- Brazil’s thin-spined porcupine (Chaetomys subspinosus) is a picky eater that lives only in dense coastal habitats with well-developed canopies that allow the animals to move between trees; however, these habitats are increasingly under threat due to coastal development.
- Researchers used radio telemetry to monitor three porcupines that had been translocated to a new, permanent preservation area, as well as one local resident; they determined that translocation is a viable conservation tool for protecting these animals.
- The research also highlights the importance of conserving the porcupines’ restinga forest habitat and its unique features.
Brazil’s coastal landscapes have rapidly transformed through the years. Development is the driving force behind these changes, boasting promises of modernization, job creation and a better future. Meanwhile, artisanal fisheries are pushed to the outskirts by gentrification, fewer areas are safe to swim due to pollution, mass fish deaths occur more frequently and staggering oil platforms have taken over the horizon. The sea view, now blocked by luxurious buildings, has become exclusive to few.
The historically devastated Atlantic Forest, particularly its lesser-known and endangered coastal ecosystems — sandbank forests known for their species diversity and sandy soils as well as mangroves — face several threats as a consequence of escalating coastal development in Brazil. Drawn to the natural beauty of its seascapes, predatory tourism and the real estate industry target these areas to construct gated communities, hotels and resorts. Other relevant threats are widespread extractive and forestry industries present throughout the region. Moreover, some of Brazil’s largest cities are on the coast, and, in most cases, urban expansion also implies the destruction or degradation of these ecosystems.
In the city of Aracruz, in the southeast, a group of Brazilian scientists rescued three thin-spined porcupines (Chaetomys subspinosus) from a sandbank forest that would be suppressed by the construction of a port terminal. This rare species, endemic to a small area of the Atlantic Forest, is the most threatened porcupine in Brazil, considered vulnerable to extinction by the IUCN Red List. Currently, their biggest threat is habitat loss driven by coastal development.
The porcupines were relocated to a nearby permanent preservation area with similar habitat conditions and were monitored using radio telemetry over various periods between October 2015 and March 2017. At the end of the monitoring period, researchers concluded that all translocated individuals achieved permanence — meaning they were well established — in the new area.
This wasn’t the first translocation of this species but is considered pioneering due to being the first well-planned and executed translocation of thin-spined porcupines. Noticeably, the study also included monitoring one resident individual to assess the impact of the translocation on the local porcupine population, as they are a territorial species. The case study was highlighted in a recent article published in the Journal for Nature Conservation.
These porcupines inhabit the coastal areas of Brazil and are not found deeper within the continent. Their main habitat choices are dense ombrophilous forests (tropical rainforests) and sanbank forests due to their well-developed canopies that allow the animals to move between trees.
Sandbank forests, known in Portuguese as restingas, are “characterized by a great diversity of plant species adapted to coastal conditions, such as sandy soils, salinity, strong winds and high incidence of sunlight,” Viviane Fonseca-Kruel, ethnobotanist and professor at the National School of Tropical Botany, explains by email.
Restingas are commonly conceived as a shrubby and herbaceous vegetation type found on beaches. However, there are also arboreal restingas located farther from the seashore. They are rare and unknown to most of us, precisely due to the high level of devastation they face.
Distinctly, arboreal restingas are unique ecosystems with intricate vegetation patterns composed of medium-sized trees shrouded by climbing plants such as vines and lianas. However, their ecological importance is often misunderstood. The dense vegetation makes these forests challenging to navigate, and they may not be particularly appealing to most people. As a result, arboreal restingas are rarely sought-after or valued by the ecotourism industry. On the other hand, the real estate industry is drawn to these locations, seeing an opportunity to construct summer houses, resorts and other types of housing.
These are some of the factors that contribute to making restingas one of the most imperiled physiognomies of the Atlantic Forest. As a consequence of escalating devastation, suitable habitats for thin-spined porcupines become increasingly scarce.
Under the circumstances, Brazilian legislation provides essential measures to mitigate and compensate for losses by requiring an environmental impact study before any development project begins. If the study confirms significant environmental impact, the responsible enterprise is obligated to address and compensate for the predicted losses. This includes the reallocation of threatened fauna to suitable alternative habitats. Consequently, translocation programs emerge as a relevant conservation tool to rescue and safeguard endangered species in vulnerable areas.
A distinctive porcupine
Previously classified as a spiny rat by taxonomists, the thin-spined porcupine is a small, yellowish arboreal and nocturnal rodent that barely has any hair, as its body is almost completely covered with quills that resemble bristles.
