Predation is the main cause of nest failure for most species of shorebirds. However, threats to beach nesting shorebirds also include natural factors and disturbances associated with human activities, therefore nest site selection and strategies that reduce predation such as habitat selection should be favoured during nest site selection (Rickleifs 1969; Martin 1992).
High tides, big seas and long heavy rain events can devastate beach-nesting shorebirds such as the Pied Oystercatcher causing nest inundation and flooding as they nest near the high tide mark. Strong winds can be equally devastating to beach nesting species as wind blown sand covers the eggs and newly hatched chicks often causing the parents to abandon the nest.
Ground nesting species are also exposed to predation by introduced such as foxes, dogs and native species for example ravens, gulls, rats and goanna’s. Predation by the Red Fox (Vulpes vulpes) is listed as a key threatening process under the TSA act in NSW. Domestic Dogs have also been recorded to take eggs and chicks but to a lesser extent than foxes.
Native Animals also prey on eggs and chicks of beach nesting birds. Gulls, Ravens and Raptors target shorebird nesting sites, along with Goanna’s (Varanus varius), Black Rats (Ratus ratus), and the Long-Nosed Bandicoot (Perameles nasuta) have been recorded taking eggs and chicks throughout Queensland and New South Wales. Raven attacks on shorebirds can result in a high mortality of eggs, nestlings and fledglings (Tella et al 1995). Australian Ravens (Corvus coronoides) between 1992 and 1995 were responsible for 67 egg losses over four seasons, with 37 of these in one season alone (Priddle and Ross 1996).
Birds perceive dogs as a greater threat than humans on foot; consequently, the avoidance response of birds is greater when faced with dogs (Leseberg, Hockey et al 2000; Lord, Waas et al. 2001). Laferty (2001a) report that 10% of humans and 39% of dogs disturbed birds during a short observation period, with 70% of birds taking flight. Similarly, New Zealand Dotterels were flushed from their nests earlier and stayed off them longer when faced by dogs than humans (Lord, Waas et al. 2001).
Human disturbance on birds can be defined as human – bird interactions which cause birds to behave differently from their baseline behavior, i.e. Behavior they would otherwise exhibit (Smit and Visser 1993; Baudains and Lloyd 2007; Madsen 2007). With
