Breeding biology of the Purple Swamphen (Porphyrio porphyrio) at Tirunelveli, South India.
Abstract: We studied the breeding biology of Purple Swamphens (Porphyrio porphyrio poliocephalus) at Nainar Pond in Tirunelveli, South India from January 2003 to May 2004. Peak breeding activity occurred from the second week of January to the first week of March. Nests were built on thick floating vegetation closest to the bank of the pond. Nesting material consisted of whole plants, stems, and leaves of Eichhornia crassipes, Jussieua repens, Pistia stratiotes, Ipomoea aquatica, and Cyperus rotundus with E. crassipes being most preferred. Nest dimensions were variable. Clutch size varied from three to seven eggs with a mean ([+ or -] SD) clutch size of 4.5 [+ or -] 1.5 and a model clutch size of four eggs. Mean volume of all eggs was 32.3 [+ or -] 3.5 [cm.sup.3]. The length of the incubation period was estimated as 19.8 [+ or -] 1.2 days. Nest and egg hatching success were estimated as 80.0% and 61.1%, respectively, while overall fledging success was 42.0%.
Article Type: Report
Subject: Rails (Birds) (Physiological aspects)
Rails (Birds) (Natural history)
Rails (Birds) (Behavior)
Rails (Birds) (Distribution)
Birds (Breeding)
Birds (Research)
Birds (Eggs and nests)
Birds (Analysis)
Birds (Nestlings)
Birds (Physiological aspects)
Authors: Doss, D. Paramanantha Swami
Gopukumar, N.
Sripathi, K.
Pub Date: 12/01/2009
Publication: Name: The Wilson Journal of Ornithology Publisher: Wilson Ornithological Society Audience: Academic Format: Magazine/Journal Subject: Biological sciences Copyright: COPYRIGHT 2009 Wilson Ornithological Society ISSN: 1559-4491
Issue: Date: Dec, 2009 Source Volume: 121 Source Issue: 4
Topic: Event Code: 690 Goods & services distribution; 310 Science & research Advertising Code: 59 Channels of Distribution Computer Subject: Company distribution practices
Geographic: Geographic Scope: India Geographic Code: 9INDI India
Accession Number: 216267545
Full Text: The Purple Swamphen (Porphyrio porphyrio) is a medium sized water bird (Ali 1981) which lives in marshes, lagoons, and reservoirs with appropriate vegetation cover and water depth. Undisturbed areas with tall, thick vegetation cover and shallow calm water are generally preferred by swamphens (Cramp and Simmons 1980, Sanchez-Lafuente et al. 1998).

The Purple Swamphen is a tropical and subtropical species with several subspecies and a distribution extending from Europe and Africa to New Zealand (Urban et al. 1986, Marchant and Higgins 1990). Its taxonomy is complex and inadequately studied; at least 13 subspecies are currently recognized, three of which could be elevated to species status (Taylor and van Perlo 1998). The nominate subspecies (P. p. porphyrio) occurs in southern Europe and North Africa (Cramp and Simmons 1980, Taylor 1996). The subspecies P. p. poliocephalus occurs in southern Asia, extending from Pakistan throughout the Indian subcontinent and east to Burma and south-central China (Taylor and van Perlo 1998). The subspecies P. p. melanotus ranges from New Guinea through Australia and New Zealand.

Purple Swamphens have been intensively studied by several investigators and facets of their breeding biology have been explored in Italy, Spain, and New Zealand. Grussu (1999) conducted intensive studies of Purple Swamphens in Italy while Craig (1980) reported on the breeding success of swamphens (P. p. melanotus) in New Zealand. Sanchez-Lafuente (1993) studied a resident population of Purple Swamphens in Spain and made the most detailed observations of the breeding cycle. These publications describe the breeding system related to incubation investment (Sanchez-Lafuente 1993), nest site selection (Sanchez-Lafuente et al. 1998), and clutch size and egg mass (Sanchez-Lafuente 2004).

Purple Swamphens are widely distributed throughout India (Manakadan and Pittie 2001), but the breeding behavior of this species is not well documented. Our objectives were to: (1) assess nesting season and peak breeding activity; (2) describe nest size and materials used for nesting; (3) quantify nest size, egg size, clutch size, incubation period, and morphometric growth parameters of newly hatched chicks; and (4) assess the reproductive success of Purple Swamphens.

