Bird Research News

Vol.7 No.4

Lidth's Jay

2010.4.21. Last Revised:2014.3.15.

Ruri-kakesu (Jpn) Garrulus lidthi

Morphology and classification
Classification: Passeriformes Corvidae
Total length:
ca. 38cm(n)Culmen length: 29.5-42.2mm (21) Tarsus length: 42.1-46.3mm (6)Wing length: 169-178mm (6)Tail length: 92-116mm (15)
Body weight: ♂ 164.8-210.4g (26) ♀170.5-194.7g (16)Total length after Yoshii (1988), body weight measured by N. Kawaji (pers. comm.),and the others measured by K. Ishida from specimens (unpubl.) .

Lidth's Jays are deep blue from thehead behind the eyes to the neck,in the outer vane of flight feathers,
the wing coverts and the upperpartof the tail. The lower abdomen
and upper back are reddish chestnut. The face, the inner vane offlight feathers and the underside of
the wing and tail are black. The Photo 1. Lidth's Jay [Mikio Takashi]edge of flight and tail feathers iswhite. There are black stripes on the wing coverts, the outer vaneof flight feathers and the upperpart of the tail. The throat has finevertical streaks. The eyes are dark brown and the bill is ivory
white. The legs and toes are charcoal gray. Occasional albinism isobserved especially in the tail feathers.

Vocalization:
Lidth's Jays make a wide variety of calls. When they are alert tothe possibility of danger, for instance, they call “Jarr- jarr”. Whenthey go in and out of the roost, or when they call between parents
and young, they utter “Kyrurr - kyrwhir, kywhir, kurrwhir". The
old nestlings sometimes make a sharp rattling noise similar to thatmade by a rattle snake. It can also have an anti-predator effect.

The egg is pale blue with no flecks,
and the size is ca. 32mm by 24mm.

Photo 2. Lidth's Jay eggs ina nest box.

Distribution:
Lidth's Jays breed in Amami-Oshima, Kakeroma-jima, Uke-jimaand Edateku-jima Islands, Kagoshima Prefecture, southern Kyushu. A femur fossil resembling this species was discovered fromthe ca. 10,000-year-old strata of Okinawa Island (Matsuoka 2000).

Habitat:
Lidth's Jays occur primarily in laurel natural forests and secondaryforests mixed with Riukyu Pines (Pinus ryuchuensis). They also
visit houses, barns and farmland 100 or 200m from a forest. They
usually roost in the canopy of a tall broad-leaved ever green tree,
but young birds occasionally roost on an electric cable along aforest road.

Life history
34breeding season

Lidth's Jays lay one egg per day during the morning. The clutch size ismostly 4 eggs with a range of 2-5eggs. Females incubate eggs and raise
nestlings. The incubation period isabout 17-20 days, but eggs usually
hatch asynchronously because females
start to incubate after they lay the firstegg or any time later. The nestling Photo 3. Lidth's Jay nestperiod is about 25 days, but the young
lings begging for food.
often fledge prematurely due probably
to predation pressure. Both incubation and nestling periods varyconsiderably between pairs and it is not uncommon that some eggs
do not hatch or some nestlings die (probably of starvation). Eggshells are carried out of a nest soon after hatching and the deadnestlings are also removed quickly (or possibly consumed) byparent birds. Nestlings are provided with food regurgitated byparents. The structure of a family flock or breeding population isstill unknown. Young birds start to form a flock around June.
Hatching rates are 50-80%, fledging rate are 7-88% (for 5-22
clutches in 11 years). Since the food is provided directly frommouth of the parent to the mouth of the young, the detail of thenestling diet is unknown.

Diet and caching

Distribution and Habitat

2Eggs:

Incubation and nestling periods and fledging rate:

Appearance:

1ary to early March. At the earliest,
however, they start to carry nest materials on a warm day in late December
and build a nest again after the failureof the first breeding attempt untilMay.

Lidth's Jays are omnivorous. The dietconsists of invertebrates (insects andspiders), vertebrates (reptiles and birds),
the fruits and seeds of plants and crops(sweet potatoes, etc.). They prefer acornsof Castanopsis sieboldii and Quercus
glauca which they feed in trees and on
the ground. They are also observed tocache Q. glauca acorns on the ground.
They can carry about six acorns at oncein the throat pouch and the bills.