“The thin-spined porcupine is a really demanding species both in terms of habitat and diet,” Mateus Melo Dias, the study’s corresponding author and ecologist, explains in a video meeting.
Which means that, unlike other species that may survive in poor conditions in degraded and anthropized environments, for thin-spined porcupines, a well-preserved habitat is strictly needed. More particularly, its conditions for life are attached to how vegetation configures itself in its native habitats.
For instance, these porcupines are known to be quite picky eaters, as approximately 85% of their diet consists solely of four plant species; these animals hold the distinction of being the most folivorous (its diet consisting mainly of leaves) species of porcupine.
Another important aspect to consider is that restinga forests provide the needed conditions for porcupines to thrive. The arboreal restinga has complex vegetation layers. The trees are interconnected by lianas (vines and climbing plants), allowing the thin-spined porcupine to safely navigate across the forest’s canopy.
“He needs more conserved forests with lianas because, unlike primates who can jump between trees, porcupines can’t, especially since he’s small. So, if the connection between the trees is interrupted by deforestation, his habitat is gone,” Melo Dias explains.
Read more: [Explainer] Woody climbers, lianas, embody the inter-connectedness of a forest
Given the species’ demanding habitat and diet, the availability of suitable areas for thin-spined porcupines is a major concern since they have access to only 13.3% of the native vegetation in their distribution area due to being a highly anthropized region. Additionally, restinga forests, which are crucial for these porcupines, make up only 0.5% of the entire Atlantic Forest. This highlights the need to protect the remaining vegetation to ensure the survival of viable thin-spined porcupine populations and help preserve the biodiversity of the Atlantic Forest.
In this regard, Melo Dias mentions that restinga forests and mangroves “are the most endangered phytophysiognomies [vegetation types] of the Atlantic Forest, both because of real estate speculation and because of historical devastation, as they were the first areas colonized in Brazil.”
The significance of restinga forests for the survival of thin-spined porcupines cannot be overstated. As these crucial habitats become increasingly scarce in their distribution area, scientific research is needed to understand and mitigate the threats faced not only by this species, but also by many others.
For instance, Fonseca-Kruel mentions that “the restinga is especially known for being an important habitat for migratory birds, which depend on these areas for food, rest and reproduction during their migratory journeys.
Monitoring the porcupines in their new habitat
According to the study, the company involved in the construction of the port terminal was responsible for translocating the porcupines, which were brought to a permanent preservation area located amid a landscape dominated by vast eucalyptus farms with scattered fragments of native vegetation. As described in the study, their new habitat, “characterized by swampy enclaves surrounded by restinga forests,” was located 2.7 kilometers (1.7 miles) away from the previous one, a restinga with sandy soil.
Scientists then monitored, in total, four porcupines (three translocated and one resident) that were manually captured and sedated and received radio collars at different times. Every three months, the individuals were recaptured so researchers could collect biometric data. Melo Dias mentions that “animals such as sloths, armadillos and porcupines are easier to capture because they are slower due to their low energetic leaf-based diet.”
Over several months, scientists observed their trajectories in their new home, paying close attention to the species’ habitat preferences and home ranges.
Yet, at the end of the third month, researchers came across an unpleasant surprise — they discovered the collar of the translocated male porcupine abandoned with a clean cut, suggesting it had been deliberately removed, likely by poachers. The porcupines’ lethargic behavior makes them vulnerable to such illegal activities. Although they may not be specifically targeted for their meat, they can be sought after as potential pets.
After 11 months, one of the translocated female porcupines was found dead, showing clear signs of predation. Noteworthily, it was also discovered to be pregnant. In spite of this “sad ending,” Melo Dias explains the importance of this event. “This example demonstrates that she has managed to establish herself within the population and despite having been preyed upon — we think it was by a wild cat, an ocelot — this shows she has entered the ecological process.”
Results and findings
One of the main study observations is that translocated individuals have a larger home range than resident ones as a consequence of the adaptation process in a new territory. Due to their selective diets, thin-spined porcupines need a larger timespan to create a navigational map of food sources and roost sites in their new environment.
In this regard, Melo Dias draws a comparison between porcupine behavior and our human struggles when being a newcomer. “In the beginning, they are just like us when we arrive in a new town. We don’t know where to go, so we go round and round, from one side to another, not really knowing where we are heading. As we get more used to the city, we become more efficient with our movements and our area of activity decreases. Animals behave similarly, so you can see their adaptation to a new place.”