METHODS

Study Area.--The study was conducted from January 2003 to May 2004 in Nainar Pond (~53 ha in size) in the center of Tirunelveli Town, South India (8[degrees] 44' N, 77[degrees] 44' E). The average depth of the pond is ~10 m and the pond receives water from Manimuthar Dam during December. The pond normally becomes dry during August and September. The aquatic vegetation of the pond consisted of water hyacinth (Eichhornia crassipes), nut grass (Cyperus rotundus), sola pith plant (Aeschenomene aspera), water lettuce (Pistia stratiotes), pickerel weed (Monochoria vaginalis), water spinach (Ipomoea aquatica), four leaf clover (Marselia spp.), waterthyme (Hydrilla verticillata), and water primrose (Jussieua repens).

Field Procedures.--We searched among floating vegetation during the breeding season for nests of Purple Swamphens. Daily visits were conducted with onset of egg laying (second week of Jan to first week of Feb) to record clutch completion. Observations were made three times each week from the first week of February to the first week of March, and were continued until the expected time of hatching (19 to 22 days). Nests were visited daily during the hatching period (first week of Mar to mid Apr) to record nest and egg hatching success. Eggs were individually marked with different colors using permanent marker pens. Length (L) and breadth (B) of eggs in all complete clutches were measured with dial calipers to the nearest 0.1 mm. Egg volume (V in [cm.sup.3]) was estimated following Hoyt's (1979) formula: V = 0.000507 x L x [B.sup.2]. Newly hatched chicks were weighed with a 100-g Pesola spring balance (accuracy = 0.1 g) and measurements of beak, wing, and tarsus length were obtained using dial calipers (accuracy = 0.1 mm) and a 2-m measuring tape (1 gradation = 1 cm). Fledging success was estimated by counting the number of young fledged.

Empty nests were collected after fledging, and the size of the nests (length, breadth, and internal depth) was obtained using a 2-m tape (1 gradation = 1 cm). Aquatic plants used as nesting materials were identified and categorized into whole plant, leaf, and stem components. Dried or decayed nest contents were discarded. Characteristics of nest sites including water depth and distance of the nest site from the bank of the pond were also measured.

RESULTS

Breeding activity of Purple Swamphens commenced in January and continued until April. Swamphens started gathering nest material in the first week of January. Peak breeding activity (when breeding pairs completed nest construction and started to lay eggs) occurred between the second week of January and the first week of March. Nests were built on the thick floating vegetation (especially Eichhornia crassipes) which was closest to the bank of the pond. The average ([+ or -] SD) distance at which nests were placed from the edge of the pond was 2.95 [+ or -] 0.91 m (range: 14.5 m, n = 25). Nest dimensions were variable. The length, breadth, and depth of 25 nests averaged 37.7 [+ or -] 3.9, 31.6 [+ or -] 4.1, and 4.7 [+ or -] 0.9 cm, respectively.

Purple Swamphens started nest building activity 2-3 days prior to egg laying. Only living vegetation from the area adjoining the nest site or the nest was uprooted and used for nest building. Whole plants, stems, and leaves of aquatic plants (i.e., Eichhornia crassipes, Jussieua repens, Pistia stratiotes, Ipomoea aquatica, and Cyperus rotundus) were used as nesting materials. Leaves, stems, and whole plants of Eichhornia crassipes were observed in all nests, followed by whole plants of Pistia stratiotes in 60% of nests, stems of Jussieua repens in 45% of nests, and stems of Cyperus rotundus in 45% of nests (Table 1).

Clutch size varied from three to seven eggs with a mean clutch size of 4.5 [+ or -] 1.5 (n = 25) and a model clutch size of four eggs. Six (of 25) nests each contained seven eggs, two nests each contained five eggs, 10 nests each contained four eggs, and seven nests each contained three eggs. Mean egg length for all eggs was 52.5 [+ or -] 2.8 mm (range: 47.1-59.7 mm; n = 113) while mean egg breadth was 34.8 [+ or -] 1.1 mm (range: 32.3-37.4 mm; n = 113). Mean volume of all eggs was 32.3 [+ or -] 3.5 [cm.sup.3] (range: 26.5-42.3 [cm.sup.3]; n = 113) (Table 2). Egg volume varied among the eggs of the same clutch (ANOVA; R.sup.2] = 1.4, [F.sub.47.5] = 18.9, P = 0.0001).

The hatching period continued for 2-5 days and hatching was asynchronous. The incubation period ranged from 19 to 22 days and averaged 19.8 [+ or -] 1.2 days. We recorded 113 eggs in 25 nests. Sixty-nine eggs (61.1%) hatched successfully, 21 (18.6%) were damaged due to destruction of the nest, 13 (11.5%) disappeared from the nest and the cause could not be ascertained, and 10 (8.8%) were addled. There were 2.8 [+ or -] 1.7 (n = 25) eggs per hatched nest. Overall nest hatching success was 80% and 47 young fledged, representing 42% of the eggs laid or 61% of the eggs hatched.

