Diversity in Australia’s tropical savannas: An integrative taxonomic revision of agamid lizards from the genera Amphibolurus and Lophognathus (Lacertilia: Agamidae)

Authors: Jane Melville, Euan G Ritchie, Stephanie N J Chapple, Richard E Glor And James A Schulte II

Published in: Memoirs of Museum Victoria, volume 77

Abstract

The taxonomy of many of Australia’s agamid lizard genera remains unresolved because morphological characters have proved to be unreliable across numerous lineages. We undertook a morphological study and integrated this with a recent genetic study to resolve long-standing taxonomic problems in three genera of large-bodied Australian agamid lizards: Amphibolurus, Gowidon and Lophognathus. We had broad geographic sampling across genera, including all currently recognised species and subspecies.

Using an integrative taxonomic approach, incorporating mitochondrial (ND2) and nuclear (RAG1) genetic data, and our morphological review, we found that both generic and species-level taxonomic revisions were required. We revise generic designations, creating one new genus (Tropicagama gen. nov.) and confirming the validity of Gowidon, giving a total of four genera. In addition, we describe a new species (Lophognathus horneri sp. nov.) and reclassify two other species.

Our results provide a significant step forward in the taxonomy of some of Australia’s most iconic and well-known lizards and provide a clearer understanding of biogeographic patterns across Australia’s monsoonal and arid landscapes.

Melville J, Ritchie EG, Chapple SNJ, Glor RE Schulte II JA (2018) Diversity in Australia’s tropical savannas: An integrative taxonomic revision of agamid lizards from the genera Amphibolurus and Lophognathus (Lacertilia: Agamidae). Memoirs of Museum Victoria PDF DOI

Towards meaningful monitoring: A case study of a threatened rodent

Authors: Hayley M Geyle, Gurutzeta Guillera‐Arroita, Hugh F Davies, Ronald S C Firth, Brett P Murphy, Dale G Nimmo, Euan G Ritchie, John C Z Woinarski, and Emily Nicholson

Published in: Austral Ecology

Abstract

Detecting trends in species’ distribution and abundance are essential for conserving threatened species, and depend upon effective monitoring programmes. Despite this, monitoring programmes are often designed without explicit consideration of their ability to deliver the information required by managers, such as their power to detect population changes.

Here, we demonstrate the use of existing data to support the design of monitoring programmes aimed at detecting declines in species occupancy. We used single‐season occupancy models and baseline data to gain information on variables affecting the occupancy and detectability of the threatened brush‐tailed rabbit‐rat Conilurus penicillatus (Gould 1842) on the Tiwi Islands, Australia. This information was then used to estimate the survey effort required to achieve sufficient power to detect changes in occupancy of different magnitudes.

We found that occupancy varied spatially, driven primarily by habitat (canopy height and cover, distance to water) and fire history across the landscape. Detectability varied strongly among seasons, and was three times higher in the late dry season (July–September), compared to the early dry season (April–June). Evaluation of three monitoring scenarios showed that conducting surveys at times when detectability is highest can lead to a substantial improvement in our ability to detect declines, thus reducing the survey effort and costs.

Our study highlights the need for careful consideration of survey design related to the ecology of a species, as it can lead to substantial cost savings and improved insight into species population change via monitoring.

Geyle HM, Guillera-Arroita G, Davies HF, Firth RSC, Murphy BP, Nimmo DG, Ritchie EG, Woinarski JCZ, Nicholson E (2018) Towards meaningful monitoring: A case study of a threatened rodent. Austral Ecology, PDF DOI

Dingo dinners: what’s on the menu for Australia’s top predator?

By Tim Doherty (Deakin University), Chris Dickman (University of Sydney), Dale Nimmo (Charles Sturt University), Euan Ritchie (Deakin University) and Thomas Newsome (University of Sydney).

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The dingo is Australia’s largest land-based predator, occurring across most of the mainland and on many nearshore islands.

Our new research, published in the journal Mammal Review, reveals the breadth and diversity of dingo diets across the continent.

We compiled and analysed 73 sets of data, containing details of more than 32,000 dingo droppings or stomach contents, to document the range of different species that dingoes eat, and how their diets vary between different environments.

A wide-ranging diet

We found that dingoes eat at least 229 vertebrate species. This includes 62 small mammals (less than 500 grams in mass), 79 medium-sized and larger mammals, 10 species of hoofed mammals, 50 birds and 26 reptiles. Dingoes also eat insects, crustaceans, centipedes, fish and frogs.

The true number of species is likely to be much higher because dingo diets have been poorly studied in many parts of Australia, such as Cape York Peninsula.

Large (at least 7 kg) and medium-sized (0.5 to 6.9 kg) mammals were the most common components of dingo diets, followed by small mammals, rabbits, arthropods, reptiles, birds and hoofed animals.

