Meet the Philippine Tarsiers: Where Stress Could Kill
By: Maria Banez
Meet the Philippine Tarsiers! Despite being a part of the Philippine national heritage and being a massive tourist mascot for the nation, the Philippine Tarsier (Tarsius syrichta) is understudied and in need of conservation support. Many nations around the world (North America, Europe, and other Asian nations) have attempted to keep tarsiers in captivity and breed them; however, many of the tarsiers did not survive their transportation and many more died after arrival. There were no successes for any second-generation reproduction in all those captivities; therefore, over time no other Philippine tarsiers were captive outside of the Philippines.
Not much is known about the Philippine tarsier and studying them has become a challenge for many due to their sensitive and solitary characteristics. This is worsened by the fact that their populations are in decline due to habitat loss, hunting, and illegal animal trade. If being in captivity and residing in their own habitats can be dangerous for them, what is the best way to help them reproduce and prevent their population from declining?
What are Philippine tarsiers?
Tarsiers are a group of primates endemic to Southeast Asia. The Philippine tarsier is exclusive to the Philippines and can be found in the nation’s southern regions. They are nocturnal and are known for their massive eyes and rotating heads. These tarsiers can be seen in small groups, but they are regarded as solitary animals. They are also the world’s second smallest primates, and they are small enough to fit into your hand. On average, male tarsiers who were caught in the wild weighed about 154 grams while females weighed about 114 grams –both of which are lighter than the typical can of soda (about 340g)!
Additionally, studies have found that they mate annually; however, their relatively slow reproduction rate has not been able to compensate for their population decline. It is important to know that these tarsiers are extremely sensitive to stress. They reside in high temperature and high humidity regions in the Philippine tropical rainforests and struggle in other environments. This is exacerbated by their popularity, as they have been displayed as mascots and tourist attractions in the day (recall that they are nocturnal); and high stress has even led to tarsier suicide. In 2015, they were classified to be among the 25 most endangered primates by the International Union for Conservation of Nature Primate Specialist Group, International Primatological Society, Conservation International, and Bristol Zoological Society.
Study in the Philippines
“Successful breeding attempt of a pair of Philippine tarsiers (Tarsius syrichta) in a conservation center in Bilar, Bohol, Philippines and recommendations for tarsier husbandry” was a study conducted by Milada Řehákov in 2019. As suggested in the title, the study was held in a tarsier conservation site in Bohol which is an island located in the southern region of the Philippines. In the conservation site, the average daily temperature was 24.3°C (or 75.74°F) with the average humidity of 95.2% (which were almost identical conditions to the Philippine tarsier’s natural habitat). The conservation site was a 3 hectare-area region covered with grassland forests. Within the site, they built large and small enclosures that were exposed to the environment (making it as identical to the tarsiers’ habitat as possible).
In the study, they regularly monitored the health and consumption of the tarsiers and focused their attention on pregnant tarsiers. Given their sensitive and solitary characteristic, they required the most attention and received the least interaction with humans to help decrease their stress (interactions were limited to nightly observations and observations through cameras installed in the enclosures).
What did they find?
Stress was the highest contributor to the tarsiers’ mortality rate and offspring survival. If the mother were stressed, she could give birth to a stillborn. Smith and her team made sure to expose the tarsiers to low human interactions, their known prey (only foods tarsiers consume), and most familiar environment to help decrease stress. With their attempts at providing the most comfortable environment, they were able to see an offspring finally survive and be of good health.
Why should we care?
For years, there has been many unsuccessful attempts of placing Philippine tarsiers in captivity and breeding them outside of their own habitats. The sensitivity of tarsiers highly influences their mortality rates and greatly impacts how research can be conducted on them — which may be why they are among the least known primates in the world. By analyzing how successful breeding was maintained in the study, we recognize that there is a significance in incorporating species preferences into their conservation. Having the right environment for a given species can help with their reproductive success and survivability. This is especially significant for endangered species.
Many species that are endangered are sensitive to the changes that are happening in their habitats — this may be why they are endangered in the first place. Their inability to survive and thrive in their changing environments is threatening their existence and this study is an insight on the possible actions we may have to consider as we conduct our conservation and mitigation plans. Species preferences are considered in conservation, but all species are unique and sometimes offsite conservation (providing conservation outside their habitats such as zoos) may not be enough. Unless the habitats are inaccessible, this study on the breeding and husbandry for Philippine tarsiers showcase why we should invest our conservation plans for many other sensitive species in their own habitats.
References
Řeháková, Milada. “Successful Breeding Attempt of a Pair of Philippine Tarsier (Tarsius Syrichta) in a Conservation Center in Bilar, Bohol, Philippines and Recommendations for Tarsier Husbandry.” Zoo Biology 38.6 (2019): 516–21.
Schwitzer, Christoph, et al. Primates in Peril: the World’s 25 Most Endangered Primates 2014–2016. IUCN SSC Primate Specialist Group (PSG), International Primatological Society (IPS), Conservation International (CI), Bristol Zoological Society (BZS), 2015.