The average body mass of day-old chicks was 24.0 [+ or -] 1.7 g (n = 10). Beak, wing, and tarsus length averaged 11.7 [+ or -] 0.4 mm (range: 11.0-12.3 mm; n = 10), 34.4 [+ or -] 1.4 cm (range: 32.2-36.7 cm; n = 10), and 8.7 [+ or -] 0.6 cm (range: 8.0-9.7 cm; n = 10), respectively. Newly hatched young were pink in color and covered with black, woolly down feathers. The eyes were open at birth and the forehead was flattened and marked by the complete absence of feathers. The beak was white in color with well-developed red markings. The young were active within an hour of hatching.

DISCUSSION

The breeding activity of Purple Swamphens in southern India, especially egg laying that started in January, is typical of P. p. porphyrio in southern Spain (Grussu 1999), but earlier than in Portugal (Ramos 1994) where egg laying commenced in March and clutch initiation ceased in mid June. Earlier breeding activity in our study area is probably related to water depth and availability of floating vegetation. Walkinshaw (1973) reported that water depth was a significant limiting factor for initiation of nesting in some water birds.

We documented that nest sites of Purple Swamphens were closest to the bank of the pond (1-4 m from the bank). The area used for nesting had thick floating vegetation which provided concealment and more accessible nest sites than non-nesting sites (i.e., in the center of the pond). del Hoyo et al. (1996) reported that habitats used by swamphens included the margins of fresh or brackish water that are stagnant, or slow-flowing, and over grown by marsh plants such as Carex, Cyperus, Phragmites, and Typha.

The structure and size of swamphens nests in our study area (37.7 [+ or -] 3.9 cm) was larger than in Spain (Sanchez-Lafuente et al. 1998). The average external diameter of nests reported by Sanchez-Lafuente et al. (1998) was 30.20 [+ or -] 1.33 cm. Cramp (1980) proposed that structure, size, and shape of nests depended on the plant species available. Nests are usually constructed from aquatic plants found opportunistically by adults near the nesting site. Nests in Dona Aldonza lagoon were mostly composed of leaves and young stems of Typha spp., Scirpus spp., Phragmites spp., etc. (Sanchez-Lafuente et al. 1998). Nests in our study area were mostly constructed from free floating water hyacinth, which is not a rigid construction material and may have resulted in the larger swamphen nests in our study area.

Clutch size in our study ranged from three to seven eggs with a mean of 4.5. This was higher than for P. porphyrio in the Mediterranean area. Manez (1997) reported a clutch size of 3-5 eggs/ nest in Spain while Schenk (1993) reported a clutch size of 4-6 eggs in Italy. Moali and Isenmann (2000) reported a clutch size of 3-6 eggs in Algeria. The mean clutch size in our study population was lower than for P. p. melanotus in New Zealand (Craig 1980), which was 5.6 and ranged from two to 10 eggs. Thus, clutch size of swamphens varies geographically, usually decreasing with latitude. This supports Lack's (1947) hypothesis derived from earlier observations on different avian species.

The incubation period in our study was apparently shorter than for other subspecies of Purple Swamphens. The recorded incubation period for P. porphyrio in the Mediterranean area was 23-25 days (Manez 1997), 24-27 days (Schenk 1993), and 22-26 days (Moali and Isenmann 2000). Craig and Jamieson (1990) reported an incubation period of 23-27 days for P. p. melanotus in New Zealand. One possible explanation for asynchronous hatching in our study was the initiation of incubation. Magrath (1990) argued that females begin incubating their eggs before clutch completion, resulting in asynchronous hatching.

Hatching success in our study was high as 61% of 113 eggs hatched. Analogous values from Purple Swamphens in different areas of south-eastern Spain were lower and ranged from 45.2 to 57.9% (Sanchez-Lafuente et al. 1998). Craig (1980) reported hatching success was high (73%) for P. p. melanotus in New Zealand. Hatching failure in our population resulted from loss of entire clutches or loss of 1-2 eggs per clutch. Loss of 1-2 eggs may be due to predation, but loss of whole clutches may be attributed to nest destruction due to wind and wave action. Helm et al. (1987) reported that floating nests of Purple Gallinules (Porphyrio martinica) in Louisiana drifted ~75 m during strong winds.

