Impacts of seabirds on plant communities
Seabird islands are islands that have high populations of seabirds. They are often remote and in many cases lack the predators found on the mainland or islands closer to the mainland. Seabird islands occur worldwide and they are of high conservation value because they often have very high levels of endemism and may serve as “safe havens” for species that are rare or no longer present on the mainland. However, many of the islands have been invaded by non-native predators such as rats, cats, and foxes, with devastating effects for native bird, reptile and mammal populations. Restoration of hundreds of islands has focused on the removal of these predators, but little attention has been paid to other aspects of restoration beyond monitoring seabird populations.
Aorangaia island (Poor Knights, New Zealand); close-up of seabird burrows; moving carefully across burrow-riddled ground
SEAPRE (Seabird Islands and Introduced Predators: Impacts of Presence and Eradication on Island Function): I was the Principal Coordinator of this Research Coordination Network, which brought together people from across the world for cross-system comparisons and synthesis of the impacts of seabirds and introduced seabird predators on island ecology, with the further aim of improving restoration plans for islands on which these introduced predators have been or are being eradicated. The main product from this network was a book: Seabird Islands: Ecology, Invasion, and Restoration, published by Oxford University Press in 2011.
RASP (Rats and Islands Project). In this project, run in collaboration with Manaaki Whenua - Landcare Research and Department of Conservation (both of New Zealand) examined the effects of invasive rats on vegetation and soils, both directly (e.g. through changes in seed or seedling consumption) and indirectly (by reducing or eradicating seabird populations). For more details, see Fukami et al. 2006, Wardle et al. 2007, Mulder et al. 2009, Towns et al. 2009, Bellingham et al. 2010, Grant-Hoffman et al. 2010a, Grant-Hoffman et al. 2010b.
Decomposing leaves marked while on the tree (middle) ; graduate students Mel Durrett (left) and Nikki Grant-Hoffman (right) on New Zealand islands