Aspects of the behaviour and vocalisations of captive Antipodes Island parakeets (Cyanoramphus unicolor, Lear), and comparisons with other Cyanoramphus taxa

Abstract

Research into the behavioural repertoire and vocalisations of the Antipodes Island Parakeet (Cyanoramphus unicolor) in captivity was undertaken. Observations and vocalisations were recorded at five North Island institutions from late 1987 to early 1989. For comparative purposes, information was gathered on the other Cyanoramphus taxa held by these institutions. The introductory chapter covers literature on the taxonomic status of Cyanoramphus, the current state of research on Cyanoramphus species, including C.unicolor, and relevant behavioural research on other Psittacines. A descriptive comparison of behavioural repertoires is made between the Antipodes Island Parakeet, the Red-crowned Parakeet (C.n.novaezelandiae, Sparrman) and the Yellow-crowned Parakeet (C. a. auriceps, Kuhl). These comparisons are based upon personal observations and published descriptions. The observational field data were used for an activity budgets analysis. This revealed that C.unicolor spends approximately twenty percent of its time on the ground. The results highlighted a significant shift of activities between breeding and nonbreeding seasons as well as during four different time periods of the day. These results were then compared to an activity budget analysis for wild Red and Yellow-crowned Parakeets by Greene (1988). The observed vocalisations along with the preceeding and resultant behaviours from the activity budgets dataset were used for an analysis of the behavioural context of vocalisations. The vocal repertoires of C. unicolor, C. n. novaezelandiae, and C. a. auriceps were examined using sonographic analysis. The call types were identified using names based on call characteristics and function. From this a descriptive listing of repertoires for these species was compiled. C. unicolor occupies a cold-climate tussock/scrub habitat. It is a relatively large crypto-gamically coloured Cyanoramphus that spends most of its time on or near the ground. Its diet consists of leaves and buds with some adventitious foods (Taylor, 1975b). It is thought to be territorial during the breeding season (Taylor, pers.comm.) and has developed a male courtship dance with vocalisations which occur on the ground (Goudswaard, 1988). The act of copulation is modified to occur on the ground. The incubation and fledging periods are relatively long with the chicks already down-covered at hatching. C.unicolor's vocal repertoire contains unique courtship and territorial call types:it has diverged from the basic Cyanoramphus chatter call to the extent that it contains only three to five chatter calls in a total repertoire of fifteen major and fifteen minor call types. This species is non colonial and does not produce synchronised group chatter calls. C. n. novaezelandiae occupies a grassland/scrub/forest margin niche. This species is semi-colonial and eats seeds, flowers, fruits, nectar and buds which it may obtain from the ground. During breeding only the nests are defended (Dawe, 1979). This parakeet has a vocal repertoire of eight to ten call types plus minor function call types. These are nearly all chatter calls which can also be utilised as group calls. In the absence of other Cyanoramphus species the Red-crowned Parakeet can be found in other habitats, e.g.mature forest and open grasslands. It is argued that this relatively unspecialised species must be closest to the original Cyanoramphus stock. Other C. novaezelandiae subspecies appear to be less like the nominate subspecies, both physically and vocally, the greater their distance from New Zealand. C. a. auriceps occupies a mature forest habitat. On Little Barrier Island its diet was found to comprise a high percentage of bark insects, seeds, flowers, fruits and buds when available (Greene, 1988). This species rarely ventures to the ground, unless in a predator-free habitat. C.a.auriceps is considered territorial for the breeding season and semi-colonial for the rest of the year. This species' niche may broaden if other Cyanoramphus species are not present. The Yellow-crowned Parakeet has a repertoire of eleven major call types plus some minor call types. At least two of the major call types are distinct and are associated with territoriality. The calls are chatter type calls, but only three types are used for group-calling in the nonbreeding season. Preliminary results indicate that there is no appreciable difference between the vocalisations of C.a.auriceps and C.malherbi (Souance). However C.a.forbesi (Rothschild), which has similar colouration and niche to C. a. auriceps, has a markedly distinct vocal repertoire.