Comparison of Woodland Caribou Calving Areas Determined by Movement Patterns Across Northern Ontario

Abstract

Adult female survival and calf recruitment influence population dynamics, but there is limited information on calving and neonatal mortality of boreal woodland caribou (Rangifer tarandus caribou; caribou) in Ontario, Canada. We identified calf parturition sites and 5-week neonatal mortality using a movement-based approach across 3 northern Ontario study regions (Pickle Lake, Nakina, and Cochrane) that vary in their capacity to support caribou populations. In comparing 22 caribou-years of video-collar footage during 2010-2013 to predictions of the movement-based approach, we found live parturition events were 100% correctly classified, date of parturition was within 1.08 ± 0.28 (x ± SE) days, and mortality events up to 5 weeks postpartum were 88% correctly classified. Across study regions, 87% of 186 caribou were pregnant and 76% of 107 caribou-years indicated birth events with median parturition dates a week later in Cochrane (23 May) than in Pickle Lake (17 May) and Nakina (16 May). Based on selection ratios of caribou-years with calves-at-heel (n = 80), caribou consistently selected for lowlands and closed-canopied forests and mostly against early-seral stands (<20 yrs old) and areas near linear features during the neonatal and the post-neonatal period (up to 35 days postpartum). Based on the video footage and movement models, 30% of 81 caribou-years that indicated live births also showed females lost their calf within the first 5 weeks postpartum, with higher risk of neonatal mortality associated with increased use of lowlands and greater postpartum movement rates. This study provides informative metrics of caribou reproduction across northern Ontario that will contribute to future population modeling and identifies important landscape features to be considered in future industrial development and land use planning for caribou conservation.

A Burning Question: What are the Implications of Forest Fires for Woodland Caribou?

“…The relative response of predators and primary prey to burned areas may vary regionally (Johnson et al 2020). For example, conifer forests in the Boreal Shield of Saskatchewan, Canada, typically recover without creating the early seral vegetation (Hart et al 2019) needed to support high densities of moose (McLoughlin et al 2005); whereas, in northern Ontario, Canada, more productive mixed‐wood forests regenerate with more vascular browse (Walker et al 2020, Fryxell et al 2020). Regional habitat‐fire dynamics also influence the distribution of lichen available to caribou in burns; on the Boreal Plains of western Canada, lichen is concentrated in large, forested peatlands and wetlands, which are less likely to burn than the dryer upland forests where lichen is concentrated in the Boreal Shield of eastern Canada (Cuesta et al 2009, Kansas et al 2016, Silva et al 2019).…”

Climate‐informed forecasts reveal dramatic local habitat shifts and population uncertainty for northern boreal caribou

“…We attribute this to model and reproducibility limitations, all of which can be addressed in future iterations of this work. For example, boreal caribou rely on unfragmented lowlands throughout the year (DeMars et al, 2020; Walker et al, 2021); we can currently only simulate changes in forested areas, not unforested areas composed of shrub, bryoid, or wetland vegetative cover (i.e., successional change; see Micheletti et al [2021], Appendix II for details). Predicting changes to anthropogenic disturbance is difficult, relies on socioeconomic drivers, and lies outside the scope of this work; hence, landscape fragmentation by linear features is held static within our integrated framework.…”

Continental synchrony and local responses: Climatic effects on spatiotemporal patterns of calving in a social ungulate

“…We adapted the individual‐based method developed by DeMars et al (2013) to infer calving events for boreal populations of woodland caribou ( Rangifer tarandus caribou ; Walker et al, 2020, but see Bonar et al, 2018 for contrasting results). Although boreal caribou are nonmigratory and are mostly solitary during calving, this method has been successfully adapted to barren‐ground caribou from the Western Arctic Herd, which are also considered in this study, and found to have an overall accuracy of 77% when validating this method against aerial survey data (Cameron et al, 2018).…”

“…We adapted the individual-based method developed by DeMars et al (2013) to infer calving events for boreal populations of woodland caribou (Rangifer tarandus caribou; Walker et al, 2020, but see Bonar et al, 2018 for contrasting results). Although boreal caribou are nonmigratory and are mostly solitary during calving, this F I G U R E 1 Conceptual framework of hypothesized relationships linking seasonal weather conditions to calving timing (plain arrows) and calving location (dashed arrows).…”