Barren‐ground caribou (Rangifer tarandus groenlandicus) behaviour after recent fire events; integrating caribou telemetry data with Landsat fire detection techniques

Abstract

Fire regimes are changing throughout the North American boreal forest in complex ways. Fire is also a major factor governing access to high‐quality forage such as terricholous lichens for barren‐ground caribou (Rangifer tarandus groenlandicus). Additionally, fire alters forest structure which can affect barren‐ground caribou's ability to navigate in a landscape. Here, we characterize how the size and severity of fires are changing across five barren‐ground caribou herd ranges in the Northwest Territories and Nunavut, Canada. Additionally, we demonstrate how time since fire, fire severity, and season result in complex changes in caribou behavioural metrics estimated using telemetry data. Fire disturbances were identified using novel gap‐free Landsat surface reflectance composites from 1985 to 2011 across all herd ranges. Burn severity was estimated using the differenced normalized burn ratio. Annual area burned and burn severity were assessed through time for each herd and related to two behavioural metrics: velocity and relative turning angle. Neither annual area burned nor burn severity displayed any temporal trend within the study period. However, certain herds, such as the Ahiak/Beverly, have more exposure to fire than other herds (i.e. Cape Bathurst had a maximum forested area burned of less than 4 km2). Time since fire and burn severity both significantly affected velocity and relative turning angles. During fall, winter, and spring, fire virtually eliminated foraging‐focused behaviour for all 26 years of analysis while more severe fires resulted in a marked increase in movement‐focused behaviour compared to unburnt patches. Between seasons, caribou used burned areas as early as 1‐year postfire, demonstrating complex, nonlinear reactions to time since fire, fire severity, and season. In all cases, increases in movement‐focused behaviour were detected postfire. We conclude that changes in caribou behaviour immediately postfire are primarily driven by changes in forest structure rather than changes in terricholous lichen availability.

Observed and predicted effects of climate change on Arctic caribou and reindeer

“…Caribou tend to select mature stands (>40 years old) containing relatively abundant lichen cover (Joly et al 2003) and avoid immature stands, although recent studies have found that there may be more individual variation in the use of these areas than previously thought (Anderson and Johnson 2014), and some individuals may take advantage of these areas for increased vascular forage (Joly et al 2003). Caribou may also use immature stands as habitat for movement (Rickbeil et al 2016) or possibly to reduce predation risk through enhanced visibility (Anderson and Johnson 2014). The effects of fire on caribou winter habitat, and associated avoidance by individuals, extend well beyond the short-term loss of vegetation due to the recovery time of lichen species.…”

From ecology to remote sensing: using animals to map land cover

“…For example existing datasets on barren ground caribou ( Rangifer tarandus groenlandicus ) could provide samples from tundra and grasslands (Rickbeil et al. , ), greylag geese ( Anser anser ) could inform us on the existence of permanent – and temporary – water bodies (Kleinhenz and Koenig ), and forest elephants ( Loxodonta cyclotis ) could inform us on both grasslands and forests (Mills et al. ).…”

“…Although this paper focuses on agriculture, the potential of movement data to map land cover is far reaching. For example existing datasets on barren ground caribou (Rangifer tarandus groenlandicus) could provide samples from tundra and grasslands (Rickbeil et al 2017(Rickbeil et al , 2018, greylag geese (Anser anser) could inform us on the existence of permanentand temporarywater bodies (Kleinhenz and Koenig 2018), and forest elephants (Loxodonta cyclotis) could inform us on both grasslands and forests (Mills et al 2018). To achieve this, we encourage research on the environmental requirements of different species and on the link between these requirements and concrete land cover types.…”

“…Behaviours such as resting and foraging have specific environmental requirements (P eron et al 2016;Abrahms et al 2017) that can potentially be translated into land cover classes. However, while the relationship between movement and land cover has been roughly explored (Da Silveira et al 2016;Brown et al 2017;Rickbeil et al 2017), this premise has not been tested for the purpose of land cover mapping.…”

Changing northern vegetation conditions are influencing barren ground caribou (Rangifer tarandus groenlandicus) post‐calving movement rates

“…Additionally, if habitat changes are to be documented, repeat measures of habitat conditions over time are required. These challenges are encouraging the development of novel methods for tracking habitat conditions in the north that involve using ex situ data such as space-borne remote sensing (Falldorf, Strand, Panzacchi, & Tømmervik, 2014;Rickbeil, Coops, & Adamczewski, 2015;Rickbeil, Hermosilla, Coops, White, & Wulder, 2016). There are multiple remote sensing platforms and sensors that can be employed for habitat change analysis.…”