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Cats aren’t evil, but they are a problem David Winter Jan 22

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It seems Gareth Morgan has declared a war on cats. It will, I’m sure, come as a great surprise to you that Morgan’s description of cats as ruthless and sadistic killers that we must eventually purge from the land  has met some opposition. Invoking outrage is pretty good way to get free advertising in New Zealand, and if you measure the campaign’s success in tweets, comments and talkback calls I guess Morgan is on to a winner. But I’d like to think we can do better than simply setting up an argument between supporters of Morgan’s Maoist purge and cat lovers who think their moggie can do no harm.

Cats are a problem

Most of the reaction to Morgan’s campaign has been to basically treat it as a joke. We should be clear then, that introduced predators are the number one threat to New Zealand species. Stoats, weasels possums and rats all contribute the decline of birds and lizards (and invertebrates, though we don’t monitor those species closely enough to track their progress). Cats are certainly part of that problem. They have contributed to the extinction of at least 6 bird species  in New Zealand, and many more populations and subspecies have been lost partly as a result of predation by cats (Merton, 1978). Cats continue to pose a threat to our wildlife. The impact of feral cats on shorebirds  (plovers, dotterels, oystercatchers) and kakapo is well documented (Karl and Best, 1981 doi: 10.1080/03014223.1982.10423857). In the space of a week one cat managed to kill 102 native short tailed bats.

The problem isn’t restricted to wild cats. Pet cats will attack and kill native birds and lizards when they have the chance. In Dunedin the impact of tame cats is large enough that it’s been estimated local bird populations (including natives) wouldn’t survive if they weren’t replenished by migrants from around the fringes of the city (van Heezik, et al. 2010. doi: 10.1016/j.biocon.2009.09.01)


Getting rid of cats isn’t necessarily a solution

It’s clear then, that cats are a problem for the conservation of native wildlife. But it’s not nearly as clear that simply getting rid of cats will be much help. Every study of the diet of cats in New Zealand has found that cats kill a lot of mice and rats. These rodents are themselves predators of birds so removing one predator from our country may simply let another run amok. When feral cats were removed from Little Barrier island it led to an outbreak in kiore (Pacific rat), which threatened Cook’s Petrel populations on that island (Rayner et al, 2007 avaliable via PMC ).

Should we phase out cats in New Zealand?

So, if Morgan’s plan was actually do-able, should we do it? I have to honest here and tell you, I don’t know. It’s abundantly clear that cats, both feral and domestic, can kill native animals. It’s clear that in at least some cases that killing can have a major impact on populations, but removing cats might not help all that much. If you want to know whether the impact of your typical urban moggy justifies Morgan’s campaign, especially given the abundance of rats in New Zealand, you’d have to ask a conservation biologist. That’s something no news organization has bothered with yet, as far as I can tell.

Is this the conversation we should have started?

It’s fairly obvious that Morgan’s website, with its strange anthropomorphism (cats are predators sure, sadists? no) was designed to draw headlines and “start conversations”. But what hope is there for environmentalists in conversation where our side wants to take people’s kittens away?

Introduced predators are the biggest threat to New Zealand’s biodiversity, so the goal of eventually controlling these predators so tightly that they no longer pose a threat is a very worthy one. But the sort of change required to get us from today, where only 12% of the conservation estate is managed for predators, to that goal has to come from the ground up. Picking fights like this will get you headlines, but I don’t think it will change anyone’s mind.


Merton, Donald V. “Controlling introduced predators and competitors on islands” pp 121-128. In Temple, S.A. (ed.) Endangered birds: management techniques for preserving threatened species 1978

(image at the top via Pauline Dawson/ArtAndMyLife)

Sunday Spinelessness – Giant weta are amazing… but not the biggest bugs David Winter Dec 04

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I’m probably as big a cheerleader as you’ll find for New Zeland’s unique and wonderful invertebrates. So, you’d think I’d be happy to see one of our insects make the pages (or the pixels) of the The Daily Mail, The Sun, Boing Boing, The Huffington Post, The Mirror, The Times of India, io9 and damn near every other blog and newspaper in the world. Instead, I’ve spend the whole time feeling like the grinch that stole the gloss from the headlines.

