Animal behaviour: diverse insights across Aotearoa New Zealand and the South Pacific

Animal behaviour is an inherently fascinating topic. For many of us, watching animals is what sparked our initial curiosity and eventually led us to become zoologists. Pondering why one animal behaves one way, while another animal behaves differently – is a simple thing to wonder. But at the same time, answering that question is incredibly difficult. Animal behaviour is among the most complex and challenging of the sciences because it is a broad amalgamation of so many different sub-disciplines. Behaviour spans from the responses of individual cells (e.g. detecting light or sensing temperature) to the function of entire ecosystems, and indeed, via animal movement, it connects ecosystems. Consequently, animal behaviour is central to a wide variety of fields including evolution, population and community ecology, disease ecology, genetics, and environmental science, and it plays a critical role in conservation and biosecurity.

Aotearoa New Zealand and the rest of the Australasian and South Pacific region are rightly famous for the diversity of the species and the remarkable behavioural adaptions its species have evolved to suit the equally extraordinary variety of habitats. Given our amazing taonga (treasured species) and the breadth of animal behaviour as a discipline, it is not surprising that this special issue spans taxa from dolphins to wētā, bats to sex-changing fish, and includes a strong representation from the birds. The issue also includes topics that range from neuroanatomy to the effects of anthropogenic light on foraging, with emphases on social behaviours, habitat use and vocal behaviour. As a result, it is challenging for this editorial team to categorise and summarise the incredible array of work represented here – but we will try to do it justice. This special issue’s 15 papers cover a lot of territory, but there are a few broad themes.

First, three papers are loosely focused on habitat use in birds and bats. Two studies on pekapeka tou roa | long-tailed bats investigate how humans can alter bat habitat use. Robinson et al. examine the use of artificial roosts by bats (Robinson et al. 2024), while Schmhart et al. investigate the negative effects of artificial light at night, leading to a decline in detection rates (Schamhart et al. 2024). McLean et al. continue this focus on anthropogenic effects on behaviour, but instead of pekapeka, they focus on our perpetually curious kea. Their findings show that birds living near humans show enhanced neophilia (interest in novel objects), and experience reduced longevity due to those interactions (McLean et al. 2024).

A second large theme examined species, sub-species, population, or morph differences in behaviour. At the morph level, Thompson et al. ask whether the different colour morphs, or sexes, of stone wētā differ in terms of activity, refuge seeking behaviour or defensive behaviours (Thompson et al. 2024). White et al. take a different tact and ask whether populations of toutouwai | South Island robins that experience different levels of predation pressure show different levels of boldness, finding that higher levels of predation pressure may reduce bold behaviour (White et al. 2024). Roper and Brunton examine species differences in accessing artificial feeders and test whether this leads to the exclusion of smaller species. They found that though there are species and sex differences in feeder attendance, hihi | stitchbirds are unlikely to be excluded by the more dominant korimako | bellbirds (Roper and Brunton 2024). Expanding even further, Naikatini et al. examine territorial responses of a variety of Fijian birds across an elevational gradient, finding that high elevation species show stronger defence behaviour at higher altitudes (Naikatini et al. 2024). Pyper et al. review the role of post-invasion behavioural change in invasive species, showing that this is a ripe area for future research (Pyper et al. 2024). They call for long-term studies that track behavioural change over time, and for studies that investigate the role of genetics in behavioural change.

Reproductive behaviours are of perennial interest and have a substantial presence in this issue. Two papers focus on sex-specific breeding behaviour. Merien et al. provide the first evidence of direct oviposition in female New Zealand rō | stick insects, answering a persistent question of how and where stick insects lay their eggs (Merien et al. 2024). LeGrice et al. focus instead on males and explore the rules of engagement in wild pepeke nguturoa | New Zealand giraffe weevils, using sequential analysis to identify mutual assessment during male-male contests (LeGrice et al. 2024). The other two papers focus on male-female interactions. McCallum and Shaw examine individual differences in courtship feeding behaviour in toutouwai | North island robin, finding important differences in courtship generosity that may reflect male quality (McCallum and Shaw 2024). In contrast, Roberts et al. focus on the other end of the breeding cycle and examine chick feeding and parental defence behaviour in tara iti | New Zealand fairy terns, with the aim to aid conservation managers in understanding the relationship between feeding rates and breeding success in this critically endangered species (Roberts et al. 2024).

The final category focuses on vocal behaviour in New Zealand animals. Moran et al. use a novel playback method to test for titipounamu | rifleman chick’s ability to learn novel noises while in the nest (Moran et al. 2024). The results are null, but the method provides an interesting alternative to traditional vocal learning experiments that only occur in the lab. Making the point that birds are not the only noisy species, Brunton explores vocal variation in bottlenose dolphin populations, finding that different populations use different types of whistles at different frequencies (Patiño-Pérez et al. 2024). While it is challenging to untangle why populations might differ in their vocal behaviour – social, environmental, and cultural factors could all be at play – this study provides an important starting point for exploring this concept further.

Finally, in a category all their own, Kamstra et al. provide the first brain atlas for the sex-changing paketi | New Zealand spotty wrasse (Kamstra et al. 2024). The neural mechanisms underlying their fascinating sex-changing behaviour are poorly understood and require neuroanatomical reference for solid progress. This study provides a critical tool to better understand this amazing endemic species’ behaviour.

Together, this diverse array of research shows the field of animal behaviour is alive and well in Aotearoa New Zealand and the South Pacific, but there is still much to learn about our species. Studying animal behaviour can help us better manage the impacts of anthropogenic disturbances on native species. Similarly, an understanding of the fundamental aspects of behavioural ecology is sorely lacking for most of our native species, and the research presented in this special issue provides some important foundations for future work. But native and endemic species are not the only species worth studying. Research on exotic species can provide important scientific insights, and knowledge of invasive species is critical to effective control. Finally, the sheer taxonomic diversity of species found in Aotearoa New Zealand and its neighbours shows that this is an exciting place to carry out animal behaviour research.

Needless to say, we are very excited to present this special issue. We’d like to thank all the authors for their contributions, and the reviewers for their helpful insights and thoughtful feedback. Special issues provide a unique opportunity to showcase the latest advances while also shining light on the sometimes surprising commonalities in topics, species, methods and interests in Aotearoa New Zealand and around the world – and that certainly is the case here. We hope to see future special issues that track the progress of this field, and perhaps expand our geographic coverage, encompassing Aotearoa New Zealand and the entire Southern Hemisphere, the Pacific Rim, and Antarctica.