Oceanic Storytellers Integrative methods for seabird conservation monitoring

Abstract

Faced with a rapidly changing climate, there is a need to improve methods for conservation monitoring and management of seabirds, the most threatened group of birds in the world. To better understand the impacts of environmental variables on seabird health, links must be drawn between their diet, distribution, health, and the fluctuations of the physical environment. Given a paucity of local data, my thesis aims to generate baseline information on these parameters for four Procellariiform species (fluttering shearwater, little shearwater, Buller’s shearwater, and fairy prion) breeding in northern Aotearoa New Zealand. I review the utility of ecophysiological tools for seabird conservation (Chapter 2) and test the fluctuations of haematological parameters in my four study species to determine if this tool has the sensitivity required to monitor seasonal changes in bird condition (Chapter 3). Haematological parameters are subject to within-season fluctuations but do appear to be useful for monitoring population health across seasons. I assess the isotopic niche partitioning of these four species during a period of high local resource competition during the breeding season (Chapter 4) and determine that there are within-season shifts for two species for targeting higher trophic level prey during chick-rearing, and a consistent trophic structure between the species that could be impacted by local scale environmental change. I use GPS tracking to profile the at-sea distributions of these four species during chick-rearing (Chapter 5) and illustrate the variable scales at which environmental conditions can impact each species, as well as providing evidence for different foraging strategies, spatial overlap and partitioning, and a lack of overlap with current Marine Protected Areas. A marine heatwave in December 2021 enabled a targeted assessment of physiological, dietary, and foraging stability in fluttering shearwaters, the most inshore-foraging species of the four, and showed evidence for the sublethal impacts of anomalous sea surface temperatures (Chapter 6). Taken together, these data are discussed in the context of improving the ability of conservation monitoring techniques to detect and respond to rapid change (Chapter 7), by assessing sublethal signs of stress as an ‘early-warning signal’ for seabird populations.