Bird Research News

Vol.4 No.9

2007.9.13.

Chestnut-cheeked Starling Komukudori (Jpn) Agropsar philippensis
Morphology and classification
Classification: Passeriformes Sturnidae
Total length:
192mm (183-198) nWing length: ♂ 106.76±2.12mm (41)
Tail length:♂ 52.71±2.16mm (41)
Culmen length: ♂ 19.61±0.63mm (40)
Tarsus length: ♂ 24.09±0.91mm (41)Weight:♂ 46.70±2.77g (38)♀ 104.55±2.36mm (33)
♀ 51.36±1.76mm (33)
♀ 19.39±0.52mm (33)
♀ 23.89±0.95mm (33)
♀ 47.22±3.88g (33)

Total length after Enomoto (1941). Other measurements are of the breeding period in
Niigata City (mean ± S.D.) by the author.

Appearance:
Males are white on the head witha brown patch on the cheek. This
patch varies in size between individuals. The back is lustrous
purple black. The wing and tailare lustrous greenish black. Thereis a white part on the shoulder.
The flank is gray and the rump ispale brown. Females, on the other hand, are brown all over. The
bill and mouth are black both inmales and females.

3530252015105Distribution and Habitat
Distribution:
Chestnut-cheeked Starlings breed north of central Japan (centralHonshu to Hokkaido), in the southern Kuril Islands as far as southern Sakhalin.

Habitat:
They breed in the woodland of ranches and highlands in the hills,
and groves on rivers and fields as well as vegetation-rich backyards of villages and towns in the lowlands. They prefer an open
habitat with a mosaic of the woods and meadows.

Life history
3wintering
period4

56

breeding
period78

910

molting migration
period11 12

Breeding system:
Chestnut-cheeked Starlings arrive at the breeding grounds of Niigata City, Niigata Prefecture from early April to early May. They
are monogamous, but they remain their pair-bond for a single
breeding season alone, and they do not necessarily pair with thesame partner the following year. When they succeed in their firstbreeding attempt, they do not breed for the second time in thesame season.

Nest:
They nest in tree cavities and often use nest boxes. Both males andfemales build a nest. When old nest materials remain in a nest,
they carry them out. They mostly use dry pine needles and grass asnest materials, but occasionally add green leaves. They line theinner cup with finer materials and sometimes place green leaves
and feathers there as well.

4♪ http://www.bird-research.jp/1_shiryo/koe/komukudori_100610_nikkou.mp3
Toshiaki Hirano

temperatures (℃)

Photo 1. Chestnut-cheeked Starling male (left) and female(right).

Chestnut-cheeked Starlings sing like "Kyu-kyu-kyu, pee-pee,
pippbee-peebibi" for about eight seconds. They sing to attract females, not to defend their territory. Their call sounds "Gyuk"
which is lower than White-cheeked Starlings (Spodiopsar cineraceus).

2The egg was solid blue in color
and was 24.4 ± 0.3mm by 18.1 ±0.1mm (mean ± S.E., n = 13) insize. Chestnut-cheeked Starlings
laid eggs from late April to early
June, but about half of them started laying in mid-May in Niigata
City from 1978 to 2005. "Meanfirst egg-laying date" varied be- Photo 2. The egg and nestlings of
Chestnut-cheeked Starlings
tween the years. The clutch size
immediately after hatching.
was 3-9 eggs and a clutch of 5-6
eggs represented more than 70%of the clutches. The clutch size decreased as the breeding season
progressed. They usually laid an egg every day from six to teno'clock in the morning. The morning egg-laying was also confirmed by measuring a difference in temperature between the insideand outside of a nest using a temperature logger placed in a fakeegg (Fig. 1).
40

Vocalization:

1

Egg:

the female left the nest due toinvestigation disturbanceFig. 1. Temperatures of
the inside and outsideof a nest in the egglaying period. Hoursof a great differencein temperature conoutside temperature
centrate in the morning, which shows that0 6 12 18 0 6 12 18 0 6 12 18 0 6 12 18
the female stays in theMay 26
May 27
May 28nest to lay an egg in(second egg) (third egg) (fourth egg)
the morning.
temperature
within the nest

