sign in sign up
<<
Home , Australian pelican, Brown pelican, Great white pelican

Australian Field Ornithology 2012, 29, 93–101

Temporal variation in the behaviour of the Australian Pelecanus conspicillatus in an urban wetland environment

Kylie A. Robert

Department of , La Trobe University, Bundoora VIC 3083, Email: [email protected]

Summary. The behaviour of the Pelecanus conspicillatus was monitored over a 3-month period (August–October 1995) to determine the daily activity budgets at a man-made wetland in Cronulla, New South Wales. Data were collected on the proportion of the time-budgets devoted to performing behaviours (, roosting, foraging, and other). Time of day had a significant effect on behaviour, with the majority of allocating the morning for preening and foraging, the middle of the day for foraging, and the afternoon for preening and roosting. In addition, early courtship behaviour was noted and compared with the courtship behaviour described in previous studies from rural localities in NSW.

Introduction The Australian Pelican Pelecanus conspicillatus is a gregarious that forages, travels, roosts and breeds in large groups. There are seven of pelican worldwide, and the Australian Pelican is found throughout Australia, and western , with occasional reports in and various western Pacific islands (Voous 1962; Boles 1994). It is widely distributed from cool temperate to tropical , rivers and , and is strongly nomadic and prone to erratic dispersal (Lindsey 1986). For such a conspicuous and regularly observed diurnal bird that inhabits a wide variety of habitats, there are few scientific studies on its behaviour and basic biology. The majority of studies on pelicans are focussed on the foraging or breeding ecology of African or American species (Schaller 1964; Brown & Urban 1969; Berry et al. 1973; Pyrovetsi 1989; Anderson 1991; Hatzilacou 1996), with only a few Australian studies on breeding behaviour and nesting (Macgillivray 1923; Vestjens 1977; Battam et al. 1986; Marchant & Higgins 1990). To my knowledge, there are only two studies specifically examining daily activity budgets in the P. erythrorhynchos (King & Werner 2001; Werner 2004), one in the American P. occidentalis (Croll et al. 1986) and one in the African P. onocrotalus (Guillet & Crowe 1983), but no similar studies on Australian Pelicans. Burke & Brown (1970) noted that the African Pink-backed Pelican P. rufescens roosted in the evenings and foraged in the early mornings, whereas Lindsey (1986) and Reid (2009) stated that the Australian Pelican flew at great heights during the middle of the day or afternoon. This paper attempts to quantitatively examine temporal variation throughout the day in the behaviour of the Australian Pelican at a man-made wetland in Cronulla, New South Wales (NSW). During the study, courtship behaviour was also identified and compared with observations from other colonies. 94 Australian Field Ornithology K.A. Robert

50 m Study area: Metromix Wetland, Cronulla, NSW. Image provided by Pty Ltd. Figure 1. Australian Pelican behavioural time allocation 95

Methods Study area The behaviour of Australian Pelicans at differing times throughout the day was studied at the Metromix Wetland, Cronulla, NSW (34o02′S, 151o10′E), between August and October 1995. This wetland (Figure 1) is a man-made coastal wetland constructed following sand mining, and enhanced to provide habitat for migratory by Metromix Pty Ltd in consultation with the Department of Planning, National Parks and Wildlife Service, the NSW Field Ornithologists Club and the Cumberland Bird Observers Club in 1993.

Data collection Direct observations were made using both descriptive (ad libitum) sampling and instantaneous scan sampling (Altmann 1974) with the day divided into three different time periods: morning (0700–1100 h), middle of the day (1101–1500 h) and afternoon (1501–1700 h). Descriptive sampling was initially used to gain familiarity with the type of behaviours to expect in to develop an ethogram of the behaviours for instantaneous scan sampling. Instantaneous scan sampling was used to record the behavioural state at the instant ending at a predefined time interval of 5 minutes. To avoid bias in recordings, scans were made after the time signal at a count of five and scanned from left to right. Observations were made ~250 m from the birds, from the northern side of the wetland, using binoculars (14 × 30 magnification). Behaviour of each bird was observed and recorded directly onto data sheets when the number was small (<20 individuals), but descriptions were recorded on a handheld microcassette recorder (Sanyo) and transcribed onto data sheets when there were ≥20 Pelicans. From the collected data, the percentages of time spent at a location or in an activity were calculated. Equal amounts of data were collected for each time period, over a total of 36 h of observation. Data were arc sin transformed and analysed using a 2-factor nested ANOVA in gmav5 to test the hypothesis that pelican behaviour is independent of time of day. Model: X = Mean + Behaviour + Time (Behaviour) + Residual.

