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Admiralty Rat (Rattus detentus) – Critically Endangered (Possibly Extinct)

Formally described only as recently as 2016 from Manus Island of Papua New Guinea, this species has only ever been recorded a handful of times. Unfortunately, hope for this species is slim, as multiple surveys undertaken between 1962 and 2014 have failed to record it. Local hunters in 2014 considered it too rare to be worth hunting, and targeted surveys and ethnographic questionnaires since then have failed to find evidence of the species. It is possible that is has already disappeared.

Applying the IUCN’s recommended extinction assessment framework, we estimated the probability that the species is extinct to be 0.76. The Admiralty Rat now joins the 15 other rodent species that are already listed as Possibly Extinct.

Bahaman Hutia (Geocapromys ingrahami) – Critically Endangered

Populations of this hutia have already been extirpated from parts of the Bahamas due to a hunting, predation by dogs and possibly cats, and competition with other invasive mammals. This species is now only thought to occur on three cays, though persistence on one of these is uncertain.

Since this species has such a small, restricted distribution, it is only found in a few locations, and there is ongoing decline, it has reached the status of Critically Endangered. A Species Action Plan which considers future reintroduction options is urgently needed.

Heath Mouse (Pseudomys shortridgei) – Endangered 

The Heath Mouse is found in parts of South and Western Australia, where lack of success in targeted surveying has raised cause for concern. It’s thought that climate change, wildfires, habitat loss and degradation, as well as predation by cats and foxes, have been driving a decline in numbers. Now, based on its small area of occupancy, low number of locations, and continuing decline, this species is Endangered.

Seram Orange Melomys (Melomys fulgens) – Vulnerable 

This species – previously unrecorded since 1920 and assessed as Data Deficient – was recently documented as surviving on the island of Seram in Indonesia, in research led by SMSG Deputy Chair for Conservation Actions, Prof. Sam Turvey.

Whilst this “rediscovery” is incredibly promising for the species, its recent Red List assessment highlights that we must take action to continue survey work. It has been listed as Vulnerable based on its small distribution and threats to its lowland forest habitat (logging and agriculture).

Western European Hedgehog (Erinaceus europaeus) – Near Threatened

A well-recognised and widely-loved small mammal, the Western European Hedgehog is nowadays facing a multitude of threats. Roads, agricultural intensification and urban growth have likely affected populations across its range. With evidence indicating local and national declines thar are approaching, and in some areas, exceeding 30% over a decade, this hedgehog has been moved from the category of Least Concern to Near Threatened.

Have you ever heard of a muskrat island? On the rocky Isles of Shoals in Maine and New Hampshire, in an environment that should, in theory, be poorly matched to muskrats, these rodents are thriving.

Undergraduate researcher Max Zeltsar, supervised by our Deputy Chair for Eulipotyphla, Dr Alexis Mychajliw, has been studying these island populations to help us understand how they are surviving. Hear more from Max about his project, below:

Hello, my name is Max Zeltsar and I am a student and undergraduate researcher at Middlebury College in Vermont. Over this past summer, I have been working in collaboration with the Shoals Marine Laboratory and my advisor, Dr. Alexis Mychajliw (Middlebury College), to study an incredibly unique population of muskrats (Ondatra zibethicus) that live on the Isles of Shoals in Maine and New Hampshire. While most people remember these islands for the many gulls and seals that call them home, us mammalogists affectionately call them the “muskrat islands” on account of the successful muskrat population.

Muskrats were introduced to the islands sometime between the late 1800s and early 1900s. Currently, there is no documentation explaining why they were introduced, but given the timing, it is possible that humans brought them to the islands to supplement the fur trade. Regardless of the reason for the introduction, muskrats have thrived on the Isles of Shoals since their arrival to the archipelago.

The ongoing survival of these muskrats raises many interesting questions about our understanding of the species. Muskrats are semi-aquatic mammals and inhabit wetland and stream ecosystems. While they can live in saline and freshwater environments, they are reliant on aquatic plants, a network of permanent or longstanding waterways, and soft workable mud for shelter, food, and safety. The Isles of Shoals are primarily composed of rocky coastal zones and patches of scrub brush and exposed grass. Freshwater sources are largely driven by the presence of rain and most large bodies of water can dry up within a couple of days. Although most of their traditional predators don’t live on the islands, gulls that inhabit the islands during their breeding season will predate muskrats as well as chase them away from their nesting sites. In other words, the Isles of Shoals should be virtually uninhabitable for muskrats and yet they continue to survive in remarkably high densities.

Despite how incredible and bizarre the ongoing presence of muskrats on Shoals is, there has been very little research to understand their ecology. The goal of my research is to understand how muskrats are surviving on the Isles of Shoals. By answering questions about their habitat selection, behaviour, and diet we can understand what may or may not be limiting their populations. Investigating these topics required a range of approaches. From June to August, an 8-week-long camera trap survey was implemented to observe their distribution and study their activity patterns. Scat transects were also used to monitor changes in activity and to understand what environmental factors (e.g. ground cover, exposure, presence of territorial gulls) influenced the density of that activity. Lastly, stable isotope analysis is being conducted to understand what the muskrats are consuming and how flexible their diets may be.Through a combination of these various techniques, we can gain a deeper understanding of the ecology of Shoals muskrats. Given their status as an introduced species, it is particularly important to understand how these muskrats are interacting with the Shoals ecosystem. The Isles of Shoals provide important nesting habitat for many globally important species of seabirds and learning how muskrats may or may not be impacting that habitat is essential for proper management and conservation. Furthermore, learning how muskrats are living on the Isles of Shoals can contribute to our broader understanding of the species. Muskrats are declining across their endemic range and their traditional wetland habitat is becoming increasingly threatened by anthropogenic development. Studying how muskrats are surviving on the Shoals archipelago could contribute to broader conservation efforts and help us understand how adaptable or resilient the species may be. Lastly, this research contributes to the theory of island biogeography and our concept of what happens genetically, morphologically, and behaviourally to various species and taxa when they become isolated. Whilst this population of muskrats may seem like a very specific research topic, the knowledge that can be gained from them has the potential to be incredibly far-reaching. In other words, the Shoals muskrats are small mammals with big impacts!

