Behavioural tactics used by invasive cane toads (Rhinella marina) to exploit apiaries in Australia

Abstract

Behavioural flexibility plays a key role in facilitating the ability of invasive species to exploit anthropogenically-created resources. In Australia, invasive cane toads (Rhinella marina) often gather around commercial beehives (apiaries), whereas native frogs do not. To document how toads use this resource, we spool-tracked cane toads in areas containing beehives and in adjacent natural habitat without beehives, conducted standardized observations of toad feeding behaviour, and ran prey-manipulation trials to compare the responses of cane toads versus native frogs to honeybees as potential prey. Toads feeding around beehives travelled shorter distances per night, and hence used different microhabitats, than did toads from nearby control sites without beehives. The toads consumed live bees from the hive entrance (rather than dead bees from the ground), often climbing on top of one another to gain access to the hive entrance. Prey manipulation trials confirm that bee movement is the critical stimulus that elicits the toads' feeding response; and in standardized trials, native frogs consumed bees less frequently than did toads. In summary, cane toads flexibly modify their movements, foraging behaviour and dietary composition to exploit the nutritional opportunities created by commercial beehives, whereas native anurans do not.

Challenges of dehydration result in a behavioral shift in invasive toads

“…Furthermore, when the surrounding landscape is dry, cane toads appear unwilling to disperse away from sources of moisture (Brown et al 2011). Our current findings cannot directly indicate an increase in sedentary behavior within the invasive guttural toad population, as seen by cane toads in Australia (Brown et al 2011;Silvester et al 2018); however, maintaining a close position to an important resource is a critical behavioral shift to cope with the challenges of invasion (Gruber et al 2017b). We suggest that further research use in situ spatial ecology of invasive and native populations to further test this hypothesis by examining shifts in dispersal rates and movement patterns.…”

“…This suggests that after toads from the invasive population found a critical resource, they were more prone to remain close to it, when compared to conspecifics from the native range. Similar patterns have been seen in cane toads in Australia, which remained close to a food source at night and over a period of weeks (Silvester et al 2017(Silvester et al , 2018. Furthermore, when the surrounding landscape is dry, cane toads appear unwilling to disperse away from sources of moisture (Brown et al 2011).…”

Increased rates of dispersal of free-ranging cane toads (Rhinella marina) during their global invasion

“…Adult cane toads were captured in the wild, fitted with small radio-transmitters on waist belts (Holohil model PD-2, 2.5 gm, < 3% of toad body mass), released at the site of capture, and then relocated on a daily basis (where possible) for at least 5 days thereafter. We did not include data from spool-tracking studies 24 , 57 , or from studies with longer intervals between relocations 39 . Most of the studies were conducted by members of the same research group, over a 16-year period (2005 to 2020).…”