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Burrowing into the past: reconstructing distributions of Procellariiformes

André Bellvé, Janet M. Wilmshurst, Edin Whitehead, Jamie R. Wood, George L. W. Perry

School of Environment, University of Auckland.

Seabirds play a crucial role in linking marine and terrestrial ecosystems by moving phosphorus from the ocean to the land. Although contemporary seabird diversity and abundance are relatively high in Aotearoa, the fossil bone record reveals they were more abundant and widespread in the recent past. Seabirds declined rapidly following human arrival c. 750 years ago as a result of predation by introduced mammals, human harvesting, and habitat loss. As a result, the pre-human breeding range and influence of seabirds on native ecosystems remains uncertain, although in some places, nutrient fluxes are known to have collapsed. Understanding the past and present distributions of seabird colonies is essential from a conservation perspective to help identify favoured breeding habitats and the processes that restrict their current breeding grounds. Identifying past and present breeding sites also provides a basis for characterizing shifts in the land-ocean nutrient fluxes that are an integral component of Aotearoa’s forest ecosystems. However, scanty fossil bone deposits and the restricted ranges of extant seabirds limit the ability to provide such information.  Here, we overcome these limitations by presenting species distribution models of pre-human and contemporary breeding sites for native Procellariiformes built using presence-only data. We collated an extensive nationwide database of contemporary breeding colonies to predict the distribution of breeding habitat and contrasted this with models built on historical accounts and fossil records. We collapsed these observations into groups based on weight and behavioural ecology. Across all groups, there was non-random loss in seabird breeding ranges, with models using (pre)historic data predicting seabirds across the interior of both North and South Islands. These distributions can inform conservation management, including determining the most suitable sites for habitat restoration and translocation.