How the bleating tree frog invaded Lord Howe Island

The story of the cane toad is one of many from history that involves the misguided introduction of exotic animals to vulnerable areas. When Europeans first arrived in Australia they missed the sights and sounds of the homeland and brought over many animals for familiarity and comfort, some of which are now considered to be the most destructive in Australia. But the deliberate introductions of animals for aesthetics and agriculture are not the only pathways for invasive species. Lots of organisms sneak through customs and immigration as stowaways and by human carelessness.

Lord Howe Island, as with many remote islands, has a unique and exciting, but vulnerable ecosystem.

Lord Howe Island, as with many remote islands, has a unique and exciting, but vulnerable ecosystem.

As we reported in our article in the journal PLOS ONE this year, paradise destination Lord Howe Island has become yet another recent victim of the carelessness of trade and transport. The World Heritage listed group of islands comprises stunning volcanic mountains surrounded by the world’s most southern coral reef. It sits several hundred kilometres off the coast of New South Wales and is home to only a few hundred residents that work in tourism and local industries.

Far-flung islands like Lord Howe are frequently protected by the vast oceans that surround them, but the isolation that protects them also makes them vulnerable. Volcanic islands rise from the sea and the animals and plants that live there are restricted from breeding with organisms on the mainland. In many cases, wildlife on remote volcanic islands is endemic – meaning it’s found there and nowhere else. Lord Howe Island has remained largely pristine since it was settled, with lots of untouched forest and a lagoon teeming with wildlife. Sadly though, lots of the endemic wildlife of Lord Howe has been devastated by introduced animals.

The bleating tree frog - small, but noisy!

The bleating tree frog – small, but noisy!

Despite this knowledge, the march of invasive animals continues. The bleating tree frog, a small noisy amphibian from south-eastern Australia, was introduced to Lord Howe Island accidentally – likely with a boat load of supplies, in the 1990s. To investigate how the frog got to the island, we took genetic samples from the Lord Howe population of frogs and compared them with the genetic information of the bleating tree frogs on the mainland to find their closest relatives. We were able to determine that the Lord Howe Island population originated in northern coastal New South Wales.  While we were there we also collected data on the distribution of the frogs across Lord Howe Island, their breeding activity and habitat use. We found that the frog is widespread and successfully making use of most habitats on the island, including the forested areas, cattle pastures and buildings.

The habitat of picturesque Lord Howe Island has remained largely untouched, but the wildlife has been negatively impacted by the introduction of non-native species.

The habitat of picturesque Lord Howe Island has remained largely untouched, but the wildlife has been negatively impacted by the introduction of non-native species.

Due to their intolerance of seawater, amphibians are rare on volcanic islands such as Lord Howe. They must be introduced by humans to be able to colonise such isolated places. The bleating tree frog has been the only frog that has successfully invaded Lord Howe Island so far, but without careful consideration for the future, other animals may follow its path. Although it remains to be seen if the bleating tree frog will be a disaster to the Lord Howe Island wildlife, scientists continue to call for greater biosecurity controls and awareness to help prevent further animals and plants slipping through the net and destroying native systems.

Citation: Plenderleith TL, Smith KL, Donnellan SC, Reina RD, Chapple DG (2015) Human-Assisted Invasions of Pacific Islands by Litoria Frogs: A Case Study of the Bleating Tree Frog on Lord Howe Island. PLoS ONE 10(5): e0126287. doi:10.1371/journal. pone.0126287

This work is published in an open access journal, which means anybody can read it! Find it here.

Just how much animal blood do vegetarians have on their hands?

An online article claiming vegetarians are causing more animal deaths than meat eaters continues to cause arguments between the two camps. I am amazed this story is still doing the rounds. My understanding is that the original article appeared in The Conversation in 2011, maybe (it’s not all that clear in the article – there’s a link, but no reference) inspired by a book by Peter Singer. This week, IFLS has discovered it and it has been copied and shared and passed on in social media and via e-mail. The Conversation article represents one of the few pieces of literature (to my knowledge it is not what the scientific community would consider a true piece of peer-reviewed published research) that suggests meat eating is “better” than a vegetable-based diet and consequently has received a lot of attention, particularly (in my experience) from meat-eaters. It has probably been quite the boost for the associated authors’ careers. I have seen similar responses to articles refuting climate change…

My biggest concern with the original article (and therefore any further articles which claim scientific substance) is that it is based on figures of the number of mice killed per hectare of arable land, compared with the number of pasture raised cattle killed for meat. Even assuming that the questionable figures are accurate in the first place, it makes no mention of mice deaths in cattle pasture. In my view, they should have analysed the number of ALL sentient beings killed in each farming practice, since they are concluding from the mouse/cattle data that there are more individual deaths in arable farming than meat.

Also of significance is the displacement of animals which is also ignored in the article. Pasture is a dramatically different ecosystem to a native, unimproved grassland. This article considers the killing of mice as the only significant problem, but there are many more that will die or not be born as a result of the decreased area of habitat, as native animals are pushed out by cattle and sheep.

The article also ignores import/export, which is a major factor in Australian agriculture and the food industry. I don’t know the current figures, but about 10 years ago, Australia was simultaneously the world’s second largest importer and exporter of beef. Aside from us destroying our native habitat to produce cattle for an overseas market, we also import and export huge amounts of vegetable matter for food. Australia is part of the global market and food trade routes pass in and out of our productive country.