The story, as it was presented in the tabloids at least, goes that an American tourist traveled to a remote island of the coast of New Zealand where he spent several days searching for a fabled giant bug before finally uncovering the creature and in the process breaking the record for the largest ever insect.

 
The only problem with the story is that every single detail of it is wrong. The “American tourist” is, in fact, Mark Moffett, former curator of Ants at the Havard Museum of Comparative Zoology turned explorer and a constant feature in National Geographic and in various other media. Little Barrier Island isn’t particularly remote; it’s two hours boat ride from Auckland, almost always has scientific and conservation workers living on it and even has electricity provided by a solar panels. The insect in this photograph is certainly endangered, but it’s apparently not very hard to find on Little Barrier. Most importantly, there is really no way that the insect chomping down on a carrot in this photograph is the largest insect ever recorded. 
The creature in question is a  Giant Weta, wetapunga (“god of ugly things”) in Māori and Deinacrida heteracantha (“mighty locust with differing spines”) in Latin. Here in New Zealand, we give the name “weta” to a large and taxonomically diverse group of cricket-like insects. Most weta are relatively small, not much larger than what you might think of as a standard cricket. Even the small species have a way of freaking people out. Cave weta (called “camel crickets” in other countries that have them) often roost in piles of firewood – I don’t know how many logs have been dropped on how many toes as a result of long antennae an spindly legs poking out form an armful of wood. Perhaps even worse, ground weta (like the hibernating one I recently disturbed) seek cool and dark roosts for the day time, so frequently sleep inside shoes, much to the alarm of  those owners who blindly poke their toes into them and meet resistance.

People that are scared of the smaller weta probably don’t want to contemplate the eleven species of giant weta that make up the genus Deinacrida. The body of these species is about 10 cm long, and they have antennae and legs to add to that (they don’t as io9 and several other outlets suggested, have a “wingspan”, what, with them being flightless). Although the reporting of Moffett’s “discovery” has made a lot about this being the biggest ever giant weta, it’s been rather short on actual numbers. In fact, the one number that keeps coming up in reports is 71 grams. That’s the current record for the heaviest adult insect, and it belongs to a Little Barrier Island Giant Weta, but there is no way the one in this photo can come close to it. In the wild, once weta have mated they move down from the trees in which they live and deposit their eggs deep into soil via that impressive “spike” they carry on their back-end (which is called an ovipositor). However, if you keep giant weta in captivity, unmated and with no access to soil in which to deposit their eggs, they just accumulate egg after egg after egg. The 71 gram behemoth that holds the current record was a captive female, which was retaining eggs and, so, quite unlike anything that would be crawling around trees on Little Barrier. In the wild females with eggs might be able to maintain a weight close to 40 grams. According to people who know, the female pictured with the carrot here isn’t particularly big for the Little Barrier species, so there is no reason to think she approaches the record holder.

I feel a little unpatriotic about this, but I also have to point out that even that 71 gram beast isn’t the largest insect in the world. Goliath beetles (from the scarab beetle family) and the titan beetle (a long horn beetle) probably both beat the the local contender on this front. The internet is full of claims of adult goliath beetles weighing up to 100 grams, but this appears to be one of those fact-like-objects that are often repeated but have no basis in reality. David M. Williams, who has tried to get to the bottom of the largest insect problem, thinks it might be a  result of the the reasonable metric measure “35 grams” entering an imperial brain as “3.5 oz”. In fact, it seems adult goliath beetles probably weight in the order of 30-50 grams – quite likely more than the natural range for giant weta. The titan beetle is longer than the goliath, but it’s not clear that these beetles are bulky enough to weigh more than the giant scarabs. What is clear however, is that the larvae of goliath beetles leave weta in the shade. These 13 cm long grubs tip the scales at around 80-100 grams. Scientists have yet to find the larvae of titan beetles, but they may well get even bigger. I struggle to see a good reason to restrict the “largest insect” to only adult forms, so I’m afraid the weta will have to lose that crown.

