A recent study has uncovered a serious ecological crisis unfolding on Mikura Island, a small remote island in the Izu archipelago of Tokyo. Researchers from the Forestry and Forest Products Research Institute and partner universities have revealed that feral cats are preying on massive numbers of Streaked Shearwaters—a species of migratory seabird. The cats, originally brought to the island by construction workers in the 1980s, have since established a feral population, and the study estimates that each cat consumes around 330 birds annually. With at least 106 feral cats on the island as of 2022, the total number of Streaked Shearwaters killed per year is estimated at a staggering 35,000.

 

What Are Streaked Shearwaters and Why Are They Important?

The Streaked Shearwater (Calonectris leucomelas) is a migratory seabird that breeds primarily on Japanese islands, including Mikura Island. These birds are known for their long-distance flights, often traveling thousands of kilometers across the Pacific. They nest in burrows dug into forested hillsides, which makes them particularly vulnerable to predators like cats.

Historically, Mikura Island was home to an estimated 1.75 to 3.5 million breeding Streaked Shearwaters in the late 1970s. That number has plummeted to around 100,000 in recent years. This decline is largely attributed to cat predation, which affects not only the shearwaters but other native species as well, including the Izu Thrush and the Whistling Green Pigeon—both nationally protected species in Japan.

 

Similar Cases Around the World

This is not a problem unique to Mikura Island. Similar cases have occurred on other isolated islands worldwide. For example:

• New Zealand has battled feral cat populations that have devastated endemic bird species like the Kakapo and Kiwi.

• In Australia, cats are responsible for the extinction of over 20 native mammal species and are considered one of the greatest threats to biodiversity.

• The Galápagos Islands have also suffered ecological imbalance due to introduced predators like cats, rats, and goats.

Even in Japan, similar issues have been documented in the Ogasawara Islands, where cats almost eradicated the Bonin wood pigeon, and in Okinawa, where the endangered Yanbaru rail is under threat.

 

Why This Issue Is So Difficult

Addressing the problem is far from simple. The terrain of Mikura Island is mountainous and densely forested, making it hard to locate and capture wild cats. Even if cats are caught, transporting them to the mainland or finding adopters is logistically difficult and expensive.

Additionally, public sentiment complicates matters. While cats are undeniably cute and beloved as pets, their impact on native wildlife is severe. There is a strong cultural resistance in Japan—and in many countries—toward euthanizing feral cats, despite the fact that controlling their population may be necessary to protect native ecosystems. Efforts like trap-neuter-return (TNR) programs are popular, but they may be insufficient in a closed island environment where even a few remaining predators can cause enormous damage.

 

What People Are Saying Online

The story has sparked passionate debate across online communities. Many agree that cats, as non-native predators, pose a real threat to island ecosystems. One user compared their impact to that of more commonly discussed invasive species like the raccoon or the mongoose, questioning why cats are often treated differently.

Others argue that the root of the problem is not the cats themselves but irresponsible human behavior. Abandoning pets, failing to neuter them, or releasing them into the wild are all human decisions that have led to this crisis. Some called for stronger regulations on pet ownership, including licensing, mandatory spaying/neutering, and even the end of commercial pet sales.

There are also concerns about public health. One commenter pointed out a recent fatal case in Japan where a veterinarian contracted SFTS (Severe Fever with Thrombocytopenia Syndrome), a disease carried by ticks and transmitted via contact with infected cats. This adds another layer to the issue—uncontrolled feral populations could be a public health hazard as well.

However, not all voices are in agreement. Some protest that cats are being unfairly demonized and argue for more compassionate solutions. Still, even these commenters often concede that some form of human intervention is necessary.

 

A Broader Reflection on Human Responsibility

This crisis on Mikura Island is not just a local issue. It reflects a broader tension between human affection for animals and our responsibility to the environment. Whether it is cats on a forested island or bears wandering into city suburbs, human choices have deeply shaped ecosystems. In the case of Mikura Island, the evidence is clear: without immediate and coordinated action—both humane and effective—the island’s once-thriving seabird population may never recover.

 

The discussion now turns to policymakers and communities. Can Japan and the global conservation community find a solution that protects biodiversity while respecting animal welfare? The answer may define how we confront the growing challenge of invasive species in the Anthropocene era.

 

Source: Sankei News

Getting to Mikura Island is an adventure in itself, as it’s a small, remote volcanic island in the Izu archipelago, part of Tokyo prefecture, but located far out into the Pacific Ocean. The island is known for its lush nature, wild dolphins, and steep, dramatic landscapes. Here is a complete guide for travelers planning a visit.

 

To get to Mikura Island by public transportation, the most common route is via a ferry from Tokyo. The ferry departs from Takeshiba Pier, which is accessible from JR Hamamatsucho Station or Takeshiba Station on the Yurikamome Line. The ferry is operated by Tokai Kisen and usually leaves in the evening and arrives on Mikura Island the next morning.

