Introduction Food dunking, or dipping food in water (Morand-Ferron et al. 2004), is a behaviour that has been noted across a range of bird species (Purser 1959; Morand-Ferron et al. 2004; Dearborn & Gager 2009; Kasper 2012). Dunking can be an important food-processing behaviour because it might allow animals to include items in their diets that would be otherwise unpalatable or toxic (Kasper 2012). For example, dunking might remove unpalatable tastes (Menkhorst 2012) or help to moisten or soften food, which may aid in digestion (Jones 1979; Morand-Ferron et al. 2004). Dunking has been observed in at least 25 bird species across 16 genera (Morand-Ferron et al. 2004), and appears to be particularly widespread in groups that possess high cognitive abilities (Morand-Ferron et al. 2004), such as the Corvidae (Cnotka et al. 2008; Emery et al. 2004). The Australian Magpie Gymnorhina tibicen is a member of the Corvides (Kearns et al. 2013; previously known as the core Corvoidea: Jønsson et al. 2016), and is believed to exhibit similar high cognition (Kaplan 2008), as demonstrated by behaviours such as food storing (caching: Rollinson 2002) and tool use (McCormick 2007), but until now dunking behaviour has not been noted in this species. We observed potential dunking behaviour by two Australian Magpies within the Talbingo Caravan Park, 1.15 km from Kosciuszko National Park, New South Wales (35°35′S, 148°17′E). The caravan park comprises permanent caravans, huts, and open campgrounds backed by open non-native forest, with sparse mid-storey vegetation coverage. The observation was recorded on a Sony HDR Handycam Camcorder as part of a larger study investigating the Mountain Katydid Acripeza reticulata (Orthoptera) (Umbers et al. unpubl. data), a putatively toxic and distasteful local insect (Umbers & Mappes 2015). As part of the study, live katydids were presented to wild Magpies, which were individually identifiable by their distinct territories, markings and family structures. There were few Magpies in the vicinity, so individuals were easy to track. The katydids were collected within the nearby Kosciuszko National Park and, given the proximity to the Park (1.15 km) and range of the Mountain Katydid, it is likely that the Magpies tested in this trial had encountered Mountain Katydids before. Following the presentation of one katydid to an adult male Magpie, we observed apparent food-dunking behaviour in a puddle by both the adult and a nearby juvenile Magpie. Footage is available at: http://www.youtube.com/watch?v=9aYJwOSeeTg. Observations Adult male Australian Magpie An adult male Magpie was presented with two katydids, the second one 2 minutes after the first. When presented with the first katydid, the Magpie picked up and held the insect by the body or an appendage and carried the katydid for short distances, interspersed with repeated bouts of vigorous wiping (slow, repeated dragging of the item on the ground) or thrashing (vigorous beating of the item from side to side on the ground). After 12 minutes 28 seconds, the Magpie appeared to cache the katydid under a bush. The Magpie processed the second katydid as follows: (1) It carried the katydid to a tree midway between the presentation point and a puddle that had formed around a leaking tap attached to one of the campsite buildings; (2) It thrashed the katydid on the ground for 14 seconds before moving a short distance and thrashing it on the ground for another 10 seconds; (3) It picked up the katydid and moved near the puddle (~1.5 m away), wiping the katydid on the ground for c. 48 seconds; (4) It dunked the katydid in the water and thrashed the katydid on the bottom of the puddle for c. 7 seconds, although the katydid was never clearly submerged as the puddle was very shallow (Figure 1a); and (5) It placed the katydid on the side of the puddle, and walked away. Juvenile (fledgling) Australian Magpie While the male was dunking the katydid, a juvenile Magpie was <30 cm away. Two minutes 7 seconds after the male left the second katydid on the side of the puddle, the juvenile picked up the katydid, thrashed it in the puddle for 33 seconds (Figure 1b), and then thrashed it on the bank. A novel observation of food dunking in the Australian Magpie Gymnorhina tibicen