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Santa Catarina’s Guinea Pig: the rarest rodent in the world?

Santa Catarina’s Guinea Pig (Cavia intermedia) has the smallest geographical distribution of any known mammal. It occurs on a 10-ha island within the coastal archipelago of Moleques do Sul in Santa Catarina State, Brazil. This small, scrubby island is home to a few handfuls of guinea pigs, and has been for thousands of years. 

It is thought most likely that Santa Catarina’s Guinea Pig descended from another guinea pig, C. magna, inhabiting the nearby Santa Catarina coastline. The guinea pigs became isolated on Moleques do Sul probably when rising seas formed the archipelago some 8,000 years ago. Since then, relatively little has changed. The island hosts no significant predators, competitors or humans, and its supply of food for herbivores is plentiful – a perfect scenario for the guinea pigs. 

Over time, characteristics of this species have been shaped by island conditions in a phenomenon termed “island syndrome”. Santa Catarina’s Guinea Pigs have high survival rates, small home ranges and slow reproductive processes relative to that of similar continental species. Consequently, their population is small in number; surveys undertaken in 2004-2005 suggested that the island was inhabited by less than 50 individuals which qualified the guinea pigs for Critically Endangered status on the IUCN Red List. The IUCN later cited them in a list of the 100 most threatened species on the planet 

Despite their small numbers, the Santa Catarina’s Guinea Pig population might in fact be considered stable – it is highly possible that numbers have remained unchanged for centuries. Such a small population, nevertheless, is extremely vulnerable to chance events that could have a critical impact on the species. Insular rodent populations in the past have fallen victim to pathogen introduction or rising sea levels. For the guinea pigs, additional threats include fire, poaching and general human disturbance; the island is sometimes accessed illegally by fishermen who station themselves there overnight.

Surveying and safeguarding island guinea pigs

Camera on Moleques do Sul

Santa Catarina’s Guinea Pigs have scarcely been studied. They were discovered only a few decades ago and, since then, any effort to monitor them has been made difficult by the limited accessibility to the archipelago. One researcher, however, is committed to conserving this species.  

Brazilian biologist Dr Carlos Henrique Salvador is the Small Mammal Specialist Group’s Key Species Champion for Santa Catarina’s Guinea Pig. Carlos led the initial project to survey the guinea pigs in 2004-2005 and is today working on monitoring the current population using a network of trail and security cameras, which were kindly funded by a Greensboro Science Center (GSC) grant. After testing the sampling design, the data gathered will ultimately be used to investigate things such as population size and feeding areas.  

Captured by a Greensboro Science Center-funded camera trap

“The general goals are to monitor the species remotely, its habitat, and illegal use of the island by humans,” explained Carlos. “We have over 1 terabyte of images to process from the first sampling period. However, the island conditions make it difficult for deploying and running electronic devices, and adjustments will need to be made for future sampling rounds.” 

In recent years, Carlos and his colleagues have also published a species action plan for Santa Catarina’s Guinea Pigs. The action plan focuses on increasing monitoring efforts – which have of course been initiated – and also deals with how to protect the island from illegal use whilst raising more awareness of this species. 

It is hoped that such conservation and monitoring efforts will be enough to keep the population safe and stable. Although it may be the rarest rodent in the world, Carlos says “I am optimist, and I believe we can mitigate the risks posed to Santa Catarina’s Guinea Pigs.”

Check out some of the footage captured on one of Carlos’ GSC camera traps below!

Author: Abi Gazzard (SMSG Programme Officer)

Images & video: Carlos Henrique Salvador & Tabuleiro Institute

New SMSG paper on species prioritization

The Small Mammal Specialist Group (SMSG) is happy to report the recent publication of a paper in the open-access journal Diversity detailing the process, and results, of species prioritization exercises for conservation planning and action. The exercises were carried out by the SMSG as well as a second IUCN SSC specialist group, the Antelope Specialist Group (ASG). 

Given the limited resources and finances available in conservation, strategically determining which species to focus on can be the most fair and effective way to guide conservation efforts. But how do we do this? Simply selecting species based on the level of threat they face, for example, ignores the importance of functional and phylogenetic diversity.  

It can therefore be helpful to use systematic prioritization methods that incorporate multiple criteria. Previous examples have included the ranking of species based on e.g., the cost and logistics of a project, the likelihood of conservation success, and/or metrics of species value, such as their status as an umbrella species, evolutionary distinctness, or cultural significance. Sometimes, these criteria are assigned different weightings depending on their relative importance. There exists no universal method for selecting and using such criteria, however. 