Furthermore, both resident and translocated porcupines demonstrated a strong preference for restingas over eucalyptus plantations. This was confirmed by analyzing data on habitat availability and usage. Despite being significantly less abundant (19.5% habitat availability), restinga forests showed 82.7% of habitat use, while areas dominated by eucalyptus were avoided (7.9% habitat use versus. 71.4% habitat availability).
In short, this could be explained by the fact that, unlike restingas, “large eucalyptus monocultures provide a simple and structurally poor forest environment, with little or no canopy connectivity” the study mentions.
Another important issue scientists highlighted is that translocated porcupines have an impact on local populations. “Especially in females because they are much more territorial than males,” explains Melo Dias. He mentions the case of a resident female that migrated after the translocation, moving to an area nearly 2 km (1.2 mi) away. While 2 km might seem a small distance for us, for thin-spined porcupines, which have limited mobility and a very slow metabolism, it is as if she had crossed the country. Researchers suggest that it could be due to the stress of putting on the radio collar.
Another important observation was that female thin-spined porcupines’ home ranges did not overlap, suggesting that the species’ territorial behavior is a relevant factor to consider when planning translocations.
Implications for future conservation efforts
This case study successfully demonstrated that translocations are viable conservation tools and highlighted significant management measures for future thin-spined porcupine translocation projects — including assessing the stability of translocated individuals’ home ranges over many months, conducting prior evaluations of the resident population in release areas, focusing on density and sex ratio, monitoring resident individuals for comparison and control of translocation effects, avoiding release areas with poaching signs due to the species’ gentle behavior and selecting release areas with similar environmental conditions to the capture site and suitable natural habitats.
“Our article sheds light on the importance of dealing with the conservation management of these cryptic, hidden, small and not-so-pretty species,” says Melo Dias.
Thin-spined porcupines, despite being unique and the most threatened porcupine species in Brazil, remain largely unacknowledged by the general population and even by conservationists. This serves as a reminder of the urgent need for increased awareness and coordinated efforts to protect and preserve both the species and their crucial habitat, the restinga forest.
“The restinga vegetation plays a key role in terms of biodiversity and ecosystem services,” Fonseca-Kruel says. “It shelters a great diversity of plant species, countless endemic and/or endangered species, as well as animals and microorganisms. Such diversity is crucial to ecological stability and ecosystem resilience.”
Fonseca-Kruel describes some of the many important ecosystem services that restingas provide. “Coastal protection, acting as a natural barrier against the action of storms. The plant species with deep root systems, such as bushes and trees, help to stabilize the soil and reduce the impact of waves and currents,” she says. “This coastal protection is fundamental in the conservation of the inhabited areas close to the coast, preventing the loss of land and the degradation of coastal ecosystems.”
Restingas also contribute with “local climate stabilization, because the vegetation acts as a thermal regulator, affecting the temperature of coastal areas through evapotranspiration and shading. This is especially beneficial in regions with hot climates, where restingas provides relief from the intense heat.”
Furthermore, Fonseca-Kruel mentions that restingas also provide human communities with plant species that have multiple uses, such as sources of food, fuel and medicine.
As restingas become more fragmented, the thin-spined porcupine loses its necessary conditions to thrive. As a result, maintaining forest interconnectedness is an urgent priority when considering relevant measures for conserving this species. Researchers stress that maintaining restinga remnants outside of protected areas through permanent protected areas is key to long-term conservation of this species.
On this subject, Fonseca-Kruel also adds that environmental education that integrates local communities, students and visitors, such as interpretive trails, outdoor learning programs and lectures, helps raise awareness of the ecological values of restingas, promoting conservation and sustainability.
Unfortunately, uncharismatic, unknown and unappreciated species may struggle for recognition, as conservation efforts are mostly geared toward popular flagship species. Case studies like this highlight their relevance and, more importantly, demonstrate how to take action preserving these marginal threatened species using rigorous scientific methodology.
In this regard, Melo Dias says translocations are a viable tool, beyond research, that scientists can make use of to help preserve the species they study — and not only flagship species, but others that are “not commercial and not marketable. Species that still need a lot of action to be conserved.”
He says, “Sometimes, as biologists, we feel that we study a lot to say that a species is endangered, that it needs more conservation measures, but we don’t actually do anything. We already know what the animal needs, we know where the animal goes, what it likes and what it eats. But then, what are we going to do to solve this problem? Just pointing it out at the conclusion of the article, that something needs to be done, will not solve anything. So, we take action as a conservation measure for this species.
Banner image: Brazil’s thin-spined porcupine (Chaetomys subspinosus) is a picky eater that lives only in dense coastal habitats with well-developed canopies. Image courtesy of Leonardo Merçon/Instituto Últimos Refúgios.
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