Contraception

Nathan Beerkens - Wednesday, September 27, 2017

Burrowing bettong contraception trial off to a great start

By Holly Cope, PhD candidate from the University of Sydney

All photos taken by Holly Cope.

A bit about me…

I’m currently a PhD candidate at Sydney University studying under the supervision of Dr Catherine Herbert, examining the use of contraception in the management of endangered species. Most of my work has been on Tasmanian Devils in the Devil Facial Tumour Disease (DFTD) free insurance population. We are using contraception on selected female devils based on their genetics with the aim of maximising genetic diversity, and only giving females which have not yet reproduced or are genetically under-represented the chance to breed. This also lets us keep them housed in groups, which helps to stop them from adapting to captivity, while keeping a mixture of breeding and non-breeding females in with males. This is the best way to make the most of limited resources and housing space in the conservation program.

Holly Cope with a Western Barred Bandicoot.

Why am I using contraception on burrowing bettongs?

My project at Arid Recovery examines another way of using contraception on endangered species. Burrowing bettongs are excellent breeders, and with the removal of most predators, have become locally overabundant within the reserve, with around 8 thousand individuals living inside the fenced enclosure. They are damaging the vegetation and overrunning the other species housed in the reserve, so Arid Recovery is keen to reduce their population to a more manageable size in an ethical and cost-effective way. Fertility control using contraceptive implants is one of the options being considered, but we need to figure out a few things first – does the Suprelorin® implant work on female bettongs? How long will it last? Are there any negative side effects? How many would we need to implant to have an impact on the population? Is this a feasible option logistically and economically?  I aim to answer these questions with a pilot study on around 50 female bettongs in the 1st expansion of the reserve.

Burrowing Bettong in a cage trap.

How does it work?

The Suprelorin implant gradually releases a gonadotrophin-releasing hormone (GnRH) agonist called deslorelin as it dissolves. The continuous release of deslorelin affects the pituitary gland, and stops it from releasing follicle stimulating hormone (FSH) and luteinising hormone (LH), which are both responsible for ovulation. Without FSH and LH, the bettongs will be unable to ovulate and shouldn’t conceive any offspring for some time.

How did it go?

Over 10 nights in August 2017 I set traps with the help of my volunteer, Lachlan, in the late afternoon, checked them after sunset and then reset them for checking again at sunrise. We set and checked traps 408 times and captured bettongs 347 times. We identified 119 individuals (48 females and 71 males), and treated 30 females with contraceptive implants.

For every bettong that we captured, we gave them ear tags if they weren’t already tagged, measured their head and pes (foot) lengths as indicators of age, checked their body condition score and measured tail width as indicators of condition. We also checked their gender and then either measured testes width or checked the reproductive status of the pouch. The boys didn’t appreciate that in the cold mornings! We had four females with small joeys less than a week old, a few others had young at foot and most others had recently weaned a joey. We injected contraceptive implants in 30 females overall (our minimum target), leaving every third untreated to act as a control in the study (to compare the final results against the contracepted females). We had hoped to treat 50 females, but we found a 2:1 ratio of males to females in traps which made it difficult to catch enough!


Injection of the conctraceptive implant, Suprelorin®, under the loose skin between a bettong's shoulders.

We also found a few other mammals enjoying the peanut bait ball! We microchipped and health checked a bilby and a few western barred bandicoots, and released some Spinifex hopping mice and plains mice. We spotted a shingleback and a bearded dragon out sunning themselves too which was quite a treat!

A gorgeous Greater Bilby being processed.

Where to now?