The trip takes around 7 to 8 hours overnight. The cost depends on the seat or cabin type. A regular second-class ticket (no bed, just a seat or shared space) costs around 8,000 to 9,000 yen one-way. More comfortable cabins or private rooms can go up to 20,000 yen or more. However, ferries may not dock if the sea is rough. Mikura Island is known for its steep cliffs, and if the sea conditions are not suitable, the ship may bypass the island altogether. This means it’s important to have flexibility in your schedule and check updates before departure. There is no air travel option to Mikura Island, and no car ferry service either, so visitors must travel on foot.

Once on the island, there is no public transport system. The island is small enough that you can get around by walking, though the terrain can be steep. Some accommodations may offer pick-up services from the port.

 

There are a few small inns and guesthouses on the island. These are often family-run and provide meals, usually featuring local fish and produce. It is essential to book in advance, especially during peak seasons, as the number of places to stay is limited. English may not be widely spoken, so having some basic Japanese phrases or a translation app is helpful.

The delicacies of Mikura Island include fresh local seafood, particularly flying fish and horse mackerel. In season, visitors may also enjoy dishes using locally foraged vegetables or preserved island pickles. The meals served in minshuku (family inns) are often homestyle and made with care, offering an authentic rural Japanese food experience.

 

The main attraction of Mikura Island is dolphin watching. The waters around the island are home to a stable population of wild Indo-Pacific bottlenose dolphins. You can book dolphin swim or dolphin watching tours through local operators. These are strictly regulated to minimize impact on the animals, and guides ensure safe and respectful interactions. Snorkeling with the dolphins in clear blue water is a major highlight and draws many nature lovers and eco-tourists.

Other things to enjoy include hiking in the dense island forest. Mikura Island is covered in ancient laurel forests, which are unique and protected. The hiking trails can be challenging but rewarding, offering views of waterfalls, deep valleys, and rare plant life. However, trails can be slippery or closed in poor weather, so good shoes and awareness of conditions are important.

The beaches on Mikura Island are not the sandy kind most travelers might imagine. The island’s coastline is steep and rocky, but places like Igaya Cove offer access to the sea for swimming or snorkeling. Kamane Beach is another small area suitable for swimming. These beaches are more about rugged natural beauty than lounging on the sand.

 

Popular spots on the island include Mount Oyama, the highest point on Mikura Island, which offers breathtaking views, though reaching the summit requires serious hiking. The Mikura Shrine, nestled in the forest, provides a quiet, spiritual experience surrounded by towering trees. For photography and sea views, places like Yakiuchi Coast or Sannobana Cliff are stunning.

The best time to visit Mikura Island is from late spring to early autumn, particularly between May and September. This is when the sea conditions are most stable for ferry docking, and dolphin swims are in season. The weather is warm, and the forest is lush and green. Summer is popular, but also more crowded and humid. Early autumn offers slightly cooler temperatures and fewer visitors.

Even if you visit during less ideal times, such as winter, you can still enjoy the island’s natural beauty, though dolphin swims are not offered during the cold months. Hiking is still possible on clear days, and the island is peaceful with few tourists. Winter is also a good time to appreciate the local lifestyle, enjoy warm meals, and relax in nature without distractions.

 

Travelers should come prepared with cash, as there are no banks or ATMs on the island that accept foreign cards. Bring all necessary personal items, as shopping is very limited. Mobile signal may be weak in some areas, and internet access can be unreliable.

 

 

In short, Mikura Island offers a quiet, nature-rich escape with unique wildlife encounters, especially for those interested in marine life and ecological travel. While it requires some effort and flexibility to reach, the reward is a rare and untouched island experience.

How to Get to Mikura Island (御蔵島)

1. From Tokyo by Ferry (Most common route)

• Departure Port: Takeshiba Passenger Terminal (竹芝客船ターミナル), near Hamamatsucho Station, Tokyo

• Ferry Company: Tokai Kisen (東海汽船)

• Ship Name: Sarubia Maru

• Schedule:

  • Departs Tokyo at around 22:30 nightly

  • Arrives at Mikura Island around 05:30 the next morning

• Duration: About 7 hours

• Fare:

  • Second class (open seating): ~7,000–8,000 yen one way

  • First class/private rooms: ~13,000–20,000 yen depending on the type

• Important:

  • Docking is not guaranteed due to rough seas and no harbor. If the weather is bad, the ship may skip Mikura and go directly to Hachijojima.

  • Bring motion sickness medicine if you're sensitive to waves.

  • Check docking status the day before: The island often publishes updates via Tokai Kisen or local tourist sites.

2. From Tokyo by Air (not direct to Mikura)

• Fly from Haneda Airport to Hachijojima Island (~55 minutes via ANA)

• Then take a ferry or helicopter to Mikura Island (but the helicopter only operates from Miyakejima).

• Not recommended for casual travelers—it’s complicated and weather-dependent.

Where to Stay on Mikura Island

There are no hotels on the island. Only small family-run guesthouses (minshuku or 民宿) are available.

 

• Average price: ~8,000–10,000 yen per night with two meals included

• Reservations:

  • Must be made by phone or email (usually Japanese only)

  • Some guesthouses require you to join a dolphin swimming tour to stay

• Examples:

  • Minshuku Misaki

  • Minshuku Yamashita

  • Minshuku Hisamatsu