Max’s project is funded by the Middlebury College Undergraduate Research Office. Find out more about small mammal research in the HEDGE lab here: https://insectivora.org/our-research/, and the Shoals Marine Lab here: https://www.shoalsmarinelaboratory.org/

Thank you to Dan Bowen who joined our SMSG team on a summer internship! Dan has recently completed his placement, during which he focused on bringing a number of Japanese endemic small mammal Red List assessments up to date. We were delighted to have Dan working on spiny rats, moles, shrews and more! Hear from Dan, below:

“I’m Dan and I undertook an internship with the IUCN Small Mammal Specialist Group drafting Red List reassessments for some Japanese endemic species. I grew up in Shropshire, attending state schools and volunteering at my local wildlife trust in my spare time. Despite being from a working-class background, I worked hard and made it to the University of Oxford. I am studying Biology, and am on my final year doing my Masters in Biology research project, which I hope will support me in my career in ecology and conservation.

At university, I have been very fortunate to have access to a wide range of internship opportunities, including this one with the IUCN SMSG. My internship involved performing literature research for Japanese endemic species, researching if there had been any changes in distribution or population trends. If so, I would add this new information to the current species distribution map and update the running species information sheet, preparing the drafts for review by species experts.

During my internship, I have learned new insights into conservation and developed my researching skills. I have a better understanding of the process behind the IUCN Red List system, and a greater appreciation for the work that goes on behind the scenes in ensuring this information is available to the public.

I wanted to say thanks to the IUCN SMSG, and especially my supervisors Abi and Ros, who have all been very welcoming and supportive throughout my internship. I look forward to see the work I have been performing with the group contribute to the current understanding we have around these rare species.”

A Tokudaia (spiny rat) species. Source: Daderot, Wiki.

Texas A&M University is pleased to continue their involvement with the Small Mammal Specialist Group (SMSG) through the appointment of new members Maria Alejandra Hurtado Materon, a PhD student in Ecology and Evolutionary Biology Program, and Dr Michelle Lawing, Associate Professor at Texas A&M in the Department of Ecology and Conservation Biology. They will work closely with Emeritus Professor Thomas Lacher (Co-Chair of the SMSG), as he will serve as advisor to the team while they focus on coordinating the next round of Red Listing for small mammals in the Americas.

Find out more about Michelle and Maria below:

Michelle and Maria

Maria Alejandra Hurtado Materon is a Ph.D. student in the Interdisciplinary Ph.D. program in Ecology and Evolutionary Biology at Texas A&M University. Her research focuses on the ecological and evolutionary processes that drive current and historical biodiversity patterns. She uses an integrative approach that combines functional traits, biogeography, phylogenetic comparative methods, and modeling techniques. Additionally, she is developing a periodic table of niches for mammals. Since Spring 2024, Maria has been working as a research assistant in the TAMU-Red List Partnership.

A. Michelle Lawing is an Associate Professor in the Department of Ecology and Conservation Biology (lawinglab.org). Her research is focused on how biodiversity responds to climate and environmental change and her approach involves interdisciplinary work at the nexus of conservation biology, ecology, evolution, and paleontology. She is particularly interested in functional traits of mammals and reptiles and how they are aligned with environments in the Anthropocene, Late Pleistocene, and throughout the Miocene to present.

The Texas A&M team will be involving undergraduate students in Red List assessing and drafting species updates before seeking input from species experts. Equally, this work will spread awareness of the Red List process and help to build new skills earlier in the training process of the conservation workforce. Undergraduate students at Texas A&M will have the opportunity to participate in assessments by joining a year-long Aggie Research Program and becoming certified Red List and Green Status assessors.

Maria Alejandra and the Texas A&M team have also been working to develop an R script to assist assessors in the mapping stages. This script includes tools for occurrence cleaning, map modification, and the calculation of AOO (Area of Occupancy) and EOO (Extent of Occurrence) metrics in accordance with IUCN requirements. Moreover, there are plans to explore a broader assessment process; we have started to work on select Green Status assessments through the help of the SMSG’s current intern, Salomé.

The SMSG is thrilled to have the Texas A&M team in place and look forward to bringing you more assessment updates.

During my 7-week internship with the IUCN SSC Small Mammal Specialist Group, I acquired invaluable experience and knowledge in the fields of small mammal conservation and research. My primary responsibility was to create a field guide dedicated to Sulawesi’s small mammals, a significant outcome of the Sulawesi workshop held in May 2023. This task involved meticulously compiling resources from red list assessments and articles to develop up-to-date species profiles for Sulawesi’s endemic rodents and shrews. Additionally, I generated range maps for each species, enhancing my proficiency in R programming. I also participated in the review process of an article intended for publication, and was tasked with seeking funding opportunities to support the publication of the field guide. I am grateful for the opportunity to contribute to a resource that will directly benefit researchers and students in Sulawesi.

Prior to this experience, having just completed my undergraduate degree, I held the belief that academia was the sole avenue for pursuing a career in biology. However, this internship has broadened my perspective, revealing that roles involving research and conservation need not be mutually exclusive. Moreover, it has provided me the opportunity to establish valuable connections that will be undoubtedly beneficial for my future career in conservation. Finally, I would like to express my gratitude to Ros and Abi, whose support and warm welcome into the organisation have made this internship a truly enriching experience.