Bird Research News

Vol.7 No.12

Mountain Hawk-Eagle

2010.12.20.

Kuma-Taka (Jpn) Nisaetus nipalensis

Morphology and classification
Classification: Accipitriformes Accipitridae
Total length:♂ 71.4cm (69.6-72.7cm)
Wing length: ♂ 48.8cm (46.0-50.5)
Tail length:♂ 34.2cm (32.0-39.5)
Culmen length: ♂ 34.0mm (31.9-35.8)
Tarsus length: ♂ 113.0mm (96.2-120.2)
Weight:♂ 2.2kg (2.3-2.7)♀ 76.3cm (73.3-80.5)♀ 51.6cm (49.5-53.3)♀ 35.6cm (33.5-37.2)♀ 37.0mm (35.6-38.1)♀ 118.2mm (105.1-128.9)♀ 3.1kg (2.5-3.9)

Measurements in the Suzuka Mountains by the Mountain Hawk Eagle Ecology Research Group.

Appearance:
Adult Mountain HawkEagles are dark brown allover and blend in withthe surroundings whenperched on a tree in aforest (Photo 1). The
head is dark, with blackandbrown
verticalstreaks from the throat tothe chest. The head plumage deepens in color with Photo 1. Adult (left) and juvenile (right) ofage, and the coloration
Mountain Hawk Eagles [SusumuNakano]from the chest to theabdomen becomes increasingly tinged with dark brown with age. There are black andwhite lateral stripes on the underpart of the wing. Mountain HawkEagles normally have a short crest on the back of the head, which
may be more elongated in some individuals in southern Kyushu(southern Japan). Juveniles are pale in plumage coloration. They
are particularly white from the chest to the abdomen, which makes
them conspicuous even in the distance. The iris varies greatly incolor depending on the age. Their irises are ashy blue in fledglings,
pale yellow at the age of 3, and almost yellow at the age of 4-5.
Afterward, the yellow of the iris gradually deepens with age tobecome orange, changing from orange to red and finally wine red.

Vocalization:
Mountain Hawk-Eagles do not call very often in the non-breeding
season, but the male and female of a pair call each other "Po-hee,po-hee" or "Pip-pee, pip-pee" in a far-reaching voice in the breeding period, especially while nest building. They also utter a lowpitched alarm call that sounds like "Gfitt, gfitt" when they sense
danger near the nest in the incubation and nestling periods. Nestlings call "Pip-pip-pee, pip-pip-pee" repeatedly in a loud voicefrom the late nestling period at least until the early post-fledging
period when they beg the parents for food.

Distribution and Habitat
Distribution:
Mountain Hawk-Eagles are distributed in southwestern India, SriLanka, the Indo-China Peninsula, China, the Russian Far East andJapan. In Japan a subspecies Nisaetus nipalensis orientalis occurs
as a year-round resident in mountainous regions from Kyushu toHokkaido across Japan. In a mountainous region covered with anextensive forest suitable for their habitat, they are continuously
distributed in a density of approximately a pair per 20-40km2. The
distance between the nests of neighboring pairs is generally 3 or
4km. In Hokkaido (the northernmost main island), on the other
hand, the breeding distribution is lower in density and more irregular than in Honshu (the largest main island). Mountain HawkEagles are also irregularly distributed in the areas where Golden
Eagles (Aquila chrysaetos) breed because they tend toavoid the breeding sites of Golden Eagles.
64♪ http://www.bird-research.jp/1_shiryo/koe/kumataka_140211_tottori_kuroda.mp3
Haruo Kuroda

Habitat:
The habitat of Mountain Hawk-Eagles is a mountainous region
covered with forests which abound with small and medium-sizedanimals. Mountain Hawk-Eagles occur in laurel forests, summer
green deciduous forests and plantations. They live in a mature
forest with ample space in the understory, regardless of tree species and type of forests. In addition to these habitat requirements,
however, they need for breeding a large enough tree to build a nest
on a mountainside.

Life history
1 2 3 4 5 6 7 8 9 10 11 12
breeding season (until fledging) non-breeding season

Breeding system:
Mountain Hawk-Eagles are a monogamous breeder. Breeding pairs
stay in their nest site-centered home range throughout the year, butthey live separately in the non-breeding season. It is because they
have high fidelity to sites, such as the hunting grounds that theyusually pair with the same partner every year. In autumn, they startto perform displays, such as a boat bottom-shaped flight, undulating
flight, parallel flight, approaching stoop and exhibiting perch. InJanuary, they begin to build a nest in parallel with the displays, andcall each other more frequently. They usually breed every other year
because they feed fledglings until about next February.

