Spatiotemporal predictions of the alternative prey hypothesis: Predator habitat use during decreasing prey abundance

Abstract

The alternative prey hypothesis supposes that predators supported by a primary prey species will shift to consume alternative prey during a decrease in primary prey abundance. The hypothesis implies that during declines of one prey species, a predator modifies their behavior to exploit a secondary, or alternative, species. Despite occurring in many systems, the behavioral mechanisms (e.g., habitat selection) allowing predators to shift toward alternative prey during declines in the abundance of their primary prey are poorly understood. We evaluated habitat selection and use by a generalist predator with respect to two prey species during a dramatic decrease in the abundance of primary prey. Further, we evaluated how spatial variation in access to primary prey affected habitat selection, and assessed similarity and overlap between habitats used by each prey species. Coyotes (Canis latrans) exhibited decreasing selection for cottontail rabbits (Sylvilagus spp.; primary prey) during population decreases but did not shift habitat selection toward neonate mule deer (Odocoileus hemionus; alternative prey). Use of rabbit habitat remained high even during historically low rabbit abundance, while mule deer habitat was used in proportion to its availability. Coyotes seemingly do not make large shifts in habitat selection toward alternative prey following spatial and temporal decreases in the abundance of primary prey, but instead, take advantage of habitat overlap to facilitate prey‐switching behavior. Our work extends previous research conducted under the alternative prey hypothesis by explicitly evaluating the influence of habitat overlap between prey species and variation in access to prey habitat as factors affecting prey‐switching behaviors in predators.

Coursing the mottled mosaic: Generalist predators track pulses in availability of neonatal ungulates

“…Our observations of selection and fine-scale movement behavior of coyotes indicate that abundance of primary prey played a negligible role in the shifts in selection and fine-scale movement behavior during Parturition and that coyotes actively seek neonatal prey as a means to increase energetic gain for a limited time period. Future work that evaluates optimal foraging and its context within the density of primary prey will provide important insights into the effects of primary prey on predator behavior and the cascading effects on alternative prey such as neonatal ungulates (Brunet et al, 2023). Foraging behavior of pack-living animals such as coyotes may be influenced by social hierarchy (Gilbert-Norton et al, 2013).…”

Spatial prey availability and pulsed reproductive tactics: Encounter risk in a canid–ungulate system

“…Coyotes are one of the primary predators of neonate mule deer, with predation being a potential contributor to population dynamics, particularly within multi‐predator, multi‐prey systems where predators exhibit prey‐switching behaviours (reviewed by Forrester & Wittmer, 2013, and relevant to our study area Brunet et al., 2023). Neonate mule deer often are most vulnerable to predation during the period of early life associated with pulsed parturition (Huggler et al., 2023; Petroelje et al., 2014; Ruprecht et al., 2022) and are actively defended from predation by maternal females (Lingle, 2005; Lingle & Pellis, 2002; Wenger, 1981).…”

“…with occasional stands of quaking aspen (Populus tremuloides) and subalpine fir (Abies lasiocarpa). The study area has been described in detail elsewhere (Brunet et al, 2022(Brunet et al, , 2023Huggler et al, 2022).…”

“…Coyotes are one of the primary predators of neonate mule deer, with predation being a potential contributor to population dynamics, particularly within multi-predator, multi-prey systems where predators exhibit prey-switching behaviours (reviewed by Forrester & Wittmer, 2013, and relevant to our study area Brunet et al, 2023).…”

“…small mammals; Huggler et al., 2023; Ruprecht et al., 2022). Proximity or overlap in habitat between prey species may facilitate use by predators and correspondingly increase risk for ungulates (Brunet et al., 2023). Despite the potential for intensified use of ungulate prey motivated by the birth pulse, birth synchrony itself can afford prey respite from predation risk (Furey et al., 2016; Ims, 1990; Michel et al., 2020).…”