Behavioural responses of Chroicocephalus novaehollandiae nesting in human dominated ecosystems during their breeding season
Bird tourism is increasingly becoming popular, which results in varying degree of pressure on the avian fauna. Chroicocephalus novaehollandiae, a ground-nesting endemic gull of Australia, which breeds in colonies have their nesting sites often becoming tourist attractions. This study looks into the altered behaviour of breeding birds induced by the presence of tourists in the vicinity of their nesting sites. Nest density showed positive correlation with the distance from the boardwalk. Gulls nesting <5 m from the boardwalk were more vigilant towards a stationary investigator than the birds stationed farther away. Gulls within 5m of the structure exhibited high level of investigator oriented behavior (39% of occasions). Visual observation of the investigator (28% of occasions), flight (8%) and intrusion into neighbor’s territory (3%) were noticed. Investigator oriented behavior in birds tend to decrease with increasing distance from the boardwalk. The gulls apparently perceived larger groups of tourists as more threatening. Parents with mobile chicks showed increased intra-specific aggression. These groups were nested farther from the boardwalk, as early comers tend to occupy better nesting sites leaving less favorable sites for the latecomers. Presence of an investigator often resulted in the temporary neglect of nest in 12% of the birds stationed at a distance of <5 m from the boardwalk. Reduced focus on nesting activities among the Silver gulls, their increased energy expenditure and stress levels due to heavy tourist traffic may affect their reproductive success.