Bird Research News

Vol.2 No.2

2005. 2.10.

Japanese Sparrowhawk
Morphology and classification
Classification: Accipitriformes Accipitridae
Total length:
Wing length:
Tail length:
Culmen length:
Tarsus length:
Weight:♂ 265mm♀ 304mm♂ 168.51 ± 8.35mm ♀ 192.21 ± 7.13mm♂ 123.5 ± 4.33mm ♀ 143.22 ± 6.61mm♂ 11.1 ± 0.34mm♀ 13.5 ± 1.13mm♂ 43-48mm♀ 52-57mm♂ 90g♀ 135.8g

Tsumi (Jpn) Accipiter gularis
but the many individuals of the northern areas are observed tomove south in the autumn. The population that breeds in theYaeyama Islands, southern Japan is classified as a distinct subspecies, Ryukyu Tsumi A. g. iwasakii.

Habitat:
In Japan they occur in the woodlands in plains and mountains andeven in cities. Since they nest in an isolated tree in a logged-overLife history

Lengths of natural wing, tail and beak (mean ± SD) are based on Hirano & Endo
(unpublished data). Total length and weight are from Enomoto (1941).

incubation

Appearance:
Male upperparts are dark gray tinged with blue and underparts are
pale reddish brown from the chest to flank. The reddish brownvary between individuals from almost white to red brown. Eyes areblack with red tint. Legs are yellow. In the female, on the other
hand, upperparts are dark gray and underparts are off-white withdark brown lateral bars. Eyes are yellow. Both sexes of juveniles
have dark brown upperparts with thick brown bars on the chest andbelly. There are superciliary ridges on the head.

pairing period
nest building
laying periodbroodingfamily period after fledging

Breeding system:
Monogamous. Extra-pair copulation is observed on rare occasions(Ueta & Hirano 1999).

Nest tree:
They nest in coniferous trees, such as red pines Pinus densifloraand cryptomeria and deciduous trees, such as oaks, cherries andevergreen oaks. Among them, the most preferred nesting tree is thered pine. The mean dbh and height of nest trees are 38.3 cm and18.6 m, respectively. Nest-building period is from early to midApril. Both male and female carry nest materials, but the work
sharing between the pair varies significantly from one pair to theother.

Male (left) and female (right) Japanese Sparrowhawks

Clutch size, incubation period, fledging rate and postfledging period:

Vocalization:

Laying period is mid-April to early May. The clutch size is estimated to be 2-5 eggs. Incubation period is 26 to 29 days. Chicks
fledge about four weeks after hatching. The number of fledglings
per nest is 2.35 ± 1.76 birds (mean ± SD, N = 78). The young remain in the vicinity of the nest site for about three weeks afterfledging. Some fledglings were recorded to be fed by their parents
as late as late August and mid-September . A pair of Japanese
Sparrowhawks attempted to breed twice a year. (Hirano 1998) .

Four major calls are distinguished (Hirano 1994). A call thatsounds like "Pyoh-Pyo- Pyo-Pyo" with falling intonation are usedby both sexes to threaten predators. In addition, males use this callas communication with their mates, and females as territory declaration. A shrill and continuous call that sounds like "Kek-kek-kek"
is used mainly by female as food begging and territory declaration.
A "Coo, coo " call is used by both sexes as communication between the mates and a sharp "kit" call is used in a battle.

Display:
Aerial displays include soaring, diving and pursuit. Wing shiveringand tail-up displays are observed between the male and female in
the pre-laying period (Figure 1, Hirano 1999).
abc

Fig. 1. Prelaying display of Japanese Sparrowhawks.
a) Tail-up
display b)
and c) Wing
shivering
displays.

