Head-bobbing in the Ring-billed Gull (<i>Larus delawarensis</i>)

Abstract

Lisney, Thomas J., and Nikolaus F. Troje. 2016. Head-bobbing in the Ring-billed Gull (Larus delawarensis). Canadian FieldNaturalist 130(2): 174-177.Many birds bob their head as they walk or run on the ground. The functional significance of this behaviour is unclear, but there is strong evidence that it plays a significant role in enhancing visual perception. If head-bobbing is advantageous, however, then it is a puzzle that some birds do not head-bob. As a group, gulls (Laridae) are among the birds that reportedly do not head-bob, yet here we report head-bobbing among Ring-billed Gulls (Larus delawarensis), observed and filmed in Ontario, when walking relatively slowly while foraging on the ground. This suggests that head-bobbing plays a key role in the visual detection of food items in this species. We suggest that head-bobbing may be a relatively common behaviour in foraging Ring-billed Gulls and speculate that other gulls (and indeed other birds) previously thought not to head-bob may in fact do so under certain circumstances.

Extended animal cognition

“…Head-bobbing is the rhythmic head movement that characterizes several species of birds, such as pigeons (Columba livia), ring-billed Gulls, (Larus delawarensis) and quails (Coturnix coturnix) (cf. Nyakatura & Andrada 2014;Lisney & Troje 2016). Thus, it is a common activity that several species of birds engage in by moving their head back and forward in a rhythmic manner.…”

“…Moreover, the thrust phase is fundamental, because it allows the bird to gather depth cues through motion parallaxes (cf. Lisney & Troje. 2016;Kral & 2003).…”