Aggressive vocalizations during intergroup interactions in roost defense in the Spix's disk‐winged bat

Abstract

Animals engage in agonistic interactions to gain exclusive access to territories and resources. Understanding these interactions in bats, however, has proven difficult given their high mobility and nocturnal habits. For bats, roosts are a critical resource; thus, the study of agonistic behaviors associated with the use of these resources could provide valuable information to understand how and whether individuals monopolize them. Here, we used Thyroptera tricolor to study agonistic behaviors associated with access to a roosting resource. We experimentally studied the behavioral responses of focal groups when interacting with different intruders during the occupation of an ephemeral roosting resource. We found that T. tricolor responds more aggressively to intruders than to members of its own group, increasing the number of aggressive vocalizations. We also found differences in the rate of agonistic behaviors based on the identity of the intruders. Specifically, we observed that bats produced a large number of aggressive vocalizations when interacting with nearby intruders, supporting the “nasty neighbor” hypothesis. This study provided the first empirical evidence that aggressive vocalizations may serve as a mechanism to defend and maintain exclusive roosting sites in social groups of T. tricolor.

Food-associated calls in disc-winged bats

“…Therefore, the production of "screech" calls in this species, while strongly associated with foraging activities, is not considered to be exclusively associated with a feeding context (Clay et al, 2012). In contrast, the evidence collected in our study, together with results of previous studies (Chaverri et al, 2018(Chaverri et al, , 2021Chaverri & Gillam, 2016;Chaves-Ramírez et al, 2023;Montero & Gillam, 2015), shows that food-associated calls in T. tricolor are emitted exclusively in a feeding context, and that calls prompt social recruitment. Future studies are needed to confirm that T.…”

“…Our recordings of feeding bats show that many individuals emitted distinct vocalizations while consuming an abundant prey item. This type of call has not been previously described in disc-winged bats (Chaverri et al, 2018, 2021; Chaverri & Gillam, 2016; Montero & Gillam, 2015), and is markedly different from calls emitted by this species in situations of distress (Chaves-Ramírez et al, 2023). We also observed that vocalizations prompted two responses in receivers which are typically associated with food-calling (Clay et al, 2012), namely increasing feeding-related behaviors and social recruitment.…”

Calling to the collective: contact calling rates within groups of disc-winged bats do not vary by kinship or association

“…When searching for roosts, individuals probably target those areas, which would reduce the probability of flying bats accidentally joining other groups and roosting bats responding to non-groupmates. The events would be costly because individuals entering a roost occupied by another group face the risk of aggression [45].…”

“…Alternatively, contact calling rates may not be explained by the individual identity of the receivers. In some taxa, call rates are influenced by the risk of becoming separated from one's group [41,42]; thus, contact calls may be produced for the entire group, not targeted at a single receiver, to remain in close contact with group members [43,44] or to avoid inter-group interactions, which could result in aggression [45]. In that case, we expect the best predictor of calling rate to be the caller, rather than the receiver or its kinship or association with the caller.…”