Average occurrence of eight food types in the diet of dingoes. Values represent the percentage of droppings/stomachs that contained each food type.

A range of introduced pest species also feature in dingo diets, including deer, goats, rabbits, hares, black rats, house mice, foxes and cats. In recent decades, the occurrence of sambar deer in dingo diets has increased as this invasive species has expanded its range.

Dingoes also eat sheep and cattle, although dietary samples are unable to distinguish between predation and scavenging, and hence tell us little about dingo impacts on livestock production. Dietary samples also do not reveal instances of dingoes killing livestock without eating them.

Regional variation

We found that what dingoes eat depends on where they live. For instance, in arid central Australia, birds, reptiles, rabbits, small mammals and insects form major parts of dingo diets. In contrast, these food groups are less important in temperate and subtropical eastern Australia, where medium-sized and large mammals such as kangaroos, bandicoots and possums are more important.

Frequency of different food groups in dingoes’ diet. Each circle represents a study and is scaled proportionally with dietary occurrence; larger circles represent a higher frequency of that food type. Top row: arthropods and small mammals (less than 500 g); middle row: reptiles and medium-sized mammals (0.5-6.9kg); bottom row: rabbits and large mammals (at least 7 kg).

The higher occurrence of medium-sized mammals in dingo diets in eastern Australia may be due to the lower extinction rates of native mammals there. In contrast, central Australia is a global mammal extinction hotspot, which probably accounts for the low occurrence of medium-sized mammals in dingo diets in arid and semi-arid areas.

Nonetheless, one medium-sized mammal was a major food item for dingoes in arid areas: the European rabbit. In some areas, more than 50% of dingo droppings or stomachs contained the remains of this invasive species. It is possible that native medium-sized mammals previously constituted a major part of dingo diets in arid Australia, but have since been replaced by rabbits.

Local prey availability plays a major role in determining what dingoes eat. For instance, in the Tanami Desert, reptiles were most common in dingo diets during warmer months when they are most active. However, very few studies have collected data on prey availability, partly because of the sheer number of different animals that dingoes eat.

Threatened species

Dingoes kill or eat at least 39 native species that are classed as threatened or near-threatened on the IUCN Red List. These include the northern quoll, golden bandicoot and bridled nailtail wallaby.

This tally is higher than the number of threatened species in feral cat diets (based on a previous study that used similar methods), even though cats eat almost twice as many different species overall as dingoes (400 and 229, respectively).

Today’s threatened native species co-existed with dingoes for a long time before European colonisation, which means they were able to withstand dingo predation without going extinct.

But now a combination of small population sizes of some threatened species and exacerbating factors such as habitat loss, foxes and cats means some threatened species could be vulnerable to even low levels of dingo predation. Predation by dingoes should therefore be a key consideration when attempting to conserve or restore threatened species.

Dietary studies are one way we can understand how dingoes interact with other species. Our study also highlights that we still have much to learn about our native top predator. In many parts of Australia, the favourite foods of dingoes are still a mystery.

The authors acknowledge the contribution of Naomi Davis, Dave Forsyth, Mike Letnic, Russell Palmer, Joe Benshemesh, Glenn Edwards, Jenny Lawrence, Lindy Lumsden, Charlie Pascoe, Andy Sharp, Danielle Stokeld, Cecilia Myers, Georgeanna Story, Paul Story, Barbara Triggs, Mark Venosta and Mike Wysong to this research.
The Conversation

Continental patterns in the diet of a top predator: Australia’s dingo

Authors: Tim S Doherty, Naomi E Davis, Chris R Dickman, David M Forsyth, Mike Letnic, Dale G Nimmo, Russell Palmer, Euan G Ritchie, Joe Benshemesh, Glenn Edwards, Jenny Lawrence, Lindy Lumsden, Charlie Pascoe, Andy Sharp, Danielle Stokeld, Cecilia Myers, Georgeanna Story, Paul Story, Barbara Triggs, Mark Venosta, Mike Wysong, and Thomas M Newsome

Published in: Mammal Review

Abstract

Conserving large carnivores is controversial because they can threaten wildlife, human safety, and livestock production. Since large carnivores often have large ranges, effective management requires knowledge of how their ecology and functional roles vary biogeographically.

We examine continental‐scale patterns in the diet of the dingo – Australia’s largest terrestrial mammalian predator. We describe and quantify how dingo dietary composition and diversity vary with environmental productivity and across five bioclimatic zones: arid, semi‐arid, tropical, sub‐tropical, and temperate.

