Inside Voices: Studying the Maternal In-nest Vocalisations of the Kea Parrot (Nestor Notibilis)


  • George McClelland Comenius University in Bratislava



Native to the alpine regions of New Zealand’s South Island. Detailed analysis of the structural properties of kea vocalisations [1] lead to the classification of 7 distinct call types, however observations of the nesting ecology [2] revealed a structurally distinct call type seemingly specific to nesting mothers. As yet little is known about the possible function of these nest-specific vocalisations, although initial analysis by [2] showed the calls to be structured in a way that would minimise the risk of predation (i.e. low amplitude and high entropy), and led to the tentative hypothesis that the calls serve multiple functions, including stimulating embryos during hatching and aiding the location of the mother’s beak during feeding.

Few studies have looked at parental communication in nesting parrots in general. This project aims therefore to identify behavioural contexts correlated with these vocalisations to better understand their possible function, communicative or otherwise. The findings will then be contextualised within the wider literature of parent-offspring communication.


Video data from 3 nests will be collected twice a week during nest-building (1-2 weeks), incubation (3 weeks), and the first week of the youngest chick’s life. The videos will then be coded for pre-specified behavioural categories (e.g. feeding, returning to the nest, interacting with the male etc.). From this a baseline calling rate (during periods of inaction) will be derived, against which the call rate during specific behaviours can be compared.

Possible Function of Vocalisations

Research on the effect of parental vocalisations on the developing embryo in fowl shows that postnatal sound preferences are at least partially innate, but that they can be shaped and enhanced by in embryonic exposure to maternal calling.

Similar plasticity in response to the mother’s voice is also likely in the prenatal human brain, and has been hypothesised to facilitate the early stages of linguistic development as early as the womb [3].

In the case of kea, juvenile calls have been shown to be influenced by those of conspecifics with which they have regular contact during development. This provides an interesting parallel to phonemic specification during the development of vocal control in human infants.


[1] A. Wein, R. Schwing and L. Huber. “Kea parrot mothers Nestor notabilis produce nest-specific calls with low amplitude and high entropy,” Ibis vol. 162 pp.1012–1023. 2020.

[2] R Schwing, S Parsons and X Nelson. “Vocal repertoire of the New Zealand kea parrot Nestor notabilis,” Current Zoology vol. 58, pp.727–740. 2012.

[3] A. Webb, H. Heller, C. Benson and A. Lahav. “Mother’s voice and heartbeat sounds elicit auditory plasticity in the human brain before full gestation,” PNAS vol. 112 no.10 pp. 3152-3157. 2015.