Results Australian Pelicans were monitored for a total of 36 h, with the first 6 hours utilised for the initial descriptive sampling to build an ethogram of behaviours, and 30 hours devoted to data collection [10 h for each time period: morning (0700–1100 h), middle of the day (1101–1500 h) and afternoon (1501–1700 h)].

Behaviours Four behaviours were used in the ethogram for instantaneous scan sampling: 1. Preening (Figure 2a). Self-grooming of feathers with the bill. The bird can preen in a sitting, standing or moving position, using the bill to manipulate feathers. 2. Roosting (includes resting and standing) Resting (Figure 2b). The bird is motionless, sleeping or resting, with its bill placed on its back between the wings. Standing (Figure 2c). Any standing stationary on one or both legs (Vestjens 1977). 3. Foraging (includes moving and feeding) Moving. Any movement of half a body length or more (includes swimming, diving, walking and flying). 96 Australian Field Ornithology K.A. Robert

Figure 2. Australian Pelican behaviours used in the study (see text): (a) preening, (b) resting, (c) standing, (d) feeding, (e) scratching, (f) bathing and (g) wing-stretching. Figures c, e and g from Vestjens (1977); Figures a, b, d and f drawn from sketches and photographs. Australian Pelican behavioural time allocation 97

Feeding (Figure 2d). Apparent ingestion of either food or water. The bird plunges the bill under water and lifts its head vertically to consume the contents of the bill. 4. Other Any other active or inactive behaviour, including: Scratching (Figure 2e). The bird scratches its chest, head or bill-pouch with one foot (Vestjens 1977). Bathing (Figure 2f). The bird flaps its wings and dips its head, covering the body with water while swimming, usually followed by head-rubbing. Head-rubbing. The bird uses its head to rub at its shoulders, wings and sides. Generally follows bathing. Wing-stretching (Figure 2g). The bird stretches its wings by raising its wings up away from its body and holding them open (Vestjens 1977). Wing-beating. The bird beats/flaps its wings rapidly. Body-shaking. The bird stretches its head and neck vertically with its wings slightly raised, then shakes its body vigorously, usually followed with a tail-wag. Interacting. Any interaction with another conspecific bird (includes approach, aggression and vocalisation).

Daily activity The Pelicans spent 23.3 h (78%) of the observation period (0700–1700 h) active and 6.7 h (22%) inactive. The proportion of time spent performing different behaviours was significantly influenced by time of day (ANOVA: F12,179 = 18.20, P <0.001), with Pelicans utilising the morning more for preening, the late morning and middle of the day more for foraging, and more time was devoted to preening and roosting in the late afternoon (Figure 3).

Courtship behaviour During the final 2 weeks of observation, the number of Pelicans increased threefold (from <20 to ~60), interactions and movement became more frequent, and behaviours not previously seen were observed. During this period, Pelicans were seen to stand, roost and sit on the islands, when previously they had been observed only standing and roosting in the extreme shallows and on sandy banks. Several Pelicans sat and roosted on trampled-down reeds and grasses, and two appeared to have occupied a Black Swans’ Cygnus atratus nest from the previous season. Vocalisations increased from an occasional grunt to a chorus of honking and grunting. Most vocalisations accompanied threat displays between individuals (see p. 98). New behaviours observed during this period included: Pouch-rippling. With the pouch hanging low, the bird vibrates the pouch in waves (Vestjens 1977; Marchant & Higgins 1990). Pouch-stretching (Figure 4a). The bird stretches the pouch downward over its neck with its bill open (Vestjens 1977). Sitting. The bird sits on land either roosting or resting its head and bill on its chest or shoulders. Threats (low and high: Figures 4b–c). In a low threat, the bird opens its bill while 98 Australian Field Ornithology K.A. Robert Percentage of time spent in each activity

Time Period Figure 3. Temporal variation in the proportion of time spent by Australian Pelicans performing behaviours during three time periods: morning (0700–1100 h), middle of the day (1101–1500 h) and afternoon (1501–1700 h). Roosting comprises standing and roosting; foraging comprises moving and feeding; and other includes all other behaviours except preening. stretching its neck vertically and then closes its bill in a clapping motion. With a high threat, the bird opens its bill wide while pointing at another Pelican and vocalising (orrh-orrh-orrha), then thrusts its bill towards the other bird (Vestjens 1977; Marchant & Higgins 1990). Throwing-and-catching. The bird throws sticks or weeds into the air and catches them. This is usually repeated many times (Marchant & Higgins 1990). These additional behaviours were consistent with those described by Vestjens (1977) and Marchant & Higgins (1990) for Australian Pelicans. In addition, the following courtship displays of walking/strutting, swimming and flying, as described by Vestjens (1977) and Marchant & Higgins (1990) for the Australian Pelican, Schaller (1964) for the American White Pelican, and Brown & Urban (1969) for the African White Pelican, were also observed. Courtship walking or strutting. During a walking display a female walks through a group of Pelicans with a high strutting action, raised wings and often with tail- wagging, leading a few males. During these walks, both males and females perform Australian Pelican behavioural time allocation 99

