Shorebirds can adopt foraging strategies that take advantage of human fishing practices

Abstract

Human presence and activities are considered to be a potential threat to many species, mainly because they interfere with the abilities of many animals to exploit essential resources. In this study we investigate the influence of human presence and activities on the behaviour of nine shorebird species in an intertidal area at Baía de Todos os Santos, north-eastern Brazil. The area is used both by shorebirds and traditional human community to extract invertebrates for food, and also used by people for recreation. We analyse and compare the foraging behaviour of shorebirds under three different conditions: absence of humans, presence of humans manually gathering shellfish (shellfishing), and presence of humans engaged in recreational activity. Recreational activity was associated with greater behavioural change to the shorebirds than shellfishing. Shorebirds were less plentiful, showed lower foraging rates and moved around more when exposed to recreational activity. Larger shorebirds were less abundant when shellfishing or recreational activities were taking place. Intertidal areas of sediment manually overturned by shellfishers had higher rates of shorebird foraging and agonistic encounters, suggesting that shorebirds’ foraging strategies take advantage of human shellfishing. These results can be interpreted within a conservation framework to provide guidelines for the management decisions in areas used by shorebirds.