The northern rockhopper penguin (Eudyptes moseleyi) is an endangered species undergoing continued population decline, making ex situ conservation and evidence-based breeding management increasingly important. Yet, behavioural data from ex situ populations remain limited. We provide the first systematic assessment of selected breeding-related behaviours in 13 pairs at Vienna Zoo during the 2024 breeding season using focal video observations. We quantified sex-specific investment in incubation, brooding and nest building, recorded agonistic interactions and nest-material competition, and derived composite indices of pair bonding, coordination, conflict exposure, and aggression initiation. Females contributed significantly more to incubation, whereas males invested more time in nest building, initiated more contact aggression and stole nest material more frequently. Males also received more non-contact aggression but fewer contact aggression events. Higher pair coordination was associated with lower conflict exposure, but the behavioural indices did not reliably predict reproductive success. Birth-origin composition (zoo versus wild-born) was associated with breeding outcome, with mixed-origin pairs showing lower breeding success than same-origin pairs. This exploratory association should be interpreted cautiously given the small sample size and possible confounding by demographic or pair-history characteristics. Our findings identify complementary sex-specific roles, nest-material competition and pair-level coordination as components of ex situ breeding behaviour.

Felids are top predators with a significant impact on ecosystems worldwide. Yet many species are endangered, and their behaviour remains poorly studied. Felids rely on acoustic signals to convey a wide range of information over long distances and sometimes dense habitats. These signals reflect key behavioural contexts, such as mating, cub-rearing, and territorial defence - aspects relevant for conservation and habitat management. Our systematic literature review provides an overview of current knowledge on the structure and function of acoustic signals in undomesticated felids, evaluates their potential for acoustic monitoring and outlines future applications of acoustic methods in conservation, research and management. In January 2025, we searched Scopus and Web of Science for English and German publications on acoustic signals in all 40 undomesticated felid species, excluding only the domestic cat (Felis catus), identifying 51 relevant publications. Most studies focused on large-sized felids such as lions and cheetahs. For 32 of the 40 felid species researched, no species-specific studies were found. Felids share a basic acoustic repertoire, but exhibit species-specific variations that suggest adaptive functions. Most call types studied in detail encode information such as caller's age, sex, or identity, suggesting high potential for acoustic monitoring and implications in conservation.