Photo 4. Lidth's Jays areactive on the ground.
The photo was takenwith an automatedcamera.

Topics of ecology, behavior and conservation● Predator:

567891011 12

non-breeding season

Breeding:
They are generally monogamous breeders, but an uncertain oldreport on a helper is known.

Nest:
Lidth's Jays use as a nest site tree cavities (including cavities at thebase of trees), tree branches, thickets of epiphytic ferns, the hollows of slopes and cliffs, eaves and even on human houses. Thenest is 30-50cm in diameter with an inner cup about 10cm across.
They build a cup-shaped nest using fine twigs and vines for thebase and fine dead grass for the inner cup from late Janu-Habu vipers (Protobothrops flavoviridis) can be one of the major
predators of Lidth's Jays because the remains of Lidth's Jays havebeen often found in the stomach of a Habu viper, their carcasses
with Habu bites have been collected and Habu vipers have been
observed to be in their active nest. Large-billed Crows and Grayfaced Buzzards may also be a predator because a Large-billed
Crow was sighted to take an egg out of a Lidth's Jay nest andLidth's Jays have been observed to mob the two species especiallyin the breeding season. An invasive introduced Small Indian
mangoose was reported to attack a Lidth's Jay nest which is wellcontrolled at present since 2006 or later.

4♪ http://www.bird-research.jp/1_shiryo/koe/rurikakesu_0903_amami_ishida.mp3
Ken Ishida♪ http://www.bird-research.jp/1_shiryo/koe/rurikakesu_091224_amami_ishida.mp3
Ken IshidaBird Research News

Vol.7 No.4

2010.4.21. Last Revised:2014.3.15.

© Japan Bird Research Association
Sumiyoshi 1-29-9, Fuchu, Tokyo, Japan

バードリサーチ生態図鑑

Acorn production(number of healthy acorns / m 2)

● Acorn production affecting Lidth's Jay breeding performanceclutch size

Fledging rate (%)

When C. sieboldii
200
Kinsakubaru
Kawauchipredominating in the150
natural forests of100
Amami-oshima Island
bears acorns, eaten
50
acorns are found in
0100
5
great numbers on theforest floors because
480
Lidth's Jays consume360
them in a flock if they240
are green but matured.
We would find the120forest floor full of00
acorns on the ground2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013at the rich crop years. Fig. 1. Relationship between acorn abunResearch has shown
dance (above) and Lidth's Jay breedingthat the acorn producperformance (below). Fledging rate wastion varies greatly
estimated based on that of 10 (2003-2008)
and 20 (2009-) nest boxes. Acorn abunfrom year to year anddance was measured by bucket traps.
affects the breeding
performance of Lidth'sJays (Fig. 1). It is assumed that an acorn failure has less effect onLidth's Jays than rats (Ratus ratus) because Lidth's Jays feedacorns on trees before rats which eat fallen acorns on the ground.
In a poor year for acorns, however, they are at higher risk fromnest predation probably because other animals also suffer a foodshortage.

● Possibilities of helpers and intra-specific egg destruction
Young nestlings usually beg for food with open mouths, but older
nestlings may utter alarm calls and lie flat in a nest when research
workers approach the nest to band them. Once they are taken outof the nest, however, they open their mouth to beg for food or theyeven draw themselves closer to the researcher's feet when they arelaid on the ground. A flock of several birds which is assumed to bea family is often observed in the nestling period, which suggests
they have a helper, though the author and others have not yet confirmed it. The presence of a helper bird was reported at a nest
about 30 years ago, but the author has not yet found one in morethan ten years' study of breeding pairs in nest-boxes. Lidth's Jaysare also assumed to be social because their vocal communication
has been highly developed. There were some cases that eggs had
disappeared from their nests. Lidth's Jays usually abandon theirnests when they lose their eggs due to nest predation. From the factthat the parent continued laying eggs and incubated them after theegg disappearance, some of the eggs were suspected to be stolen
by members of the same species. Such an intra-specific egg destruction is reported on Acorn woodpeckers and Florida Scrub Jays
(Carin et al. 2002). Some of such nests, however, succeeded tofledge young. Comparison in behaviour and ecology with Florida
Srub Jays will be interesting, as the latter has been studied intesively (Woolfenden & Fitzpatrick 1984, 1991). Plumage andbase sequence analyses of DNA suggest that Lidth's Jays are mostclosely related to Black-headed Jays (G. lanceolatus), which inhabit Himalayan forests of acorn production (Yamashina 1941,Kajita et al. 1999, Asimova 2007). Both of these jays are thought
to be relict species.

