Rafael Freire

Many mammalian predators leave volatile chemical signals in the environment. These scent cues can alert prey species to the presence of predators and may elicit fear-like avoidance responses in their native prey. However, naïve prey may not be able to associate a scent with a novel exotic predator, because the length of co-existence between these invasive predators and native prey has been too short. This study investigated the ability of Australian birds to recognise native and exotic predators. We used scented and unscented bird baths as an avian equivalent to a Y-maze, commonly used in scent experiments on rodents and reptiles, to test whether seven species of honeyeaters respond to the odours of a native predator (brush-tailed possum), two exotic predators (cat and brown rat), and a native herbivore (koala). We expected honeyeaters to avoid the odours of native possums, but not the odours of cats and rats, as they have co-existed with these exotic predators for only 100–200 years. Honeyeaters visited baths with possum scent less often than control baths and they also spent less time at these scented baths. Honeyeaters were also less likely to drink or wash in possum-scented baths than in control baths. Honeyeaters also avoided rat- and cat-scented bird baths, but the aversion to these baths was less strong than to possum-scented baths. We demonstrate that some birds, like mammals and reptiles, use olfaction to assess predation risk, but how strongly honeyeaters responded to predator scents varied depending on co-evolutionary history with a predator.

Researchers are increasingly engaged in studies to determine and correct negative welfare consequences of animal husbandry and behaviour modification procedures, not least in response to industries’ growing need to maintain their social licence through demonstrable welfare standards that address public expectations. To ensure that welfare recommendations are scientifically credible, the studies must be rigorously designed and conducted, and the data produced must be interpreted with full regard to conceptual, methodological, and experimental design limitations. This commentary provides guidance on these matters. In addition to, and complementary with, the ARRIVE guidelines that deal with animal studies in general, there is a need for additional specific advice on the design of studies directed at procedures that alter behaviour, whether through training, handling, or restraint. The COMPASS Guidelines offer clear direction for conducting welfare-focused behaviour modification research. They stand for the following: Controls and Calibration, emphasising rigorous design, baseline measures, equipment calibration, and replicability; Objectivity and Open data, ensuring transparency, validated tools, and data accessibility; Motivation and Methods, with a focus on learning theory, behavioural science, and evidence-based application of positive reinforcers and aversive stimuli; Precautions and Protocols, embedding the precautionary principle, minimising welfare harms, listing stop criteria, and using real-time monitoring; Animal-centred Assessment, with multimodal welfare evaluation, using physiological, behavioural, functional, and objective indicators; Study ethics and Standards, noting the 3Rs (replacement, reduction, and refinement), welfare endpoints, long-term effects, industry independence, and risk–benefit analysis; and Species-relevance and Scientific rigour, facilitating cross-species applicability with real-world relevance and robust methodology. To describe these guidelines, the current article is organised into seven major sections that outline detailed, point-by-point considerations for ethical and scientifically rigorous design. It concludes with a call for continuous improvement and collaboration. A major purpose is to assist animal ethics committees when considering the design of experiments. It is also anticipated that these Guidelines will assist reviewers and editorial teams in triaging manuscripts that report studies in this context.

The captive breeding and release of threatened small-bodied freshwater fish is a common conservation method, yet many of these fish lack the behavioural profile to survive in the wild. Soft-release sites that provide wild-like experiences with minimal threat to survival can improve post-release outcomes. Here, we investigated whether captive-bred first generation Southern pygmy perch (Nannoperca australis) exposed to six months of soft-release experience develop natural behaviour. In laboratory tests, we compared the behaviour of fish from a hatchery, a soft-release site, or the wild in emergence, exploration, habitat choice, predator response, and novel food tests. As predicted, we found that fish from the soft-release site showed similar behavioural responses to wild-caught fish. However, soft-release fish were significantly larger (14.6 mm, 1.6 g advantage) and made greater use of refuge structures (basket ledges). Also, while trends suggested altered anti-predator responses, statistical support was limited, warranting further investigation. We conclude that soft-release experience enhances growth and shelter-seeking behaviour in this species, though further tests in a more natural environment should be undertaken to confirm ecologically important experience-dependent changes in behaviour. We recommend prioritising soft-release programmes that maximise natural foraging opportunities, reduce competition, and provide complex structures to support shelter use. Finally, the overall similarity in behaviour of fish from different environments suggests that, in this species, behaviour appears mostly inherited.

Parrots (Aves, Psittaciformes) in captivity have been reported to show dance behaviour in response to music, which may involve complex cognitive processes including imitation, vocal learning and entrainment. Dance behaviour in parrots may be indicative of a positive welfare state raising the possibility of using music as a form of environmental enrichment. In this study we studied dance behaviour in cockatoos (Cacatuidae) through an online video study and a playback experiment. First, we identified and defined cockatoo dance movements to music from videos posted on social media to reveal the extent of this behaviour in different species. Second, to test whether music elicited dance behaviour we conducted a preliminary playback experiment on captive cockatoos, whereby birds were presented with periods of music playback, no audio playback and an audio podcast. From 45 online videos representing five different cockatoo species we identified and described 17 new dance movements. We also found 17 rare movements observed in only one bird and not previously reported in the literature, which in many cases consisted of combinations of different movements. A cluster analysis indicated that inter-species similarities in dance movements were not related to phylogenetic relatedness. In the playback study, which involved zoo-housed male-female pairs of three species of cockatoos, all birds in all treatments showed dance behaviour but there was no significant effect of treatment on the probability of showing dancing behaviour. We conclude that dance behaviour in cockatoos is composed of a wide range of different movements and further research would be beneficial to determine if music can trigger dance in captive birds and serve as a form of environmental enrichment.