Nest and egg:
Mountain Hawk-Eagles generally use as anest tree the large tree which has a diameter of more than 60cm at breast height andlateral branches suitable to build a nest on.
The nest tree species vary greatly betweenregions. For instance, they use conifers(Pinus densiflora, Cryptomeria japonica, Photo 2. Egg of Mountain Hawk EaglesAbies firma, Tsuga sieboldii and Pinus(left) and chickenparviflora), broad-leaved deciduous treesegg (right).
(Fagus crenata and Quercus crispula) andevergreen broad-leaved trees (Castanopsis spp. and Quercus spp.).
The nest size is 120cm by 100cm on average, and the thickness
varies according to the age of use. They use thick dead branches forthe frame and relatively thin branches for the upper structure. They
lay twigs with green leaves in the inner cup.
They usually lay eggs from February to April. The clutch size is oneegg. The egg is white in color. It is about 57mm by 70mm in size
and about 100-110g in weight.

Incubation and nestling periods and fledging rate:
The incubation period is about 43-50 days. Females mostly incubate
eggs and nestlings, while males provide food. The nestling period isabout 70-80 days and the young fledge from June to August. The
fledging day is difficult to determine because the fledglings frequently return to the nest even after they left the nest and receive thefood that the parent birds bring back. The few long-term monitorings of breeding Mountain Hawk-Eagles showed that the mean
fledging rate of three years was 21.4% in Yamagata, Shiga andMiyazaki Prefectures (the Study of the Rare Birds of Prey, JapaneseSociety for Preservation of Birds 2004). However, the pairs withgood reproductive performance bred almost every other year, andthe fledging rate varied greatly between the pairs.

Diet and foraging behavior
Mountain Hawk-Eagles prey on small to medium-sized animals,
such as mammals (hare, racoondog, marten, flying squirrel, squirrel
and shrew mole), birds (Copper Pheasant, Eurasian Jay and others)
and reptiles (snake and skink). However, the prey items increase as
more studies are conducted and the diet varies greatly depending on
regions because Mountain Hawk-Eagles capture a wide variety ofsmall to medium-sized animals which are abundant and readily

Bird Research News

Vol.7 No.12

2010.12.20.

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

バードリサーチ生態図鑑

available in their habitat. They hunt primarily in forests and at theiredge. They usually perch on a tree and wait for their prey to comealong or move from one spot to another in its search, but occasionally fly around right above the tree canopy, looking for their preyanimals.

Topics of ecology, behavior and conservation● Internal structure of the home range
行動圏
A breeding pair of Mountain
飛地
コアエリア
狩場
Hawk-Eagles has a home range
飛地
狩場
with a definite internal structure.
コアエリア
There is a nesting tree (site) in the飛地
center of a home range. A nest
狩場
site is surrounded by the area the飛地
狩場
juvenile mostly use after fledging
until next February. This area is行動圏
usually within a radius of lessthan 500m (or 1,000m depending
コアエリア
遠出場所on geographical features) from a
行動圏
nest tree. Breeding behaviors,such as nest material transporta- Fig. 1. The internal structure of ation, call exchange and copulaMountain Hawk Eagle hometion are carried out in a breeding
range. Red (N): Nest tree, gray:the other large trees suitable forterritory including a juvenile area.
nesting. Red polygon: breeding
A breeding territory is an excluterritory, Blue polygon: home
sive zone set up in the breeding
range of a juvenile, Green polyperiod, which is defended bygon: core/hunting area of a breedbehaviors, such as exhibitinging pair, Olive polygon: homeperch (perching on a conspicuous
range of a breeding pair.
tree for self-display with chestfeathers fluffed out) and the chasing-out of intruders. A breeding
territory covers about 3km2, which contains suitable trees for nesting other than a nest tree. A radius of roughly 1.5km from a nest tree
is the core area of a home range (ca. 7-8km2). A core area includes
the most part of the main hunting ground and major roosting sites aswell as a breeding territory. The core area generally does not overlap with that of a neighboring pair. Since a pair has other hunting
sites outside its core area, the outer boundary of the home range of apair overlaps with that of its neighboring pair. Each breeding pair ofMountain Hawk-Eagles possess a home range of similar size withan internal structure, and the distance between the nests of neighboring pairs is usually about 3km which is double the radius (1.5km) ofa core area.
幼鳥の行動範囲