● History of conservation
Since the last 19th and earliest 20th centuries, thousands of theLidth's Jay were killed to be exported to Europe or North America
for millinery use. It was listed as a national natural monument in1921. They were designated as an “Endangered Species” in theRed List of the Ministry of the Environment because it was fearedthat their population would decline due to the rapid deforestationof their habitats and the range expansion of introduced small Indian mongooses from about the 1970s to the 1990s. The density ofmongooses has been greatly reduced due to the large-scale mongoose control project started by the Ministry of the Environment in2000. Forests have recovered in their major habitats with the decline of forestry. The population of Lidth's Jays has stabilized. Asa result, Lidth's Jays were removed from the Red List in 2008.

● Lidth's Jays as a flagship and indicator species
in the ecosystem management
Lidth's Jays have characteristic traits such as endemism to a restricted region and habitat, and to have a significant interaction
with the acorn production of the dominant trees of the local forestof the Amami Island. These traits, as well as their remarkableplumage and closeness to the islanders' life, make them a good
flagship and indicator species of the issues of ecosystem management and biodiversity conservation. My colleagues and I are currently studying their ecology, pathology and genetics. We havealso started a new ex-situ conservation project with zoos since
2002 (Connolly & Cree 2008).

Literature
Akimova A., Haring E., Kryukov S., & Kryuko A. 2007. First insights into a DNA
sequence based phylogeny of the Eurasian Jay Garrulus glandarius. Экспрессвыпуск 356:567-575.
Fujisaki I., Pearlsine EV. & Miller M. 2008. Detecting population decline of birds
using long-term monitoring data. Population Ecology 50:275-284.
Garvin J., Reynolds SJ. & Schoech SJ. 2002. Conspecific Egg Predation by Florida
Scrub-Jays. Wilson Bull. 114: 136-139.
Connolly JD. & Cree A. 2008. Risk of a late start to captive management for conservation Phenotype differences between wild and captive individuals of aviviparous endangered skink (Oligosoma otagense). Biol. Cons. 141:1283-1292.
Kajita M., Kawaji N., Yamaguchi Y. & Khan A.A. 1999. Systematics of Garrulus
Lidthi, with DNA and morphological analysis. Annual meeting of OrnithologicalSociety of Japan. [J]Matsuoka H. 2000.The late Pleistocene fossil birds of the central and southern
Ryukyu Islands, and their zoogeographical implications for the recent avifaunaof the archipelago. Tropics 10:165-188.
Woolfenden GE., & Fitzpatrick JW. 1984. The Florida Scrub Jay, demography of acooperative-breeding bird, Princenton University Press, Princeton, 406pp.
Woolfenden GE. & Fitzpatrick JW. 1991. Florida scrub jay ecology and conservation. In: Perrins CM., Lebreton JD. and Hirons GJ. (eds,), Bird Population Studies, Relevance to Conservation and Management, Oxford University Press,Oxford: 542-565.
Yamashina Y. 1941. On the phylogenetic status and biogeographic significance ofthe three endemic species of the Ryukyu Islands. J. Japan Biogeography 3:319328. [J]Languages of literature cited other than English: [J] in Japanese, [J+E] in Japanesewith English summary.

AuthorKen ISHIDA the University of Tokyo
I have visited Amami-oshima Island to study birds and forests since1988. I am interested in the population dynamics of Zoothera (dauma) major and G.
lidthi in relation to C. sieboldii acorn production, and forest ecosystem management.
I have also been conducting a long-term
ecological plot survey, Ratus ratus monitoring and others, collaborating with local nature conservation groups, such as the Amami
Orniholotists' Club.
ishiken@es.a.u-tokyo.ac.jp
http://forester.uf.a.u-tokyo.ac.jp/~ishiken/e/
amami/amami.eng.html

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