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Berry consumption by Bighorn Sheep (Ovis canadensis) in the arid interior of British Columbia.

Bighorn Sheep (Ovis canadensis) occur in varied environments, and several studies have been undertaken to examine their diet across their range (for example, Halloran and Crandell 1953; Todd 1975; Miller and Gaud 1989; Fulbright and others 2001; Wagner and Peek 2006). From these studies it appears that Bighorn Sheep diets are highly variable, both seasonally and regionally. Altogether, >400 food items have been reported (Krausman and Bowyer 2003) with grasses being by far the most often used forage class, followed by herbs and shrubs (Shackleton 1985, 2013; Krausman and Bowyer 2003). In arid environments, such as deserts, diet niche breadth tends to be greater than in wetter ecoregions (Shackleton 1985, 2013; Krausman and Bowyer 2003). Bighorn Sheep in arid areas tend to include much more browse in their summer diet (Rominger and others 1988; Miller and Gaud 1989), presumably because they seasonally provide succulent forage. For example, Shackelton (2013) and Krannitz and Hicks (2000) noted that Bighorn Sheep in the arid southern interior of British Columbia may browse the succulent leaves of shrubs such as Antelope-brush (Purshia tridentata) year-round, possibly as a means to obtain moisture. Frugivory is noted primarily from populations in deserts, where water is limited. In these regions, Bighorn Sheep have been observed consuming the fleshy fruits of various species of cacti (Ferocactus spp., Opuntia spp.), likely as a means of meeting their water demands (Warrick and Krausman 1989; Wikeem and Pitt 1992; Tarango and others 2002). Other types of fruits consumed by Bighorn Sheep are generally not noted. Here, we report observations of berry consumption by Bighorn Sheep in an arid region of British Columbia, Canada.

On 25 August 2013, we observed the feeding behavior of a group of 11 adult female Bighorn Sheep at the Vaseux-Bighorn National Wildlife Area (49.295[degrees] N, 119.523[degrees] W), about 7 km southwest of Okanagan Falls, British Columbia. At 11:55 and 12:48 PDT, we observed a single sheep feeding on the fruit (berries) of Blue Elderberry (Sambucus caerula). Different sheep fed on berries during the 2 observations; one of which was recognized because it wore a radio-collar and an orange ear tag, while the other did not. The fruits were about 1.5 to 2.0 m above the ground and in both instances the animals reared up on their hind legs to reach the bunch of berries (Fig. 1). In both observations the entire bunch of berries was consumed. Only 1 animal was observed eating berries during each observation. Other sheep in the group did not appear to react to the sheep eating the berries and did not also eat berries at that time. The temperature was about 30[degrees]C. Blue Elderberry occurred at low densities (approximately <6/ha). Common shrubs in the area included Big Sagebrush (Artemisia tridentata) and Antelope-brush; however they did not bear fleshy fruit.


While Bighorn Sheep diets have been well studied, we could find no reference to berries being previously found in the diet of Bighorn Sheep. To the best of our knowledge, this is the 1st report of Bighorn Sheep eating berries. Several workers have reported berry-bearing shrubs in the diet of Bighorn Sheep; however, these studies referred to the consumption of leaves or twigs, not berries. For example, Wikeem and Pitt (1992) studied the seasonal diets of a Bighorn Sheep population at Skaha Lake, 12 km north of Vaseux Lake, and did not note the consumption of berries; although that population seasonally consumed the leaves of shrubs with berries such as Saskatoon Berry (Amelanchier alnifolia) and Wax Currant (Ribes cereum), albeit in trace amounts. Also working nearby, Blood (1967) reported trace use of Wax Currant, Bearberry (Arctostaphylos uva-ursi), and Grouseberry (Vaccinium scoparium) leaves by Bighorn Sheep, but not the berries. The congeneric Mouflon (Ovis aries oreintalis) is reported to eat berries (Hadjisterkotis 1996; Marchand and others 2013).

Blue Elderberry berries are commonly eaten by other large mammals, including American Black Bears (Ursus americanus; Parish and others 1996; Auger and others 2002) and Rocky Mountain Elk (Cervus canadensis nelsoni; Kufeld 1973). While Bighorn Sheep are adapted to arid environments, access to water may be a key limiting factor for Bighorn Sheep, particularly in deserts (Halloran and Deming 1958; Cain and others 2008a, 2008b). A crude estimate is that a mature Blue Elderberry may contain >50 bunches of berries, each bearing about 25 to 75 berries. Bunches of berries potentially provide a substantial amount of water, along with nutrients that may be lacking from their primary forage species. As such, we suggest that Bighorn Sheep in the arid interior of southern British Columbia may occasionally consume berries primarily as a means of supplementing their water intake.

Blue Elderberry was locally common, but occurred at low densities on the slopes where our observations were made. Their importance for Bighorn Sheep in seasonally meeting their water requirements may deserve further attention. If Blue Elderberry is an important source of berries, and hence water, for Bighorn Sheep in arid regions, then their value should be recognized in range management plans.

Key words: Bighorn Sheep, Blue Elderberry, diet, fruigovory, Ovis canadensis, Sambucus caerula

Acknowledgments.--Matthias M Clyde, D Forest Clyde, and SK Aspen Clyde assisted with our field observations.


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101 Talus Drive, Whitehorse, YK Y1A 0E3 Canada (TSJ, KJC);; kclyde@northwestel. net. Submitted 9 October 2013, accepted 5 December 2013. Corresponding Editor: Robert Hoffman.
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Title Annotation:GENERAL NOTES
Author:Jung, Thomas S.; Clyde, Karen J.
Publication:Northwestern Naturalist: A Journal of Vertebrate Biology
Article Type:Report
Geographic Code:1CANA
Date:Mar 22, 2014
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