Lidth’s Jay

BirdJapan

Oct 22

Written By Alexander Julius Jensen

Garrulus lidthi

Lidth's jay is only found on a few of the Ryukyu Islands in southwestern Japan. Its existence has been threatened by the introduction of mongooses and an increased crow presence on these islands. As of a 2016 survey, fewer than 3,900 mature jays are estimated to remain.

Amami Ōshima

Autumn is perhaps the most beautiful seasLike a necklace of pearls in the sea, the islands of the Ryukyu Arc curve westward; from the tip of Kyushu, Japan's southernmost large island, to Taiwan. In the northern part of this crescent chain lies a particularly beautiful pearl; the island of Amami Ōshima. Its origins are volcanic, and since its emergence from the sea, its highest tip has reached 605 metres (1,985 ft) into the sky as the peak of Mount Yuwanda. Forests of broad-leafed evergreen trees, such as laurels, carpet the slopes — about 65% of the island is forested — transforming into extensive stretches of primaeval, gnarled mangroves near the coast. Beyond the mangroves, mudflats, and white-sand beaches lies a crystal sea strewn with coral reefs.

A link in a broader archipelago chain and boasting a balmy subtropical climate, Amami Ōshima is a near-perfect nursery for life — much of it endemic. Here lives a nocturnal black rabbit and a spiny-furred rat. Pointy-nosed frogs and those mottled like mossy pebbles. Venomous coral snakes and harmless green snakes. But above all, in terms of diversity, are the birds. You'll hear trilling woodpeckers and see strutting woodcocks. The island has rare robins, flycatchers, and owls, as well as an exclusive thrush. And, not least, a unique species of jay.

The Amami Jay

No other jay is feathered like this one. Its body is a rusty red. Its wing and tail feathers are dark blue and barred. It wears a complementing hood of blue that becomes a black mask over its face, often with wisps of white beneath its chin. Its beak is ivory. The Amami jay, also known as Lidth's jay — after a Dutch zoologist with a snappy name (Theodoor Gerard van Lidth de Jeude) — exists only on a few islands of the Ryukyu archipelago. Its main home is Amami Ōshima, but it's also known to live on the island of Tokunoshima to the south. It is most at home in natural forests of laurel and secondary mixed forests, from the lowlands to the higher slopes of Mt. Yuwanda.

It hunts among the branches, using its strong beak to climb as a parrot does, and carefully scrutinises each leaf, crevice, and hole in search of a snack. Alternatively, it hops along the ground. It eats anything from insects and spiders, to reptiles and small birds, to fruit, berries, and seeds. Acorns and chestnuts are a favourite — it can carry up to six acorns at once, crammed into its throat pouch and bill — and if it can't eat them all at once, it stores them in a cache for later. But, like any good corvid, Lidth's jay doesn't let a good opportunity pass it by. It will stray from the woods, venturing into farmlands and villages a few hundred metres from the treeline; open land where it can, perhaps, more easily find food.

Practical Parenting

This jay's nesting preferences are as varied as its diet. Its nest is made from thin twigs and vines, woven into a cup, and lined with soft grass and roots. It may build its nest in a tree hollow, among the branches, or in the leaves of a fern. It may find a hole in a rocky cliff. Or even build its nest inside an old building or the eaves of an inhabited house. 3–5 pale blue eggs are laid within and, once they hatch, the egg shells are promptly removed by the parents. The chicks are cared for by both mum and dad — who sate their hungry chicks through regurgitation. If a chick happens to die, it too is swiftly removed from the nest, or possibly eaten by one of the parents — morbid but efficient.

Other jays (other than the parents) often appear around an occupied nest. This is assumed to be the family group since jays are typically social birds with a wide repertoire of grating calls. However, the intentions of these nest loiterers aren't actually known. They might be there to help raise the brood, or alternatively, they may be trying to snatch an egg for themselves (as occurs in other jay species, like the Florida scrub-jay).

But the graver threat comes from other predators. A stolen egg is certainly a loss, but the parent jays still have the rest of their clutch. However, if a couple suspects that their nest is being targeted by a predator, they will usually abandon it completely. And, in the past century, the predators on Amami Ōshima have only become more numerous and deadly.

The Mongoose Busters

In 1979, around 30 small Indian mongooses ¹ were brought to Amami Ōshima and intentionally released. Their directive was to control the island's population of venomous habu vipers and pests like rats. Of course, mongooses don't follow commands. They quickly expanded their menu to include the eggs and chicks of Lidth's jay, adding to the predation pressure that local predators — such as the large-billed crow — already posed. And, to add insult to injury, the crows on the island were only becoming more numerous, more competitive and ravenous.

Prior to the arrival of the invasive mongooses, Lidth's jay had already suffered more directly at the hands of humans. Since the late 19th and early 20th centuries, this jay was killed in the thousands, to be shipped to Europe or North America for millinery use — that is, to stick its feathers into fancy hats. Lidth's jay was listed as a national natural monument in 1921, but the cease-fire on hunting was counteracted by rapid deforestation, leaving the jay with less and less habitat. Its population fell further, until eventually it was listed as an 'endangered' species.

