Bird Research News

Vol.9 No.6

House Swift2012.6.25.

Hime-Amatsubame (Jpn) Apus nipalensis

Morphology and classification
Classification: Apodiformes Apodidae
Total length: About 15cm
Wing length: 12.7± 0.4cm (n = 611)
Tail length: 4.9±0.2cm (889) Weight:
28.8±2.5g (2623)

Nest:

Total length after Chantler & Driessens(1995), other measurements are after
Hotta et al.

Appearance:
Both male and females arebrownish black all over, with awhite throat and rump.

Vocalization:
They utter"Churrrrr".

"Jyurrrrr"

orPhoto 1. House Swift[Nobutoshi Sato]

Distribution and Habitat
Distribution:
House Swifts range in the tropics and subtropics, such as southcentral Africa, northern Africa (Morocco and Tunisia), India, Nepal, Bangladesh, southeastern China, Southeast Asia, the northern
Philippines, Taiwan and Japan. Recently, however, House Swiftsof the areas east of Nepal and Bangladesh, which include Japan,
have been treated as a different species (House Swift A. nipalensis), separated from those of India and Africa (Little Swift A.
affinis) because the former has darker plumage and a longer tailwith a slightly M-shaped tip. House Swifts (A. nipalensis), which
did not originally occur in Japan, came to be observed in
Tanegashima Island (Kagoshima Prefecture, southern Japan), Kochi (Shikoku, western Japan) and Kamakura (Kanagawa Pref.,central Japan) in the 1960s. And they were first confirmed to breedin Shizuoka City, Shizuoka Pref., central Japan in 1967. Since
then, they have expanded their range along the Pacific coast southof the Kanto region, central Japan and locally occurred as a yearround resident. The species, which is highly gregarious, tends toform a breeding colony of several hundred pairs and roost in alarge flock.

Habitat:
House Swifts primarily range in and around urban areas of thelowlands.

Life history
1 2 3 4non-breeding
season56 7 8 9 10breeding season

11 12

Breeding system:
House Swifts are monogamous and both sexes are equally responsible for incubation and feeding. The pairs in the same colony
breed two or three times synchronously between mid-April andNumber of females20

1st breeding

01987
30

60

90120

150

Dates counted from April 14Egg:
The clutch size is 2-4 eggs, but it varies significantly depending on
the breeding attempt and the age of females. Two-year-old females
lay 3.3 eggs on average at the first breeding attempt, with 2.4 eggs
at the second and 1.9 eggs at the third one. For females of overthree years old, on the other hand, the mean clutch size is 3.6 eggs
in the first breeding, 2.9 eggs in the second and 2.0 eggs in thethird one (Two-year-old females: n = 24, females over 3 years old:n = 72).

Incubation and nestling periods and fledging rate:The incubation period is about 20 days, and the nestling period
lasts 36-51 days. There was no difference in hatching rate between
the ages of females or the breeding attempts, but the fledging rate
was significantly low in the third breeding attempt of two-year-oldfemales.

3rd breeding

1000

Both male and females
build a hemisphericalnest primarily underthe eaves of concrete
structures,
gluingfeathers and plantleaves and stems collected in the air by
their saliva. It takes aremarkably long period of time to complete
a nest. Pairs of oneyear-old and over twoyears old spend about
five and two months innest building, respectively. Since it takes
such a long time tobuild a new nest, theyusually use old nests Photo. 2. Nesting colony of House Swifts
with four nests (above). The soil partiallyof Asian House Marremains on the wall shows that these aretins (Delichon dasyreused old nests of Red-rumped Swallows.
pus) and Red-rumped
Another colony composed of over 20 nests
Swallows(Hirundo(below).
daurica) when available. Newly established pairs build a new nest by themselves if ausable old nest is not available in their breeding colony. The nest
is an important resource for House Swifts not only because it takes
a long time to build it but also because it is used as a roost sitethroughout the year as well as for breeding.

1986

2nd breeding10

early December in Japan. They usually lay eggs in mid or late
April, mid-July and late September to early October. Older females over three years lay eggs earlier than two-year-olds. Almost
all pairs bred twice, but the third breeding was attempted by a little
more than 60% of the females over three years old and a little lessthan 40% of the two-year-old females (Hotta 1996).

180Fig. 1. First
egg-laying
dates ofHouse
Swifts in1986 and1987.

Photo. 3. A collapsed nest
with House Swift nestlings. This is the reused
nest of Red-rumped
Swallows the inner cupof which is lined firmly
with feathers.

Bird Research News

Vol.9 No.6

2012.6.25.

