For such a small island the wildlife of Yakushima is surprisingly rich. There are 16 species of mammal and 4 sub-species including the Yakushima macaque and the Yaku deer that are endemic to the island. The Japanese fieldmouse is endemic to Yakushima and the neighbouring island of Tanegashima. Around 150 bird species are found on the island. Four of these have been designated as national monuments: Izu thrush, Izu leaf-warbler, Ryukyu robin and the Japanese wood pigeon. There are 15 species of reptile including the loggerhead turtle and the green turtle. 8 kinds of amphibian and an incredible 1900 species of insects.
Hiking through the forests, you may well not be aware of the abundance of wildlife around you. The tree cover is so dense that birds are difficult to spot, indeed there are not many birds in the higher woodland area due to a lack of food. Walk around Shiratani or Yakusugi Land and you'll be surpised how quiet it is. The majority of Yakushima birds are found around the lowland and coastal region. Yakushima is a migratory destination for some birds and so species differ according to the season. Small lizards and frogs are numerous, but hibernate in the winter. From spring to late autumn spiders, butterflies and a plethora of other insects are everywhere around the coastal regions, but less so in the higher areas. The sea turtles arrive in the late spring. The largest animals are the deer and the monkeys which can be seen all year round, particularly on the hiking courses and the Seibu Rindo – the western forest road.
Macaque and deer watching precautions
1. Never offer food. It will change the animals natural feeding behaviour, leading to more crop damage for the locals and it will also cause ill health for the animal. If animals change their diet it will also effect the balance of the ecosystem.
2. Stop your car safely before watching the animals. The western forest road is very narrow and winding. Drive slowly and if you see a group of animals you want to watch, first safely pull in to the side of the road and pay attention to other vehicles that may want to pass.
3. Keep a safe distance of at least 10m from the animals. It is much less stressful for the animals and safer for you if you observe them from the safety of your car. Remember you are entering their world and no matter how calm and peaceful they look they are wild animals and therefore unpredictible.
4. Don't make eye contact with macaques. Your curious look to a macaque signals something very different, it is a sign of agression. Eye contact will therefore make a macaque feel threatened and it may respond with agrression towards you. Watching from behind your camera is safer or gazing without staring.
5. If a macaque threatens you don't panic. Don't shout, avoid eye contact, keep a neutral face and walk away slowly and quietly. Do NOT turn your back on the macaque. Avoiding eye contact signals to the macaque that you are not a threat and you are not taking part in this interaction. Be careful not to smile, a human smile looks like a submissive gesture to a macaque which can actually encourage it to be more agrressive. A neutral face again signals that you are not a threat . Turning your back is an invitation for it to attack you. Macaques attack each other by jumping on each other's backs. Once the macaques have calmed down and returned to their own business and you are at a safe distance, then you can turn around and walk away.
Below is a brief introduction to a few of the animals you are likely to encounter on Yakushima.
Yaku Deer (Yaku Shika – 屋久鹿)
The estimated deer population on Yakushima in 2014 was 19,000 and they can be seen all over the island: from the coastline to the mountain tops. To put this figure into perspective, the human population on the island is around 13,500. However, culling in recent years has increased with around 4,000 culled during 2014. The numbers are set to be reduced even further as a slaughterhouse was opened in October 2014 and deer meat is now 'on the menu'. The recommended number of deer for Yakushima is as low as 2,500 deer!
Yaku shika are a sub-species of the mainland Honshu Shika (the annoying ones you may meet on a trip to Nara or Miyajima). The yaku shika are smaller than the mainland species. The yaku shika adult weight ranges from 19 to 37 kg – compare this to the Honshu Shika which is 49 to 80 kg. Another main difference is that male yaku shika grow smaller antlers with only 3 points while the mainland deer antlers have 5 points. The deer have a long history on the island and they are often mentioned in some of the myths relating to Yakushima. They are very placid and usually unperturbed by humans, particularly in the hiking areas and the Seibu Rindo where they are not hunted. The only natural predator to the deer on Yakushima is man and as hunting has become less of a necessity for the local population so the number of deer have risen. The impact of this is that the deer have a greater competition for food and have begun to eat plants that they considered unsavoury in the past. The damage to the indigenous plant life is evident and they cause considerable crop damage. The aim of the cull is to re-balance the deer numbers with the 'regular' food supply on the island and to prevent the deer from creating further damage in the forests.
Yakushima Macaque (Yaku zaru – ヤクザル)
The Yakushima macaque is closely related to the Japanese macaque found on the mainland. The Yakushima macaque is smaller and has a thicker grey coat with darker hands and feet. There are estimated to be around 6,000 – 8,000 macaques on the island and they are commonly seen under altitudes of 800m. The macaques have a life expectency of between 20 to 25 years. They live in matriarchal groups. Macaque babies are usually born in late spring, although you can see young macques at any time of the year. The young males stay in their group until the age of around 2 when they are forced out of the group and either wander alone, or remain with young males of a similar age. The macaques are omnivores, but mainly eat a plant-based diet. Research has shown that they eat over 150 different species of plants and also enjoy mushrooms and a variety of insects. The best area to see macaques is on the Seibu Rindo – Western Forest Road which runs between Kurio and Nagata. There is a strict policy on the island to never feed the macaques – please observe this. Should you book a YES Island Tour then the YES guide would be able to give you a lot information about the macaques and the deer on the tour.
Yakushima Wonderful Green Hairstreak (Lycaenidae)
This is an endemic sub-species closely related to Hairstreaks found on the mainland. The photo on the left is of the mainland sub-species (male). The Yakushima Wonderful Green Hairstreak has shorter appendages on the hindwings. It can be found among evergreen oaks and laurel-leaved trees.
White Eye (Shima Mejiro – 島目白)
Often found around fruit trees during the winter, but in the summer months it moves to higher altitudes. In the late winter and early spring the White Eye is the primary pollinator of the camellia trees. The white eye has a very distinctive and beautiful song. It is a very sociable bird and often allows other species into its 'community'.
Yakushima receives 40% of the northern Pacific Ocean Loggerhead Turtle female population when they make their way to nest upon the beaches of the island. The adult Loggerhead measures around 90cm and the females arrive to Yakushima between early May to late July to lay their eggs. They lay around 100 – 120 eggs per nest and usually make 3 or 4 nests a season. However, the adult survival rate is 0.0002% . Loggerheads are omnivores and when they are adults their diet consists of crustaceans – hence their large head so that they have a jaw large enough to crush the shells of crabs and lobsters. YES run night time turtle-viewing tours between May – July and these popular tours convey a lot of information about the turtles as well as the conservation work on the island.