Urban Naturalist S. Raymond and C.C. St. Clair 2025 No. 77 1 2025 Urban Naturalist 77:1–7 Fisher Use of an Ecological Corridor Near the City Center of Edmonton, Canada, A City of Over One Million People Sage Raymond1* and Colleen Cassady St. Clair2 Abstract - Cities limit landscape connectivity for urban-avoiding species. Using snow tracking and a remote camera, we detected a Fisher (Pekania pennanti) in Edmonton, Canada, where contiguous natural areas in a river valley and adjacent ravines provide connectivity within a city of over 1 million people. Because Fishers typically avoid open or urban environments and had not previously been documented so close to the center of a large city (~2.5 km), this detection was unusual, and we speculated that this individual was dispersing. This observation suggests that Fishers may use ecological corridors in highly urbanized landscapes even closer to city centers than previously thought and adds to a body of evidence showing the value of forested corridors for urban-avoiding, forestadapted species. Introduction Urban landscapes limit use for many wildlife species because human disturbance, limited resources, landscape homogenization, and habitat loss contribute to increased mortality, reduced connectivity and gene flow, and changes in patterns of stress and disease (Lowry et al. 2013, McKinney 2006). Corridors that provide connectivity through cities and connect urban green spaces to non-urbanized areas outside of city limits can provide habitat resources (Douglas and Sadler 2011), enable dispersal (Evans et al. 2017), and support gene flow among subpopulations (Munshi-South 2012). Relative to urban-adapting and urban-exploiting species, which successfully use urban resources and occupy cities (Blair 1996, Shochat et al. 2006), urban-avoiding species do not adapt well to anthropogenic landscapes or disturbances (Blair 1996, McKinney 2006). For such species, cities represent a considerable barrier, and corridors may be especially important (Riley et al. 2014). Pekania pennanti Erxleben (Fishers) are an example of a species with many characteristics that are hypothesized to limit urban adaptation (Kark et al. 2007, Santini et al. 2019): they are solitary, have large home ranges, and consume a semi-specialized, carnivorous diet (Feldhamer et al. 2003). Fishers use a diversity of forest types for travel, as long as they provide adequate cover (Olson et al. 2014), including use of suburban areas in eastern North America (LaPoint et al. 2013), but they are poorly adapted to open and urban areas (Olson et al. 2014; Sauder and Rachlow 2014, 2015; Weir and Almuedo 2010) and depend on habitat features of mature forests (i.e., cavities) for denning (Weir and Almuedo 2010). They generally avoid human disturbance (Kordosky et al. 2021). Consequently, Fishers rarely occur in large cities: among research grade observations of Fishers from iNaturalist (inaturalist.org), the only observations within 20 km of city centers larger than 1 million occurred near Montreal, Canada (n = 3) and Ottawa, Canada, (n = 33), with only a single observation of a Fisher within 10 km of these cities. There were no such observations 1Department of Biological Sciences, University of Alberta, 116 St and 85 Ave, Edmonton, Alberta, Canada, T6G 2R3, rraymon1@ualberta.ca.2Department of Biological Sciences, University of Alberta, 116 St and 85 Ave, Edmonton, Alberta, Canada, T6G 2R3. Associate Editor: Jeremy Pustilnik, Yale University. Urban Naturalist S. Raymond and C.C. St. Clair 2025 No. 77 2 in proximity to large cities in western North America (i.e., west of Eastern Time Zone) where Fishers are also generally rarer (Figure 1; Feldhamer et al. 2003). In this note, we describe an observation of a Fisher within the city limits of Edmonton, Canada, a city with a population size of over 1 million (1,010,809 in 2021; Government of Canada 2022). We detected this individual via both snow tracking and a remote camera while conducting a study of boldness in urban Canis latrans Say (Coyotes) using novel objects. Study area Edmonton is the northernmost city of > 1 million people in North America with a sprawling urban footprint, covering 684.4 km2 (City of Edmonton 2019). Edmonton is unusual for the large network of protected areas surrounding the North Saskatchewan River and adjacent ravines (Fig. 2), which is the largest contiguous urban natural area in Canada (City of Edmonton 2024). Most of this area is forested with a mix of young and old deciduous stands and, to a lesser extent, old conifer stands, interspersed with recreational resources such as trails, sports fields, picnic areas, and parki ng lots. Methods Between February 1 and April 3, 2024, we deployed a network of 26 remote cameras (Browning HP4 Recon Force Elite) to study the behaviour of urban coyotes. We deployed cameras in green spaces with varying levels of urbanization within Edmonton city limits, targeting sites where snow tracking indicated high levels of coyote activity and low levels of use by humans and domestic dogs. All sites were separated by at least 1 km, and we deployed cameras evenly among the four quadrants of the city (Northeast, Northwest, Southeast, Southwest). Cameras were set to video mode, and we maintained them twice weekly. Once Figure 1. Location of Fisher observations from iNaturalist (research grade) and Stevenson (2022) in relation to cities of more than 1 million inhabitants within Fisher historical range in western North America. Insets show the city centers of Edmonton and Calgary, Alberta. Urban Naturalist S. Raymond and C.C. St. Clair 2025 No. 77 3 weekly, each site was baited with ~1 tsp of canned sardine (Avrin et al. 2021), which hung above the field of view in a decomposable tea bag. While accessing remote camera sites, we routinely noticed and identified tracks in snow. The observer (S.R.) was professionally certified (specialist) in wildlife track and sign identification (trackercertification.com). Results On February 12, 2024, while accessing a site to maintain a remote camera, we detected Fisher tracks in the snow in a municipal park (Strathearn Park; Fig. 3). We identified the tracks based on the presence of a 2x2 lope, which is typical for mustelids moving in deep snow (Elbroch and McFarland 2019). The tracks were too large to be from a Martes americana Turton (American Marten), and the