Enhanced understanding of predator–prey relationships using molecular methods to identify predator species, individual and sex

Abstract

Predator species identification is an important step in understanding predator-prey interactions, but predator identifications using kill site observations are often unreliable. We used molecular tools to analyse predator saliva, scat and hair from caribou calf kills in Newfoundland, Canada to identify the predator species, individual and sex. We sampled DNA from 32 carcasses using cotton swabs to collect predator saliva. We used fragment length analysis and sequencing of mitochondrial DNA to distinguish between coyote, black bear, Canada lynx and red fox and used nuclear DNA microsatellite analysis to identify individuals. We compared predator species detected using molecular tools to those assigned via field observations at each kill. We identified a predator species at 94% of carcasses using molecular methods, while observational methods assigned a predator species to 62.5% of kills. Molecular methods attributed 66.7% of kills to coyote and 33.3% to black bear, while observations assigned 40%, 45%, 10% and 5% to coyote, bear, lynx and fox, respectively. Individual identification was successful at 70% of kills where a predator species was identified. Only one individual was identified at each kill, but some individuals were found at multiple kills. Predator sex was predominantly male. We demonstrate the first large-scale evaluation of predator species, individual and sex identification using molecular techniques to extract DNA from swabs of wild prey carcasses. Our results indicate that kill site swabs (i) can be highly successful in identifying the predator species and individual responsible; and (ii) serve to inform and complement traditional methods.

Spatiotemporal heterogeneity in prey abundance and vulnerability shapes the foraging tactics of an omnivore

“…When we detected a mortality signal, we conducted a systematic field investigation to determine the cause of death. Additionally, we verified many field assessments using laboratory necropsy of collected remains or DNA analysis to identify the cause of death (further details in Mahoney et al, 2016;Mumma, Soulliere, Mahoney, & Waits, 2014).…”

Field calibration of blowfly-derived DNA against traditional methods for assessing mammal diversity in tropical forests

“…TFR, comprising logged dipterocarp forest (5°11=N, 102°41=E), is one of 17 ecological linkages recognised in the Malaysia Federal Government's "Central Forest Spine Master Plan for Ecological Linkages" to restore connectivity between four fragmented forest complexes (DTCP and DOF 2012). (Catling et al 1997) Operates 24 h without supervision (Catling et al 1997) Difficult to standardise (varying dimensions, baited/un-baited, and deployment location effects) (Fontúrbel 2010;Torre et al 2010) Medium (Garden et al 2007) Mist nets Frugivorous bats (Stoner and Timm 2004) Readily portable (Kuenzi and Morrison 1998) Must be monitored constantly, as bats can become easily entangled and must be freed individually (Kuenzi and Morrison 1998) Low (Kuenzi and Morrison 1998) Harp traps Insectivorous bats (Kingston et al 2003) Does not require constant monitoring (Tidemann and Woodside 1978) Bulky and not easy to transport (Tidemann and Woodside 1978) High (Tidemann and Woodside 1978) Camera traps Medium to large-bodied mammals (Bernard et al 2013) Effective in detecting species rarely recorded from live traps or direct observations (e.g., Hose's civet, Diplogale hosei; Bernard et al 2013) May under-represent species with specific habitats and unable to distinguish closely related species (e.g., muntjac and mouse-deers; Bernard et al 2013) High (Sanderson and Trolle 2005) Indirect signs Medium to large-bodied ground dwelling mammals (Catling et al 1997) Effective in detecting species inhabiting open areas (e.g., otters and ungulates; Catling et al 1997) Imprecise in species identification (Davison et al 2006;Mumma et al 2014); Accuracy and precision are dependent on field conditions and expertise of identifiers (Silveira et al 2003) Low (Garden et al 2007 (Valderrama et al 1999;Ebert et al 2010) Low (Castro-Arellano et al…”

Experimental evaluation of genetic predator identification from saliva traces on wildlife kills

“…Recently, the usefulness of saliva traces as a source of noninvasively collected DNA has been realized. Various studies have successfully isolated DNA from saliva traces left by predators on carcasses of livestock (Ernest and Boyce 2000;Williams et al 2003;Blejwas et al 2006;Sundqvist et al 2008;Caniglia et al 2013), wild mammals (Pun et al 2009;Wengert et al 2013;Mumma et al 2014), and birds (Steffens et al 2012) or by ungulates on twigs (Nichols et al 2012). These studies have helped elucidate human-predator conflicts (e.g., predation on livestock, pets, or game species), predator-prey interactions (e.g., addressing the relative impacts of invasive predators on native fauna- Steffens et al 2012), and the foraging behavior of ungulates.…”