Clever strategists: Australian Magpies vary mobbing strategies, not intensity, relative to different species of predator

Abstract

Anti-predator behaviour of magpies was investigated, using five species of model predators, at times of raising offspring. We predicted differences in mobbing strategies for each predator presented and also that raising juveniles would affect intensity of the mobbing event. Fourteen permanent resident family groups were tested using 5 different types of predator (avian and reptilian) known to be of varying degrees of risk to magpies and common in their habitat. In all, 210 trials were conducted (across three different stages of juvenile development). We found that the stage of juvenile development did not alter mobbing behaviour significantly, but predator type did. Aerial strategies (such as swooping) were elicited by taxidermic models of raptors, whereas a taxidermic model of a monitor lizard was approached on the ground and a model snake was rarely approached. Swooping patterns also changed according to which of the three raptors was presented. Our results show that, in contrast to findings in other species, magpies vary mobbing strategy depending on the predator rather than varying mobbing intensity.

The association between evidence of a predator threat and responsiveness to alarm calls in Western Australian magpies (Cracticus tibicen dorsalis)

“…Since magpie alarm calls can vary according to predator type (i.e. terrestrial or aerial), and urgency (proximity of predator), we repeated the same alarm call type throughout the playback, to prevent presenting conflicting calls within the playback (Kaplan et al, 2009; Koboroff, Kaplan & Rogers, 2013). Only alarm calls directed at terrestrial predators were used for playback.…”

Audition and Hemispheric Specialization in Songbirds and New Evidence from Australian Magpies

“…Field studies of behavioural laterality in birds are still relatively rare, but the few undertaken so far have shown that laterality may play a role in vigilance behaviour [1,2], in predation and sexual behaviour [3,4] and even in tool manufacture, as shown in the New Caledonian crow, Corvus moneduloides [5]. In fact, in the special case of tool use and manufacture by crows, the activity appears to be strongly lateralized because birds were seen to use their right eye even when this posed some difficulties [6].…”

Mobbing behaviour in a passerine community increases with prevalence in predator diet

“…Animals adjust the strength of their mobbing behaviour according to the perceived risk associated with the predator's threat level (Koboroff et al . , Billings et al . , Dutour et al .…”

“…Mobbing can be beneficial and may cause a predator to leave an area (the 'move-on hypothesis'; Curio 1978, Pettifor 1990, Flasskamp 1994, Pavey & Smyth 1998, but may also be costly by increasing the risk of injury or death to the mobbing individual (Curio & Regelmann 1986, Sordahl 1990, Dugatkin & Godin 1992. Animals adjust the strength of their mobbing behaviour according to the perceived risk associated with the predator's threat level (Koboroff et al 2013, Billings et al 2015, Dutour et al 2016.…”