Turnstone-like feeding in Redshank

• Main Author: A. Barbosa
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Pyke; Sandy Beach; Arenaria interpres
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.561.6353; http://digital.csic.es/bitstream/10261/9378/1/p00034-p00035.pdf

Foraging behaviour of waders has been widely studied and different feeding strategies well established (Goss-Custard 1969; Baker & Baker 1973; Pienkowski 1978; Puttick 1979). Sandpipers (Scolopacidae) usually feed with a continous searching strategy as they walk. Turnstone Arenaria interpres how six feeding techniques; routing, turning stones, digging, probing, hammer-probing and surface pecking (Marshall 1981; Whitfield 1990). It is important o describe deviation from the usual foraging pattern in species forming mixed flocks (Paulson 1990) because of the relevance of this information to optimal foraging theory (Schoener 1971; Pyke et al. 1977). On the other hand feeding specializations have importance for evolutionary game theory and the concept of alternative strategies (Maynard Smith 1982; Whitfield 1990). Such concepts suggest hat three main mechanisms may be responsible for individual feeding preferences, including individuals assessing how other individuals are feeding (Dawkings 1980; Davies 1982). In the course of a study of waders foraging behaviour at the Ebro Delta (one of the main wintering areas for waders in the Mediterranean; in NE Spain), I observed a deviation from the usual foraging technique of Redshanks Tringa totanus. A flock of about 120 Dunlins Cal/•lris alpina, eight Redshanks and one Turnstone Arenaria interpres were foraging on a sandy beach. Dunlins foraged in their usual manner in the water. Turnstones fed using the routing technique, bulldozing piles of seaweed and pecking to investigate or capture prey along the shore (Withfield 1990). technique as Turnstone, that is routing along the shore. The observation was made for twenty minutes. Foraging rate was determined from probing, pecking or routing (Table 1). The substrate exposed for foraging was only four metres wide as the tidal range is only a few metres in the Mediteranean Sea (Martinez-Vilalta 1984). This routing behaviour has never been described for