Incubation and nestling periods and predators:
Males and females incubate eggs alternately during the daytime.
During the night, however, only females do. Not only females but
also males develop a brood patch (a feather-lost bare skin area) on
the abdomen. Males do not feed their partner. The incubation period is 12-13 days, but the eggs begin to hatch 11 days after the last
egg was laid in more than 50% of the nests because the incubation
starts before the clutch is completed. As a result, the nestling that
hatched one day later sometimes grow slowly. Both males andfemales feed the nestlings. For a while after hatching, the parent
birds brood over the nestlings after feeding them. When the nestlings grow up, the parents stop brooding at nighttime as well. They
mostly feed larvae of moths to the nestlings, but also give adults ofmoths, spiders and grasshoppers to them
(Photo. 3). In addition to these invertebrates, fruits of cherry trees, oleaster(Elaeagnus spp.) and Lonicera morrowii
account for 20-30% of the food. The nestling period is about 18 days. During theincubation and nestling periods, somenests fall victim to the predation of snakes Photo 3. Male withand weasels (Mustela itatsi). Parent birds
larvae and imagoesof moths at the nest.
feed the young for a while after fledging.

Roost:
Chestnut-cheeked Starlings form a communal roost from summerto autumn. Although they may roost with a flock of White-cheeked
Starlings, they tend to make a single species flock by themselves.
They leave the roost for the foraging grounds in a small flock in themorning, but they gradually disperse.

Migration:
Most Chestnut-cheeked Starlings leave the breeding grounds andhead south by the end of September. They travel through the Nansei Islands, southernmost Japan, Taiwan and the Philippines to thenorthern part of Borneo Island to spend the winter. In spring, they
retrace their migratory route and arrive at the breeding grounds
from April to May (Brazil 1991).

Bird Research News

Vol.4 No.9

2007.9.13.

© Japan Bird Research Association
Sumiyoshi 1-29-9, Fuchu, Tokyo, Japan● Dispute over a nesting site
A dispute between males overa nest site is fierce. Nest owners threaten other males intruding into the territory, fluffing
their feathers up and calling
vigorously. If the intruders
refuse to leave, the nest owners
attack them fiercely or may
perch at the nest hole andthreaten them, with their blackmouth open. The males occasionally fall to the ground,grappling with each other. Photo 4. Male Chestnut-cheeked
Starling singing in front of a nest
Once a dispute over territorialbox.
claims has been settled, however, neighboring males usually stop fighting. Since the function of aterritory is to secure a nest site, they do not establish a large territory to acquire the foraging grounds, which allows them to breed
relatively close together. In the study site, for example, they breed
in a territory of about 200m2. It is assumed that this behavioral
flexibility contributes to the effective use of insufficient nestingsites.
When males have secured a nesting site, they sing vigorously to
attract females (Photo 4). When females come flying close tothem, they stop singing. They lower the wings slightly and makethemselves slender, and then start to sing again, but softly thistime. They also perch at the nest hole or go in and out the nest,
when they may carry green leaves into the nest in the bill. Chestnut-cheeked Starling males show females that they own a suitable
nest site as well to win their heart. Males tend to try to secure as
many nest sites as possible early in the breeding period, whichleads to polygamous pair formation. However, this polygamous
relationship is temporary which accounts for 1% of the breedingpairs, and most pairs breed monogamously (Koike 1988, 1997).

