Foraging behaviour and territoriality of the strawberry poison frog (Oophaga pumilio) in dependence of the presence of ants

Abstract

The present study investigates foraging and territorial behaviour of the strawberry poison frog (Oophaga pumilio) in dependence of the presence of formicine and myrmicine ants, which constitute the main food source of the frogs. Species of the formicine ant genera Brachymyrmex and Paratrechina contain highly toxic alkaloids (pumiliotoxins), which the frogs incorporate and accumulate in their skin what may serve for predator deterrence. Twelve male frogs of two populations (primary and secondary forest) in Hitoy Cerere, Costa Rica, were observed each for a full day. Calling time, feeding attempts and time spent inside and outside the core area of their territories were recorded. Furthermore, twelve males of both populations were observed during the main foraging time to determine, whether the frogs search for prey in specific patches of their territories. The ants inside the core areas of twenty four frog territories were collected and classified to genus. Ants of the genera Brachymyrmex and Paratrechina were classified to species or morphospecies, respectively. The presence of formicine and myrmicine ants in territorial areas was compared to non-territorial sites. We found that formicine ants (Brachymyrmex and Paratrechina) were more present inside the territorial core areas than outside. The higher presence of these ants in the core areas was associated with longer foraging times. We verified that toxic alkaloids of the pumiliotoxin group are present in the dendrobatid frogs of Hitoy Cerere. The results of this study suggest that toxic diet may be linked to territoriality in this frog species.

Female–female aggression is linked to food defence in a poison frog

“…In our study area, we mainly found myrmicine ants (Table 2). These ants are considered as potential dietary sources for histrionicotoxins which are the most frequent toxins in male frogs in Hitoy Cerere (Staudt et al, 2010). Our study showed ants to be more abundant in the territories of the females, indicating that ants influence the distribution and territorial behaviour of them.…”

“…The main purpose for aggressive territorial behaviour in male O. pumilio is to guarantee the availability of calling sites, access to females and suitable sites for courtship and oviposition (Meuche, Linsenmair, & Pröhl, 2012;Pröhl, 2003;Pröhl & Berke, 2001). Furthermore, males spend more time feeding in their territories, even though the availability of insect prey is the same in and outside of their territories (Staudt, Meneses Ospina, & Pröhl, 2010). Recent studies showed that also the females of O. pumilio exhibit intrasexual aggressive behaviour (Haase & Pröhl, 2002) particularly in the intensely used core areas of their home ranges (Meuche et al, 2011).…”

“…However, female home ranges are spatially closely associated with potential tadpole-rearing sites (i.e., water-filled leaf axils) and overlap near these (Pröhl & Berke, 2001). Because of the much higher energetic costs of maternal care compared to male care and the importance of access to high quality food, necessary for toxin sequestration (Staudt et al, 2010), we assume female habitat occupancy and aggressive behaviour to be linked to the exploitation of food resources (Meuche et al, 2011).…”