Species‐specific strategies increase unpredictability of escape flight in eared moths

Abstract

Many prey species overlap in time and space and are hunted by the same predators. A common anti‐predator behaviour is using evasive manoeuvres to escape an attacking predator. The escape‐tactic diversity hypothesis postulates that species‐specific differences in evasive behaviour will increase the overall unpredictability experienced by predators within a predator–prey community. Evolutionary, escape‐tactic diversity would be driven by the enhanced predator protection for each prey individual in the community. However, escape‐tactic diversity could also be a functional consequence of morphological differences that correlate with evasive capabilities. Echolocating bats and eared moths are a textbook example of predator–prey interactions. Moths exhibit evasive flight with diverse tactics; however, the variability of their evasive flight within and between species and individuals has never been quantified systematically. In addition, moth species show variation in size, which correlates with their flight capability. We recorded flight strength during tethered flight of eight sympatric moth species in response to the same level of simulated bat predation. Our method allowed us to record kinematic parameters that are correlated with evasive flight in a controlled way to investigate species‐specific differences in escape tactics. We show species‐specific and size‐independent differences in both overall flight strength and change of flight strength over time, supporting the escape‐tactic diversity hypothesis for eared moths. Additionally, we show strong interindividual differences in evasive flight within some species. This diversity in escape tactic between eared moths increases the overall unpredictability of evasive flight experienced by bat predators, likely providing increased protection against predatory bats for the single individual.

Hunting bats adjust their echolocation to receive weak prey echoes for clutter reduction

“…To our surprise, we found large variations in the relative bat-prey approach speeds [1.4 to 4.9 m/s (95% data range), derived from the slopes of the echo streams; fig. S1], indicating that bats used nonstereotypic motor approaches when tracking prey with potentially different evasive strategies (20). Some of the typical aerial prey types targeted by greater mouse-eared bats belong in families with ears (e.g., Geometridae, Notodontidae, and Noctuidae), allowing these moths to perform evasive maneuvers.…”

Low foraging rates drive large insectivorous bats away from urban areas

“…This wide range of observed approach speeds, ranging from 5 to 15 m/s, and buzz durations, ranging from 150 to 500 ms, indicate that the bats are employing a diverse set of hunting tactics at both study sites. This reflects their sensory‐motor behavior likely in response to different prey types that across both study sites exhibit a suit of different evasive maneuvers (Hügel & Goerlitz, 2019) (Figure 2). This is in contrast to other mammalian synanthropic species that adjust to an urban setting by generalizing their diet (Scholz et al., 2020) or by adjusting to new food sources (Athreya et al., 2016; Bowers & Breland, 1996; Wist et al., 2022).…”

Contrasting laboratory and field outcomes of bat–moth interactions

“…Predator–prey interactions represent key interspecific behaviours (Abrams, 2000; Chase et al, 2002). However, the impact of predator–prey interactions on the dietary composition of predators that consume mobile prey, particularly nocturnal and small‐bodied mobile prey like insects, remains largely unexplored (Andreas et al, 2023; Hügel & Goerlitz, 2019; Shultz et al, 2004; Suzuki et al, 2022; Wray et al, 2021). This knowledge gap can be attributed to the challenges associated with observing interactions between predators and small‐bodied mobile prey, as well as the difficulty in quantifying the proportions of small prey in predator diets (Clare et al, 2009; Corcoran & Conner, 2016; Fernández et al, 2022).…”