In the year 2000, the concurrent mongoose population on Amami Ōshima peaked at around 10,000. The Ministry of the Environment finally took the problem in hand. They sent in a professional, one might say "special ops" group, known as the “Amami Mongoose Busters”. The Busters planted over 30,000 traps and 300 camera traps across Amami Ōshima. They also brought in "mongoose detection dogs" to sniff out slippery miscreants. Since they've begun, the team has captured some 32,000 mongooses — the last one in April of 2018. On the 3rd of September, 2024, the Ministry of the Environment announced that the mongooses had been eradicated from Amami Oshima Island.

During that time of mongoose "busting", forests on the island had been going through a process of recovery, coinciding with the decline of the forestry industry. With a major threat gone and its home slowly returning, in 2008, Lidth's jay was reclassified as 'vulnerable' and moved off of the 'Red List' of endangered species.

A small Indian mongoose (*Urva auropunctata*).

¹ The small Indian mongoose (Urva auropunctata) finds its name on countless lists — and not for a good reason. Chief among these is the "100 of the World's Worst Invasive Alien Species" list.

This mongoose's native range stretches from Iraq, through northern India, and into parts of Southeast Asia. But the mongoose is an intrepid traveller — if not a voluntary one. Today, populations of small Indian mongooses infest islands worldwide. They're found throughout much of the Caribbean, on islands from Cuba to Trinidad and Tobago; throughout the Pacific on islands such as Hawaii and Fiji; on the Dalmatian Islands in the Adriatic Sea, off the coast of Croatia; and Okinawa in Japan. All in all, it's been introduced to at least 64 islands.

The story was essentially the same every time; there was a pest that needed exterminating, and the small Indian mongoose looked like the killer for the job. Humans caught, shipped, and unleashed the mongoose onto unsuspecting island ecosystems. And wherever the mongoose made port, the predictable consequences followed — a swift decline in vulnerable local species.

**Where Does It Live?**

⛰️ Mature pine and broadleaf evergreen forests, as well as gardens.
📍 Japan’s Ryukyu Islands; on Amami Ōshima and Tokunoshima.

‘Vulnerable’ as of 01 October, 2016.

IUCN

Size // Small
Wingspan // N/A
Length // 38 cm (15 in) in total length
Weight // 165 – 210 g (5.8 – 7.4 oz)
Activity: Diurnal ☀️
Lifestyle: Solitary/ Pair (during breeding season) 👤/ 👥
Lifespan: N/A
Diet: Omnivore
Favorite Food: Acorns and chestunuts 🌰
Class: Aves
Order: Passeriformes
Family: Corvidae
Genus: Garrulus
Species: G. lidthi

This jay's main home is on Amami Ōshima — part of the Ryukyu Islands in southwestern Japan — but it's also known to live on the island of Tokunoshima to the south.

It's named after a Dutch zoologist with a snappy name; Theodoor Gerard van Lidth de Jeude.

It forages in trees, using its bill to climb like a parrot does, or hops along the forest floor.

Its diet is diverse; from insects and spiders, to reptiles and small birds, to fruit, berries, and seeds.

Acorns and chestnuts are a favourite food — it can carry up to six acorns at once, crammed into its throat pouch and bill — and if it can't eat them all at once, it stores them in a cache for later.

Lidth's jay builds a nest from thin twigs and vines, woven into a cup, and lined with soft grass and roots.

3 to 5 pale blue eggs are laid in its nest and, once they hatch, the egg shells are promptly removed by the parents. If a chick happens to die, it too is swiftly removed from the nest, and possibly eaten by one of the parents — morbid but efficient.

Other jays often visit occupied nests — these are assumed to be part of a family group, but the intentions of these nest loiterers aren't actually known. They might be there to help raise the brood, or alternatively, they may be trying to snatch an egg for themselves (as some other jay species, like the Florida scrub jay, do).

A jay pair will usually abandon their nest completely if they suspect that it's being targeted by a predator.

In 1979, around 30 small Indian mongooses were brought to Amami Ōshima and intentionally released with the goal of controlling the island's population of venomous habu vipers and pests like rats.

In the year 2000, the concurrent mongoose population on Amami Ōshima peaked at around 10,000 and they constituted a considerable threat to the island's native species, including Lidth's jay.

The Ministry of the Environment sent in a specialised team known as the “Amami Mongoose Busters”, who planted over 30,000 traps and 300 camera traps across Amami Ōshima and brought in "mongoose detection dogs" to sniff out slippery miscreants.

Since they've begun, the Busters have captured some 32,000 mongooses — the last one in April of 2018. On the 3rd of September, 2024, the Ministry of the Environment announced that the mongooses had been eradicated from Amami Ōshima Island.

With the forests on Amami Ōshima making a comeback (thanks to the decline of the forestry industry) and the removal of the mongooses, in 2008, Lidth's jay was reclassified from 'endangered' to 'vulnerable'.

However, as of a 2016 survey by the IUCN, there are still likely fewer than 3,900 mature jays living in the wild.