There is also a suggestion by the author that the rangelands can only be used as cattle grazing or arable land. I would argue that although there may be no nutritional value in not farming land, by reducing the pressure caused by invasive species (such as cattle) and the direct manipulation of the habitat required to do as such in some areas, the increase of intensity in areas currently used as arable fields is at least in part mitigated.

The author states: ” if you want to minimise animal suffering and promote more sustainable agriculture, adopting a vegetarian diet might be the worst possible thing you could do” which, aside from the sensationalist, deliberately vague language, is not the same message of the next paragraph: “we should choose the way that causes the least unnecessary harm to animals.” which is also not the same as “sustainable agriculture”. The author does later touch on the surface of sustainability in agriculture, but the piece of research that this article is primarily based upon does not have any significant claims either way about sustainability. The message of this article is confused as well as erroneous.

Lastly, it is essential to remember that the book was published by an ethicist. Whilst I don’t think that alone is grounds to discredit it, it does explain why much of the bigger ecological picture has been ignored. The untangling of ethics and ecology is a long-standing problem, as can be attested to by anyone trying to perform research in the field. In this story though, the application of ecological principles to what started as a purely ethical discussion is abused and/or misguided.

So if you are going for steak, please make it kangaroo. I am still undecided entirely about the merits of it – there is no shortage of examples of species being eaten to extinction – but as long as we don’t all immediately do it, it’s probably the better choice at present. This is an important discussion to continue and we have a responsibility to research and question the impact of our diet, so please do not cherry pick the numbers to suit your lifestyle. Ethics, ecology and food security are real and important issues affecting us now and in the future.

Shark week special

Sharks swim in human-infested waters. Our fair weather relationship with the sea, our disrespect for our marine environment and our fear of the unknown, fuelled by media sensationalism puts undue stress on all ocean-going creatures. More recently, sharks have taken the brunt of this issue*, to the point where we have started to appease swimmers with inhumane and unethical treatments of sea life, causing death, disruption and suffering. All this, despite opposition from marine biology experts.

Sharks do not represent a real risk to us; even when we swim in their habitat. Not a real risk. A quick browse of the The International Shark Attack File will show how small the risk really is. Not like driving a car or getting married (to someone who might kill or injure you) and certainly not like cigarettes or fatty food. The act of swimming in the ocean is more likely to kill you through drowning than shark attacks.

Killing sharks offers a visible reduction in their numbers and therefore a perceived reduction in the perceived threat. Rare, endangered species (such as white sharks) are actually targets of the programmes. It also reduces numbers of all animal “bycatch”. Sometimes more so than the target species, as recognised by the authorities that continue to implement the programmes.

Sharks are bioindicators (a living being, or group thereof, that signifies the health of an ecosystem). They eat dead matter in the oceans. They are incredibly diverse. They perform the tasks of an apex predator, keeping the species below them in the food web healthy and in equilibrium. Sharks are more useful than the credit they are afforded. Sharks are more important than I have space to write.

A recent study showed that sharks could be removed and released, safely and successfully whilst reducing shark attacks and eliminating the need for killing, inhumane or otherwise. The location of the study, Brazil, has one of the largest number of shark attacks in the world and this is a promising step in reducing shark attacks and respect for the life of our oceans.

We need sharks more than we realise, but perhaps more importantly, right now they need us. So spread the word about the low low risk of shark attacks. Sign petitions to stop the drumlines and write to your politicians about reducing the harm we are doing to the oceans. We will miss them if they go.

*Most of this research appears to be open access (which means you can read it for yourself) and I implore you to see what the scientists have to say on the issues addressed briefly here.

Hazin, F. H. V. & Afonso, A. S. (2014) Response: A conservation approach to prevention of shark attacks off Recife, Brazil. Animal Conservation, 17(4), 301-302.

House, D. (2014). Western Australian Shark Hazard Mitigation Drum Line Program 2014-17.
Meeuwig, J. J., & Ferreira, L. C. (2014). Moving beyond lethal programs for shark hazard mitigation. Animal Conservation, 17(4), 297-298.

Shiffman, D. (2014). Keeping swimmers safe without killing sharks is a revolution in shark control. Animal Conservation, 17(4), 299-300

This is the only photo I have of a shark, but it's one I took and I was very excited!

This is the only photo I have of a shark, but it’s one I took and I was very excited!

P.S. I make no excuse for three marine-centric articles in a row. The saltwater portion of our planet is the most significant, the most endangered and the least known. Because we don’t live within its limits we are foolish enough not to protect it to the standards we should.

What is your motivation for conservation?

Although potentially controversial, I am a strong advocate for conservation based mainly on intrinsic value.

We also know of the financial value of wild areas or animals (safari brings many tourist dollars for example) and the environmental goods and services argument (e.g., we need rivers as a source of fresh water).

I am planning a research paper investigating these motivations and would love to hear from you (regardless of your background/occupation or education). Are you motivated to conserve or preserve? Why? Does it make you happy just to know that you walk the same planet as koalas, or when you get in the ocean you know there’s a blue whale out there somewhere in the same water? Do you enjoy garden visitors such as butterflies or birds? Are you worried that the cure for cancer may be found in the rainforests that we are logging? And/or do you appreciate that we need trees to breathe and a sustainable source of food to eat?

Please let me know in the comments below. Thanks!