Selecting small mammals 

For large taxonomic groups such as small mammals (encompassing over 2,800 rodents, eulipotyphlans and tree shrews), prioritization approaches are invaluable in identifying how to best allocate already-stretched conservation resources. As such, in 2018, the SMSG developed and undertook a species prioritization exercise in Mexico. Mexico had been previously highlighted as a region with high aggregations of both globally threatened and data deficient small mammals. 

Mexico species prioritization workshop

Experts in Mexico first undertook a high level review of the Red List status of each of the 76 small mammal species found in the country. Those identified as Critically Endangered were then assessed against variables such as threat status, the proportion of a population falling within protected areas, and extent of existing captive breeding or conservation management efforts. Species were then scored based on urgency of conservation action, feasibility (i.e., the capacity to implement conservation action and research), and the number of other threatened small mammals that would also benefit from conservation action for said species.  

The top six species identified were those with the highest scores – all were rodents with highly restricted ranges, three of which are found only on islands (Cozumel Harvest, Catalina Deer and Angel Island mice). Based on these scores, draft action plans have since been developed and channeled into attempts to secure conservation funds. Proposals for the Cozumel Harvest Mouse and Angel Island Mouse have, however, been unsuccessful, something which the authors describe as “a recurring difficulty in supporting rodent conservation”.

Nevertheless, the Diversity paper sets out a framework that proved to be effective in selecting species to prioritize. It also underlines the importance of participation from regional experts; without local expertise, the feasibility of working on particular fauna can be misjudged. Some species, for example, might occur in regions where local experts know that opportunities to conduct field research or conservation activities are limited by economic or safety considerations. 

One of the top 6 species: Magdalena Rat

Overall, the framework jointly developed by the ASG and SMSG was successfully fed into prioritization exercises for the respective groups, with the results leading to new proposals and increased interest in certain species of conservation concern. The framework will be applied again in future workshops; for small mammals, there are plans to conduct a similar assessment in Sulawesi later this year. 

Lacher T.E., Mallon, D., Kennerley, R.J., Relton, C. and Young, R.P. (2022) Tools and metrics for species prioritization for conservation planning and action: Case studies for antelopes and small mammals. Diversity 14(9) 704. 

Author: Abi Gazzard (SMSG Programme Officer)

How gold mining is threatening Chile’s endangered chinchillas

The chinchilla, a small, nocturnal South American rodent, has previously been pushed to the brink of extinction for its prize fur. It is now protected from hunting but remains at risk as demand increases for another high-value product  –  gold. 

Chinchilla sp.

The two species of chinchilla (the long-tailed Chinchilla lanigera and the short-tailed Chinchilla chinchilla) were once widespread across the coastal regions and foothills of the Andes in Chile, Peru, Argentina and Bolivia. Commercial hunting for fur drove their numbers down dramatically from the 19th century, and at one point, half a million skins were being exported per year. A ban on hunting in 1929 increased the value of their fur even more and intensified demand. By the mid-1900s, it was thought that chinchillas had been hunted to extinction. 

Fortunately, C. lanigera and C. chinchilla populations were rediscovered in northern Chile by the turn of the century, and a colony of C. chinchilla was additionally found in Bolivia in 2017. However, the rediscovered chinchilla populations are small and isolated – chinchillas live in colonies made of modest family groups, hundreds of kilometres away from the next. Numbers continue to decline and, currently, they are listed as Endangered on the IUCN Red List 

Sitting on a gold mine 

Camera trap images of long-tailed chinchillas. Source: Amy Deane.

In addition to poaching and habitat loss associated with agricultural and grazing activities, mining has become a substantial threat to chinchillas. Multiple colonies in Chile are known to be living on top of huge quantities of extractable gold.  

According to the Chilean government’s national chinchilla conservation plan, mining activities lead to the loss and degradation of habitat, and directly impact individuals or colonies through noise or vibration disturbance, death or displacement of individuals, and loss of food resources.  

Amy Deane, who is a member of the Small Mammal Specialist Group and founder of Save The Wild Chinchillas, has stressed that gold mines pose a grave threat, particularly given the slow reproductive rate of this species (one or two young are produced per litter, once or twice a year).

 “Both species of wild chinchillas are paper protected, meaning that they are protected by laws and treaties,” says Amy. “However, the reality is that their protection in disputed areas, such as mining concessions, is continually under threat, and there is growing pressure to ease some of the restrictions safeguarding those populations.” 