Based on 73 published and unpublished data sets from throughout the continent, we used multivariate linear modelling to assess regional trends in the occurrence of nine food groups (arthropods, birds, reptiles, European rabbits Oryctolagus cuniculus, medium‐sized (25–125 kg) and large (169–825 kg) exotic ungulates (including livestock), and other small (<0.5 kg) medium‐sized (0.5–6.9 kg) and large (≥7 kg) mammals) in dingo diets. We also assessed regional patterns in the dietary occurrence of livestock and the relationship between dietary occurrence of rabbits and small, medium‐sized and large mammals.

Dingoes eat at least 229 vertebrate species (66% mammals, 22% birds, 11% reptiles, and 1% other taxa). Dietary composition varied across bioclimatic zones, with dingo diets in the arid and semi‐arid zones (low‐productivity sites) having the highest occurrence of arthropods, reptiles, birds, and rabbits. Medium‐sized mammals occurred most frequently in temperate and sub‐tropical zone diets (high‐productivity sites), large mammals least in the arid and sub‐tropical zones, and livestock most in the arid and tropical zones. The frequency of rabbits in diets was negatively correlated with that of medium‐sized, but not small or large mammals.

Dingoes have a flexible and generalist diet that differs among bioclimatic zones and with environmental productivity in Australia. Future research should focus on examining how dingo diets are affected by local prey availability and human‐induced changes to prey communities.

Doherty TS, Davis NE, Dickman CR, Forsyth DM, Letnic M, Nimmo DG, Palmer R, Ritchie EG, Benshemesh J, Edwards G, Lawrence J, Lumsden L, Pascoe C, Sharp A, Stokeld D, Myers C, Story G, Story P, Triggs B, et al. (2018) Continental patterns in the diet of a top predator: Australia’s dingo, Mammal Review, PDF DOI

Species definitions shape policy

Authors: Euan G Ritchie, Bradley P Smith, Lily M van Eeden, and Dale G Nimmo

Published in: Science, volume 361, issue 6,409 (September 2018)

The names we assign to organisms, and why, have important ramifications for our understanding of Earth’s diversity and, more practically, how it is managed. For example, wolves, coyotes, domestic dogs, and other canids are often considered distinct (1), but their members can, and frequently do, interbreed (2). Differing concepts of species—which might take into account morphology, ecology, behaviour, genetics, or evolutionary history (3) —could describe canids as very few or many species, depending on which concepts are used and how strictly they are applied. Which definition scientists adopt can have political and ecological consequences.

The dingo (Canis dingo) has traditionally been considered native in Australia, given evidence of its presence before the year 1400 (4) and indications that it has lived in Australia for at least 5,000 years (5). This designation meant that Western Australia had to have a management strategy in place for the dingo, along with other native fauna. However, a recent paper (6) argues that dingoes are in fact C. familiaris because they don’t satisfy zoological nomenclature protocols nor sufficiently differ genetically or morphologically from other canids, including domestic dogs.

The Western Australian government cited this work in justifying its recent decision to declare the dingo a non-native species under the state’s Biodiversity Conservation Act (BCA) (7). The new order removesthe government requirement to manage the species. As a result, dingoes can now be killed anywhere in the state without a BCA license. A potential increase in lethal control of dingoes could have dire consequences for Australia’s ecosystems. The dingo is Australia’s largest terrestrial top predator (adults typically weigh 15 to 20 kg (8)), it fulfils a crucial ecological role, and it has strong cultural significance for Australia’s Indigenous people (8).

Taxonomy serves a critical purpose for cataloguing and conserving biodiversity, but different interpretations and applications of species concepts can affect management decisions. Policy-makers may use the interpretations that justify their preferred values, such as prioritizing livestock more than biodiversity protection. It is therefore imperative that scientists carefully engage in the policy decision-making process. Scientists must work with policy-makers to convey the multiple dimensions and values that can affect species delineation and make clear the potential consequences of applying such classifications.

  1.  J.Clutton-Brocketal.,Bull.Br.Mus.Nat.Hist.Zool. 29,117 (1976).
  2. Z.Fanetal.,Gen.Res.26,163(2016).
  3. F.E.Zachos, Mammal Rev.10.1111/mam.12121(2018).
  4. Department of the Environment and Energy, Australian Government, “Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act)” (1999); http://www.environment.gov.au/epbc
  5. K.M.Cairns, A.N.Wilton, Genetica 144,553(2016).
  6. S.M.Jackson et al., Zootaxa 4317,201(2017).
  7. M.Bamford, “Dingoes to remain classified as non-native wild dogs under reform to Western Australian law,” ABC News (2018); http://www.abc.net.au/news/2018-08-28/dingoes-will-no-longer-be-native-animals-in-western-australia/10172448
  8. M.Letnic et al., Biol.Rev. 87,390(2012).

