150 AUSTRALIAN

BIRD WATCHER

AUSTRALIAN BIRD WATCHER 1988, 12, 150-153

Observations on Feeding Flocks of the Red-rumped Parrot Psephotus haematonotus in Parklands near Melbourne, Victoria

by MICHAEL F. BRABY1 and CHRISTIAN RANTZAU 2

121 Cromwell Street, Eltham, Victoria 3095 25 McLachlan Street, Northcote, Victoria 3070

Summary Field observations on feeding flocks of the Red-romped Parrot Psephotus haerruuonotus were

conducted during autumn 1984 in suburban parklands in the lower Yarra valley near Melbourne, Victoria. Parrots were found to feed on a variety of introduced plants, but mostly fed on introduced Wireweed Polygonum aviculare. Of the various food types eaten, leaf material comprised the major component. Seeds and occasionally flowers were also eaten. On numerous occasions flocks of feeding birds responded to intraspecific warning calls of other bird species, particularly White-plumed Honeyeater lichenostomus penicillatus . In response to such calls, Red-romped Parrots often took flight and sought cover amongst foliage of nearby trees. The data and observations are discussed in relation to possible factors contributing to the adaptive success of this species in urban environments.

Introduction The Red-rumped Parrot Psephotus ho.ematonotus is a common bird of parks, gardens

and farmland, spending much of its time on the ground searching for food (Forshaw 1981; Lendon 1979; Blakers et a!. 1984). The species usually prefers open-grassed areas for feeding (Forshaw 1981; Ambrose 1982) and flocks of feeding parrots can often be observed at close range without disturbing them. Little information is available on their feeding behaviour and details of their food requirements, such as plant species selected, are poorly documented (Forshaw 1981). This paper presents information concerning aspects of their diet and behavioural responses to potential predators in suburban parklands of the Yarra valley near Melbourne, where the species is relatively abundant (Warringal Conservation Society 1981) .

Methods During an intensive short study between 22 April 1984 and 8 May 1984, flocks

of feeding Red-rumped Parrots were observed in a number of parklands throughout the lower Yarra valley, within 20 km north-east of Melbourne (Table 1). In general, the parklands visited consisted of extensive grassland, mostly of introduced species, with some open woodland comprising a mixture of indigenous eucalypts and exotic trees.

Fifty different flocks of feeding parrots were observed with 7 x 50 binoculars at distances of 10-20 metres. Hides were not used. For each flock, the bird(s) closest to the observer was watched for approximately 30 minutes and samples of the plants eaten (species and food type) were collected for identification. Behavioural responses of the flock to disturbances or potential danger were noted.

Results Most observations (74%) were made on flocks of 2-30 birds and very few

observations (12%) were made on flocks of more than 50 birds. Most observations (72%) were made in open areas where tree cover was absent, and nearly half ( 42%) of all observations were made on sports fields.

VOL. 12 (5) MARCH 1988

Diet

Red-rumped Parrots, Feeding near Melbourne 151

A total of seven plant species, all of which are herbaceous perennials, were eaten by Red-romped Parrots (Table 2). Of these, only one species, Nodding Saltbush Einadia nutans was native. The most commonly eaten species was Wireweed Polygonum aviculare which accounted for over three-quarters (n=45) of the total number of observations (n=57). This species was common in all parklands, particularly on sports fields and in open, exposed areas where other plants appeared unable to grow. The major food type was leaf material (82 .5% of all feeding observations) , although seeds, and to a lesser extent flowers, were also eaten (Table 2).

Predator responses

On many occasions flocks of feeding Red-romped Parrots responded to intraspecific warning or alarm calls of other species, particularly the White-plumed Honeyeater Lichenostomus penicillatus and occasionally the Noisy Miner Manorina melanocephala. Warning calls given by these other species generally coincided with potential danger, for example, human disturbance, or sometimes with appearances of birds of prey, notably the Australian Hobby Falco longipennis and the Brown Falcon F. berigora.

The level of response shown by Red-romped Parrots appeared to depend on the intensity of the warning call. Low-intensity warning calls usually caused birds to momentarily stop feeding, and if no immediate danger was detected after 5-15 seconds they would resume feeding. In contrast, high intensity (louder and longer) warning calls invariably caused birds to stop feeding, survey the surrounds (0-2 seconds) and then fly, usually as a single flock, to a nearby tree within 20-50 metres for refuge. Generally a 'sharp' call was given by one or more birds during flight, and often a call was given by one bird before the flock flew from the feeding site. Usually the birds returned to the same feeding site some 5-10 minutes after the danger or disturbance had ceased.

Discussion Little published information is available on plant species selected by Red-romped

Parrots, particularly for the Melbourne area. The only comparable data are those of Fleming (1974) who recorded parrots feeding on seeds of three introduced species: Fennel Foeniculum vulgare, Scotch Thistle Onopordon acanthium and Artichoke Thistle Cynara cardunculus. These findings, together with the data presented here, indicate a striking ability to utilise introduced plants. The ground cover vegetation of most suburban parklands largely contains exotic plant species, resulting from past habitat alteration, degradation and weed invasion (N.H. Scarlett pers. comm.), and this adaptive feeding behaviour of Red-romped Parrots is one factor which accounts for their occurrence in such environments.

