Category Archives: Research

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

Eradicating abundant invasive prey could cause unexpected and varied biodiversity outcomes: The importance of multispecies interactions

Authors: Miguel Lurgi, Euan G Ritchie, and Damien A Fordham

Published in: Journal of Applied Ecology

Abstract

Abundant and widely distributed invasive prey can negatively affect co‐occurring native species by competing for food and/or shelter, removing vegetation cover and reducing habitat complexity (changing predation risk), and by sustaining elevated abundances of invasive mesopredators. However, information regarding the community and trophic consequences of controlling invasive prey and their temporal dynamics remain poorly understood.

We used multispecies ecological network models to simulate the consequences of changing European rabbit Oryctolagus cuniculus abundance in an arid mammalian community. We quantified how changes in the dominant prey (rabbits) affected multiple trophic levels, examining changes in predator–prey interactions through time and how they affected native prey persistence.

Our results suggest that removal of rabbits can benefit native biodiversity immediately at removal rates between 30% and 40%. However, beyond these levels, densities of small native mammals will decline in the short term. The processes underpinning these declines are: (a) increased competition for resources (vegetation) with kangaroos Macropus spp., whose numbers increase due to their release from competition with rabbits and (b) increased predation (prey switching) by feral cats Felis catus. Both effects are mediated by dingoes Canis dingo, a native apex predator.

Importantly, native mammal abundance recovers after a time delay, which is prolonged when high rates of rabbit control are applied. This is likely due to a reduction in hyperpredation by invasive feral cats and red foxes Vulpes vulpes following rabbit removal.

Continued eradication of rabbits in arid Australia will benefit native species due to a decrease in apparent competition for resources and by alleviating hyperpredation from invasive mesopredators. Furthermore, ecosystem‐level conservation benefits of reducing invasive prey abundance are as important as direct control of invasive mesopredators.

Synthesis and applications: Multispecies ecological network models provide wildlife managers with tools to better understand and predict the complex effects of species removal and control on both intact and modified ecosystems. Our results show that management of the Australian arid zone can benefit from controlling invasive prey as well as invasive predators. However, invasive species control can cause unexpected outcomes on native biodiversity. This extends to other systems where dominant prey may play fundamental roles in ecosystem structure and function.

Lurgi M, Ritchie EG, Fordham DA (2018) Eradicating abundant invasive prey could cause unexpected and varied biodiversity outcomes: The importance of multispecies interactions, Journal of Applied Ecology, PDF DOI 

The Conversation: Killing sharks, wolves and other top predators won’t solve conflicts

Black tip sharks swim with tropical fish in a lagoon in French Polynesia.

By Robert Lennox (Carleton University), Austin Gallagher (University of Miami), Euan Ritchie (Deakin University) and Steven J Cooke (Carleton University).

This article was originally published on The Conversation. Read the original article.

In French Polynesia, fishing is an integral part of everyday life. The people living here fish on the flats and along the reef using nets, hooks and line, harpoons, spearguns and traditional artisanal traps.

They fish for food. They are also seeing the benefits of using their traditional knowledge to guide recreational fishing tourists — a business with potential to improve long term employment security.

Abundant sharks in the lagoon led to questions about their contribution to the fishery and whether it would help the fishery if they were targeted. This is a question that is often on the minds of humans when they encounter predators.

As an ecologist working with the fish populations in French Polynesia, I went looking for research about what happens to an ecosystem when a predator is removed. Are the responses predictable? Does it work? Can we make generalizations?

Our new study, published in Biological Conservation, surveyed the research on predator removal and identified several interesting — and perhaps unexpected — trends.

Humans and other predators

Predators are among the most charismatic animals on Earth — lions, eagles and sharks adorn many human symbols. On land, in the air and in water, predators fascinate and inspire, they are quintessential representations of nature’s majesty and might.

In spite of their ecological, economic and cultural significance, predators are among the most heavily persecuted animals, due to conflict with humans and their assets.

Predators attack and kill livestock, hunt economically important prey and can kill or injure people or be perceived as a threat to human safety. These conflicts may motivate humans to try to manage predators to lessen the damages.

One of the oldest and most rudimentary methods is to cull or remove them, even though predators are already rare and some are threatened with extinction.

The motivation to remove predators is easy to understand, but what if predator removal does not even achieve the desired outcomes?

In balance

Predators are essential to ecosystems because they regulate prey populations. Without predators, prey can become over-abundant. This can result in damage to local plants, as well as disease outbreaks that can spread to domesticated animals.