Ritchie EG, Smith BP, van Eeden LM, Nimmo DG (2018) Species definitions shape policy, Science PDF DOI

The Conservation: Guardian dogs, fencing, and ‘fladry’ protect livestock from carnivores

Livestock guardian dog breeds, such as Maremma, are often raised with and trained to consider themselves part of a livestock herd and so protect their herd from threats. Image via Shutterstock.

By Lily van Eeden (University of Sydney), Adrian Treves (University of Wisconsin-Madison), and Euan Ritchie (Deakin University).

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Farmers have struggled for millennia to protect their livestock from wolves, lions, bears, and other large carnivores. It’s expensive and time-consuming for farmers, governments and related agencies. Many current approaches have led to dramatic reductions or the complete loss of some apex predators from many regions of the globe.

Despite these substantial costs and their long history, we have remarkably little understanding of what methods best reduce livestock attacks.

A recent synthesis study, led by Lily van Eeden, Ann Eklund, Jennie Miller, and Adrian Treves with a total of 21 authors from 10 countries, found that there’s a worldwide dearth of rigorous experimental studies testing the effectiveness of interventions to protect livestock from carnivores.

Where studies do exist, results were mixed. Some management interventions did reduce livestock losses, some made little to no difference, and some resulted in increased livestock losses. This means that for some methods, farmers would be better off doing nothing at all than using them.

Poor evidence, poor outcomes

The scant evidence is cause for concern. Aside from financial waste, preventable livestock attacks cause economic, emotional, and social costs for farmers. And both livestock and carnivores may be left maimed and suffering by human failures to separate the two sets of animals.

Too often, studies and management programs measure success based on money spent or saved, numbers of community members who contributed, or carnivores killed. None of these factors necessarily mean livestock loss is prevented or reduced.

In fact, livestock owners, policy makers, and scientists should work together to build an evidence base and discover what works best to reduce attacks on livestock under different conditions.

What works and why

Where we found rigorous studies quantifying livestock loss, three methods were consistently effective: livestock guardian dogs, some kinds of fencing, and a deterrent called “fladry” (a Polish word for strips of cloth or plastic flagging hung at regular intervals along a rope or fence line).

Livestock guardian dogs have been used successfully in Europe for centuries and are now seeing a revival elsewhere, including in North America and Africa.

Livestock guardian dog breeds, such as Maremma and Komondor, are typically much larger than herding dogs. They are raised with and trained to consider themselves part of a livestock herd and so protect their herd from threats.

While dogs are most common, they’re not the only guardian animals: llamas, alpacas, and donkeys are also used to protect livestock from smaller predators like coyotes and foxes, but more research is needed to determine how effective they are.

Fencing can be simple post-and-wire, an electric fence, or corrals, kraals or bomas (circular enclosures used in some parts of Africa) constructed from stones or wood.

Livestock can be kept within fenced areas all the time, or only at night when they are most vulnerable to carnivores (who often hunt at night, dawn, or dusk).

Our study didn’t find sufficient evidence to show that all kinds of fencing work, but there was enough that they should be considered generally effective and adapted to local conditions.

“Fladry” is a Polish word for strips of cloth or plastic flagging hung at regular intervals along a rope or fence line. Fladry is usually red, which is considered the most effective colour for scaring away carnivores. This method has been proven effective at deterring predators like grey wolves and coyotes from entering pastures.

Interestingly, all three of the methods we found to be generally effective do not involve killing carnivores.

This is good news for carnivore conservation, because it means that management can simultaneously protect livestock and carnivores. Large carnivores can play crucial roles in ecosystem regulation, so removing them can cause cascading consequences for landscapes and biodiversity.

Given the damage that ineffective management can cause to farming communities, animal welfare, and ecosystems, we hope our research serves as a catalyst for policy-makers and practitioners to think critically about the methods they use and why.

Too often, we continue to use a particular method due to habit and history, but that doesn’t mean it’s the best way to protect assets.

Governments that continue to fund and encourage ineffective management are not giving farming communities the best chance of success.

The Conversation

Expanding the role of targets in conservation policy

Authors: Tim S Doherty, Lucie M Bland Brett A Bryan, Timothy Neale, Emily Nicholson, Euan G Ritchie, and Don A Driscoll

Published in: Trends in Ecology & Evolution

Conservation targets perform beneficial auxiliary functions that are rarely acknowledged, including raising awareness, building partnerships, promoting investment, and developing new knowledge. Building on these auxiliary functions could enable more rapid progress towards current targets and inform the design of future targets.

Doherty TS, Bland LM, Bryan BA, Neale T, Nicholson E, Ritchie EG, Driscoll DA (2018) Expanding the Role of Targets in Conservation Policy, Trends in Ecology & Evolution, PDF DOI