Bird Research News

Vol.2 No.11

2005. 11.15.

Brown-eared Bulbul

Hiyodori (Jpn) Hypsypetes amaurotis
fails due mostly to predation. It is not until July, therefore, that theygenerally breed successfully (Fig. 1).

Morphology and classification
Classification: Passeriformes Pycnonotidae

Nest:

Total length:
Tail length:
Wing length:
Culmen length:
Tarsus length:
Weight: :Brown-eared Bulbuls build a bowl-shaped nest at the fork of abranch with dense foliage at a height of 1-15m above the ground.
The nest is 6-10cm in diameter and 3-6cm in depth, which is small
for their body size. They use twigs and ivies for the exterior and finegrass stalks and roots for the interior. In urban areas, however, plastic
strings are used for the exterior in almost
all their nests.

249-290mm
115.1 ± 6.4mm (106)125.9 ± 5.7mm (110)30.8 ± 1.3mm (60)22.9 ± 1.3mm (105)79.9 ± 12.1mm (111)

Total length after Enomoto (1941). The other measurements (average ± SD) are by theauthors in the Tsukuba City. The measured individuals include both breeding andwintering birds. Though females are slightly smaller than males, individual and regional variations are too great to distinguish clearly between sexes.

Appearance:
Both male and female are gray from thehead to the back, with the wings and tailashy brown. The ear coverts are conspicuous reddish brown. They have ashy brown
vertical stripes from the chest to the belly.
They tend to be paler in plumage coloration in the northern regions and darker inthe southern areas. Since Hypsitepes am- Photo. 1. Brown-eared
aurotis amaurotis and H. a. magnirostris
Bulbul feeding on ain particular are gray but the other subspecherry in a cherry treecies are dark brown on the chest, whichmakes it relatively easy to distinguish these two subspecies from theothers (Saito 2002).

Distribution and Habitat
Brown-eared Bulbuls are distributed in Sakhalin, the southern part of
the Korean Peninsula, Taiwan, northern Philipinines and Japan. The
populations in Japan are classified into eight subspecies, with H. a.
amaurotis in the four main islands including Tsushima, Yakushima,Tanegashima, the Osumi Islands and the Izu islands, H. a.
squamiceps in the Ogasawara Islands, H. a. magnirostris in the Volcanic Islands, H. a. borodinonis in the Daito
islands, H. a. ogawae in the Amami Islands,
H. a. pryeri in the Okinawa and Miyako
Islands, H. a. stejnegeri in the Yaeyama
Islands excluding Yonaguni Island and H. a.
nagamichii in Yonaguni island. It is stronglyrecommended, however, to review the classification of these subspecies (The Ornitho- Photo. 2. Hypsypetesamaurotis ogawae
logical Society of Japan 2000).

Habitat:Brown-eared Bulbuls occur in the open woods in a wide variety ofhabitats, such as farmland and urban areas from lowlands to considerably high mountains. They generally used to be a winter resident inurban areas. In Tokyo, however, they have started to stay in urban
areas even in spring and summer since around 1968 and breed in thecenter of the city in the 1980s (Karasawa 1997).

Life history
Breeding system:
Brown-eared Bulbuls are monogamous and breed from May to September. There is a record of a pair which bred three times successfully in the same breeding season, but they usually attempt to breed twoor three times because their first or second breeding attempt often
MayJunePair AJuly○Pair B

4○××××

Augusut

September○Photo. 3. Eggs of Brown-eared Bulbuls.

Incubation and nestling periods and fledging rate:
Females chiefly incubate for 12-14 days, and both male and female
raise their young. The nestlings fledge about ten days after hatching
without their flight feathers fully-grown, but they stay close to thenest for several days because they cannot fly very well. The parentbirds look after the fledglings for one or two months afterwards(Haneda & Kobayashi 1967, Kamon 1995). Ten pairs of Browneared Bulbuls attempted to breed 2.3 times per pair per year on average in the study site of Tsukuba City, Ibaraki Prefecture, central
Japan. Overall, they attempted to breed 23 times and succeeded 11times. Eight of the ten pairs fledged their young successfully. Predation was primarily responsible for their breeding failure (Kamon1995, Tanaka 2000).

○In contrast with the other subspecies, the nominotypical subspecies
H. a. amaurotis that occurs in the main islands of Japan migrates.
It sometimes moves as far as Amami-Oshima and Okinawa Islands
to winter. It is known to fly across some bays and straits in a flockof one to several hundred birds. It is also observed to migrate in aflock of several to several dozen birds throughout Japan.

