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Cooperative provisioning of nestlings in the White-crested Laughingthrush Garrulax leucolophus

By Philip D. Round

Note: This article was originally published in Forktail 22 (2006) the journal of the Oriental Bird Club (OBC) and was kindly submitted by Philip D. Round.

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INTRODUCTION
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.

REFERENCES
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: 251–156.

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, Cambridge, U.K.

Putland, D. (2001) Has sexual selection been overlooked in the study of avian helping behaviour? Anim. Behav. 62: 811–814.

Kindly submitted by:

Philip D. Round, Department of Biology, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand. Email: pdround@ksc.th.com