Habituation and habitat changes can moderate the impacts of human disturbance on shorebird breeding performance

Abstract

Disturbance by humans is widely expected to reduce the reproductive fitness of nesting birds if disturbance reduces nest attentiveness, and unattended eggs experience increased risk of predation or exposure to potentially lethal temperature extremes. Yet, relatively few studies have examined the physiological or behavioural mechanisms whereby disturbance influences reproductive fitness, or the extent to which the costs of disturbance may be reduced through habituation. We compared the behavioural responses, egg temperatures and reproductive success of shore-nesting white-fronted plovers Charadrius marginatus to disturbance at two breeding sites experiencing low versus high human recreational activity, respectively. Daytime nest attentiveness decreased with increasing experimental disturbance at both sites, but this relationship differed between sites; for any given level of disturbance, incubating birds at the more disturbed site had greater nest attentiveness. They achieved this through habituation, allowing a closer human approach before leaving the nest, and returning to the nest faster after a disturbance event. Despite lower average daytime nest attentiveness at the more disturbed site, incubation temperatures did not differ significantly between sites. Nest mortality, mostly by natural mammalian and corvid predators, was significantly lower at the site experiencing high recreational activity. However, chick mortality was significantly greater at the more disturbed site, most likely because of predation by domestic dogs. Chick mortality may have been increased by the habitation of chicks, whose escape responses were much reduced at the more disturbed site. Nonetheless, annual fecundity was substantially higher at the more disturbed site, showing that the overall reproductive fitness of wild birds is not always compromised by human disturbance and urbanization.

Use of urban marine habitats by foraging wading birds

“…For example, Yasue (2006) found that human disturbance was not influencing habitat selection in shorebirds using coastal habitats in British Columbia, Canada, and in fact the time taken for the birds to resume feeding after a disturbance was less in areas of high prey availability. Evidence of habituation to human disturbance has also been noted in nesting shorebirds and piscivorous waterbirds (Newbrey et al 2005;Baudains and Lloyd 2007). In our study, wading bird density was greater at sites with more shallow open water (i.e., open water <15 cm) and higher prey density (i.e., high prey availability), suggesting that the birds may be to some extent tolerating the effects of surrounding urbanization to utilize enhanced prey resources.…”

“…As a result, intra-and inter-specific competition and density-dependent phenomena may not be as prominent at our sites. Also, the urban setting of our study area may have supported lower densities of both mammalian and avian predators, thus lowering the predation risk for birds foraging at our sites (Johnsen and vanDruff 1987;Blair 1996;Baudains and Lloyd 2007). However, there is also the possibility that the absence of top-level predators in urban landscapes may lead to higher densities of mammalian predators such as red fox Vulpes vulpes coyote Canis latrans that are known to frequent coastal marshes.…”

Response of tropical avifauna to visitor recreational disturbances: a case study from the Sinharaja World Heritage Forest, Sri Lanka

“…Visitors feeding blue magpies and junglefowls were a common observation during field studies. Such visitor behavior along with exposure to recurring recreational disturbances can alter the normal behavior of birds and induce habituation to human presence (Marcum 2005;Peters and Otis 2006;Baudains and Lloyd 2007;Smith-Castro and Rodewald 2010).…”

AvianBuffer: An interactive tool for characterising and managing wildlife fear responses

“…In the context of wildlife management, habituation will decrease the disturbance to birds caused by humans and may therefore be favourable (although decreased responsiveness can be maladaptive; e.g. Baudains and Lloyd 2007). However, in the context of pest management, habituation will decrease animal responsiveness to deterring stimuli and multi-faceted approaches must therefore be adopted (see below).…”