Red-eared sliders invade Auckland city waterways

Cowboy_Ken

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Auckland is on the brink of an "explosion" in red-eared slider turtles - a pest regarded by conservation authorities as one of the world's 100 most-invasive species. New Zealand banned the importation of red-eared sliders in 1965, but it is legal to own and breed the reptiles.
With a lifespan of up to 50 years though, families who once bought a cute 4cm pet for children have found decades later they're stuck with a fully grown turtle the size of a dinner plate. Some have been releasing the critters into Auckland's waterways.
As a result, Auckland is staring down the barrel of a serious infestation of the species introduced from the southern United States. The council has begun a major pest management review, which includes looking at a law change on ownership and a cull of those in the wild.
"People think they're doing what's in the best interest of the animal by releasing these turtles into the wild, but it's really not in the interest of the wider ecosystem," Dr Imogen Bassett, council biosecurity adviser, said.
"We don't have any hard numbers on their abundance but we do know they're commonly found in waterways around much of the region, including wetlands, lakes, creeks, drainage and ditches in southern and western Auckland.
"It's not known whether it's warm enough in those regions for the animals to breed." Bassett said the full impact on Auckland's ecosystem is not yet known, although existing pressures on Auckland's diminishing wetlands are clear. "We have lost a huge proportion of our wetlands to drainage. The last thing these already under-pressure water bodies need is to have turtles added to the mix," she said.
UK evidence also says sliders are a threat to nesting waterbirds - taking over nests and preying on eggs and hatchlings. "They are opportunists when it comes to food," she said.
"They will eat vegetation, small birds or insects." Red-eared sliders, which take their name from a distinctive red stripe behind each eye, also pose a salmonella risk. Manawatu and Waikato are also encountering the species roaming wild.
Waikato Regional Council's pest management review means fines of up to $5000 can now be slapped on anyone caught releasing one of the turtles. Angie Harvey, who works with SPCA to help rescue the reptiles, has more than 70 sliders at her sanctuary in Massey, West Auckland.
"A lot of people have these animals but want to get rid of them.
"I set up a Facebook page a year ago hoping to educate people on how to look after them, but I have more turtles coming in than going out," she said. Harvey, who receives no funding for her sanctuary, also called for mass breeding of the species to be stopped in New Zealand.


I received the following letter in response which was published the next day in the New Zealand Herald.

The letter:

The headline “Turtles invade Auckland city waterways” was way off the mark. There are a lot of reasons for this. Here are a few:

Prior to importation being banned in 1965 about 30,000 red-ear slider turtles had been brought into the country. Since then about 2000 turtles have been bred per year in New Zealand. That’s a total of about 130,000 animals. If they were able to survive and reproduce in the wild there would now be many millions of them running around Auckland yet only a handful are found each year.

There are two reasons why we are NOT being invaded. The first is that turtles cannot reproduce here without human help. Turtle eggs require high temperatures and lots of moisture to hatch. The few areas where it’s warm enough are inevitably too dry for the eggs to survive. There have been a few cases of turtle eggs hatching outdoors but they have always been situations near a north facing rock wall or other heat sink that was watered consistently. The sex of hatchling turtles is controlled by ground temperatures so even those situations are only able to produce males because of the cooler temperatures.

The other problem for turtles in New Zealand is that it is too cool in the summer and too warm in the winter. The cool temperatures in summer prevent them from being able to warm up enough to digest the vegetation they eat (they do NOT eat live fish, birds or eggs) and the relatively warm winter temperatures keep them from hibernating properly so they lose weight and die of starvation and disease after about four years.

Turtles are also no threat to the few natural wetlands in New Zealand because the water is too cool for them to be able to warm up enough to eat. Turtles might survive for a few years in warmer man made ponds, backwaters of the Waikato River and the numerous weed choked canals in the Hauraki Plains but, even there, they inevitably die after a few years.

Hopefully when the Auckland Council goes through their “major pest management review” they will consult with someone that is actually familiar with the biology of turtles.


Dr. Mark Feldman
Dr. Feldman has regularly spoken at the TSA conference concerning updates to recommendations on drugs and doses to induce egg laying in turtles. His research is carried out at the largest turtle farm in the USA where they have large numbers of turtles available to develop new drugs and determine dosages, and in New Zealand where he has maintained a colony of turtles for 25 years so he can detect any long term side effects. He has also spoken in Australasia at the vertebrate pest conference on real and perceived threats of introduced turtle species, published articles on the real and perceived threats of turtles under New Zealand conditions and consulted for, and spoken at, a conference of the US Fish and Wildlife service on American turtle farms and their relevance to turtle conservation.
His address- 50 Darwin Road
Kerikeri
 

enchilada

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im sure RES is not the worst invasive species in New Zealand .
Before human discovered new zealand, the only mammals on these islands are couple species of bats.
 
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