I really do feel awful about being such a downer on this rare occasion of a New Zealand invertebrate getting some exposure in the worlds’s press. I trust the poor reporting that came out of the story can be blamed on the tabloids that broke it and the other sources which ran it without doing any checks, and that it’s not a case of someone trying to buy themselves a headline by flying into the country and spotting an insect they knew they’d find. Still, it’s shame that the stories have been about the bogus “discovery” of this animal, and the claim that it’s a record breaker, because there are plenty of good reasons to talk about giant weta. In many ways, these bugs are a prefect example of the wierdness of biology in New Zealand. Our islands are just isolated enough from the rest of the world that, for the most part, invasions from overseas are rare and the bulk of species that live here live nowhere else. Those species that do establish themselves need to adapt to unique conditions and interactions that come with life on our islands, and the results are often very strange indeed. Where else would you end up with the kakapo, a giant flightless parrot in which the males attract mates with a near sub-sonic “boom” that is broadcast up to 5 kilometers from its origin. Giant weta might not be quite as bizarre as the kakapo, but they are a huge flightless cricket that has adapted to life entirely in the trees – that’s pretty cool.

The giant weta exemplify another story that is too common in the New Zealand flora and fauna. The weta and the kakapo seem to have developed in a country that was free from large mammalian predators*, and so never needed to evolve ways to escape or fight off such threats. The introduction of mice, rats, stoats, weasels and possums to our naive ecosystems, and the massive habitat losses that came at the same time, have had a  disastrous effect on our natural heritage. At least 60 species of vertebrate have become extinct since human settlement, and many more invertebrates will have past unnoticed. There are about 150 kakpo left, and only a few mainland enclaves and offshore islands play host to giant weta. Most of the other weta species are doing better than the giants, but they are still having to deal with predators for which their evolutionary history provides them no counter-measures. It’s easy to look at the  recent history of life in New Zealand and feel forlorn - I wish I had the chance to see a pair of Huia feeding or find a half-metre long gecko – but with the weta at least we have a chance to help. The giants need to be managed, and that means we need to make sure the Department of Conservation is funded to the extend that it can live up to its name. The main threat to the smaller weta species, at least in suburban settings, are mice and rats. Providing weta with a few roosting sites that are too slim for a mammal to squeeze into in your garden is enough to stack the odds in the insects’ favour. The Department of Conservation even has plans that you can use to bulid your own weta motel. And for those that think wetas are just too creepy to help in this way – I’m sure providing them safe lodgings will keep them out of your shoes!


You should check Mike Bok’s great post on the biggest insects here and David Williams chapter on the same, discussed above. I’m not going to link to all the news sources that ran with the silly version of this story, by kudos to Alan Boyle at MSNBC and The New Zealand Herald for digging a bit deeper.

 *There are two endemic species of bat, one of which is adatpted to feeding on the ground but probably wouldn’t take on an adult giant weta. There is also a 20 million year old fossil species of mammal that was probably more distantly related to modern placental mammals than marsupials are. We know precisely nothing about how this mammal, or its relatives made a living in New Zealand but the one that got fossilised was very small.

Conserving Don Merton’s achievements David Winter Apr 19

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Don Merton smiling, holding a ridiculously giant Parrot

Don Merton holding Richard Henry, an important Kakapo. Photo is CC 3.0 from here (thanks to Errol Nye from DoC)

Don Merton probably saved more species from extinction than anyone on earth. If it wasn’t for his efforts we would have lost the Chatham Island’s Black Robin and the Kakakpo, and the methods he pioneered as used by conservation projects all around the world. Last week Don Merton died.

Don’s most famous achievement was his heroic rescue of the black robin. The species was reduced to five adults and only one fertile female called ‘Old Blue’, all living on a tiny rock sticking out of the sea in the Chatham Islands. By going against the “hands off” approach to conservation that prevailed at the time and translocating the surviving birds to a larger island and ‘fostering out’ Old Blue’s eggs to the local tomtits Don founded a population that now has 300 or so birds. Their future is a long way away from being secure, but the fact they exist at all is down to Don Merton’s creative thinking, hard work and perseverance.

Don also led the team that rediscovered female kakapo after that species was considered ‘functionally extinct’, and the team that captured Richard Henry, the kakapo he’s holding in the photo above this story. (A bird so important for the kakapo recovery program that his death was recorded by Wired magazine). On top to those achievement you can add hundreds of projects in New Zealand and overseas which Don contributed to, or made use of the methods he’d developed here

Nic Valence spoke to Don about the robin project a few years ago.

