Many insects have auditory systems capable of detecting the ultrasonic calls of insectivorous bats and use these cues to evade capture. I tested the hypothesis that bats can decrease the conspicuousness of their echolocation calls by varying three call features: duration, repetition rate and ramp times. This was done by examining the AN2 command interneuron’s response to these features in the cricket, Teleogryllus oceanicus, after describing the firing pattern necessary for evasive behaviour. Past studies on duration and repetition rate suggest increased thresholds for short durations and low repetition rates. Measurements of the AN2 response, which controls evasive behaviour, indicated that increased thresholds were a result of a decrease in bursting, raw spike numbers and an increase in latencies in the AN2. Results suggest that there is pressure on bats to evade early detection and that this can be done by employing large ramp times in search phase echolocation calls.

Many insects have auditory systems capable of detecting the ultrasonic calls of insectivorous bats and use these cues to evade capture. I tested the hypothesis that bats can decrease the conspicuousness of their echolocation calls by varying three call features: duration, repetition rate and ramp times. This was done by examining the AN2 command interneuron’s response to these features in the cricket, Teleogryllus oceanicus, after describing the firing pattern necessary for evasive behaviour. Past studies on duration and repetition rate suggest increased thresholds for short durations and low repetition rates. Measurements of the AN2 response, which controls evasive behaviour, indicated that increased thresholds were a result of a decrease in bursting, raw spike numbers and an increase in latencies in the AN2. Results suggest that there is pressure on bats to evade early detection and that this can be done by employing large ramp times in search phase echolocation calls.

I investigated Lake Sturgeon (Acipenser fulvescens) foraging and anti-predator behaviour. My goals were to understand: (1) The role of environmental change on foraging and anti-predator behaviour trade-offs. (2) The relative cost/benefit trade-off between escape behaviour and cover-seeking behaviour. (3) How development of several independent morphological traits affects anti-predator behaviours. I used simulated river mesocosms to study Lake Sturgeon behavioural ecology under controlled conditions. I found: (1) Foraging intensity was significantly higher during the night than the day as well as in turbid environments versus clear environments, indicating that decreased turbidity alone, may in part drive anti-predator behaviour and constrain foraging activity. (2) In high-risk clear-water environments, Lake Sturgeon responded to danger by evoking an escape response and seeking cover in rocky microhabitats. However, in low-risk turbid environments, Lake Sturgeon responded to danger by seeking cover in rocky microhabitats, but not fleeing to a significant degree. Cover-seeking behaviour may therefore be a relatively low-cost/high-benefit anti-predator strategy. (3) Strong evidence for trait co-dependence between escape responses and body size, where larger fish were able to elicit stronger escape responses. I also found that cover-seeking behaviour exhibited a complex multi-tiered relationship, representing a mixture of trait compensation and trait co-specialization that is dependent on specific combinations of morphological traits. These findings are important because they help us understand: (1) The degree to which anti-predator behaviour can be influenced by changing environmental conditions. (2) The relative cost/benefit trade-off between two common anti-predator behaviours. (3) How behaviour and morphology interact in species with a complex anti-predator phenotype.