Indian Cliff Swallow Colonial Nesting

Streak-throated Swallow Commonly known as Indian swallow, Cliff Swallow, Petrochelidon Fluvicola.

Introduction:

The streak-throated swallow or the Indian cliff swallow (Petrochelidon fluvicola) is a species of swallow found as Native (breeder, year-round resident or winter visitor) in South Asia in the countries of Afghanistan, Bangladesh, India, Nepal and Pakistan.

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Indian Cliff Swallow is a small swallow with glossy steel-blue colour. The forehead, crown, and back of the neck is chestnut with faint dark streaks. Ventrally white with blackish on side and pale brown rump, and is more prominent in flight. The back is glossy deep blue with a few narrow whitish streaks on head. Underparts are buffy white with blackish-brown streaks, especially the chin, throat, and upper breast. The wings are blackish-brown. Tail is darkest- brown, almost square-ended slightly forked and short. And comparatively weak flight. Sexes are similar. Juvenile is duller and browner than adult, with buff feather edges and faint streaks on underparts. It is resident and partly migratory.

Cira lake, Tumkuru, Karnataka.

Colonial nesting involves a number of factors.

Indian Cliff swallow/ Petrochelidon fluvicola are one of the favorite subjects for behavior ecology studies because of their gourd shaped enclosed structured nest construction behaviour. The nest construction preferably takes place beneath the cliff, under surface of bridges, sloping edges of the man- made constructions, against the gravitational pull. Cliff swallows are good architects and builders in the nature. Cliff swallows use mud for construction slightly reinforcing the organic fibrous contents. Mud is a plastic material that can be molded when wet into required shape & structure on drying it hardens to give a durable shape. Nearly 5% of the bird species use mud as the vital material in nest construction. Mud bear load in compression and in cliff swallows the nests built on rock overhanging are not supported from below. The addition of grass, feather & hair in to the mud probably provides the strength in tension. Mud may vary in its contents. The mud is selected by swallows only when there is a consistency appropriate for building the nest.

Selection of nest site is an important task in colonial breeding. Birds usually prefer their nesting sites within the foraging site so as to reduce the number of trips to the nest. Closer feeding sites also help in increased vigilance of the nest and minimize chances of predation of eggs and nestlings

SOCIAL BEHAVIOUR IN NESTING INDIAN CLIFF SWALLOWS

These gregarious swallows keep in large rabbles in close of water along with other Swallows. All the ordinary activities of Cliff Swallows were performed in groups, and positive social responses were readily seen on the loafing perches, at the foraging areas, at mud and grass-gathering areas, and at the nesting colonies.

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Telephone wires were the commonest perching sites for loafing swallows after seven o’clock in the morning. Habit seemed to be involved in the selection of loafing areas, An hour or so of sun-bathing and preening for out of the many miles of wires accessible to the birds.

At mud- and grass-gathering areas: The gathering of mud and of grass for the nest was a major activity of Cliff Swallows during the nest building phase of the breeding cycle and irregularly thereafter as nests needed repairing.

Mud for the nest shell was gathered at rain puddles or along open muddy banks of lakes, streams and sloughs and carried as small pellets in the bill to be added to the nest rim. Grass for the lining was collected in exposed dry spots where the strand was sparse and the grass texture fine. Mud and grass gathering were highly social activities. All participating birds typically concentrated their activity on one or two areas of a few square yards regardless of the extent of suitable facilities in the neighborhood. One or two birds would start the activity by descending to a particular mud site, others would follow, and soon the entire flock would be gathering mud and carrying it back to their nests. From ten to thirty birds might be clustered together in this limited area while dozens more were shuttling back and forth to the nests. Each bird appeared to work independently, holding its wings high above the back and fluttering them as it pecked repeatedly until a large beakful had been secured.

Collecting the mud usually required 15 to 40 seconds and placing it on the nest from 30 to 40 seconds. The time required to make the commuting flights was determined by the distance, being‘ about 10 seconds for every 100 yards.Nesting Materials.–The availability of mud thus affected the rate of construction. Mud for nest construction was gathered at sites from twenty feet to at least one-half mile from the nesting colony. After rains, almost any puddles close to the nests were utilized, but at other times the birds went farther afield. . Mud collecting was an intermittent activity in which nearly all members of a flock participated as a group. Dried grass for the nest lining was commonly collected near the nesting site. The collecting of this material was, as with the mud, a social activity in which many birds from a flock participated as a group. The period of greatest grass gathering activity was in the early morning before mud gathering had started.

Territorial threat and fighting were most frequent at partially built nests where a wide entrance meant a relatively large area, to defend or close approximation of neighbouring entrances and many avenues of approach for intruders. That it was this that occasioned the fighting rather than the attainment of a particular stage in the breeding cycle is indicated by the prompt reappearance of intrusion and fighting at nests which had been broken back by the observer.

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The completion of a narrow tunnel entrance apparently served to reduce the occasion for quarreling at the nest. The construction of an enclosed mud shell surrounding the nest proper is a behavioral specialization of considerable theoretical interest. This characteristic, as already suggested, appears to be related to the intense localized territorialism of the species, the shell screening the nesting bird from its numerous close neighbours and thus enhancing social stability in the group.

A comparison of the mud nests of cliff- and ledge-nesting swallows reveals a series ranging in complexity from a simple cup as found in the Barn Swallow to an elongate retort with entrance tunnel such as that built by the Cliff Swallow. Homologous relationships seem to exist through the series: the mud frame or cup has merely been ex-tended upward and outward until the retort form is achieved. Construction in the Barn Swallow and the Cliff Swallow proceeds in a closely similar manner up to the time of egg laying. At this point the Barn Swallow stops while the Cliff Swallow continues to complete its retort and to maintain it in repair.

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Indian_Cliff_Swallow #Streak-throated_Swallow #Petrochelidon fluvicola #Nahar Ababil #Bhekhad Ababil: https://www.youtube.com/playlist?list=PL-BYiNWpklmf9o0KKqfskQv-fRAj9eOHQ

Information collected from these sources:
1. John T. Ellen, JR www.jstor.org/stable/1364635

2. Chaya H C et al Int. Journal of Engineering Research and Applications www.ijera.com ISSN : 2248-9622, Vol. 4, Issue 3( Version 1), March 2014, pp.925-930

Thanks to Devadatha Kumar SR for contributing the photos.

https://www.jstor.org/stable/1364635