Nic also found a quote from an interview with Don that makes a fitting eulogy. Talking about New Zealand’s natural heritage he said:

’They are our national monuments. They are our Tower of London, our Arc de Triomphe, our pyramids. We don’t have this ancient architecture that we can be proud of and swoon over in wonder, but what we do have is something that is far, far older than that. No one else has kiwi, no one else has kakapo. They have been around for millions of years, if not thousands of millions of years. And once they are gone, they are gone forever. And it’s up to us to make sure they never die out.

Though I struggle to understand them, there are people who are not sold on the importance of conservation by comments like that one. So here’s another quote from Don, this one recorded by Douglas Adams when he visited Don and the kakapo as part of Last Chance to See

All we can do is perpetuate them during our lifetime and try to hand them on in as good a condition as possible to the next generation and hope like heck that they feel the same way about them as we do.

If we are so careless that we still lose the kakapo, or the black robin we won’t just lose a unique product of our countries long history; we will lose something that Don Merton, and thousands of other people have committed their lives to. If we let that happen we are vandals, just as surely as someone who defaces a monument is.

Sunday Spinelessness – Protecting the katipo David Winter Jun 13

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New Zealand has a pretty benign fauna. We have no snakes, no carnivorous mammals bigger than our little bats and, ever since Haast’s Eagle was the driven to extinction, the apex of our natural food webs has been occupied by the karearea. The karearea is the native falcon, and a fierce predator, but it holds no threat to humans. In fact, we only have one native animal capable of doing people any harm, a venomous spider known as the katipō. So, some people were a little surprised to hear the katipo had been added to list of “absolutely protected” animals included in the wildlife act, the same level or protection offered to kiwis and the tuatara.

A female katipō, photograph is CC 2.0 from Jon Sullivan


The katipō’s name is a testament to the punch its bite packs, it translates as “night stinger”. Actually, the fact the species has a māori name at all sets it apart from our other spider species, the rest of them fall under the name pÅ«ngāwerewere. The katipō certainly deserves special recognition, it’s a cousin to the black widow and the redback and its neurotoxic venom can produce the same suite of symptoms that make those spiders feared the world over.

Although the katipō’s bite is excruciatingly painful, the spider’s unique ecology means they seldom bite humans. The katipō is very closely related to the Australian redback (the two can still hybridise) but whereas the Australian species is a generalist that lives in amongst rocks and logs and human debris, the katipō has become a specialist. It builds its web in driftwood and grass on sand dunes. That specialised lifestyle has been the katipō’s undoing. In the last hundred years the total area of sand dunes in New Zealand’s coastline has decreased by 70%. Not only has most of the katipō’s habitat been destroyed in the last hundred years, most of the the remainder has been degraded. We introduced marram grass to sure up dunes that have been disturbed by agricultural and urban development. While that grass does a great job of collecting sand and holding up dunes, it’s also very invasive and the katipō doesn’t much care for it (preferring the relatively sparse growing native sedge pingao).

Marram grass isn’t the only invasive species driving the katipō’s decline, a distantly related South African spider called Steatoda capensis has become widespread in New Zealand. S. capensis is another generalist which has not trouble getting by in marram filled dunes and breeds more quickly than the katipō. Add the damage done by recreational activities like quad bike riding to the pressures already listed and you start to realise why there are eight populations of katipō left it the South Island.

There is no doubt that the katipō is threatened with extinction. Adding it to the list of species protected under the Wildlife Act* gives DoC the ability to post scary sounding warnings around remaining habitat, and to prosecute people who willfully damage that habitat. But it’s clear from a few comments around the web that not everyone is on board with saving the katipō. Why should we try and hold on to our only dangerous animal? The risk posed by the katipō is really infinitesimal, they aren’t living on your downpipes or your living rooms. Even if you wander into the sand dunes you’ll have to go out of your way to find a katipō and get it scared enough to bite you. New Zealand’s biota is already so depleted by human enduced extinctions, it really would be shamefull to lose another species because of ill informed fear.


* Reading the actual law really does my head in, I think it means for the purposes of that act terrestrial vertebrates are protected unless other wise noted, and inverts are not unless specially picked out.

And a wee note for all the spineless fans (there are some, right?..), next Sunday I will be in a series of airports on my way to the USA for the Evolution meetings in Portland. So, Sunday Spinelessness will take a break ’till early July.

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