Seasonal and daily use of canal culverts by mammals, reptiles, amphibians, and invertebrates

Abstract Landscape connectivity is critical to the long‐term conservation of wildlife populations. Although anthropogenic linear infrastructures (ALI), including roads and canals, provide important resources to humans, they can affect wildlife through habitat fragmentation and reduced movement through landscapes. To increase landscape connectivity, crossing structures, including underpasses, can facilitate wildlife movement across landscapes experiencing ALI. However, little is known about how a suite of small‐ to medium‐sized species use underpasses across seasonal and daily time periods, especially for some ALI such as major canals. We used specialized camera technology (i.e., the Hobbs Active Light Trigger [HALT] camera) to evaluate use of culvert underpass crossing structures (hereafter culverts) along the Central Arizona Project canal, Arizona, by a suite of mammals, reptiles, amphibians, and invertebrates. Specifically, we evaluated (1) which wildlife species used culverts, (2) how the frequency of use varied across seasons (i.e., hot‐dry, hot‐wet, cool‐wet) and (3) daily activity patterns of wildlife using culverts. We detected 31 species of wildlife using culverts, which included small‐ to medium‐sized mammals (56.4% of crossings), reptiles (21.0% of crossings), amphibians (19.0% of crossings), and invertebrates (3.6% of crossings), including some species of conservation concern, such as the Sonoran Desert tortoise ( Gopherus morafkai ) and Gila monster ( Heloderma suspectum ). However, crossings by larger mammal species were less effectively detected with the HALT cameras. Reptile crossing frequency was similar between the 2 seasons that they were active during the hot‐dry (May–June) and hot‐wet (July–October) seasons and crossing frequency by some species of amphibians and invertebrates was higher in the hot‐wet season. Throughout the entire year, small mammals used culverts more frequently in hot seasons (i.e., hot‐wet and hot‐dry) compared to the cool‐wet (November‐March) season. In addition, daily activity patterns varied by species, where species crossed culverts during diurnal (e.g., desert spiny lizards, Sceloporus magister and coachwhip snakes, Masticophis flagellum ), crepuscular (e.g., cottontail rabbits, Sylvilagus audubonii and western diamondback rattlesnakes, Crotalus atrox ), and nocturnal (e.g., deer mouse species, heteromyid species, woodrat species, desert stink beetle species) time periods. Our information can be used to manage wildlife crossing areas and increase landscape connectivity in relation to ALI.