Top predators like wolves dominate small predators like coyotes, keeping those populations in check too. Without predators, ecosystems become unbalanced in many ways because plants, herbivores and small predators change in response to their loss.

In a perfect scenario, successful predator removal would strike a balance. It would reduce conflict and be sustainable, but not cause the predator population to disappear entirely. However, our review of 141 studies of predator removal revealed that success is rarely achieved.

Livestock attacks weren’t always reduced when predators were removed, and the human-wildlife conflict remained. On top of that, new predators often moved into vacated territory and recolonized areas where others had been removed. For example, when caracal (a type of wild cat) and leopard were culled in South Africa, predator conflicts on farms increased.

A small number of studies have shown successful removal of predators without harming the predator population, and led to increases in the prey population. However, these examples of success were generally from the Arctic where wolves were removed to increase caribou or moose numbers. In that scenario, there are fewer links in the food web, possibly making responses more predictable.

Generally, however, the responses were unpredictable and removing predators often failed for one reason or another.

Coexistence, not conflict

Ecosystems are complex networks of species. They include plants, decomposers, naturally subordinate predators (such as feral cats, foxes and coyotes), pathogens, predators and their prey. Together, they all play vital roles in regulating each other.

When humans remove predators, the effects are consistently negative. The action can, for example, fracture wolf packs into smaller units, or increase the reproductive rates of coyotes to produce even more offspring. This can have knock on effects, including an increase in disease, plant damage if herbivore populations explode and even an increase in the number of collisions between large herbivores, such as moose, and vehicles.

Instead of killing predators, there are other measures we can take to reduce conflict and learn to live with wildlife. In parts of Alberta, biologists are encouraging landowners to use electric fencing around bee hives and chicken coops to fend off bears. These types of non-lethal solutions can be tested and may often be more effective than removing the predator.

Other studies have suggested that “rewilding” an ecosystem — that is, reintroducing species into the ecosystem — can reduce conflicts. When their prey are abundant, the predators have less interest in nearby livestock. One study showed that lynx conflict with farmers increased when their natural prey, roe deer, were scarcer.

Essential elements

Instead of removing predators to manage human-wildlife conflict, we should be looking towards non-lethal alternatives. Using deterrent devices (lights, sounds or flapping material) can keep predators away from homes, fields and livestock.

The services that predators and functioning ecosystems provide to humans are of enormous value, and we would be wise to work hard to conserve and maintain them for the benefit of all.

Predators aren’t only symbols, they are essential parts of healthy terrestrial and aquatic landscapes. And beyond what we value, we should feel an imperative to preserve the diversity of life we share Earth with, most of which precedes our own evolution.

Of course, there will be times when predator removal may be necessary to protect people and their interests. Interventions that champion the principles of coexistence between humans and predators may be more successful and justifiable approaches to managing wildlife.

Efforts to protect predators or proactively promote their return, rather than continue contributing to their decline and extinction, are among the greatest conservation challenges we face.
The Conversation

Crowdfunding biodiversity conservation

Authors: Eduardo Gallo-Cajiao, Carla Archibald, Rachel Friedman, Richard A Fuller, Edward T Game, Tiffany Morrison, and Euan G Ritchie

Published in: Conservation Biology

Abstract

Raising funds is critical for conserving biodiversity and hence so too is scrutinizing emerging financial mechanisms that might help achieve this goal. In this context, anecdotal evidence indicates crowdfunding is being used to support a variety of activities needed for biodiversity conservation, yet its magnitude and allocation remain largely unknown.

We conducted a global analysis to help address this knowledge gap, based on empirical data from conservation‐focused projects extracted from crowdfunding platforms. For each project, we determined the funds raised, date, country of implementation, proponent characteristics, activity type, biodiversity realm, and target taxa.

We identified 72 relevant platforms and 577 conservation‐focused projects that have raised US$4,790,634 since 2009. Whilst proponents were based in 38 countries, projects were delivered across 80 countries, indicating a potential mechanism of resource mobilization. Proponents were from non‐governmental organizations (35%), universities (30%), or were freelancers (26%). Most projects were for research (40%), persuasion (31%), and on‐ground actions (21%). Projects have focused primarily on species (57.7%) and terrestrial ecosystems (20.3%), and less on marine (8.8%) and freshwater ecosystems (3.6%). Projects have focused on 208 species, including a disproportionate number of threatened bird and mammal species.

