Disk-winged bats (Thyroptera spp.) are the only mammals that use suction to cling to smooth surfaces, having evolved suction cups at the bases of the thumbs and feet that facilitate attachment to specialized roosts: the protective funnels of ephemeral furled leaves. We predicted that this combination of specialized morphology and roosting ecology is coupled with concomitantly specialized landing maneuvers. We tested this by investigating landings in Thyroptera tricolor using high-speed videography and a forcemeasuring landing pad disguised within a furled leaf analogue. We found that their landing maneuvers are distinct among all bats observed to date. Landings comprised three phases: (1) approach, (2) ballistic descent and (3) adhesion. During approach, bats adjusted trajectory until centered in front of and above the landing site, typically the leaf's protruding apex. Bats initiated ballistic descent by arresting the wingbeat cycle and tucking their wings to descend toward the leaf, simultaneously extending the thumb disks cranially. Adhesion commenced when the thumb disks contacted the landing site. Significant body reorientation occurred only during adhesion, and only after contact, when the thumb disks acted as fulcra about which the bats pitched 75.02±26.17 deg (mean±s.d.) to swing the foot disks into contact. Landings imposed 6.98±1.89 bodyweights of peak impact force. These landing mechanics are likely to be influenced by the orientation, spatial constraints and compliance of furled leaf roosts. Roosting ecology influences critical aspects of bat biology, and taken as a case study, this work suggests that roosting habits and landing mechanics could be functionally linked across bats.

Individuals within both moving and stationary groups arrange themselves in a predictable manner; for example, some individuals are consistently found at the front of the group or in the periphery and others in the center. Each position may be associated with various costs, such as greater exposure to predators, and benefits, such as preferential access to food. In social bats, we would expect a similar consistent arrangement for groups at roost-sites, which is where these mammals spend the largest portion of their lives. Here we study the relative position of individuals within a roost-site and establish if sex, age, and vocal behavior are associated with a given position. We focus on the highly cohesive and mobile social groups found in Spix's disc-winged bats (Thyroptera tricolor) given this species' use of a tubular roosting structure that forces individuals to be arranged linearly within its internal space. We obtained high scores for linearity measures, particularly for the top and bottom positions, indicating that bats position themselves in a predictable way despite constant roost-switching. We also found that sex and age were associated with the use of certain positions within the roost; for example, males and subadults tend to occupy the top part (near the roost's entrance) more often than expected by chance. Previous studies have shown that communally-roosting species often scramble to gain access to central positions, which are typically occupied by dominant individuals; thus, we speculate that our findings could also indicate some form of dominance hierarchy in our study species.

Roosts are vital for the survival of many species, and how individuals choose one site over another is affected by various factors. In bats, for example, species may use stiff roosts such as caves or compliant ones such as leaves; each type requires not only specific morphological adaptations but also different landing manoeuvres. Selecting a suitable roost within those broad categories may increase landing performance, reducing accidents and decreasing exposure time to predators. We address whether bats select specific roost sites based on the availability of a suitable landing surface, which could increase landing performance. Our study focuses on Spix's disc-winged bats (Thyroptera tricolor), a species known to roost within developing tubular leaves. Since previous studies show that this species relies on the leaves’ apex for safe landing and rapid post-landing settlement, we predict that bats will prefer to roost in tubular structures with a longer apex and that landing will be consistently more effective on those leaves. Field observations showed that T. tricolor predominantly used two species for roosting, Heliconia imbricata and Calathea lutea, but they preferred roosting in the former. The main difference between these two plant species was the length of the leaf's apex (longer in H. imbricata). Experiments in a flight cage also show that bats use more consistent approach and landing tactics when accessing leaves with a longer apex. Our results suggest that landing mechanics may strongly influence resource selection, especially when complex manoeuvres are needed to acquire those resources.

Roosts are vital for the survival of many species, and how individuals choose one site over another is affected by various ecological factors. Biomechanical constraints could also affect roost selection, particularly in volant taxa that require sites with easy access, thereby reducing costs (i.e., predation, accidents). To date, no studies have established an association between landing performance and roost-site selection, as predicted by biomechanical constraints associated with flight. We aim to determine roost-site selection in disc-winged bats (Thyroptera tricolor), a species known to roost within developing tubular leaves. This study is coupled with various experiments that measure how a conspicuous apex affects landing tactics and performance. We show that T. tricolor prefers leaves with a longer apex, the space typically used for landing. Bats also approach and enter these leaves more consistently, increasing task performance while reducing the risk of injuries.

Roosts are vital for the survival of many species, and how individuals choose one site over another is affected by various ecological factors. Biomechanical constraints could also affect roost selection, particularly in volant taxa that require sites with easy access, thereby reducing costs (i.e., predation, accidents). To date, no studies have established an association between landing performance and roost-site selection, as predicted by biomechanical constraints associated with flight. We aim to determine roost-site selection in disc-winged bats (Thyroptera tricolor), a species known to roost within developing tubular leaves. This study is coupled with various experiments that measure how a conspicuous apex affects landing tactics and performance. We show that T. tricolor prefers leaves with a longer apex, the space typically used for landing. Bats also approach and enter these leaves more consistently, increasing task performance while reducing the risk of injuries.