I will be returning every 2-3 months over the next 12 months to re-trap the females in the study and check inside their pouches. Bettongs are able to mate while their current joey is still in the pouch, and this new embryo enters suspended animation (embryonic diapause) until their joey leaves the pouch. This means that some bettongs may have already conceived a new joey before contraception, which we can work out by figuring out the birth date of their next joey. We hope to see no new pouch young conceived after contraception. We will also be monitoring for any weight gain, which can be a common side effect of contraception. The information generated through this project will be given to Arid Recovery managers to help them decide on a course of action for reducing and then maintaining the bettong population at a more sustainable density. If the bettongs appear to still be contracepted at the end of the 12 months, monitoring may be continued by Arid Recovery staff/interns to see when the bettongs begin breeding again. The findings from this research will also be relevant to other reserves housing bettongs or small marsupials that may be facing similar issues.

What a beautiful place to work!

        

  

 

A Stickie Living Situation

Nathan Beerkens - Thursday, September 21, 2017

A Stickie Living Situation

By Emily Gregg and Maddy Wilcox-Kerr

Celebrating the architecture of stick-nest rats

All the animals in our arid environment must find some kind of shelter to protect them from the heat of summer days, and the cool of winter nights. Most animals retreat into burrows, including small mammals such as the Spinifex Hopping Mouse, and larger ones such as the Burrowing Bettong. It’s not just our nocturnal mammals either; our reptile species also retreat to burrows during the night.

Burrows are sprawled everywhere throughout this landscape, to the point where you’re hard pressed to walk around at night here without tripping over one. These dark, sandy sanctuaries clearly provide outstanding protection from the arid elements.

Yet the Greater Stick-Nest Rat, aka Stickies, builds itself an entirely different kind of living room. Taking his or her time, a Stickie will, as their name suggests, collect a bunch of sticks and construct a nest. This isn’t a simple collection of sticks; the rats actually stick these sticks together, and with no super glue in their back sheds, they are somewhat limited in their sticky substance of choice.

Like many desert animals, Stickies don’t get a lot of water; they survive mostly off the moisture within their food. As a result, their urine is thick and sticky, almost like honey, and honey seems like a perfect substitute for glue, doesn’t it? So, yes, the rats use their urine to stick their little sticky houses together, displaying an industriousness we can surely all admire.

Since we are lucky enough to accommodate these cool critters, our team has noticed a few different styles of Stickie nests around the reserve, and we thought we should share them with you!

The Granny Flat

With the kids growing up and new family members moving in, these Stickies needed to upsize their home. Adding a granny flat to the main bungalow allows the family to prepare for the future. At Arid Recovery, it is not uncommon for Stickies to build homes up to 2m wide with intricate tunnel systems connecting sites to outside areas. In the future, these two nests may become one.



The Squatter

Forget Ned Kelly or ‘Mad Dog Morgan’, the Aussie outback has a new wave of thieving bandits. Underneath our research station we have a squatter decorating his house with stolen goods. Upon closer inspection of this nest we’ve come across pens, forks and flagging tape that look suspiciously familiar. Sometimes, Stickies will incorporate unnatural materials they find to add structure and strength to their home. Although these materials are rightfully ours, we are putting them on loan until further notice.



The Rocky Outcrop

"Little Stickie, little Stickie, let me come in."
"No, no, not by the hair on my chinny chin chin."
"Then I'll huff, and I'll puff, and I'll blow your house down!"

But the third little Stickie had built his house from Bricks and the Big Bad Dingo could not get in.

Stick-nest Rats are very resourceful, and will use whatever ready materials they can find. This inventive rat took the opportunity to build a fortress within a boulder pile by filling all the gaps between the rocks.



The Outhouse

Quintessentially Australian Stickies may choose to construct their home in the iconic outback dunny. The Outhouse will provide the Stickie with water and protect them from predators, sounds very tempting doesn’t it? Despite the smell, we have one keen Stickie who has begun their nest construction between the walls of Arid Recovery’s drop toilet. In our opinion, this Stickie has poor taste and will need to be relocated to a more suitable environment.



The Multicultural Suburb

Multiculturalism is a reality of Australian life and living in an ethnically diverse suburb keeps things interesting. Living harmoniously alongside Bettongs and Bilbies, Stickies are well and truly contributing to a diverse Australia. Some Stickies are redefining what it means to be part of a multicultural Australia and are seeking refuge inside the bettongs’ deep cool burrows to escape the extreme heat of the summer. This behaviour is not uncommon, during the hottest hours of the day most mammals like to retreat below ground.