Challenges for chinchilla mitigation

Effort has been made to mitigate the impact of mining developments on chinchillas by translocating individuals out of sites earmarked for gold extraction. However, these attempts have not yet been successful: in northern Chile, at a site owned by the company Gold Fields, translocation plans were halted in 2020 after two of four relocated chinchillas died in a soft-release enclosure and a third was found injured. This might have been down to acute stress caused by a disruption to the chinchillas’ social structure, handling procedures and movement to a new site.  

Such negative outcomes are not unusual in small mammal translocation attempts (e.g. Matějů et al. 2010; Tennant and Germano 2017, Rayner et al. 2021). Some rodents, for example, have shown high levels of homing behaviour when relocated short distances from their original range, and increased mortality when translocated over larger distances. Strong justification is therefore needed for translocation projects and, at the very least, there should be sufficient species knowledge to inform such projects. 

Case studies of chinchilla translocations are unfortunately lacking. In fact, relatively little is known about the basic biology of these animals. Without this fundamental information, it’s not clear how mining developments will move forward, only that they are indeed expected to move forward: Gold Fields intends to commence gold production when construction is completed later this year. 

It is not yet known whether the government will be allowing further translocation attempts or pushing for alternative mitigation measures. In the meantime, Amy and her colleagues at Save The Wild Chinchillas are working hard to spread awareness of the plight of the chinchillas, and to find a way to ensure the protection of the dwindling colonies that live atop unmined gold. 

Author: Abi Gazzard (SMSG Programme Officer)

SMSG research wins a silver BIAZA award

The annual British and Irish Association of Zoos and Aquariums (BIAZA) awards celebrate the achievements of zoo associations in fields such as Education, Conservation and Research. This year, Durrell Wildlife Conservation Trust has received a silver BIAZA award for research exploring global hotspots of, and research priorities for, the world’s Rodentia and Eulipotyphla. The project titled Scaling up small-mammal conservation: setting global priorities for understudied and overlooked species, was led by the Small Mammal Specialist Group (SMSG) with partners at Durrell – who host the SMSG Co-Chair and Programme Officer roles – as well as Texas A&M University, the Zoological Society of London and Re:wild. 

Small mammals exhibit remarkable functional, morphological and phylogenetic diversity. They include some of the world’s most primitive mammal taxa and can be found in virtually every terrestrial ecosystem. Yet, despite this, they are frequently overlooked in conservation science: research confirms that the poorly studied and largely ignored mammal species are those present in countries with limited scientific capacity, those that have been described only recently, or those that are small in size.

The SMSG’s award-winning project has therefore been an important step forward for the small mammal field. Using information gathered from the IUCN Red List, the aim of this project was to identify small mammal hotspots across the globe where conservation actions could have the greatest impact. The work focuses on the orders Eulipotyphla (e.g. hedgehogs, shrews, moles and solenodons) and Rodentia (e.g. rats, mice, squirrels, beavers and porcupines) which, together, make up nearly half of all living mammal species.  

Project outcomes 

In total, 76 of 454 known eulipotyphlan species and 324 of 2,231 known rodent species are classified as globally threatened on the IUCN Red List. By analysing the distribution and richness of these groups, multiple hotspots were identified: for eulipotyphlans, three regions (Sri Lanka, Western Ghats and Cameroonian Highlands) were found to contain disproportionately more at-risk species than expected. For rodents, six regions (in Mexico, Cameroonian Highlands, Southwestern Ghats, Sri Lanka, Malaysia and Indonesia) are inhabited by disproportionately more at-risk species than would be expected.  

The researchers further reported that much of the globe’s small mammal diversity does not fall within protected areas. Protected areas are considered “the single most important conservation tool yet are very rarely set up with small mammals in mind. In fact, five eulipotyphlans and 44 rodents were found to occur in regions completely outside of any protected site. 

The study additionally highlighted regions with the highest numbers of ‘data deficient’ small mammals, i.e. species for which insufficient population or distribution information is available to make a Red List assessment. These areas – within Central and South America – require urgent research attention.  

Moving forward, the SMSG have used these results to inform action on the ground. The SMSG recently hosted a small mammal workshop in one of the identified priority regions, Mexico, with plans to replicate this in more key regions in the future. Such workshops bring together experts from government, academia, NGOs and other stakeholders, facilitating the development of prioritisation methods and species action plans. 

The recognition of this work in the BIAZA annual awards is a great achievement for the SMSG and shines a light on the group’s contributions to raising the profile of, researching and conserving small mammals – congratulations to everyone involved! 

You can read the full research paper here.

Author: Abi Gazzard (SMSG Programme Officer)