Finding a Home. An Ecological and Economic Framework for Selecting Species Translocation Sites

Abstract

The main objective of my thesis research was to improve our understanding of release site selection for conservation translocations, in particular how to identify quality habitat. To achieve this task, I developed four core research components. First, I reviewed the reintroduction literature to investigate the use of habitat and habitat- related terms in the context of species translocations. The findings of this chapter are further used to inform the theoretical framework of this thesis, which is centered around a species-specific habitat concept. Using the South Island Takahē (Porphyrio hochstetteri) as a case study, I then used geographic information systems and raster data to perform a landscape-level investigation of Takahē habitat quality throughout New Zealand. I applied expert-knowledge-informed spatial overlays and found that such a time- and cost-effective approach can be used as a first-stage investigation of candidate release sites with relative ease. The spatial overlays identified, in particular, the eastern foothills of New Zealand’s Southern Alps as areas of high Takahē habitat quality. Compared to the harsh alpine regions of the Alps, or the wet West Coast, the foothills are characterized by favorable climatic conditions, remoteness, and large expanses of tussock grassland. The applied methodology, while being coarse, can be used as a time- and cost effective first-stage screening of candidate release sites. In the fourth chapter I investigated micro habitat aspects, such as nutrient contents of palatables and micro climate around Takahē nest sites, to explain possible patterns in breeding success at the Takahē captive rearing facility near Te Anau. I found that this methodology can be used as a second- stage investigation of micro habitat for pre-selected candidate release sites. I was unable to detect any relationship between nutrient/ environmental parameters and patterns in breeding success. However, a single microhabitat site was identified as an outlier with particularly low breeding success in combination with low manganese contents. Previous research suggests that manganese deficiency can lower the productivity of birds. These findings justify a more-in-depth investigation of the corresponding breeding pen, its soil contents, water regime, and plant life. In the final step, I added an economic component to my research and developed a novel spatial approach to estimate habitat management costs, acquisition costs, and opportunity costs for candidate release sites. Using information such as land cover, distance to heliports, and slope, I investigated how landscape components affect the establishment and ongoing costs of planned species translocation sites. The main finding of this chapter was the existence of a trade-off between management costs of reintroduction sites and opportunity costs. Remote and rugged areas are more labor-intensive, but they have relatively low opportunity costs, decreasing the potential of human-wildlife conflicts. Further research could include an investigation of ecosystem services provided by reintroduction sites to assess both economic costs and within a common framework.