The Modern Family

Taking the Multicultural Suburb to the next level, "The Modern Family" is a cooperative project between Stickies and Bettongs to create the ultimate warren. In most cases you’ll find these sorts of structures occupied by both Stickie and Bettong families. Because they have different foraging and sleeping habits these sorts of arrangements work quite well.



The Brutalist

Simple, powerful, intimidating. We have one architect out at our reserve willing to experiment with late 20th century styles. This is "The Brutalist", constructed in a pile of star pickets at our fencing stockpile. The ruggedness of this work is characteristic of its genre placing us in the hall of fame alongside The Australian National Gallery and UTS Tower in Sydney. 



The Mobile Home

For all those Stickies with wanderlust there is no need to buy a permanent home when you can be out there travelling the world. This construction may not be the most durable option, but for Stickies who are regularly on the move, a mobile home can be quite appealing.



The Ghost Town

These are the remains of a nest that was active 100 years ago in a breakaway overhang in outback South Australia. The nest would have been used by many generations of Stick-nest Rats over the years but is now silent and empty.

These spooky nests can be found right across the arid and semi-arid zones and are a poignant reminder of what we've lost.

Photo taken on Copper Hills Station by Peter Copley.



The Conclusion
If you want to learn more, head over to the species’ information page. If you want to help these guys out please consider adopting a Stick-Nest Rat or donating to Arid Recovery, so we can continue protecting these amazing little creatures.

Does an animal’s name affect whether people care about it?

Nathan Beerkens - Friday, September 08, 2017

Does an animal’s name affect whether people care about it?

By Jack Ashby, Manager of the Grant Museum of Zoology, University College London

It is an unfortunate but unavoidable fact that the amount of attention that different species receive often has little to do with their ecological importance, or any other scientific measure of “value”. Most members of the public care more about koalas than they do about clams, because we find it so much easier to relate to cute animals like mammals (for one thing, they have faces). This has consequences for our relationship with these species, including how easy it is to garner support for their conservation.

A rat by any other name would look as sweet

However, I would argue it’s not just how species look, but also what we call them that impacts upon how people consider them. I manage a zoology museum in London, and in my experience of talking to our visitors it’s clear that certain animal names bring about an instant negative reaction in many people. Chief among them is “rat”, and Australia has a lot of rats.

Greater stick nest rats are one of Australia’s many native rats. Photo: Hugh McGregor

My particular zoological passion is Australian mammals and I’m currently at Arid Recovery to support their ecological research programs. Encountering the incredible mammals that are thriving here on the reserve made me think about the importance of the English names these species have been given.

How to be a mammal

There are three ways to be a mammal, and their definitions are tied to the way they reproduce. First, monotremes lay eggs, and comprise just a handful of living species, restricted to Australia and New Guinea: the platypus and echidnas. Second, marsupials give birth to tiny young after a very brief period in the womb, and then do most of their development suckling milk on a teat (often in a pouch). The approximately 335 species of marsupials are only found in Australasia and the Americas. The third and by far the biggest group (over 5,000 species, with global distribution) is the placental mammals, which give birth to well-developed young after a relatively long period in the womb, and finish off their development with a short period suckling milk.

Australia is not just a land of marsupials

Australasia is the only place where all three groups are found (which is one of the reasons why I find it so fascinating), but the public perception that they enjoy is not evenly spread. I think Australia’s native placental mammals get a raw deal. It comes as a surprise to many people that nearly half of Australia’s land mammals are not marsupials. Everybody knows Australia has lots of bats, but I’ve had many conversations with people who weren’t aware that Australia also has native rodents. In fact, they comprise nearly a quarter of all Australian terrestrial mammals.

A native Spinifex hopping mouse re-released after a survey at Arid Recovery.

“You dirty rat!”

