Posts Tagged endangered species

Solved: the problem of the cross-dressing frogs Rebecca McLeod Nov 03

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The global plight of amphibians received a lot of attention last year – the official Year of the Frog. Just in case you missed it, amphibians are currently undergoing a worldwide extinction crisis, with 32% of all species threatened with extinction. The reasons for this sorry state of affairs are believed to be many – loss of habitat, increased incidence of disease, competitive exclusion from introduced species, climate change, increased UV radiation, pollution, predation, and overexploitation.

But I don’t want this to be yet another story documenting the alarming state of our global ecosystem. Recently I attended a very inspiring seminar given by Jen Germano – and it gave me hope that innovative approaches to conservation might just lead to some species recovering to healthy levels. Germano is a doctoral student at Otago University who is about to submit her PhD thesis under the supervision of Drs Phil Bishop and Alison Cree, and in collaboration with Landcare Research scientist Dr Frank Molinia.

A Maud Island frog (Leiopelma pakeka)

A Maud Island frog (Leiopelma pakeka)

Germano has spent the past 5 years focusing on ways to improve the success of conservation efforts for New Zealand native frogs (genus Leiopelma). New Zealand currently has 4 species of native frog – all classified as endangered – and 3 species that are believed to be extinct. Our frogs are from an archaic lineage and have a few traits that set them apart from those inhabiting other parts of the globe. Most notably, New Zealand native frogs do not have external eardrums, and therefore do not croak, instead communicating with chemical signals. There is also no easy way to tell males and females apart – there are no colour, size, or other morphological differences between sexes (hence the crass but attention-grabbing headline!), and this has posed problems for those trying to save them.

Jen Germano with some Maud Island froglets (babies)

Jen Germano with some Maud Island froglets (babies)

A proactive approach is being taken to frog conservation in this country, and many organizations are involved with efforts to breed and translocate frogs, to encourage sustainable populations. With other endangered species captive breeding populations have provided a form of “insurance”, but one major problem has arisen for NZ frogs – whilst our zoos have put a great deal of effort into starting captive frog colonies, they haven’t been able to successful breed any of the native frogs. This setback led Germano to develop a method for telling apart males and females based on hormone levels in their urine. The method is relatively non-invasive, and has allowed Germano and her colleagues to sex Maud Island frogs with 94% certainty. The ability to identify the sex of our native frogs is a big leap forward for captive breeding and translocation programs, as now they will be able to provide even sex ratios, which will hopefully lead to higher breeding success. Germano has been passing on her skills to staff at Auckland Zoo and Orana Park, where captive breeding programs are underway.

Germano explains that until recently, very little was known about the basic life history of our native frog species. “While I was working on frog translocations for my Masters project, I saw many of the problems that other scientists were facing when working with these frogs and it was obvious that there were huge gaps in the knowledge that we had for the basic biology of our endemic species and in the information that managers and scientists needed to conserve them.” A large part of Germano’s thesis involved determining the breeding season of Maud Island frogs – and surprisingly she found it is likely to occur in mid winter. Germano has also discovered that Maud Island frogs have incredibly low sperm counts, which may also help to explain why their numbers are so low.

With her PhD thesis soon to be submitted, Germano will be heading to Memphis Zoo in the USA to begin a position as a postdoctoral researcher in amphibian reproductive biology. But she can leave with the satisfaction of knowing that the Maud Island frogs and those working to save them in a much better position than when she began her studies.

The largest remaining population of native frogs in NZ exists on Maud Island, a predator-free island in the Marlborough Sounds.

The largest remaining population of native frogs in NZ exists on Maud Island, a predator-free island in the Marlborough Sounds.

Orokonui Ecosanctuary to open Rebecca McLeod Oct 29

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After more than 20 years of dreaming, planning and pure hard work the Orokonui Ecosanctuary will be officially opened this Friday. The 307 hectare block of land is situated near Waitati in the Blueskin Bay catchment, just a short drive from Dunedin. The opening marks the completion of the Visitor and Education Centre – a fine demonstration of eco-building. Much of the timber was milled from exotic pines that once resided within the sanctuary, the building is positioned to capture and retain sun and warmth, shipping containers have been recycled into administration areas, and waste water is treated onsite.

I was lucky enough to get a guided tour around the sanctuary a couple of weeks ago, and was incredibly impressed. There are few examples of remnant forest on the East Coast of the South Island, but here is one of them – towering broadleaves, podocarps and kanuka – these forest types are within close proximity of each other. A 2 million dollar, 10 km long pest exclusion fence was completed in 2007, and an ongoing eradication program since then has seen exotic mammals including possums, rats and stoats reduced to undetectable levels. And so enter the stars! Kaka, saddlebacks and jeweled geckos introduced since the completion of the fence have been flourishing, as have resident tomtit, brown creeper and  rifleman. The hope is that, in years to come Kiwi, Kakariki and Tuatara will be established within the sanctuary. It should only be a matter of time until Otago has a southern equivalent of the Karori Wildlife Sanctuary! I highly recommend going on a tour of this incredible place – the guides are so passionate and knowledgeable, and will no doubt have more to show us as the forest ecosystem recovers in years to come.