Diet and hunting:Japanese Sparrowhawks generally use the ambush type of hunting. They are perched in trees at the forest edge, dashing fiercely
out of the hide to capture the prey that happens to be passing. During the breeding season, the species sometimes capture large birds,
such as Bamboo Partridges and pigeons in the residential area ofTokyo and Utsunomiya. However, small song birds such as treesparrows account for more than 90% of the total prey. It also
catches insects and small mammals, such as rodents and pipistrelles (Hirano & Kimishima 1992, Ueta 1992). It caches leftovers
on tree branches and crotches by pressing them with its feet
(Hirano & Ueta 1994). It is estimated that a pair of Japanese Sparrowhawks needs a total of 354 small birds to breed successfully(Ueta 1992).
OthersGrey Starlings
pipistrelles

Distribution and Habitat
Distribution:

medium-sized birds
Brown-eard Bulbul
nknown small birds
Tree sparrow

Japanese Sparrowhawks breed in southern Siberia, Amur and Ussuri regions, Sakhalin, southern parts of the Kuril Islands, northern
Mongolia, eastern China, the Korean Peninsula and Japan. They
migrate to Southeast Asia and southern China to winter. In Japan,
however, they are residents from Hokkaido to Okinawa

Fig. 2. Proportion of prey species of Japanese Sparrowhawks in residential
areas of Utsunomiya (N = 200 from Kimishima Hirano (1992).

♪ http://www.bird-research.jp/1_shiryo/koe/tsumi_090420_kokubunji_mju.mp3♪ http://www.bird-research.jp/1_shiryo/koe/tsumi_10326_Utsunomiya_hirano.mp3

2

Mutsuyuki Ueta

0Tohshiaki Hirano

20

40
60
80
Proportion of prey (%)

Bird Research News

Vol.2 No.2

2005. 2.10.

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

Topics of ecology, behavior and conservation● Expansion into residential areas
Japanese Sparrowhawks were not common birds until the 1970s.
In the 1980s, however, they began to breed in parks and roadsidetrees in residential areas especially in the Kanto region, central
Japan (Endo, et. al. 1991) . After 1981when the breeding was confirmed in a residential area of Ageo City, Saitama Pref., the breeding range gradually expanded into the surrounding areas, such as
Tokyo, Kanagawa, Yamanashi, Shizuoka and Tochigi Prefectures
through the late 1980s. The breeding population also increased
with the range expansion. In Utsunomiya, Tochigi Pref., for example, there were seven breeding pairs in 1990, nine in 1991 and 12in 1992 in an area of 43.5km2.
It is not known exactly what induced the species to breed in residential areas, but the contributory factors are assumed to be theavailability of red pines suitable for nesting and the abundance ofsmall prey birds such as sparrows in residential areas. In addition,
the relaxed wariness of people as well as the lack of other birds ofprey specialized in small birds in residential areas probably facilitated the expansion of Japanese Sparrowhawks into the humanlandscape. And they have become one of the most common hawks
at least in the Kanto region.

● The interaction between Japanese Sparrowhawks andLarge-billed Crows
Number of fledglings

5In the 1990s, however, darksigns began to be seen in the4breeding of Japanese Sparrow3
hawks in the residential areasof Utsunomiya and Tokyo. By
2comparing the breeding status1
N=24
es of Utsunomiya in the early,
N=28
N=26
middle and late 1990s, no0
difference in the reproductive
Early 1990s Mid 1990s Late 1990s
performance was detected
Fig. 3. Changes in the reproductive(Kruskal-Wallis, H = 1.458, P
performance of Japanese Spar= 0.483, Fig. 3), while therowhawks in Utsunomiya
number of the breeding pairs(Hirano 2002).
declined from 8-9 pairs in
1991-1993 to 6 pairs in 1994-1996 and 5 pairs in 1998 and 2001
(Hirano 2002). The decline did not stop and there were only threepairs in 2002 and four pairs in 2003-2004.
The increase of Large-billed Crows is considered a major cause forthe decline of Japanese Sparrowhawk breeding pairs. The Largebilled Crow population in Utsunomiya has increased significantly
since the mid-1990s (Hirano 2000). And Large-billed Crows havestarted to breed in the woodlots where they did not breed formerly.
There are not many trees suitable for Japanese Sparrowhawks or
Large-billed Crows to nest in the woodlots of residential areas.
The two species have begun to compete for suitable nest trees. Inaddition, Large-billed Crows can prey on the adults as well as thechicks and eggs of Japanese Sparrowhawks. Although the adults
and the nests are seldom attacked by the crows, the sparrowhawks
desert the nest sites only if the crows fly around noisily there. The
sparrowhawk pairs easily abandon the breeding at the beginning of
the nest building period, though they hang on once the chicks have
hatched (Hirano unpublished data).
Interestingly, even in the woodlot where the crows breed, if there
is a suitable nest tree in the part of the woodlot that is not used by
the crows, the sparrowhawks nest in the tree (Hirano 2001). For
example, a pair of Japanese Sparrowhawks bred in a 2-ha woodlotwith a pair of Large-billed Crows and a pair of Carrion Crows forseveral years. When the Large-billed Crow nest tree died, howev-