Forshaw (1981) stated that Red-romped Parrots chiefly select seeds of grasses and herbaceous plants, occasionally green vegetable matter, and more rarely fruits and berries. In contrast, our study has revealed that birds feed predominantly on leaf material (mostly of P. aviculare), at least during autumn. Flowers of P. aviculare were in evidence during the study period, however it was not ascertained if parrots fed on these because of the minute flower size (perianth is less than 3 mm long). We did not observe Red-romped Parrots eat berries or fruits, although near La Trobe University Wildlife Reserve parrots have been observed eating the fruits of Berry Saltbush Atriplex semibaccata (R. Foster pers. comm. 1982). The closely related chenopod Einadia nutans possessed small, red berries at the time of observation, but these were not eaten.

152 BRABY & RANTZAU

Table 1

AUSTRALIAN BIRD WATCHER

Suburban parklands near Melbourne where Red-romped Parrots were observed

Parkland Locality Number of different flocks observed

Eltham Lower Park Binnak Park La Trobe University Campus Yarra Bend Park Warringal Parklands Banyule Flats Reserve W esterfolds Park Finns Reserve Total

Eltham Watsonia Bundoora Kew Heidelberg Heidelberg Templestowe Templestowe

Table 2

15 14 8 5 3 2 2 1

50

Frequency of plant species and food types eaten by flocks of Red-romped Parrots

Plant species

Poaceae *Lolium perenne L. *Sporobolus indicus (L.) R.Br. var. africanus (Poiret) Jovet and Guedes

Chenopodiaceae Einadia nutans (R.Br.) A.J . Scott

Compositae *Hypochoeris radicata L.

Cruciferae *Lepidium africanum (N . Burm.) DC.

Plantaginaceae *Plantago lanceolata L.

Polygonaceae *Polygonum aviculare L.

Total

*Introduced species

Food types

Leaf material Seeds

Leaf material

Seeds, flowers

Seeds

Seeds

Leaf material

Number of observations (%) N =57

1 (I. 8) 1 ( 1. 8)

1 (1. 8)

2 (3.5)

5 (8.7)

2 (3.5)

45 (78.9)

57 (100)

The apparent preference for leaf material during autumn may be due to a scarcity of seeds at this time, and further studies are needed to establish the relative frequencies by which seeds and leaf material are selected. It is possible that Red-rumped Parrots may vary their diet seasonally as do other parrots, for example, the Orange-bellied Parrot NeophenuJ chrysogaster (Loyn et al. 1986), according to the relative availability of these two components.

The results of this study, although somewhat limited, taken together with other published findings (Forshaw 1981) suggest that the Red-rumped Parrot is probably a generalist feeder, with the ability to utilise a relatively wide spectrum of foods and a variety of plant species, especially exotics and weeds. This is probably one important factor enabling this species to adapt to urban environments.

VOL. 12 (5) MARCH 1988 Red-romped Parrots, Feeding near Melbourne 153

Flocks of Red-romped Parrots appeared to feed predominantly in open areas, in short (regularly mown) grass, but relatively close to large trees which were used for shelter or refuge during periods of 'danger'. White-plumed Honeyeaters were very common in the parklands and warning calls were usually given by birds perched on the uppermost branches of tall trees. It is reasonable to assume that this abo real species detects potential predators, such as birds of prey (Forshaw 1981), before ground-feeding species such as Red-romped Parrots do. The behavioural response shown by parrots to intraspecific alarm calls of White-plumed Honeyeaters may be adaptive in reducing the risk of predation.

Acknowledgements The authors thank Dr R. Zann (Zoology Department, LaTrobe University) for

general assistance and his comments on the manuscript; and Mr N.H. Scarlett (Botany Department, LaTrobe University), Mr C. Beardsell (Department of Conservation, Forests and Lands) and the late Mr R.L. Foster (Keeper, LaTrobe University Wildlife Reserve) for valuable assistance with plant identifications. The authors would also like to thank Mr C. Skyllas for typing the manuscript.

References Ambrose, G.A. (1982), An ecological and 'behavioural study of vertebrates using hollows in eucalypt

branches, Ph .D. thesis, LaTrobe University, Melbourne. Blakers, M., Davies, S.J.J.E & Reilly, P.N. (1984), The Atlas of Australian Birds, Melbourne University

Press, Melbourne. Fleming, A. (1974), 'Feeding habits of Red-romped Parrots', Australian Bird Watcher 5, 184. Forshaw, J.M. (1981), Australian Parrots, second edition, Lansdowne Press, Melbourne. Lendon, A.H. (1979), Australian Parrots in Field and Aviary, revised edition, Angus & Robertson,

Melbourne. Loyn, R.H., Lane, B.A., Chandler, C. & Carr, G.W. (1986) , 'Ecology of Orange-bellied Parrots

Neophema chrysogaster at their main remnant winter site', Emu 86, 195-206. Warringal Conservation Society (1981), Birds of Heidelberg and the llirra lillley, Warringal Conservation

Society, Melbourne.

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