Diet and foraging behavior
The diet of Brown-eared Bulbuls consists of vegetable matter,such as fruit, nectar, petals, leaves, sprouts, and animal matter,such as reptiles, insects, spiders and land snails. They also feed off
breadcrumbs from people. In Tsukuba City, the food items ofBrown-eared Bulbuls included 74 species (32 families) of woody
plants, eight species (7 families) of herbs and 12 species (6 families) of farm crops (Yamaguchi 2004). They
prefer berries, but they also eat dry fruits, andtherefore their diet covers almost all kinds offruits and nuts. In addition, they cause damage to leafy vegetables, such as Japanesemustard spinach Brassica rapa var. perviridis
and cabbages in winter. The proportion ofanimal matter increases in their diet in springand summer when insects are abundant. They Photo. 4. Browneared Bulbul
are often observed to chase after large insects,
sucking nectar
such as cicadas. They mostly feed animal
from cherrymatter to their nestlings.
blossoms.

Topics of ecology, behavior and conservation● Are they year-round residents, winter residents or nomads?

nest buioding
egg laying

incubation

chick-rearing

family○breeding success ×breeding failure

Fig. 1. Breeding patterns of Brown-eared Bulbuls.

♪ http://www.bird-research.jp/1_shiryo/koe/seguroseki_090312_nasu_hirano.mp3
Toshiaki Hirano

The clutch size is about four eggs (Haneda& Kobayashi 1967, Kamon 1995). The egg
has brown flecks on a light purple brownground. The egg size is about 3cm by 2cm.

Migration:

Distribution:

Pair C

Egg:

Since Brown-eared Bulbuls are vocal and conspicuous birds, it isrelatively easy to estimate their abundance with censuses. Figure 2
shows the annual fluctuation in the number of bulbuls in the Tsukuba♪ http://www.bird-research.jp/1_shiryo/koe/seguroseki_090102_utsunomiya_hirano.mp3
Toshiaki Hirano

Bird Research News

Vol.2 No.11

2005. 11.15.

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

Number of Brown-eared Bulbuls (bird)

City, Ibaraki Pref. based on line censuses.
Approximately 20 Brown-eared Bulbuls are assumed to occur as ayear-round resident in the census area, and numerous birds fly overwithout stopping during migration periods in the spring and autumn.
It is probably because they are less active and stay in a grove during
the summer when they molt that their detection frequency decreases
in the summer census. They gradually increase afterwards and reachthe maximum number around New Year. The birds that contributed toa rise in their population can be winter visitors from northern regions
and stay in or near the study site until spring. The peak number represented in the autumn results from a large flock of bulbuls feeding on
fruit in a tree. Though the number decreased with the disappearanceof the fruit, it is not because Brown-eared Bulbuls have left the studysite but because they frequently feed in the cropland outside the census range. The peak number between February and March resulted
from feeding flocks in a Japanese mustard spinach field. These flocks
occasionally exceeded 100 birds. A large number of Brown-eared
Bulbuls feed in roadside cherry trees in April. The winter visitors
gradually left the study site afterwards and only the resident individuals stayed for the summer.
The tracking of identified individuals conducted in Tsukuba City also
confirmed the year-round residents and wintering individuals. In otherwords, Brown-eared Bulbuls observed in the city are classified into
the following three categories: year-round residents, passers-by andwintering individuals. They are known to make a long distance movements with the150
passers-by
disappearanceof
10050
fruit; one bird band0
ed in Osaka in Deresidents.
250
cember was recap200
spinach fieldroadside
tured in Wakayama
150
cherry trees
Pref. about 100km
100molting
periodaway in the next
500January(Wada
10/7 10/27 11/16 12/9 12/29 1/20 2/10 3/3 3/24 4/13 5/26 8/18
2002). This indicates that some Fig. 2. Annual fluctuation in the number ofBrown-eared Bulbuls in Tsukuba City, Ibaraki
bulbuls are nomadic
Pref. (From Yamaguchi 2005).
during the winter.

