The efficacy of reintroducing the New Zealand falcon into the vineyards of Marlborough for pest control and falcon conservation
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
In our ever more populated world, the rapid expansion and intensification of agriculture is driving worldwide biodiversity loss, and the interactions between production landscapes and wildlife conservation are becoming increasingly important. Farming systems depend on ecosystem services such as biological control, while conservationists are calling for the establishment of conservation initiatives in non-preserve landscapes. Despite this, the goals of agriculture and the goals of predator-conservation are rarely mutual. Here, I demonstrate one of the first examples of a mutually beneficial scenario between agriculture and predator conservation. I used, as a case study, a reintroduction project that translocated individuals of the threatened New Zealand falcon (Falco novaeseelandiae) from the hills of Marlborough into vineyards, to determine if predators can survive within an agricultural landscape while simultaneously providing that landscape with biological control services.
Examples of vertebrates providing biological control to agriculture are rare. I show that the presence of falcons in vineyards caused an economically important reduction in grape damage worth over US $230/ ha. Falcon presence caused a 78- 83% reduction in the number of introduced European pest birds, which resulted in a 95% reduction in the damage caused by these species. Falcon presence did not cause a reduction in the abundance of the native silvereye (Zosterops lateralis), but did halve the damage caused by this species.
To assess the conservation value of the falcon translocations, I used remote videography, direct observations and prey analysis to measure the behavioural changes associated with the relocation of falcons from their natural habitat in the hills and into vineyards. Falcons in vineyard nests had higher nest attendance, higher brooding rates, and higher feeding rates than falcons in hill nests. Additionally, parents in vineyard nests fed their chicks a greater amount of total prey and larger prey items compared to parents in hill nests. I also found an absence of any significant diet differences between falcons in hill and vineyard habitats, suggesting that the latter may be a suitable alternative habitat for falcons. Because reintroduced juvenile falcons were released in areas devoid of adult falcons, it was possible that they were missing essential training normally provided by their parents. I used direct observations to demonstrate that the presence of siblings had similar effects to the presence of parents on the development of juvenile behaviour, with individuals flying, hunting, and playing more often when conspecifics were present. Finally, through the use of artificial nests and remote videography, I identified that falcons nesting in vineyards are likely to suffer lower predation rates. I also found that falcons in vineyards are predated by a less dangerous suite of animals (such as hedgehogs, Erinaceus europaeus, and avian predators), than their counterparts in the hills, which are predated by more voracious species (such as stoats, Mustela erminea, and feral cats, Felis catus). The work presented in this thesis has also added to the current knowledge of New Zealand falcon breeding behaviour, prey preferences, and behavioural development.
Although agricultural regions globally are rarely associated with raptor conservation, and the ability of raptors to control the pests of agricultural crops has not been previously quantified, these results suggest that translocating New Zealand falcons into vineyards has potential for both the conservation of this species, and for providing biological control services to agriculture