Young Purple Swamphens are precocial and had low fledging success in our study. This was attributed to the ability of young to move away from the parents immediately after hatching, increasing their exposure to predators.

ACKNOWLEDGMENTS

We followed the Guidelines for the use of animals in research (Animal Behaviour 1991). We thank Johnson Balasingh for useful comments and support during early stages of this work. We are grateful to two anonymous referees and C. E. Braun for suggestions on an earlier version of the paper.

Received 2 August 2008. Accepted 7 June 2009.

LITERATURE CITED

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MANEZ, M. 1997. Purple Gallinule Porphyrio porphyrio. Pages 234-235 in The EBCC atlas of European breeding birds: their distribution and abundance (E. J. M. Hagemeijer and M. J. Blair, Editors). T & A D Poyser, London, United Kingdom.

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SANCHEZ-LAFUENTE, A. M. 2004. Trade-off between clutch size and egg mass, and their effects on hatchability and chick mass in semi-precocial Purple Swamphen. Ardeola 51:319-330.

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D. Paramanantha Swami Doss, (1) N. Gopukumar, (2) and K. Sripathi (1,3)

(1) Department of Animal Behaviour and Physiology, School of Biological Sciences, Madurai Kamaraj University, Madurai, Tamilnadu, India.

(2) University Grants Commission, Southwestern Regional Office, P. K. Block, Bangalore, India.

(3) Corresponding author; e-mail: sribat@rediffmail.com
TABLE 1. Materials used in Purple Swamphen nests (n = 20),
Tirunelveli, South India.

                                                   Number of items

Plant species          Plant parts used        Mean = SD         Range

Eichhornia crassipes   Whole plants        14.4 [+ or -] 5.9      6-23
                       Stem with leaves    60.1 [+ or -] 13.5    46-83
                       Leaves             379.4 [+ or -] 65.4   281-79
Pistia stratiotes      Whole plants        21.3 [+ or -] 7.5     11-32
Jussiuea repens        Stems               41.0 [+ or -] 8.1     30-53
Cyperus rotundus       Stems               35.3 [+ or -] 11.4    26-59
Ipomoea aquatica       Stems               24.0 [+ or -] 6.8     19-34

Plant species          Plant parts used   % use

Eichhornia crassipes   Whole plants         100
                       Stem with leaves     100
                       Leaves               100
Pistia stratiotes      Whole plants          60
Jussiuea repens        Stems                 45
Cyperus rotundus       Stems                 45
Ipomoea aquatica       Stems                 20

TABLE 2. Mean length, width, and volume (x [+ or -] SD) of Purple
Swamphen eggs in relation to laying sequence (range in
parenthesis), Tirunelveli, South India.

                      Egg # 1 (n = 25)    Egg # 2 (n = 25)

Length, mm            54.0 [+ or -] 2.3   53.5 [+ or -] 2.9
                         (50.0-50.7)         (48.3-59.1)
Breadth, mm           35.2 [+ or -] 1.3      35.1 + 1.4
                         (32.8-37.4)         (32.3-37.3)
Volume, [cm.sup.3]    34.1 [+ or -] 3.6       33.5+4.0
                         (27.9-42.3)         (27.0-40.6)

                      Egg # 3 (n = 25)    Egg # 4 (n = 18)

Length, mm            51.9 [+ or -] 2.0   52.2 [+ or -] 2.9
                         (49.8-58.7)         (48.3-58.3)
Breadth, mm           34.6 [+ or -] 1.2   34.5 [+ or -] 0.8
                         (32.8-36.9)         (32.3-35.4)
Volume, [cm.sup.3]    31.5 [+ or -] 2.8   31.5 [+ or -] 2.5
                         (27.9-40.1)         (26.5-36.4)

                       Egg # 5 (n = 8)     Egg # 6 (n = 6)

Length, mm            50.4 [+ or -] 3.4   50.2 [+ or -] 2.4
                         (47.1-58.1)         (47.8-53.9)
Breadth, mm           34.4 [+ or -] 0.7   34.4 [+ or -] 0.6
                         (33.4-35.4)         (33.5-34.9)
Volume, [cm.sup.3]    30.2 [+ or -] 3.2   30.2 [+ or -] 2.3
                         (26.9-36.9)         (27.2-33.3)

                       Egg # 7 (n = b)

Length, mm            50.1 [+ or -] 1.8
                         (48.0-52.8)
Breadth, mm           34.5 [+ or -] 0.8
                         (33.6-35.7)
Volume, [cm.sup.3]    30.3 [+ or -] 2.4
                         (28.1-33.3)
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