provisioning of nestlings in the White-crested Laughingthrush Garrulax
By Philip D. Round
This article was originally published in Forktail 22 (2006) the journal
of the Oriental
Bird Club (OBC) and was kindly submitted by Philip
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Most species of laughingthrush (Garrulacinae)
are strongly social birds and some have long been suspected to be
cooperative breeders, although none was identified as such in a recent
review by Ligon and Burt (2004). Unlike some confirmed social breeders
(e.g. Turdoides babblers, found in open, arid or semi-arid
habitats, and relatively easily observed), laughingthrushes are usually
shy denizens of dense, moist forest which renders detailed observation
difficult. I present here the results of brief and opportunistic observations
of a White-crested Laughingthrush Garrulax leucolophus nest
in Huai Kha Khaeng Wildlife Sanctuary, Uthai Thani province, Western
Thailand (15º36'N 99º16'E), which indicate that the species
is a cooperative breeder.
I was watching at least five White-crested Laughingthrushes in relatively
open deciduous woodland at the sanctuary headquarters on the afternoon
of 12 August 2005, when one member of the group flew in to a large,
untidy cup-nest that I had not previously noticed. The nest was situated
in a small leafy tree, close to the trunk, at a height of about 5
m, and contained two well-grown nestlings. Because of the proximity
of buildings and frequent human foot traffic, the laughingthrushes
were relatively habituated to people and I was able to count at least
five birds feeding mainly on the ground within a 30 m radius of the
nest. The area around the nest encompassed open woodland, from which
the underbrush had been removed, close to houses, as well as some
denser forest with tangled undergrowth in a steep-sided gully.
I watched the nest without interruption from 14h53 to 15h28 at a range
of about 20 m. At 15h08, three birds came to the nest tree and two
of them delivered food in quick succession, while the third individual
perched less than 0.5 m from the nest. At 15h20, two individuals again
visited the nest and fed the young, while a third bird perched nearby
with a spider in its bill. However, this bird did not visit the nest
and probably consumed the spider itself. After dark (19h40) I checked
the nest by flashlight from a range of about 15 m, and with the aid
of binoculars could see an adult brooding the young.
On the following morning I watched the nest from 06h13 to 07h00, during
which period the adults paid it a total of 15 separate visits. From
06h19 to 06h29, there were no fewer than eight visits to feed the
nestlings (including three feeds by three different individuals within
one minute). A fourth individual that fed the young at 06h17, and
again at 06h33, was individually recognisable as it had a yellow gape-spot
on the right side.
In addition, because the habitat was rather open, most birds could
be located in view simultaneously, aiding differentiation of individuals.
The usual pattern was for one bird to feed the young, and then remain
on the nest until another bird came in and displaced it. At least
four different individuals in the group provisioned the young.
The young were already well-grown, with partly grown wing and tail
feathers, a black-and-white face pattern, and rufous upperparts similar
to the adult pattern. On the morning of 13 August, one of the nestlings
clambered out of the nest and perched c.20 cm above it, flapping its
wings for 20–30 seconds before returning to the nest. When I
checked the nest that evening, it was empty and the young were presumed
to have fledged.
In addition to the two visits (out of six) on 12 August when no food
was delivered to the chicks, the 15 visits on the following day also
included three cases when an adult perched close to the nest but did
not feed the young. Two of these visits involved the individual with
the yellow gapespot. In one of these, the bird came to the nest without
food, while in the other it consumed the food itself. Such behaviours
(adults either coming in to the nest without food or consuming the
food themselves) are well known among other birds that have nest-helpers.
Boland et al. (1997) termed the behaviour ‘deceptive
helping’ and thought it was a form of advertisement that individuals
used to enhance their status within the group, perhaps increasing
their future likelihood of acquiring a mate (Putland 2001). However,
Canestrari et al. (2002) observed these behaviours, which they termed
‘false feeding’, in instances when no other individuals
were present as onlookers, and also at unassisted nests (those that
lacked helpers). Since breeding females exhibited this behaviour more
often than other group members, Canestrari et al. (2002)
suggested that deception was unlikely to be involved, and that the
decision to provision the chicks represented a trade-off between the
chicks’ hunger and that of the provisioning adult.
I thank Kihoko Tokue and Andrew Pierce for their comments on this
Boland, C. R. J., Heinshohn, R. and Cockburn, A. (1997) Deception
by helpers in cooperatively breeding white-winged choughs and its
experimental manipulation. Behav. Ecol. Sociobiol. 41:
Canestrari, D., Marcos, J. M. and Baglione V. (2002) False feedings
at the nests of Carrion Crows Corvus corone corone. Behav. Ecol.
Sociobiol. 55: 477–483.
Ligon, J. D. and Burt, D. B. (2004) Evolutionary origins. Pp. 5–34
in W. D. Koenig and J. L. Dickinson, eds. Ecology and evolution
of cooperative breeding in birds. Cambridge University Press,
Putland, D. (2001) Has sexual selection been overlooked in the study
of avian helping behaviour? Anim. Behav. 62:
Philip D. Round, Department of Biology, Faculty of Science, Mahidol
University, Rama 6 Road, Bangkok 10400, Thailand. Email: email@example.com