Our understanding of the functional importance of olfaction to birds has improved over the past 60 years, largely as the result of experimental studies testing how birds use their sense of smell in different contexts. As it is impossible to measure directly which odours birds can detect, we rely on measuring behavioural responses to scent cues or manipulations which diminish their olfactory acuity. Here, we review the findings of these studies structured by when and how birds used their sense of smell: during foraging, navigation, social interactions with con‐ or hetero‐specifics, nesting or for predator detection. Most studies investigated how birds use their olfactory sense during foraging (n = 52) and nesting (n = 42), but fewer examined how birds use olfaction during social interactions (n = 38), navigation (n = 20) or predator recognition (n = 21). Knowledge is mainly restricted to certain Orders (e.g. Procellariiformes). Although the diversity of neuroanatomical and molecular structures underlying olfaction suggests that olfactory acuity varies considerably among extant bird species, an understanding of which ecological factors drive selection for olfactory acuity in birds is mostly lacking. How experiences expand a bird's chemosensory knowledge over time and whether birds can learn to recognize odours associated with foraging opportunities or danger from predators is still poorly understood. Finally, there is a lack of knowledge about how long some volatiles remain useful to birds before they have decayed, and which volatiles, or combinations of volatiles, contained within some olfactory cues are being detected by birds. We encourage ornithologists to tackle these broader questions to better understand the functional importance of olfaction to birds.

Millions of hatchery-reared Rainbow trout are currently released in Australian waters to support recreational fisheries objectives, yet many of these fish die soon after release. In addition, little is known whether these fish harbour parasites that can potentially threaten freshwater ecosystems and human health. Here, we tested the behaviour of hatchery-reared trout using six tank-based tests at six different ages to evaluate their chances of survival and then dissected fish to investigate parasite prevalence. At 7 weeks of age fish readily emerged from a hide and showed the greatest number of startle responses to predators. Behaviour around 25–29 weeks of age was relatively “shy”, staying in shelter and avoiding open water. At around 37–41 weeks of age though, behaviour changed, with fish emerging from a hide more readily and exploring the environment. Interestingly, at 58 weeks of age fish were slower to initiate exploration, possibly indicating a return to “shyer” behaviour. All fish underwent thorough parasite examination, revealing no infections. We conclude that knowledge of the behaviour of hatchery-reared fish at different ages is useful for decisions around the timing of release that balance the needs of recreational fishers whilst managing the impact on freshwater ecosystem.

Bold behaviour of non-native species is hypothesized to facilitate invasion success, yet extreme boldness in wild and domesticated animals can be maladaptive. The purpose of this study was to compare individual behaviour among Australian native hatchery-reared (n= 33) and wild (n= 38) Murray cod (Maccullochella peelii) with invasive common carp (Cyprinus carpio;n= 30). Three laboratory tests measured individual behaviour: (1) emergence from a shelter, (2) exploration of a novel environment, and (3) approaching a predator. Wild invasive carp and hatchery-reared cod were generally faster and more likely to emerge and explore novel environments when compared with wild Murray cod. The ‘bold-type’ behaviours of hatchery-reared native cod were more like invasive carp than they were to ‘shy-type’ wild conspecifics, yet an important difference was that hatchery-reared cod spent substantially more time near a large predator while carp rapidly escaped. We suggest that these results are consistent with a bold-type invasion syndrome in invasive carp and learned boldness of hatchery-reared Murray cod. The propensity of invasive carp to rapidly explore and enter new environments, along with a fast predator escape response may have been important to their invasion success, while extreme risk-taking and predator naivety of hatchery-reared Murray cod may exacerbate post-release mortality rates in fisheries and conservation stocking programmes.

Horse training exposes horses to an array of cognitive and ethological challenges. Horses are routinely required to perform behaviours that are not aligned to aspects of their ethology, which may delay learning. While horses readily form habits during training, not all of these responses are considered desirable, resulting in the horse being subject to retraining. This is a form of cognitive flexibility and is critical to the extinction of habits and the learning of new responses. It is underpinned by complex neural processes which can be impaired by chronic or repeated stress. Domestic horses may be repeatedly exposed to multiples stressors. The potential contribution of stress impairments of cognitive flexibility to apparent training failures is not well understood, however research from neuroscience can be used to understand horses’ responses to training. We trained horses to acquire habit-like responses in one of two industry-style aversive instrumental learning scenarios (moving away from the stimulus-instinctual or moving towards the stimulus-non-instinctual) and evaluated the effect of repeated stress exposures on their cognitive flexibility in a reversal task. We measured heart rate as a proxy for noradrenaline release, salivary cortisol and serum Brain Derived Neurotrophic Factor (BDNF) to infer possible neural correlates of the learning outcomes. The instinctual task which aligned with innate equine escape responses to aversive stimuli was acquired significantly faster than the non-instinctual task during both learning phases, however contrary to expectations, the repeated stress exposure did not impair the reversal learning. We report a preliminary finding that serum BDNF and salivary cortisol concentrations in horses are positively correlated. The ethological salience of training tasks and cognitive flexibility learning can significantly affect learning in horses and trainers should adapt their practices where such tasks challenge innate equine behaviour.