable and useable data.

Three areas were spotlighted on the tablelands in the shires of Mareeba, Atherton and Eacham. Originally it was decided to spotlight as many locations as possible, and to a degree this was achieved. The results of the monitoring provided 3 distinct sites where rabbits were very active and these can now be used as future monitoring sites. These sites are: “Glenview” dairy in Eacham Shire, Peninsula Development Rd at Biboorha in Mareeba Shire, and Torchio Rd in Atherton Shire.

At each site rabbits were counted using a hand held spotlight from the back of a utility. A sample of the rabbit population was also shot to obtain blood and liver samples. These samples will be tested for Rabbit Haemorrhagic Disease Virus (RHDV), which will tell us if the rabbits have antibodies to RHDV and therefore if they are showing signs of immunity to the virus. Basic autopsy data such as sex, presence of myxo, and pregnancy status (if it was a female rabbit) were recorded.

Results The spotlighting results indicate that rabbits are located in isolated pockets throughout the tablelands. Even though populations are not blanketing the area, where rabbits do occur the densities are high. The monitoring site in the Mareeba Shire yielded 12 rabbits in a spotlight transect of approximately 6 kilometres, however all the rabbits sighted were in a section of only 200 metres around a shed and irrigation pipes (see Figure 2). Table 1 shows results of other sites that were visited.

Figure 2: Rabbits around irrigation pipes in Mareeba Shire

The Eacham Shire site contained a very high number of rabbits in a relatively small area. When sighted in the spotlight, most of the rabbits were running back towards a single warren structure that was in a pile of concrete and soil. Other sites were spotlighted in the Eacham Shire but very little rabbit activity was recorded away from the ‘Glenview’ dairy site. Map 1 shows the locations of the sites visited and their associated densities.

Herberton Shire was not spotlighted, however a daytime inspection was done and rabbit activity was seen at the local primary school. A single hole was found in the playground, see Figure 3. Hares are also active at the school and it may be that hares are falsely being reported as rabbits in some instances. This is a common mistake, particularly with young hares. There are also other sites within this shire where rabbits have been reported.

Figure 3: Rabbit burrow at Herberton Primary School

Table 1: Spotlight Results Shire and site Number No. Samples Density Rabbits Seen taken Mareeba, 12 (6km 6 HIGH Biboorha transect but rabbits seen in 200m portion) Atherton, 6 3 MED Torchio Rd Eacham, 22 (2km 6 HIGH “Glenview” transect) Atherton, 6 12 0 LOW to MED other sites

Map 1: Red dots indicate sites that were visited to measure rabbit densities

Discussion The tablelands contains areas of very suitable rabbit habitat. The topography and landscape is suitable for rabbit infestation and this is evident from the initial monitoring that has been conducted. Most importantly, there is an abundance of food all year round, with high rainfall and a temperate climate ensuring a good supply of green grass. Also, a lack of predators is a definite advantage for the current rabbit populations. Although cats and wild dogs are present in the area, there is not yet a high population of foxes in the Far North.

In areas of southern Queensland it is evident that rabbits tend to spread out from a general ‘source area’. If the source population can be removed it can save time and resources by not having to remove every rabbit from an area. I.e. treat the source and you treat the problem. For the monitoring done on the tablelands, the source population scenario is evident at the Eacham Shire site, where it appeared that most of the rabbits were spreading out from one main warren (the concrete pile that is now a rabbit warren). If this warren is destroyed, it is likely that the rabbit problem at this site would be removed also. Rather than shoot and bait and try to kill every rabbit, it is possible to treat a large area by targeting the smaller area where the rabbits breed and protect their young.

At the Mareeba site, all rabbits were sighted within a 200 metre strip of transect around a shed and irrigation pipes. If the pipes and shed were made rabbit proof, the rabbit problem in this site would more than likely disappear. Baiting and virus may help remove the rabbits currently there but long term, permanent control can be achieved if reinfestation can be stopped.

On a much larger scale, rabbits were controlled in the arid areas of where the source area was Bulloo Downs, a 10000 square kilometre property that has historically been a rabbit problem area for decades. 48000 rabbit warrens were ripped around permanent water holes during drought and the rabbits never returned when the drought broke. Permanent eradication has also been demonstrated on a 2100 acre sheep property in the south east. There is no reason why the same methods (on a smaller scale) cannot be employed in the Far North. It has been demonstrated that rabbit populations can not only be reduced, but eradicated.

The question of concern is that if rabbits are not controlled, will they spread out from the current sites?

Where to from here? It is a great benefit to have identified 3 sites that can now be used as future monitoring sites. These sites should be visited on a regular basis to keep track of densities and rabbit activity. The regularity of surveys could be every 3 or 4 months, or even twice a year. If no control is undertaken at the current sites, a regular monitoring program at the sites should at least be established. The benefits of the monitoring are: a) rabbit populations can be monitored to determine the level of rabbit activity in an area, b) there will be up to date information available to give out when reports from the public are received concerning rabbit numbers.

There is also a site approximately 100 kilometres west of Mareeba where rabbit warrens have been recorded. Rabbit counts are going to be conducted at this site in late October 2007, this data will be useful to gauge how widespread the rabbits are on the tablelands. It is recommended that this property be included in future monitoring events if rabbits are found there. There is a possibility if rabbit numbers are high and they are living in warrens on this property, they may be a source for the . As yet, no locations have been found where numerous, active warrens exist in the one area.

It would be ideal to establish a rabbit control demonstration site, whereby the landholder is assisted by local government (and Biosecurity QLD if required) staff to eradicate their rabbits. The primary purpose of the demonstration site is to aid in extension activities regarding rabbit control. For example, a field day could be held to show other landholders the control options used to eradicate rabbits from that property. This is an excellent way of educating people about rabbits in general and why they need to be controlled. It also provides a positive interaction between government staff and the local landholders.

Field days and demonstration sites are helpful in generating enthusiasm to get people involved and working together. Finally, it would provide follow-up media material to accompany the initial media coverage regarding the monitoring in early October.

Summary of Options 1. Do nothing – leave the rabbit situation as is. • Consequences: possibility of rabbit numbers increasing to a point where they are established over a large area and living in warrens. This could also have an impact on native wildlife – foxes may accompany high rabbit numbers and prey on native animals as well as rabbits. 2. Continue the current rabbit management strategy of releasing RHDV • Consequences: possibility of rabbits gaining resistance to RHDV. This method of control does not provide long term control of rabbits unless accompanied by harbour destruction. The 15 samples collected in early October will be tested for RHDV antibodies. 3. Start a systematic rabbit control program now. This would involve setting up regular monitoring of rabbits, particularly before and after control. It would benefit greatly by using a demonstration site also. This may require using a variety of control techniques such as baiting, RHDV release and warren ripping/harbour destruction. • Consequences: Long term rabbit control can be achieved.