Observations of chick feeding rates and parental defensive responses to disturbance at nests in the critically endangered New Zealand fairy tern/tara iti (Sternula nereis davisae)

Abstract

The New Zealand fairy tern/tara iti (Sternula nereis davisae; NZFT) is New Zealand’s most endangered bird, with approximately 40 individuals remaining. Due to previous poor breeding success, this species is on the brink of extinction. Nest failures occur because of adverse weather, predation, and potentially nest disturbance. We observed parental behaviour of 11 nesting pairs from November 2020 to January 2021 at three sites: Mangawhai, Waipu and Pakiri. Overall, avian predator disturbance was low at all nests, and most disturbance events were by interactions between conspecifics. Responses to conspecific disturbances were lowest for the three closely nesting pairs and highest for the three solitary nests. We measured the frequency of chick feeding and found feeding rates varied considerably between nests. Defensive response rates and feeding rates varied between nests but we found no relationship between the proportion of responses to disturbance and feeding rates. We found no relationship between feeding rate and tidal state. This could be due to our small sample size and the duration of our observation period (30 min). We urge future researchers to increase observation period time. With an understanding of feeding rates and disturbance, informed decisions can be made to support the conservation of NZFT.