● Nest box installation for conservation
The population of Chestnut-cheeked Starlings is smaller than thatof closely related White-cheeked Starlings. The breeding numberof Chestnut-cheeked Starlings is disproportionately small as wellbecause White-cheeked Starlings use tree cavities which Chestnutcheeked Starlings could otherwise use. However, Chestnutcheeked Starlings can breed in a nest box with an entrance 4cm
across without being displaced by their larger relative. An adequate supply of nest boxes is needed in open woodlands to conserve Chestnut-cheeked Starlings (Koike 1997). Even when I installed 20-30 nest boxes at 20m intervals along a woodland path,most of the boxes were used by this species.
When many nest boxes are provided in a new area and a small
number of pairs start to use them, more males and females are
attracted by the songs of nest box users and visit the area. Although the densely breeding situation may give them an image ofcolonial breeders, it is due to the placement of nest boxes that aredensely-placed. They are non-colonial breeders and often use asingle nest box installed alone.

● Effects of global warming
The study conducted in Niigata City for 28 years from 1978 to2005 revealed that Chestnut-cheeked Starlings started to lay eggs
earlier.
The regression (y = 22.94 - 0.57 x (1978 = 0)) shows that the first
egg-laying dates of 1978 and 2005 were May 22.9 and May 7.6,

respectively. The date was advanced by 15.3 days in 28 years,
which corresponds to 0.57 days per year (Fig. 2). In the breedinggrounds (Niigata City: 37° 54′ N, 139° 01′E) and the stopover site
(Naha City, Okinawa Pref.: 26° 12′ N, 127° 41′E), on the other
hand, the temperatures in the early spring (February-April) increased by 1.5°C and 1.1°C in 28 years, respectively. In addition,
the first egg-laying date is correlated with the temperatures ofthese two areas. There was a tendency for Chestnut-cheeked Starlings to lay eggs early in the years when the temperatures of thebreeding grounds or stopover site were high. The analyses suggestthat the advanced first egg-laying date was induced by a rise intemperature in the last 30 years as a result of the rapidly progressing global warming. Many pairs started breeding in a short span oftime with the advanced first egg-laying date. The clutch size also
increased from 5.0 to 6.1 eggs (Koike & Higuchi 2002, Koike etal. 2006).
May 25First egg-laying date

Topics of ecology, behavior and conservation

バードリサーチ生態図鑑

2246
7 1727May 2042May 1528May 10152330316060362831 6060

May 5May 159 59
5760

y = 22.94－0.57x (1978=0), r =－0.876, P < 0.0001, N = 22.
(One-way ANOVA: F = 48.12, df = 21,836,P < 0.0001)

1980

1985

19901995

2000

2005

Fig. 2. Annual changes of first egg-laying date (1978-2005). Figureson the graph are the number of nests studied each year. (modifiedfrom Koike et. al. 2006).

Literature
Brazil M.A. 1991. The Birds of Japan. A & C Black, London.
Enomoto Y. 1941. Wild Bird Handbook (Vol.2). Osaka Chapter of Wild Bird
Society of Japan, [J]Koike S. 1988. Breeding ecology of the Red-Cheeked Myna Sturnus philippensis.
Strix 7:113-148. [J+E]
Koike S. 1997. Chestnut-cheeked Starling. Encyclopedia of Animals of Japan.
Birds. II. 164. Heibonsha, Tokyo. [J]
Koike S., Fujita G. & Higuchi H. 2006. Climate change and the phenology ofsympatric birds, insects, and plants in Japan. Global Environmental Research
10:167-174.
Koike S. & Higuchi H. 2002. Long-term trends in the egg-laying date and clutch
size of Red-cheeked Starlings Sturnia philippensis. Ibis 144:150-152.
Languages of literature cited other than English: [J] in Japanese, [J+E] in Japanesewith English summary.

AuthorShigeto KOIKE

Teacher at Niigata Municipal Ohgata
Junior High School

It has been 30 years since I started
to study Chestnut-cheeked Starlings.
I really feel that time flies. At first I
could not understand the meaning of
their behavior, but as I continued
the study, the whole picture suddenly came into sight. I noticed that thedate of the first egg-laying wasbecoming early about 20 years afterI began to study. Since it is important to accumulate data for along period of time, I have been
studying Chestnut-cheeked Starlings
to collect data without a break.
myna@syd.odn.ne.jp5