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

Diet and foraging behavior

Food ball weight (g)They catch flying insects, such as mosquitoes, flies and winged
ants blown up by updraft while flying. They make a dense ballof captured insects in the mouth using saliva to carry them to thenestlings efficiently at a time from a considerable distance. It iseasy to know whether the parent birds have returned to the nest
with a food ball because the birds carrying it have a bulged
throat. The wet weight of a food ball was 0.3-1.6g with an average of 0.8g (n = 50). They came back to the nest with a significantly heavier food ball during the first breeding than the secondor third one. The analysis of 11 food balls showed that a foodball included 9-447 insects and spiders. The insects and arachnids
consisted of 10 orders and 35 families, 17 (48.6%) of which belonged to order Diptera. The prey species varied greatly from one
food ball to another, which applied to the food balls collected on
the same day. For instance, one species of Stratiomyidae accountedfor
2.0
1st breeding
more than 80%of the prey in
1.5
2nd breeding
two of thethree food balls
3rd breedingcollectedon
1.0
the same dayand one spe0.5
cies of Delphacidae represented
more0.06090120150
180
210240than 50% ofDates counted from April 1
the prey in theother.
Fig. 2. Differences in the wet weight of a food ballbetween the breeding attempts.

Topics of ecology, behavior and conservation● Divorces and infanticide: In search of a favorable nest andan older partner
House Swifts are monogamous and maintain the pair bondthroughout the year. Older pairs possessing a high quality nest
have a strong tendency to maintain the pair bond as long as they
do not lose their partner, but young pairs with an unfinished nestor no nest do not hesitate to divorce, especially when the opportunity arises to mate a partner of the older pair that possesses anoptimal nest but has lost the other partner (due to death). Birds
that have divorced and obtained a favorable nest and an older
partner will be able to raise a larger number of young in thebreeding attempt of the next year.
When a bird seized a nest with eggs or chicks, or mated a partnerof the pair that
had lost the otherpartner (due todeath)inthebreeding season,
the bird killed theeggs or the nestlings. Infanticide Fig. 3. A case of divorce and infanticide. Nest A
is completed with a small entrance, while nest
is committed by
B is unfinished with larger entrance. In theboth males andcolony is such a pair without nest (pair C). Iffemales that canthe male of nest A dies, males of nests B andnot start to breed
C will divorce their partners and try to acquirenest A and the bereaved female. The male that
because their own
has gained both the female and nest will kill
nest is not comthe eggs or nestlings if they remain in thepleted yet. Thenest.
bird that killed theバードリサーチ生態図鑑
nestlings can mate one of their parent birds and start to breed
earlier (Hotta 1994).

● Subsequent developments of breeding colonies
The Shizuoka Chapter of the Wild-Bird Society of Japan studied
the distribution of House Swifts between 1981 and 1983 in Shizuoka and Yaizu Cities, Shizuoka Pref.. The study showed that
there were 17 breeding colonies, one of which accommodated as
many as 254 birds. When the 17 colonies were studied again in
2011, however, House Swifts were confirmed in none of them.
House Swifts build a nest on man-made concrete structures, suchas buildings and bridges. Buildings receive regular maintenanceand are repaired if necessary. They are demolished if they havereached the end of life. The buildings had been demolished inthree of the 17 breeding sites and they had been repaired in fivesites. House Swifts sometimes use buildings which accommodatea large number of breeding pairs for more than 10 years. There isa stronger possibility, therefore, that their nesting buildings will
be repaired or demolished if they are used for a longer period oftime. Since House Swifts use their nests as a roost as well as forbreeding all the year round, their excrements reach a considerable
amount and their calls are very noisy in a large colony. House
Swifts often nest in the buildings of urban areas and sightseeing
spots, where few nests are destroyed due to their novelty at first,
but they tend to outstay their welcome.

Literature
Chantler P. & Driessens G. 1995. Swifts: A Guide to the Swifts and Treeswiftsof the World. Pica Press, Sussex.
del Hoyo J., Elliott A. & Sargatal J. (eds). 1999. Handbook of the Birds of theWorld. Vol. 5. Barn-owls to Hummingbirds. Lynx Edicions, Barcelona.
Hotta M. 1994. Infanticide in Little Swifts taking over costly nests. Anim.
Behav. 47:491-493.
Hotta M. 1996. Timing of Laying in Multiple-brooded Little Swifts Apus affinis. Jap. J. Ornithol. 45:23-30.
Hotta M. 2012. Swallow monograph: House Swift. BIRDER 26(5):17. [J]Hotta M. 2012. The swallow question box: Q5 When has the House Swift cometo Japan? Is the distribution expanding? BIRDER 26(5):37. [J]Nakamura N. & Nakamura M. 1995. Ecological Guide of Japanese Wild Birds
in color <Landbirds> . Hoikusha, Tokyo. [J]Shizuoka Chapter, Wild-Bird Society of Japan. 1983. The population status ofHouse Swifts around Shizuoka City. Strix 2:59-66. [J+E]
Languages of literature cited other than English: [J] in Japanese, [J+E] in Japanese with English summary.

AuthorMasanobu HOTTA

Nagano Environmental Conservation
Research Institute

In Nagano Prefecture, I have no chance of seeing House Swifts, but
often see Pacific Swifts (Apus pacificus). Although I have searched fora study site suitable for Pacific
Swifts, I have not found it yet.
When I occasionally visit Shizuoka and Aichi Prefectures in thePacific coast, I look up at the sky
searching for House Swifts. WhenI visited my former study site lastyear, the entrance for the birds
was closed with window panes,
and the nests had been removed
completely.
qe9m-htt@asahi-net.or.jp

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