Crowdfunding for biodiversity conservation has now become a global phenomenon and presents signals for potential expansion, despite possible pitfalls. Opportunities arise from its spatial amplifying effect, steady increase over time, inclusion of Cinderella species, adoption by multiple actors, and funding of a range of activities beyond research.

Our study paves the way for further research on key questions, such as campaign success rates, effectiveness, and drivers of adoption. Even though the capital input of crowdfunding so far has been modest compared to other conservation finance mechanisms, its contribution goes beyond funding research and providing capital.

Embraced with due care, crowdfunding could potentially become an increasingly important financial mechanism for biodiversity conservation.

Gallo-Cajiao E, Archibald C, Friedman R, Steven R, Fuller RA, Game ET, Morrison TH, Ritchie EG (2018) Crowdfunding biodiversity conservation, Conservation Biology PDF DOI

Animal recognition and identification with deep convolutional neural networks for automated wildlife monitoring

Authors: Hung Nguyen, Sarah J Maclagan, Tu Dinh Nguyen, Thin Nguyen, Paul Flemons, Kylie Andrews, Euan G Ritchie, and Dinh Phung

Published in: 2017 IEEE International Conference on Data Science and Advanced Analytics

Abstract

Efficient and reliable monitoring of wild animals in their natural habitats is essential to inform conservation and management decisions. Automatic covert cameras or “camera traps” are being an increasingly popular tool for wildlife monitoring due to their effectiveness and reliability in collecting data of wildlife unobtrusively, continuously and in large volume. However, processing such a large volume of images and videos captured from camera traps manually is extremely expensive, time-consuming and also monotonous. This presents a major obstacle to scientists and ecologists to monitor wildlife in an open environment.

Leveraging on recent advances in deep learning techniques in computer vision, we propose in this paper a framework to build automated animal recognition in the wild, aiming at an automated wildlife monitoring system. In particular, we use a single-labeled dataset from Wildlife Spotter project, done by citizen scientists, and the state-of-the-art deep convo- lutional neural network architectures, to train a computational system capable of filtering animal images and identifying species automatically.

Our experimental results achieved an accuracy at 96.6% for the task of detecting images containing animal, and 90.4% for identifying the three most common species among the set of images of wild animals taken in South-central Victoria, Australia, demonstrating the feasibility of building fully automated wildlife observation. This, in turn, can therefore speed up research findings, construct more efficient citizen science- based monitoring systems and subsequent management decisions, having the potential to make significant impacts to the world of ecology and trap camera images analysis.

Nguyen H, Maclagan SJ, Nguyen TD, Nguyen T, Flemons P, Andrews K, Ritchie EG, Phung D (2017) Animal recognition and identification with deep convolutional neural networks for automated wildlife monitoring, 2017 IEEE International Conference on Data Science and Advanced Analytics PDF DOI 

Don’t judge habitat on its novelty: Assessing the value of novel habitats for an endangered mammal in a peri-urban landscape

Authors: Sarah J Maclagan, Terry Coates, and Euan G Ritchie

Published in: Biological Conservation, volume 223 (July 2018)

Abstract

Novel ecosystems are increasingly common worldwide, particularly in areas heavily impacted by humans such as urban and peri-urban landscapes. Consequently, interest in their potential contribution to biodiversity conservation is growing, including their ability to sustain populations of threatened species. However, few studies have explored whether novel habitats can support viable populations over time and how they compare to less modified, remnant habitats.

We investigated the capacity for novel habitats to support an endangered mammal, the southern brown bandicoot (Isoodon obesulus obesulus: Peramelidae), in a highly-modified landscape near Australia’s second largest city, Melbourne. We compared bandicoot abundance and body condition between five novel and two remnant sites, and examined whether novel sites support residency and key demographic processes necessary for bandicoot population persistence. We found that bandicoot abundance was higher at novel than remnant sites, with the highest abundance at the novel site with the most urbanised surroundings. Female body condition was similar between novel and remnant sites. The majority of bandicoots at novel sites were resident, and breeding activity, recruitment of first-year adults, and survival of mature adults were observed at all novel sites.

Our results demonstrate the potential significance of novel habitats for conserving threatened species within heavily-modified landscapes, and encourage us not to judge the quality of habitats on their novelty alone. Broadening our appreciation of the potential value of novel ecosystems could increase off-reserve species conservation opportunities, a key priority within the context of the Anthropocene and unprecedented global change and biodiversity loss.

Maclagan SJ, Coates T, Ritchie EG (2018) Don’t judge habitat on its novelty: Assessing the value of novel habitats for an endangered mammal in a peri-urban landscape, Biological Conservation PDF DOI