Echoes of the Night

The findings from this study reveal important insights into the relationship between habitat type and bat biodiversity in urban environments. While both sites supported bat activity, Falaise Saint-Jacques demonstrated greater species richness, suggesting that less-maintained greenspaces may offer key ecological benefits.

The Falaise Saint-Jacques is a narrow strip of forest-edge habitat, which limits its ability to function as a viable source habitat — an area capable of sustaining and growing a self-sufficient bat population. However, in a city where natural greenspaces are rare, even this small, rewilded space provides critical shelter, foraging opportunities, and connectivity for urban wildlife. Such environments can serve as valuable refuges for species that might otherwise struggle to find suitable habitat in urban settings.

Surprisingly, the informal wetland site within the Falaise Saint-Jacques showed higher overall bat activity than the formal urban park. The wetland’s diverse vegetation and nearby water source likely created better foraging conditions, attracting more insects — and in turn, more bats. However, differences in habitat structure and environmental conditions may have also played a role. The Falaise Saint-Jacques site is located farther from major roads and experiences less artificial lighting compared to the urban park, which could reduce noise interference and improve the ability to detect bat calls, as well as encouraged bat presence more generally. Conversely, the wetland site’s denser vegetation may have created more “clutter,” potentially making it harder to detect certain species with quieter or more directional calls, such as Myotis lucifugus (Little Brown Bat) or the Tri-colored Bat (Perimyotis subflavus), both of which are known for their faint and highly directional echolocation (Veselka, N. 2013 ; Humbolt State University Bat Lab, 2011). Therefore, due to the spatial configuration of The Falaise, this study could show an underrepresentation of high frequency bat presence.

The urban park, by contrast, experienced higher levels of human traffic and artificial lighting from streetlamps and floodlights, which may have deterred some bat species or affected their behavior. Species with louder, broader-ranging calls — such as the Big Brown Bat (Eptesicus fuscus) and Hoary Bat (Lasiurus cinereus) — may have been more readily detected in this environment, as these calls travel farther and are less susceptible to interference from ambient noise(Humbolt State University Bat Lab, 2011). Therefore, placement of the microphone in the park could have caused an underrepresentation of bat presence (ie placing the audiomoth in a quieter corner of the park could better represent bat presence, as some may not fly so close to the street).

The presence of endangered bat species in this study highlights the urgent need for conservation efforts. According to the Committee on the Status of Endangered Wildlife in Canada (COSEWIC), all bat species identified in this study— except the big brown bat (Eptesicus fuscus)— are listed as endangered due to population declines exceeding 50-80% in Quebec (COSEWIC, 2013; COSEWIC, 2023). Factors such as habitat loss and degradation, white-nose syndrome, wind turbine collisions, and global declines in insect abundance have all contributed to the decline of bat species (COSEWIC, 2023). However, many bat species are classified as data deficient under COSEWIC, meaning there is insufficient information to fully assess their population status. As such, all estimates in decline and status are just that— estimates. This data gap presents a significant challenge for conservation planning, reinforcing the value of studies that document species presence.

Little Brown (Myotis lucifugus) was identified a few times based on call sequences of 4-6 well-formed calls. While these detections align with Little Brown’s characteristic call patterns, they fall short of stricter thresholds for confirmed presence (6-10 well-formed calls), according to SonoBat (Szewczak, 2022). Consequently, Little Brown has been classified as a Probable Presence rather than a confirmed detection. Nonetheless, Little Brown’s known foraging habits — which include feeding over water, along waterways, forest edges, and in forest gaps — align with the habitat characteristics of the Falaise Saint-Jacques monitoring site, and it was for this reason, along with having been detected on multiple days that it was decided to keep this identification in the study. Despite being a probably presence, this nonetheless highlights the ecological importance of preserving sites like the Falaise Saint-Jacques.

Another important note is that call frequency is not a proxy for abundance. Some bat species simply call more frequently than others, and a single bat may pass the microphone multiple times, with each pass counting as a detection. This variability makes it important to interpret results carefully.