The word “rat” tends to bring about a negative emotional reaction; perhaps even one of disgust. Black rats (Rattus rattus and Rattus tanezumi), brown rats (Rattus norvegicus) and Pacific rats (Rattus exulans) are native to Asia but have been spread by people across the globe for millennia. They have become universally associated with disease, filth and have a general “pest” status.

Unfortunately the strength of the negative public image of these “bad” rats can easily rub off on the environmentally important native rodents that are also called rat.

Rats for kids

If nearly a quarter of Aussie land mammals are rodents, why are there so few (if any?) kids’ books or cartoons about them? Wombats, possums, devils, quolls, kangaroos, platypuses, quolls and koalas fill children’s libraries, but why no native mice and rats? Perhaps this helps explain why so many people are under the impression that Australia doesn’t have any native rodents.

Rodents have been here in Australia for at least 4-5 million years, and have arrived by hopping from island to island from mainland Asia in a number of waves. They cover almost the full gamut of terrestrial diets (from seed-, leaf- and fruit-eaters to predatory carnivores), and are found in every kind of habitat.

A black-footed tree-rat in Kakadu, Northern Territory. Photo: Michael Beerkens

Rats are losing the rat race

Arid Recovery is home to a number of ratty beasts, including the most significant population of greater stick-nest rats on the Australian mainland. Following European invasion of Australia, the cats and foxes that the settlers brought with them spread like wildfire across much of the country (along with a number of other introduced species including black and brown rats). At least 29 native mammal species have since become extinct (14 of which were rodents), and the majority of the others have suffered dramatic range reductions.

Greater stick-nest rats just managed to cling on to their existence on a couple of offshore islands, in the absence of introduced predators, from where they were reintroduced to Arid Recovery. Their close relatives the lesser stick-nest rats (which also would have once been found across much of the arid zone) were not so fortunate – they became extinct by around 1950.

Because of the impact introduced predators are having on Australia’s native rodents, it’s critical that organisations like Arid Recovery are able to protect the surviving populations. In their absence the ecosystems do not function properly, and entire habitats can collapse. While it’s relatively easy to get the public to get behind charismatic species like bilbies, they have to work harder to communicate the importance of native rodents like stick-nest rats.

Rebranding the rats

I’m not sure how I feel about this, but a number of native rodents have been rebranded to remove the word “rat” from their name, which may help with their public image. After the predator-proof fence was built at Arid Recovery, the threatened plains mouse – which existed in low numbers in the region – colonised the reserve and boomed in the absence of cats. Until recently, this species had been known as the “plains rat”. Similarly the prehensile tailed-rat of north Queensland has been rebranded “tree mouse”, which certainly sounds cuter.

The rodent formerly known as “plains rat”

Marsupials are not exempt from this topic. One of the earliest European descriptions of an Australian animal was of the quokkas of Rottnest Island.  In 1696 William de Vlamingh gave the island its name (meaning “Rats’ Nest” in his native Duutch). Nicolaes Witsen reported on the voyage: “[Vlamingh] found no people but a large number of rats, nearly as big as cats, which had a pouch below their throat into which one could put one’s hand”.

 

Rat-kangaroos?

Similarly the bettongs that will be familiar to anyone who has visited Arid Recovery after dark were called “rat-kangaroos” by the first British colonist in 1788, and the name stuck. Whenever I discuss working with bettongs I see people crinkle their nose at the idea of a “rat-kangaroo”, presumably because of the connotations of the word “rat”.

Bettongs were described as “rat-kangaroos” by early British colonists. Photo: Jack Ashby

In the cases of the bettongs and quokkas, it’s not the desire to remove the word “rat” that was the driver behind the name change. These names are anglicised versions of Indigenous words for these animals. The act of naming was part of the colonisation process, and we have/had no real cause to overwrite the Indigenous names with English ones. At risk of oversimplification, by giving them back their Indigenous names, we recognise the importance of animals’ names in the way we think about them, just as we do when it comes to “rats”.

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