This viewing platform was constructed from exotic wood that was milled from within the sanctuary

This viewing platform was constructed from exotic wood that was milled from within the sanctuary

Southern right whale population on the rebound Rebecca McLeod Oct 14

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Southern right whales, hunted perilously close to extinction last century, appear to be making a remarkable recovery in New Zealand according to recent research. For the past four years a group of scientists from Auckland and Otago Universities, the Department of Conservation and the Australian Antarctic Division have been sailing south to the Auckland Islands to count and identify individual whales that go there to breed and calve. Recent DNA matches of whales recorded in both the Auckland Islands and mainland New Zealand have shown that the animals migrate between these two areas and likely form one intermingling population. Certain individuals have also been seen at the Auckland Islands, Campbell Island, mainland New Zealand and South Australia – these animals certainly get around!

The research group sails to the Auckland Islands on the R.V. Evohe, and then conducts surveys from small boats. Here they are in Port Ross.

The research group sails to the Auckland Islands on the R.V. Evohe, and then conducts surveys from small boats. Here they are in Port Ross.

Individual whales are able to be identified by unique markings on their skin. These white patches are aggregations of crustaceans, called cyamids, which cluster around skin calluses.

Individual whales are able to be identified by unique markings on their skin. These white patches are aggregations of crustaceans, called cyamids, which cluster around skin calluses.

These patches of cyamids remain remarkably consistent year on year.

These patches of cyamids remain remarkably consistent year on year.

Results of genetic analyses by Professor Scott Baker and his team at Auckland and Oregon State Universities indicate that the New Zealand population of southern rights was reduced to as few as 50 reproductive females following years of hunting in the 1800s and early 1900s, and further illegal whaling of the species by the Soviet Union in the 1950s and 60s. Since the 1960s the population appears to have been steadily increasing. Ten years ago the population was estimated to include about 900 whales, and the preliminary findings of the latest surveys, indicate that numbers have likely doubled since then. According to Dr Simon Childerhouse, the leader of the most recent expeditions, the rate of recovery of New Zealand southern right whales appears to be at least as high as that seen for populations in Australia and South Africa. In contrast, populations of northern right whales are incredibly depleted, and do not appear to be recovering. Despite right whales being protected in the northern hemisphere, mortality from ship strike and entanglement in fishing gear appears to be outweighing natural population increase. In this sense, southern right whales are fortunate – their natural home range around the Southern Ocean and coastal and offshore New Zealand, has relatively low volumes of shipping traffic.

Southern rights are baleen whales, and feed upon zooplankton such as copepods and euphausids.

Southern rights are baleen whales, and feed upon zooplankton such as copepods and euphausids.

Although, as Dr Will Rayment from the University of Otago explains, as the species starts to recolonise mainland New Zealand, it is possible that they will be more at risk of such threats. “Historically, southern right whales have aggregated in sheltered bays, including Otago and Wellington Harbours, to breed and calve. As this species makes a resurgence around the mainland, it is expected that they will again tend to spend time in these areas – although of course since they were last here the intensity of human use of harbours has changed somewhat. Their tendency to spend time in coastal areas means that they could possibly be affected by human activities such as shipping, fishing, aquaculture, and even tidal power generation. It will be interesting to see how the species and human activity interact in coming years. Here we have a unique opportunity for proactive management of an endangered species – as opposed to reactive management, which is more often the case.”

Two southern right whales, with the R.V. Evohe anchored in the background.

Two southern right whales, with the R.V. Evohe anchored in the background.

These days, Port Ross at the northern end of the Auckland Islands, is the main breeding area for New Zealand southern rights. The whales congregate there in large numbers throughout the winter months. Dr Rayment says that there may be up to 200 individuals in the harbour at any one time, and all evidence points towards the species being highly promiscuous. During the latest trip to the Auckland Islands, it was common to see several males pursuing a female, with the female often rolling on her back in an effort to stop males from mating with her. Following a one year gestation period, females tend to return to the harbour to calve, and then spend a year nursing their calf before conceiving again – resulting in most females producing one calf every three or four years. The increase in whale numbers appears to be following a typical exponential population growth often seen in recovering populations. And the increase is starting to be noticeable in mainland New Zealand – numbers of annual whale sightings recorded by the Department of Conservation are trending upwards around Otago. The current population is estimated to be only 10% of the pre-whaling numbers, suggesting that we may well be visited by a lot more southern rights in the future. In these times of doom and gloom for the marine environment (think depleted fish stocks, marine pollution, ocean acidification…), it is uplifting to see a species making a comeback.

Southern right whales often approached the research vessels during surveys.

Southern right whales often approached the research vessels during surveys.

Last year the expedition was joined by a journalist and a photographer from National Geographic – the resulting underwater photographs are truly awesome.