Figure 4. Australian Pelican behaviours observed during courtship (see text) (a) pouch- stretching, (b) low threat and (c) high threat. Figures a and c from Vestjens (1977); Figure b drawn from sketches and photographs. pouch-rippling, and males direct threats of varying degrees towards one another (Vestjens 1977; Marchant & Higgins 1990). Courtship swimming. Most often following courtship walks, females lead the following males into the water for courtship swims. The female swims in tight circles with the males following, forming a circle of birds. The closest male appears to be the most dominant bird, and pouch-rippling and threats occur between males as in courtship walking displays. The number of birds in the group fluctuates continuously. Following swimming displays, copulation has been observed (Marchant & Higgins 1990), but no copulations were observed in this study. Courtship flying. Courtship flights were observed following courtship swims. Females take off from the water with males following and fly in circles above the site, often joining up with other groups in the air (Vestjens 1977). Some flights are short, with the females taking off and landing only a short distance away and with the males following close behind.

Discussion At the Metromix Wetland, the Australian Pelican exhibited a clear diurnal pattern of behaviours. Certain behaviours are dependent on time of day, and the correlation of foraging activity (movement and feeding) with the morning and middle of the day (rather than the afternoon) may indicate a dependence on daylight for vision and prey capture, as suggested by Croll et al. (1986), or on thermal formations that facilitate soaring (O’Malley & Evans 1982; Pyrovetsi 1989). Results from the present study support observations of both Pink-backed (Burke & Brown 1970) and Australian Pelicans (Lindsey 1986) fishing and moving in the morning and roosting in the evening. Similarly, the patterns of departure and arrival at roosting sites by Great White Pelicans (Brown & Urban 1969; Pyrovetsi 1989) and the observation of fewest American Brown Pelicans at roosting sites around midday (Briggs et al. 1983) support diurnal foraging trips with highest activity in the middle of the day and nocturnal roosting. Australian Pelicans were not monitored between 1700 and 0700 h in the present study, but their higher incidence of roosting in the morning 100 Australian Field Ornithology K.A. Robert and late afternoon indicates that they may roost throughout the night. There is some evidence of nocturnal feeding in American White Pelicans associated with food shortages during chick rearing (McMahon & Evans 1992) and through winter on experimental fish ponds (Werner 2004). The proportion of time spent foraging can be related to available food resources: American White Pelicans foraging in commercial catfish ponds spent ~4% of the day foraging, whereas those foraging in other habitats spent ~28% (King & Werner 2001). Foraging time may therefore be a good indicator of the quality of the breeding grounds, and may predict the reproductive success of individuals at the time when energy demands are high (Guillet & Furness 1985; Ferguson et al. 2011). The observations made on courtship behaviour at this urban wetland are consistent with those described by Vestjens (1977) at rural locations at George and Lake Cowal, NSW. Courtship displays at the Metromix Wetland began in the final weeks of the study (in October), with the greatest activity occurring in the first three days. Behaviour changed dramatically with the onset of courtship, and affected most of the Australian Pelicans. Courtship displays in most species of pelican are similar to the Australian species, except for the Pink-backed Pelican, which performs a series of unique displays at tree-nesting locations (Din & Eltringham 1974). It is surprising how little the Australian Pelican—a large and distinctive species that is commonly sighted throughout Australia, particularly in well-populated coastal areas—has been studied. Other species, such as African, American White and American Brown Pelicans, have been the subject of numerous studies (Knopf 1979; Guillet & Crowe 1983; Anderson 1991; King & Werner 2001), yet very little is known about daily activity patterns (Croll et al. 1986). The present study demonstrates distinct temporal variation in behaviour of the Australian Pelican, but generalisations must be made with caution because of the limitations presented with the study of only one colony over a brief period of time. Spatial and temporal variations in habitat use show high plasticity in the American White Pelican, and short-term studies can oversimplify or mask significant patterns (Findholt & Anderson 1995). Further study on the behaviour of Australian Pelicans in response to time of day would be required from a number of sites over a longer period of time to include such issues as seasonal changes, fluctuations in food supply, weather and breeding cycles.

Acknowledgements The scarcity of information on the Australian Pelican prompted me to write up this work, which was completed as an undergraduate behavioural study. I wish to acknowledge John Hanns and Annette Borg from Metromix Pty Ltd for their assistance in obtaining a map of the area and permission for its use, the advice of Jackie De Kroon and Eric Dorfmann during the study, and for the helpful suggestions made by referees Peter Dann and Martin O’Brien.