feet were too furred to be from a Lontra canadensis Schreber (River Otter). Tracks were approximately 8 cm long by 6 cm wide, and groups of tracks were generally ~60 cm apart, which are consistent with literature values for Fishers (Elbroch and McFarland 2019). Video from the nearby camera revealed a Fisher detection recorded on February 10, 2024, at 23:48, which we presumed to be the same individual (see Supplemental File 1, available online at https://eaglehill.us/urna-authorname-file#.pdf). The Fisher travelled Figure 2. Location of Fisher observation in Edmonton, Canada (left) and relative to urban parks that form corridors (right), 2024. Imagery in the right panel was retrieved from Google Earth (https://earth. google.com/web/). Urban Naturalist S. Raymond and C.C. St. Clair 2025 No. 77 4 past this remote camera at a distance of ~4 m. We identified the animal as a Fisher based on loping locomotion, small ears, and a long, dark tail (Fig. 3; see Supplemental File 1). This animal was located ~2.5 km from the Edmonton city center and 8.2 km from the Anthony Henday Highway, which surrounds the most urbanized parts of the city, including our study site, and presumably limits wildlife movement (Fig. 1). The site was near the intersection of a green space corridor surrounding Mill Creek and another corridor adjacent to the North Saskatchewan River valley. The site was forested and dominated by young (mostly pole sapling) deciduous trees, especially Acer negundo Linnaeus (box elder) and Populus tremuloides Michx (trembling aspen). We estimated that the largest trees were ~20 years old. The understorey was dense, but shrub identification was challenging given winter conditions. In this area, we often observed the tracks of nocturnal Lepus americanus Erxleben (Snowshoe Hare), diurnal Tamiasciurus hudsonicus Erxleben (Red Squirrels), and nocturnal Glaucomys sabrinus Shaw 1801 (Flying Squirrels), all of which are documented Fisher prey (Feldhamer et al. 2003). Discussion Following intensive harvest and habitat loss, Fishers have been extirpated from much of their historic range, especially in western North America (Ruggiero et al. 1994). Habitat loss has exacerbated Fisher declines and range contractions, especially given their selection for habitat features primarily found in mature forests, such as tree cavities (Sauder and Rachlow 2014, Weir and Almuedo 2010). In recent years, Fishers have been documented using a diversity of forest types (Sauder and Rachlow 2015), including in suburban areas of eastern North America, such as in New York state (LaPoint et al. 2013) and Connecticut (Polansky 2016). Partially as a result of reintroductions (Lewis et al. 2012), Fishers have Figure 3. Fisher tracks in snow (left and middle) and a still frame extracted from the video of the Fisher (right), all of which were detected in Edmonton, Canada, 2024. The boot print in the middle panel measures ~28 cm long. The full video is available as supporting information. Photos taken by the author. Urban Naturalist S. Raymond and C.C. St. Clair 2025 No. 77 5 recently expanded and recolonized parts of Nova Scotia (Milton et al. 2022), California (Allen et al. 2015), and central Alberta (Stewart et al. 2017). It appears that Fishers are returning to their historic ranges while exhibiting broader habitat selection that increasingly includes urban areas. Relative to previous Fisher observations, particularly from western North American cities, this observation was noteworthy because it occurred uniquely close to the city center. Among research grade Fisher observations on iNaturalist (inaturalist.org), the previous closest to Edmonton occurred ~23 km from the city center; like our observation, this detection occurred along the North Saskatchewan River corridor. An extensive camera trap network (n = 89 cameras) deployed in and around Edmonton between 2018 and 2021 detected Fishers 6 times at 2 locations, however these locations were separated by only 2 km, occurred ≥16.5 km from city center, and were within 2 km of the banks of the North Saskatchewan River (Stevenson 2022). That we detected a Fisher only once given our sampling effort, in conjunction with the paucity and distribution of previous detections, suggests that this may have been a dispersing individual rather than a resident. Our observation aligns temporally with the dispersal period of young Fishers, which often occurs in winter (Arthur et al. 1993). Fishers are known to disperse via corridors (LaPoint et al. 2013), and dispersal has enabled them to recolonize areas from which they were previously extirpated (Allen et al. 2015, Stewart et al. 2017, Milton et al. 2022). While dispersal via Edmonton’s forested corridors (City of Edmonton 2024) likely explains the presence of this Fisher, Erethizon dorsatum Linnaeus (Porcupines) are locally abundant (authors’ pers. obs.) and may be an attractive food source for Fishers (Feldhamer et al. 2003). Areas lacking forest cover, including roads and other anthropogenic features, have been identified as barriers to Fisher movement (Hapeman et al. 2011), but their use of forested corridors is well-documented (LaPoint et al. 2013, Milton et al. 2022). It follows that forested corridors through cities may allow this species, whose populations are expanding (Allen et al. 2015, Milton et al. 2022, Stewart et al. 2017), to recolonize other parts of their historic range. Our observation of a Fisher, which has the characteristics of an urban-avoiding species (Blair 1996, Kark et al. 2007, Santini et al. 2019), adds to the body of literature suggesting that corridors can allow urban-avoiding species to travel through and potentially occupy habitat in cities (e.g., LaPoint et al. 2013) even closer to city centers than previously believed. Future management plans for cities could therefore plan connectivity of natural areas to support urban-avoiding species (City of Edmonton 2007) for the ecological services they provide. Simultaneously, cities might anticipate how the presence of carnivores in urban landscapes will require proactive mitigation of human-wildlife conflict, such as public education to reduce the chance of depredation on pets near natural areas. Acknowledgements This work was approved by the University of Alberta Animal Care Committee (AUP00003950). We thank D. 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