Big bounce in South Island wallaby numbers
South Canterbury farmers are struggling to control rising wallaby numbers.
During the past two years, Tim Morrow has spent $24,000 on a programme to poison wallabies on the 5000 hectare sheep and beef farm he manages inland from St Andrews south of Timaru.
Recreational hunters also kill 2000 wallabies on the property annually.
Morrow said it was hard to know how many wallabies were on the property but it was definitely in the thousands.
"They target the best areas. If you've got a block saved up for young sheep or calves they will find it."
Wallabies damage exotic forests, plantings, native bush seedlings, scrub and fences.
Morrow said if it was not for the wallabies he would be able to run another 1000 sheep, which equated to about $150,000 in potential income.
Morrow is just one of many farmers across South Canterbury counting the cost of lost income caused by the wallabies.
At Lake Opuha, near Fairlie, sheep and cattle farmer Dave Williams first noticed wallabies on his 2500ha farm five years ago. He has farmed in the area all his life.
"Eventually it was going to happen. My wife was sitting here watching the TV and one hopped across the lawn in front of us."
He does not have anywhere near the number of wallabies that Morrow has, but Williams is worried they are escalating and spreading out.
Environment Canterbury (ECan) bio-security team leader Brent Glentworth shares Williams' concern.
Glentworth said wallaby numbers were building and spreading out within the 900,000ha containment zone, between the Rangitata and Waitaki Rivers.
He said it was initially thought wallabies had a range of about 350,000ha and were within a core area of 170,000ha, but they were now expanding further.
"Farmers on the periphery are noticing more wallabies."
Wallabies have also set up home in two areas outside the containment zone, at Mount Cook and on the south bank of the Waitaki River. ECan has been working to eradicate these populations since they were discovered in 2008.
But within the containment zone, it is the farmers' responsibility to control the wallabies on their property.
Up until 1992, the Wallaby Control Board was in charge of fighting the pest, but it was disbanded in 1992 when farmers decided they no longer wanted to pay the board for this service. The farmers opted instead to go user pays and initiate their own controls.
But, Glentworth said wallaby numbers have increased since then.
He said the control work was not co-ordinated so one farmer could be pro-active but the neighbouring farm might not be.
He encouraged farmers to form a co-ordinated approach in the fight against the pest.
"There are still quite a few farmers not putting enough effort into wallaby control. Co- ordination is the key to pest control."
Two ECan inspectors visit farms within the containment zone to look for signs of the pest and if they believe the numbers have reached a scale of four on the measuring tool, the Guilford Scale, then they will be issued with a legal notice to do some work to reduce numbers.
If the farmer does not undertake any of this work within a given time, ECan can engage a contractor to do the work and send the bill to the farmer, Glentworth said.
"If the neighbouring property has wallaby numbers just below the trigger level then we (ECan) cannot require them to carry out wallaby control and this property can effectively act as a source for re-infesting the area where control has been completed."
However, Morrow said he would like to see the Government come up with some financial assistance to help farmers make a sizeable dent in the numbers.
"Since the Wallaby Control Board was disbanded the numbers have exploded," Morrow said.
-Wallabies were imported from Tasmania to Christchurch in 1870.
-The bennett's wallaby, found in South Canterbury, can grow up to one metre tall and weigh up to 25kg.
-Three wallabies eat the equivalent of one sheep.
-Wallabies are found in only a few places in New Zealand including South Canterbury and around Lake Tarawera.
-They are nocturnal and feed at night making them even more difficult to cull.