● Migration of Brown-eard Bulbuls

observed region

Yamashina (1934) reported that only the population of Hokkaido,
northernmost Japan was a migrant and the other populations were aresident or nomadic. Nowadays, however, Brown-eared Bulbuls seemto have changed their behavior.
Therefore, I asked the people concerned all over Japan to provide
information about migrating Brown-eared Bulbuls in the autumn of2004. The information came from 80 sites across Japan, where 88,294
birds (1,976 flocks) were observed in total. The migration was observed in eight regions excluding the Chugoku and Kyushu regions
where the number of examples was too small for analysis.
Since it was known that Brown-eared Bulbuls moved from the northto the south in the autumn migration, it was expected that the migration was also observed sequentially from the north to the south. Contrary to the expectation, however, they tended to set out on their migration later in northern
Hokkaido
areas than in southern
Tohokuones, such as the Kansai
Kantoregion (Fig. 3). TheKoshin
Hokuriku
migration was first obTokai
served in the Kansai
Kansairegion on September 9Shikoku
and continued for threemonths until November
9/1 9/11 9/21 10/1 10/11 10/21 10/31 11/10
observed date
8. In Hokkaido, northernmost Japan, on the Fig. 3. Observed period of Brown-eared
Bulbul migration in the autumn of 2004
other hand, the migrain eight regions of Japan in the ordertion was first observed
from northeast to southwest. (Fromon October 10 and last
Yamaguchi 2005).
on November 2.

バードリサーチ生態図鑑
The analysis suggested that the populations of southern regions started to migrate before the arrival of northern populations. The migration of southern populations may be the movement from the highaltitudes to the low altitudes.
Although I am collecting information about Brown-eared Bulbul
migration in the autumn of 2005 as well, the migration seems to belater than in 2004. Since there is information that nuts and fruits are inplentiful supply in most places in Japan in the autumn of 2005, it isinteresting to study the relations between Brown-eared Bulbul movement and nut and fruit production.

● Relationship of Brown-eared Bulbuls to humans
Brown-eared Bulbuls are considered to be one of the major agricultural pest species in Japan. According to the data from the Ministryof Agriculture, Forestry and Fisheries, the area of Brown-eared Bulbul damage was estimated to be 4,400ha (the 6th place among birds),
the quantity 5,300t (the second place) and the amount 894 million
yen (the 3rd place) in fiscal year 2003. They have caused serious
damage to fruit farmers in particular across Japan. The Ministry ofthe Environment reported that as many as 343,000 Brown-earedBulbuls were destroyed as a pest species and about 34,000 birds werehunted in fiscal year 2000.
Since they consume a great amount of insects (agricultural pests) insummer, however, they make a contribution to agriculture. There is apossibility of committing a major error when only their damage isemphasized. Though we have still no data on the Japanese population of Brown-eared Bulbuls, it is time we attempted to coexist withthem, adopting the technique of population management including
habitat management.

Literature
Enomoto Y. 1941. Wild Bird Handbook (Vol. 2). Osaka Chapter of Wild-Bird
Society of Japan, Osaka. [J]Kamon Y. 1995. Clarification of moving rage of Brown-eared Bulbuls Hypsipetesamaurotis. Graduation thesis. Tsukuba University. [J]Karasawa K. 1997. The Brown-eared Bulbul. The encyclopedia of Japanese Animals 4. Birds II. p.83. Heibonsha, Tokyo. [J]Saito Y. 2002. Can Brown-eared Bulbul's subspecies be really distinguished?
Yacho 649: 15-17. [J].
Tanaka T. 2000. The change of territory and moving range of Brown-eared Bulbuls
relative to the distribution of mature fruits. Master's thesis. Tsukuba University.
[J]
Ornithological Society of Japan. 2000. Check-list of Japanese birds the sixth edition. [J+E]
Haneda K. & Kobayashi T. 1967. Study of the life history of Brown-eared Bulbuls.
J. Yamashina Inst. Ornithol. 27: 61-71. [J]Yamaguchi Y. 2004. Nationwide movement and the impact on farm products byBrown-eared Bulbuls. Journal of agricultural science 59: 173-178. [J]Yamaguchi Y. 2005. Bird damage measures against Brown-eared Bulbul thoughtfrom the migration and condition of nut fruition. Research journal of food andagriculture. 28: 35-39. [J]Wada T. 2002. Brown-eared Bulbuls' food in winter and their life. Yacho 649: 6-9.
[J]
Languages of literature cited other than English: [J] in Japanese, [J+E] in Japanesewith English summary.

AuthorYasuhiro YAMAGUCHI

Agricultural Research Center,
Wildlife Management Laboratory
Six years have passed since I
started to study Brown-eared
Bulbuls. As I study them, I makemore new discoveries and face
more mysteries. But some saythat they have more often posedmysteries. Have I entered an "offlimits" area ?
yamay@affrc.go.jp

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