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Carrion consumption is increasingly recognized as an important food source for facultative scavengers (Wilson and Wolkovich 2011), including species characterized as herbivores (Gleason and others 2005). Scavenging by small or medium-sized herbivores may appear unlikely, owing to the increased mortality risk and encounter rates with predators expected near carcasses (Cortes-Avizanda and others 2009). However, carrion use, even by herbivores such as Eastern Cottontail (Sylvilagus floririanus) and Beaver (Castor canadensis) (Bumann and Stauffer 2002; Gleason et al. 2005), has been increasingly documented. These foraging strategies may represent limitations in preferred food sources (Needham and others 2014), strategic acquisition of limiting nutrients (e.g. protein; Clauss and others 2016), or opportunistic use of an abundant carrion supply (Gleason and others 2005). Although the number of reported incidences of scavenging by herbivores is increasing, more detailed analyses of its occurrence are required for numerous species in order to better characterize the importance and frequency of this phenomenon.

Snowshoe Hares (Lepus americanas) are a keystone species of the boreal forest that experience population cycles occurring over 10-y periods (Krebs and others 2001). Common food items depend on season, including a variety of herbaceous plants in the summer and mainly coniferous and deciduous woody plants throughout the winter (Hodges 2000). Previous reports have demonstrated that hares scavenge (Soper 1921; Kurta 1995). However, these reports have provided inadequate detail to assess either how common this behaviour is or the diversity of species that hares will scavenge. Here, we document and quantify several instances of snowshoe hare scavenging using motion triggered cameras, including two instances where an individual repeatedly ingested feathers.

As part of a larger study on scavenger community dynamics, we placed carcasses of several species within the Kluane Lake area of Yukon, Canada between January 2015 and July 2017. Carcasses were monitored using motioned triggered cameras (Reconyx Hyperfire) set to take 3 rapid-fire photographs when triggered with a 15-s delay. Cameras were placed approximately 2 to 4 m from the carcass and were left in place until the carcass was removed or minimal edible remains were left. We considered scavenging observations of hares 10 min apart as separate visits. Snowshoe Hares in this area have been monitored since 1976, with densities during these observations at or approaching their peak (Krebs CJ, unpublished data).

Snowshoe Hares were observed scavenging (visibly consuming or disturbing the carcass) at 12.4% of the deployed carcasses (20 of 161 carcasses). Hares were more likely to scavenge carcasses during the winter (Fig. 1), and they were not observed scavenging carcasses deployed between the months of May to August (30 carcasses total), which coincides with the availability of herbaceous plants. This potentially suggests that carrion is primarily utilized by individuals throughout the winter when food may be limited. During winter, hares rely on a variety of woody browse species that are low in protein (Hodges 2000). Individuals combat this low-protein diet by eating large quantities of browse, excreting highly fibrous pellets, and reingesting soft pellets to obtain additional protein (Sinclair and Smith 1984; Hodges 2000). This behaviour corroborates the notion that hares focus their food acquisition in winter to increase protein intake, and may be the reason scavenging appears to be more common in this season.

Hares scavenged a variety of different species, including Canada Lynx (Lynx canadensis), Common Loon (Gavia immer), Snow Bunting (Plectrophenax nivalis), Ruffed Grouse (Bonasa umbelius), and Spruce Grouse (Falcipennis canadensis). Hares appeared more likely to scavenge grouse carcasses (36%; 4 of 11 carcasses) over other species. Individuals were also observed several times scavenging hare carcasses (13 of 101 carcasses). For example, a hare carcass was placed in open-spruce forest on 24 November 2015 at 12:44. From 24 November to 1 December, hares visited the carcass 24 times. This carcass deployment was particularly unique, as multiple hares were seen at the carcass simultaneously, and based on posture and subsequent chases, it appeared that individuals defended the carcass from other hares.

On 2 different occasions, individuals ingested feathers repeatedly from a Spruce Grouse carcass. On 7 December 2015 at 11:59, a road-killed Spruce Grouse was placed in a dense patch of willow. A Snowshoe Hare first visited the carcass at 02:40 on 8 December, and over the next 5 d visited the carcass a total of 19 times (although it was impossible to determine if it was the same or multiple individuals). During each visit it was clear the hare was consuming meat from the carcass. Once the carcass was mostly plucked, the hare began to consume feathers (Fig. 2). In fact, during the last 3 d after the main body of the grouse was removed by a Common Raven (Corvus corax), the hare continued to visit, mainly to consume feathers.

Another road-killed Spruce Grouse was put out in an open stand of White Spruce (Picea glauca) on 22 February 2016 at 10:25. During the morning of 24 February, a Canada Lynx removed most of the carcass, leaving only a single wing. On 27 February at 02:45, after a light snowfall covered the wing, a hare removed the wing from the snow and carried it off-camera. A hare returned at 22:17 on 29 February, removing objects from the snow, but it was difficult to determine if it removed meat or feathers.

To our knowledge, these 2 observations represent the 1st documented occurrence of this behaviour for the species, and intentional ingestion of feathers among mammals appears uncommon. Feather consumption by hares could result from a number of mechanisms proposed in other species, such as aiding in mechanical digestion (for example, grebes; Jehl 2017), or altering the gut microbiota (for example, incidental ingestion by carnivores; Zhang et al. 2014). Alternatively, consuming feathers may simply increase protein or fiber intake. Although feathers are poorly digested by most birds and mammals (Williams and others 1991), there is evidence that species ingest more feathers when fed a low-fiber diet (van Krimpen and others 2011).

Although it is difficult to relate estimates of scavenging frequency to any measure of ecological importance or mechanism, these observations at least demonstrate that the behaviour is a regular occurrence for hares, and individuals will consume carrion from a variety of different species. This is especially true relative to other lagomorph species, as despite numerous field studies on scavenger community dynamics in the eastern United States (DeVault and Rhodes 2002; DeVault and others 2004; Olson and others 2012, 2016; Smith and others 2017; Turner and others 2017), cottontail rabbits (Sylvilagus spp.) have only been observed scavenging on 1 occasion (Bumann and Stauffer 2002). We recommend further research be conducted on scavenging in Snowshoe Hares in order to understand the factors that lead to its occurrence.

Acknowledgements.--We thank the numerous field technicians that assisted in carcass monitoring throughout the study as well as J Peers and two anonymous reviewers for comments on an earlier version of this note. MJLP was supported by an NSERC CGS scholarship.


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Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9 Canada (MJLP, YNM, SMK, SB),; Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON MIC 1A4 Canada (RB). Submitted 11 February 2018, accepted 18 June 2018. Corresponding Editor: Clayton Apps.
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Article Details
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Title Annotation:GENERAL NOTES
Author:Peers, Michael Jl; Majchrzak, Yasmine N; Konkolics, Sean M; Boonstra, Rudy; Boutin, Stan
Publication:Northwestern Naturalist: A Journal of Vertebrate Biology
Article Type:Report
Geographic Code:1CYUK
Date:Dec 22, 2018

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