繁殖 幼鳥のテリ 行動
トリー 範囲繁殖テリトリー

幼鳥の行動範囲

（メス）

繁殖
テリトリー

● Extremely limited range of daily movements
Mountain Hawk-Eagles generally spend the whole day in a corearea without widely moving around. Except when they cover a large
area by display flights or chasing out intruders, they stay in an extremely restricted area during the day because they usually perch on
trees and wait for their prey to come along in a familiar hunting
ground. In addition, after they have captured their prey, they often
spend the rest of the day sitting still at one spot.

longest flight distancefrom nest (m)● Delayed independence of juveniles
3000
The fledglings ofindividual code
Mountain HawkNo.0002
2000
No.0004
Eagles gradually
No.00031000
extend their flying range from0
Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug
the nest as they
theyear nestlings fledged
the next year
developtheirflight ability, but Fig. 2. Longest flight distances of three fledglings
they usually stayfrom their nests.
within a radius of
1km (mostly less than 500m) from the nest tree at least until next

February. During this period, they improve their hunting skills,
while food is provided for them by their parent birds, especially themale parent. Mountain Hawk-Eagles have adopted a breeding strategy to take care of their juveniles until they can acquire their huntingskills and disperse.

● A real threat is the rapid change of forests
Mountain Hawk-Eagles are widely distributed in the forests ofmountains from Kyushu to Hokkaido in Japan, but the reduced reproductivity has a profound effect on the survival of the population.
Although construction related to development may disturb theirbreeding, the decline of their reproductive rate is primarily attributed to the large-scale deforestation and the replacement of manybroad-leaved forests by the monocultural plantations of conifers,
such as Japanese cedars and Japanese cypresses (Chamaecyparisobtusa) after World War II. It is assumed that many pairs of Mountain Hawk-Eagles have lost suitable nesting sites due to the loggingof trees large enough to build a nest. Coniferous plantations without
proper maintenance not only provide them with a limited number ofsmall to medium-sized animals suitable for their prey but also hinder them from hunting in the interior. As a result, an increased number of breeding pairs cannot secure enough food to fledge their nestlings successfully. To conserve Mountain Hawk-Eagles closely
related to the mountain forest ecosystem of Japan, it is of vital importance to construct the mechanism to preserve large trees in theirfavorable nesting grounds as well as to make environmentally sustainable use of timber resources.

Literature
Gjershaug J.O. 2006. Taxonomy and conservation status of hawk-eagles (genusNisaetus) in South-East Asia. Doctorial thesis at NTNU.
Environment Agency Nature Conservation Bureau Wildlife Division. 1996. How toadvance birds of prey conservation -Especially, on the Golden Eagle, the Mountain Hawk Eagle, and the Goshawk -, Japanese Society for Preservation of Birds.
[J]Mountain Hawk Eagle Ecology Research Group. 2000. On the principle and management of the Mountain Hawk Eagle. Mountain Hawk Eagle Ecology Research Group. [J]Yamazaki T. 1996. Accipitriformes Mountain Hawk Eagle. Great encyclopedia ofJapanese Animals Vol 3. Birds I. (Higuchi H., Morioka, H. & Yamagishi S.
eds.), Heibonsha, 158-160. [J]Yamazaki T. 1997. On the ecology and the ecosystem conservation of the Golden
Eagle and the Mountain Hawk Eagle. Bulletin of Lake Biwa Research Center
15:1-8. [J]Yamazaki, T. 2000. Ecological research and its relationship to the conservation
programme of the Golden Eagle and the Japanese Mountain Hawk-Eagle. Chancellor, R.D. & Meyburg, B.-U. (Eds.), Raptors at risk. World Working Group on
Birds of Prey and Owls, Berlin, Germany. 415-422.
Yamazaki T. 2001. Conservation of Raptors and Biodiversity. Landscape Research
64:310-313. [J]Yamazaki T. 2009. The Mountain Hawk Eagle. Wildlife Conservation Society ed.
Dictionary of Wildlife Conservation. Asakura-shoten, 482-484. [J]Author
Hawk Eagle Ecology Research GroupToru YAMAZAKI Mountain
Asian Raptor Network
After graduating from the Veterinary Departmentof Tottori University, I studied the avian ecology
in the Ecology Lab of the Department of Education of Shinshu University. I was involved in theecological study and conservation of Golden
Eagles and Mountain Hawk-Eagles as a lifework,
while working in stock raising administration andlivestock epidemic prevention as a staff memberof Shiga Prefecture from 1977 to 2004. I foundedthe Mountain Hawk Eagle Ecology ResearchGroup in 1981 and am still working for the conservation management of the Mountain HawkEagles as well as the research and conservation of
raptorial birds of Asia. t-yamaza@mx.biwa.ne.jp

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