Disturbance to brood-rearing Hooded Plover Thinornis rubricollis: responses and consequences

We examined the causes and consequences of disturbance to the chicks of Hooded Plover Thinornis rubricollis in central southern Victoria, Australia. Humans were the most frequent source of encounters, and response rates to a variety of stimuli were high. Three possible mechanisms by which disturbance could reduce chick survival were evaluated. (1) Disturbance might cause thermal stress to chicks. An encounter with a human often caused brooding to cease, but it is not clear whether overall levels of brooding were compromised. Chicks found themselves un-brooded due to disturbance for up to 290 min, and in ambient temperatures of 10-46°C. (2) Disturbance might cause energetic stress to chicks. Encounters with humans usually caused chick foraging to stop. Higher levels of disturbance were associated with less chick foraging. There was a tendency for broods to forage in lower and potentially more profitable levels of the habitat in less-disturbed conditions. However, the overall pattern of habitat use was similar during disturbed and less-disturbed conditions. (3) Adult defence of broods could be compromised by disturbance. However, no brood predation occurred in disturbed circumstances, and adults stayed close to their broods even in disturbed conditions. These data suggest that defence of chicks was not compromised by disturbance.