DOI: 10.5061/dryad.2ngf1vhpv
title: Data from: Predicting multi-predator risk to elk (Cervus canadensis) in summer using predator scats

description: 1. There is growing evidence that prey perceive the risk of predation and
 alter their behaviour in response, resulting in changes in spatial
 distribution and potential fitness consequences. Previous approaches to
 mapping predation risk across a landscape quantify predator space use to
 estimate potential predator-prey encounters, yet this approach does not
 account for successful predator attack resulting in prey mortality. An
 exception is a prey kill site that reflects an encounter resulting in
 mortality, but obtaining information on kill sites is expensive and
 requires time to accumulate adequate sample sizes. 2. We illustrate an
 alternative approach using predator scat locations and their contents to
 quantify spatial predation risk for elk (Cervus canadensis) from multiple
 predators in the Rocky Mountains of Alberta, Canada. We surveyed over
 1300km to detect scats of bears (Ursus arctos/U. americanus), cougars
 (Puma concolor), coyotes (Canis latrans), and wolves (C. lupus). To derive
 spatial predation risk, we combined predictions of scat-based resource
 selection functions (RSFs) weighted by predator abundance with predictions
 that a predator-specific scat in a location contained elk. We evaluated
 the scat-based predictions of predation risk by correlating them to
 predictions based on elk kill sites. We also compared scat-based predation
 risk on summer ranges of elk following three migratory tactics for
 consistency with telemetry-based metrics of predation risk and
 cause-specific mortality of elk. 3. We found a strong correlation between
 the scat-based approach presented here and predation risk predicted by
 kill sites and (r = 0.98, P &lt; 0.001). Elk migrating east of the Ya
 Ha Tinda winter range were exposed to the highest predation risk from
 cougars, resident elk summering on the Ya Ha Tinda winter range were
 exposed to the highest predation risk from wolves and coyotes, and elk
 migrating west to summer in Banff National Park were exposed to highest
 risk of encountering bears, but it was less likely to find elk in bear
 scats than in other areas. These patterns were consistent with previous
 estimates of spatial risk based on telemetry of collared predators and
 recent cause-specific mortality patterns in elk. 4. A scat-based approach
 can provide a cost-efficient alternative to kill sites of quantifying
 broad-scale, spatial patterns in risk of predation for prey particularly
 in multiple predator species systems.
description: Scat locations and scat
 contents [<em>YHT_scat_locs_contents.csv</em>]
 We collected scats using scat-detection dogs along transects
 randomly located within a systematic grid of 57 5 x 5-km cells during 1
 July – 30
 September, 2013– 2016. Upon scat
 detection, we recorded age of scat, scat diameter and physical description
 to identify scats to species (Weaver & Fritts, 1979; Rezendes,
 1992; Elbroch, 2003), and collected DNA on a subsample of scats to assess
 our species identification accuracy. Age of scats was adapted from Wasser
 et al. (2004) and included fresh to very old (Spilker 2019). We omitted
 old scats judged to be deposited prior to 1 May from all analyses. We
 combined grizzly and black bears into one ursid category because we found
 low accuracy in our ability to discriminate the two based on DNA (&lt;
 65% correctly classified, n = 24; Spilker, 2019). We
 developed RSFs for predators (Manly et al., 2002), where ‘used’ samples
 were the locations of predator-specific scats along transect lines and
 ‘available’ samples were random locations within a 50-m x 1.3-km linear
 distance centered on the scat. We used this linear distance because it was
 the average distance moved by black bears in a 24-hour period, which was
 the shortest 24-hr movement distance among the carnivore species being
 analyzed, and it standardized availability among predators (Spilker
 2019). The 50-m width reflected the estimated detection distance of dog of
 scats. We sampled 10 random (available) points within the buffer around
 each scat location for a density of ~ 0.8 random points per
 km<sup>2</sup>, which is just under the 1 random point/km not
 uncommonly used in telemetry-based selection studies at the home-range
 scale (Hebblewhite and Merrill 2008; Mumma et al. 2017). We used an
 exponential RSF model deriving parameters using logistic regression
 (Johnson et al., 2006). We analyzed the
 contents of a subset of scats detected randomly selected from those
 detected in 2013 - 2016 for the presence of elk hair using either
 macroscopic analysis (n = 226) or DNA analysis (n = 250). For macroscopic
 analysis, we randomly selected 20 hairs from each scat, prepared hairs
 using standard methods (Ciucci et al., 1996), and identified the species
 based on characteristics of the hairs’ medulla, cuticle scale patterns,
 and scale margin distance using dichotomous keys (Moore et al., 1974;
 Kennedy & Carbyn, 1981). Three trained observers who analyzed the
 scats were subject to blind trials on known hairs, obtaining a minimum of
 80% correct classification rate prior to analysis. 
 DNA was extracted from hair shafts using QIAGEN’s DNeasy Tissue
 kits (QIAGEN Inc., Valencia, USA). Polymerase chain reaction (PCR) was
 used to amplify DNA and prey species identification was confirmed via a
 partial sequence analysis of a hypervariable region of the mitochondrial
 16S rRNA gene. This approach identified the most dominant prey species in
 the scat (<i>i.e.,</i> based on the proportion of DNA); mixed
 samples where there was no dominant species (or equal amounts of DNA from
 each species) were re-run with ungulate-specific primers to determine if
 elk DNA was present.  Elk kill sites
 [<em>elk_kills_2002to2016_summer.csv</em>]
 We captured and radio-collared adult female elk from 2001-2016 in
 February-March). During the years 2001-2012, captures were conducted using
 baited corral traps and aerial net-gunning. After 2013, all elk were
 captured using ground-darting from horseback. Elk were fitted with a
 Global Positioning System (GPS) and/or a Very High Frequency (VHF) collar
 to provide location and mortality data. Trained personnel visited
 mortality sites and determined cause of death as soon as mortality was
 detected (on average within 5.2 days (SE= 8.0), from Hebblewhite and
 Merrill (2011). Only predator kills that occured in summer months (May to
 September) are included in the dataset.