Nest Survival Models and Genomics Illuminate Hybridisation Attempts, Guiding Culturally Informed Management to Recover a Critically Endangered Seabird

Conservation management involves consideration of complex trade‐offs arising from the interplay of diverse values. Interspecific hybridisation presents a challenge for conservation, including for seabirds, as hybridisation can reduce reproductive potential or even result in extinction by hybridisation. Hybridisation attempts between two culturally significant species, the Critically Endangered Kuaka Whenua Hou (KWH, Pelecanoides whenuahouensis ) and the abundant Kuaka ( P. urinatrix ) have been observed. Given the perilous conservation status of KWH (~210 adults), we here investigate these attempts, the risk they pose, and assess the efficacy of management interventions that were both data‐ and culturally informed. We first assessed the success of hybridisation attempts through Bayesian nest survival models fitted to seven years of nest monitoring data, which suggested that despite low nest survival (0.054), some hybridisation attempts are successful. We then generated genomic data (including a reference KWH genome assembly, single‐nucleotide markers and mitochondrial genomes), confirming successful hybridisation but an absence of introgression. Nevertheless, hybridisation attempts are indeed a threat to the Critically Endangered KWH due to reduced reproductive potential of the species. All data were incorporated for culturally informed management in the field to minimise hybrid breeding attempts. Results of Bayesian mixed‐effects models indicate that the interventions are producing the intended outcomes: the reduced likelihood of hybridisation. All work, including monitoring, sampling, selecting a reference genome individual, identifying interventions, and executing and evaluating these interventions was conducted in full partnership with Kāi Tahu (the Indigenous People of southern Aotearoa New Zealand). Our study demonstrates the value of integrating multiple evidence streams for real‐world conservation management, in this case, the first culturally informed management of hybridisation attempts in a Critically Endangered seabird.