バードリサーチ生態図鑑
er, the crow pair started to breed in the area formerly used by thesparrowhawks. The sparrowhawks stopped breeding there. Thus,
the number of red pine stands where Japanese Sparrowhawks haveceased to breed, even if they are suitable for them to nest, has been
increasing.
In this way, the success or failure of the breeding of this hawk in
the residential area of Utsunomiya has been left to the behavior
and the range of Large-billed Crows. It is assumed that the growing amount of food scraps has resulted in the increase of Largebilled Crows. According to the proverb that says “Coopers make aprofit if the wind blows”, it might be said that an increase in foodscraps has reduced Japanese Sparrowhawks breeding in Utsunomiya.
What will become of Japanese Sparrowhawks breeding in theresidential areas in the future? Would they survive in marginal
spaces of the urban landscape?

Literature
Enomoto Y. 1941. The body size of Japanese birds. Japan Wild Bird Society Osaka
Branch, Osaka. [J]Endo K., Hirano T., Ueta M. 1991. Breeding situation of Japanese Lesser Sparrowhawk Accipiter gularis in Japan. Strix 10:171-179. [J+E]
Hirano T. 1994. Calls and the aerial displays of Japanese Lesser SparrowhawkAccipiter gularis in breeding season. Strix 13:31-39. [J+E]
Hirano T. 1998. The second breeding attempt of the Japanese Lesser Sparrowhawk
observed in a residential area. Strix 16:167-170. [J+E]
Hrano T. 1999. Displays of Japanese Lesser Sparrowhawks during Pre-laying
Period. Jpn.J.Ornithol.48 :157-160. [J+E]
Hirano T. 2000. About the increase of Large-billed Crows in Utsunomiya. Accipiter 6:13-20. [J+E]
Hirano T. 2001. On the usage of green space of crows and hawks for breeding in a
residential neighborhood. Strix 19:61-69. [J+E]
Hirano T. 2002. On the change in breeding status of Japanese Lesser Sparrowhawk
in residential areas around Utsunomiya: competition of nesting resources between the hawk and the Large-billed Crow. Strix 20:1-11. [J+E]
Hirano T. & Kimishima M. 1992. Food and breeding status of Japanese Lesser
Sparrowhawk Accipiter gularis in residential areas near Utsunomiya. Strix
11:119-129. [J+E]
Hirano T. & Ueta M., 1994. Caching behavior of Japanese Lesser Sparrowhawk
Accipiter gularis in the breeding season. Jpn. J. Ornithol. 43:32-35. [J+E]Ueta M. 1992. Estimation of the number of prey of the Japanese Lesser Sparrowhawk Accipiter gularis to capture during the breeding season. Strix 11:131-136.
[J+E]
Hirano T. & Ueta M. 1999. Observation of extra-pair copulation in the JapaneseLesser Sparrowhawk. Strix 17: 173-176. [J+E]
Languages of literature cited other than English: [J] in Japanese, [J+E] in Japanesewith English summary.

AuthorToshiaki HIRANO Japan Bird Research Association
In the past few years Large-billed Crows have increased in number,flying around noisily on days of food scrap collection in my hometown
as well. With glances at Large-billed Crows, I remember the days that
I was excited to see Japanese Sparrowhawks in the neighborhood.
Thinking that the hawks would nest here and there if it were not forthese crows, I feel animpulse to cry out “I hateLarge-bills!” The season
will come around soon
which brings fun andworries to me. I am looking forward to seeing
Japanese Sparrowhawks
in the neighboring parks,
cursing Large-bill Crows
this spring again.
k-grandis@helen.ocn.ne.jp3