Abstract
In order to effectively protect and conserve animals and the habitats they rely on, conservation managers must understand where those animals spend their time and which resources are important for them. Wildlife tracking studies can provide valuable information about resource needs and how animals move within, and interact with, their environment. I used newly-available ultra-light GPS tracking devices to track black-fronted terns (Chlidonias albostriatus) and banded dotterels (Anarhynchus bicinctus) in the Mackenzie Basin, New Zealand. I paired GPS tracking with extensive field observations of foraging behaviour, nesting activity and roost site use. My overarching objective was to fill knowledge gaps about these species’ movements and habitat use, and thereby provide information that can be applied to their conservation management. I investigated black-fronted tern habitat preferences, use of nocturnal roost sites, male/female patterns of incubation sharing, and the effect of breeding stage on how far they range. I explored which environmental variables drive banded dotterel habitat and nest site selection in dryland habitats, and surveyed banded dotterel nesting distribution across two dryland Conservation Areas consisting of Critically Endangered outwash gravel ecosystems.
I found that black-fronted terns moved widely around the Mackenzie Basin during the breeding season, foraging up to 46 km away from their colonies during the nesting period, and banded dotterels regularly left their nesting territory to forage up to 15 km from their nest site. Both species used networks of habitat patches. Black-fronted terns’ preferred habitats were, in order, braided rivers, low producing grassland and high producing grassland. Hundreds of black-fronted terns from multiple colonies gathered nightly at communal nocturnal roost sites up to 50 km from their colonies, including during incubation and chick rearing phases. Through spatial data analysis I located 24 previously unknown nocturnal roost sites. I detected no sex-based species-wide incubation sharing pattern for black-fronted terns, but found that each pair shared the incubation duties on their own unique schedule. Banded dotterel habitat selection was negatively correlated with vegetation moisture content and distance to water, positively correlated with distance to buildings, and strongly influenced by landcover type. Nest site selection iv by banded dotterels nesting in dryland habitat was driven most strongly by vegetation characteristics including the number of shrubs and the percentage of grass cover.
My findings indicate that off-colony nocturnal roost sites are widely used by the majority of the black-fronted tern population in the Mackenzie Basin, which strongly suggests that conservation management may need to be expanded to include key roost sites. Threats to black-fronted terns at nocturnal roosts are not well understood and should be investigated to inform conservation planning. Important roost sites need to be protected from development, weed encroachment and other degradation. My results, which showed that the glacial outwash Conservation Areas are used by banded dotterels for nesting, foraging and raising their chicks, indicate that banded dotterels should be taken into account when planning restoration and management of these sites. Banded dotterels clearly favoured open habitat with very short vegetation for both nesting and foraging, which provides further evidence in support of the protection of dryland ecosystems from the spread of wilding conifers.