Seabird breeding success is known to reflect oceanic conditions. Gray-faced petrels (Pterodroma gouldi) breeding on the east coast of Auckland, New Zealand, exhibit poor reproductive success and slow chick development compared to west coast conspecifics. This study mapped changes in physiological traits (corticosterone [CORT] and hematological parameters) indicative of sublethal stress in this Procellariiform species between the west coast (Ihumoana) and east coast (Hāwere) island colonies. We found adult gray-faced petrels on the east coast to be lighter and, unlike west coast birds, exhibited an attenuation of response CORT levels between incubation and chick-rearing phases. Such responses were also reflected in east coast chicks that were lighter and had higher feather CORT titers than west coast chicks. Measures of adult hematology and plasma biochemistry revealed significantly lower glucose levels in east coast birds and indicated that chick rearing is the most stressful phase of breeding for this species Combined; these results suggest that east coast birds are under greater nutritional stress and that parents appear to transfer the costs of poor foraging to their chicks to preserve their own condition, consequently increasing chick developmental stress. Our results suggest that any long-term decrease in ocean conditions and/or climatic shifts would be more acutely felt by east coast chicks and potentially their parents, resulting in years of poor breeding success rates on a local scale.
1. Seabirds are the most endangered avian taxa on Earth, with over a third of species globally threatened. To help slow their decline, conservation physiology seeks to determine how seabird responses to climatic and anthropogenic threats influence demographic processes, but it is not widely utilized in monitoring.2. A wide variety of metrics and methods are available to the conservation practitioner; thus, the correct method selection is paramount. This is a review of physiological tools to assess both individual and population health in seabirds, outlining which tools could be accessible enough to incorporate into conservation management strategies to increase the efficacy and range of population monitoring.3. Ultimately, the cost and expertise required limits the use of some tools in a community-based management context, but they are useful in academic research in collaboration with conservation projects to generate data to inform management strategies for threatened species.4. The value of the data available from particular tools is weighed against the invasiveness of the methodology to assess the practicality of incorporating physiological tools into routine seabird monitoring programmes. 5. A broader application of conservation physiology tools in a monitoring context could help manage threatened species; this paper summarizes a set of physiological variables from minimally invasive samples that have potential to assist in monitoring population health for seabird conservation. The full potential of these physiological tools is yet to be realized in seabirds.
Predicting species’ potential distributions and niches requires multi-scale data encompassing the past and present. Increasingly, researchers have advocated using historical contexts to inform ecological niche models (ENMs). Two key sources of past distributions are fossils and historical records. Fossils are subject to sampling and taphonomy biases but can offer insights into the temporal dynamics over millennia. Historical records are filtered by human perceptions and biases and have a shorter temporal range but compared to fossils provide different contextual information from a broader range of habitats. New Zealand has a relatively short history of human occupation and rich fossil archives and historical literature. Approximately 25% of the world’s seabirds, nearly half of which are endemic, breed in New Zealand. Since human arrival in New Zealand, many seabird populations have declined in numbers and breeding ranges, primarily due to introduced mammalian predators. Here, we explored the ecological niche space for breeding colonies of three size groups of burrowing procellariiforms using four admixtures of locational records (fossil bones, fossil bones + historical observations, historical observations, and post-1990 observational records). We fitted ENMs using the maximum entropy algorithm and calculated niche metrics. For all groups, the breeding niche space captured separately by the fossils and historical data had low overlap with each other and reflected different environmental aspects. The combined fossil + historic datasets predicted a niche that overlapped the post-1990 observed niche. Moreover, the combination of the fossil and historic datasets demonstrated that breeding grounds, now restricted mainly to predator-free settings, were once more widespread across New Zealand. We show that historical and fossil datasets complement each other mitigating biases unique to either dataset. Together, such records can provide critical insights into the historical drivers of species range contractions, contextualising current ecosystems.
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