References Altmann, J. (1974). Observational study of behaviour: Sampling methods. Behaviour 49, 226–267. Anderson, J.G.T. (1991). Foraging behaviour of the American White Pelican (Pelecanus erythrorhynchos) in western Nevada. Colonial Waterbirds 14, 166–172. Battam, H., Leishman, A.J. & Smith, L.E. (1986). Nesting of the Australian Pelican on Martin Island, Five Islands, New South Wales. Australian Birds 20, 61–62. Australian Pelican behavioural time allocation 101

Boles, W.E. (1994). Pelicans. Australian Natural History 24, 36–45. Briggs, K.T., Tyler, B., Lewis, D.B., Kelly, P.R. & Croll, D.A. (1983). Brown Pelicans in central and northern . Journal of Field Ornithology 54, 353–373. Brown, L.H. & Urban, E.K. (1969). The breeding biology of the Great White Pelican, Pelecanus onocrotalus roseus, at Lake Shala, . Ibis 111, 199–237. Burke, V.E.M. & Brown, L.H. (1970). Observations on the breeding of the Pink-backed Pelican Pelecanus rufescens. Ibis 112, 499–512. Croll, D.A., Balance, L.T., Wursig, B.G. & Tyler, B. (1986). Movements and daily activity patterns of a Brown Pelican in central California. Condor 88, 258–260. Din, N.A. & Eltringham, S.K. (1974). Breeding of the Pink-backed Pelican Pelecanus rufescens in Rwenzori National Park, . Ibis 116, 477–493. Ferguson, T.L., Rude, B.J. & King, D.T. (2011). Nutrient utilization and diet preference of American White Pelicans consuming either a mono- or multi-species diet. Waterbirds 34, 218–224. Findholt, S.L. & Anderson, S.H. (1995). Foraging areas and feeding habitat selection of American White Pelicans (Pelecanus erythrorhynchos) nesting at Pathfinder Reservoir, Wyoming. Colonial Waterbirds 18, 47–57. Guillet, A. & Crowe, T.M. (1983). Temporal variation in breeding, foraging and bird sanctuary visitation by a southern African population of Great White Pelicans Pelecanus onocrotalus. Biological Conservation 26, 15–31. Guillet, A. & Furness, R.W. (1985). Energy requirements of Great White Pelican (Pelecanus onocrotalus) population and its impact on fish stocks. Journal of Zoology 205, 573–583. Hatzilacou, D. (1996). Feeding ecology of the Great White Pelican (Pelecanus onocrotalus) nesting at Lake Mikri Prespa (northwestern Greece). Colonial Waterbirds 19, 190–206. King, D.T. & Werner, S.J. (2001). Daily activity budgets and population size of American White Pelicans wintering in south and the delta region of . Waterbirds 24, 250–254. Knopf, F.L. (1979). Spatial and temporal aspects of colonial nesting of White Pelicans. Condor 81, 353–363. Lindsey, T.L. (1986). The of Australia. Angus & Robertson, Sydney. Macgillivray, W. (1923). The nesting of the Australian Pelican Pelecanus conspicillatus. 22, 162–174. Marchant, S. & Higgins, P.J. (1990). Handbook of Australian, New Zealand & Antarctic Birds, Volume 1: Ratites to . Oxford University Press, Melbourne. McMahon, B.F. & Evans, R.M. (1992). Nocturnal foraging in the American White Pelican. Condor 94, 101–109. O’Malley, J.B.E. & Evans, R.M. (1982). Flock formation in White Pelicans. Canadian Journal of Zoology 60, 1024–1031. Pyrovetsi, M. (1989). Foraging trips of White Pelicans (Pelecanus oncrotalus) breeding on Lake Mikri Prespa, Greece. Colonial Waterbirds 12, 43–50. Reid, J. (2009). Australian Pelican: Flexible responses to uncertainty. In: Robin, L., Heinsohn, R. & Joseph, L. (Eds). Boom & Bust: Bird Stories for a Dry Country, pp. 95–120. CSIRO Publishing, Melbourne. Schaller, G.B. (1964). Breeding behaviour of the White Pelican at Yellowstone Lake, Wyoming. Condor 66, 3–23. Vestjens, W.J.M. (1977). Breeding behaviour and ecology of the Australian Pelican, Pelecanus conspicillatus, in New South Wales. Australian Wildlife Research 4, 37–58. Voous, K.H. (1962). Australian Pelican recorded in Indonesia. Emu 67, 124. Werner, S.J. (2004). Diel foraging behavior of American White Pelicans Pelecanus erythrorhynchos on experimental aquaculture ponds. Journal of the World Aquaculture Society 35, 513–517.

Received 26 October 2011