5th International Symposium-Workshop on Frugivores and Seed Dispersal (1985-2010)
The cervids include deer and their allies, including familiar moose, elk, and caribou. Member of this family occupy a wide range of habitats, from arctic tundras to tropical forests, and native species of cervids can be found over most of the world except Africa south of the Sahara, Australia, and Antarctica. Cervids range in body size from the very small Andean Pudu (around 10 kg) to the very large moose of North America and Europe (800 kg). They are hunted for sport, for meat, and for their hides. Reindeer are important domestic animals in the far north. Several species have nearly been extirpated. A few others have been introduced far outside their natural ranges, often to the detriment of native species. (Fox and Myers 2001)
Cervids have a four chambered stomach. They ruminate ("chew their cud") and use bacterial fermentation to help digest their food. Most species are browsers, but some include a substantial proportion of graze in their diets. Nonetheless, in the tropics, diet of rainforest deer comprises a large proportion of fallen fruit gathered on the ground when arboreal frugivores forage . In neotropical forest, Gayot et al. (2004) analysed the diets of the two Amazonian brocket deer (the red brocket Mazama americana - below - and the grey brocket M. gouazoubira). They are mainly frugivore-granivores, even during the annual period of fruit scarcity, and both rely heavily on fruits and seeds, but overcome the fall in fruit availability by eating significant quantities of fibres, leaves and flowers, particularly the red brocket.
(Photo top : Chital feeding on Ziziphus xylopyrus fruits. © Soumya Prasad)
Malo and Suárez (1995) analyses seed dispersal by fallow deer (Dama dama) and red deer (Cervus elaphus) in a Mediterranean dehesa (open woodland used for hunting and ranching) during the seeding season, and observed that herbivores disperse many seeds (spring averages are 6–15 seeds per gram of dry dung and maxima of 25–70) from a large number of species (totals between 52 and 78). Mouissie et al. (2005) observed that 24 out of 25 seeds survived ingestion and defecation by captive Fallow Deer, and that the ecological correlates of seed survival (e.g. seed mass × variance of seed dimensions) can help to estimate the ability of plant species to disperse seeds over long distances (see also Pakeman and Small 2009).
In the tropics, Kitamura et al. (2002) studied interactions between fleshy fruits and frugivores in a tropical seasonal forest in Kbao Yai National Park, Thailand. As observed elsewhere in Southeast Asia, frugivores consumed small fruits and large, soft fruits with many small seeds are consumed by a wide spectrum of frugivores while larger fruits with a single large seed are consumed by relatively few potential dispersers such as sambar deer (Rusa unicolor), and red muntjac deer (Muntiacus muntjak, above © J. Broadie). These two deer dispersed by seeds that are 17.5 x 10.6 in length and width (Forget et al. 2007). Broadie et al. (2009) further compared the influence of the two deers on the demography of a shared host tree in Thailand, Choerospondias axillaris (Anacardiaceae). While sambar deposited many seeds under female tree canopies, muntjac were the only disperser to move seeds to open microhabitats, where C. axillaris seed germination, seedling survival, and initial growth are enhanced. Muntjac, by taking some of the seeds to open microhabitats, are projected to have a greater positive impact on C. axillaris demography than either sambar. At Rajaji National Park, northwest India, Prasad et al. (2004, 2006) found that Phyllanthus emblica fruits (right) were consumed by chital (Axis axis) and red muntjac deer, the former being the most frequently observed frugivore of P. emblica than the later, and later regurgitated (or spitting) at bedding sites, thus dispersing seeds away from parent.
Will et al. (2007) carried out experimental studies to study the transport of diaspores on animal hairs (epizochory). They found that the ability of a diaspore to attach to the hair (attachment potential, or AtP) differed widely between coat types (sheep wool, cattle and roe deer hair), but also between plant species, diaspore surface structure and diaspore exposition being the most important plant traits regulating AtP. They concluded that attachment can be considered to be as equally as decisive as retention in terms of epizoochorous dispersal.
As other cervids, Reindeer are ruminant mainly eating lichens in winter, but also eat the leaves of willows and birches, as well as sedges and grasses. Meanwhile, recent work has highlighted the importance of Reindeer as biotic factors limiting the dispersal and the invasibility of the tundra matrix by tree species. In northern Sweden, Cairns et al . 2004) suggest that the presence and range expansion of large numbers of small trees above the current tree line at a site in northern Sweden is due to limited reindeer (Rangifer tarandus) herbivory. Alternatively, the locations with higher reindeer populations have considerably fewer small trees, suggesting that range expansion is more slowly, if at all. Whether herbivory by Reindeer is an additional control at some tree lines (Cairns et al. 2004), it also influences herbaceous plant diversity. Bråthen et al. (2007) found indications that diaspores of ferns are viable after passing the digestive tract of Reindeer in Danemark. There, higher Reindeer densities at the level of landscape areas, as indexed through faeces abundance, were related to both less species and lower abundance of emerging plants from faeces. For instance, ericoid species, the dominating plants in the pastures, were also the most abundant seed plants found to emerge from the faeces.
Eycott et al. (2007) have investigated the number and species composition of viable seeds deposited in faeces of deer in a forest in eastern Britain, and found that the red deer and the fallow deer disperse more species (96) than the introduced and invasive Reeves's Muntjac (Muntiacus reevesi, right) (31). Due to differences in faecal seed density among habitats combined with the ranging behaviour of animals, more seeds were deposited in younger stands, enhancing the potential contribution of macroherbivores to population persistence by dispersal and colonisation in a successional mosaic. The invasive M. reevesi deposited the fewest seeds per gram of faecal pellet material and hence fewer seeds per unit area than other deer species despite their numerical dominance, while C. elaphus/D. dama deposited the most.
Vellend (2002) examined white-tailed deer (Odocoileus virginianus) feces in five mature forest stands in central New York, USA, and showed that white-tailed deer have tremendous potential for contributing to the spread of invasive honeysuckles (Lonicera tatarica, left), a role that was primarily mainly attributed to birds. (see Vellend et al. 2002; Myers et al. 2004).
(Southern Red Muntjac or Indian Muntjac Muntiacus muntjac feeding on Terminalia bellerica fruits. © Soumya Prasad)
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(Sambar Rusa unicolor feeding on Xeromphis spinosa fruits © Soumya Prasad)
Fox, D. and P. Myers. 2001. "Cervidae" (On-line), Animal Diversity Web. Accessed December 29, 2009
Thanks to Soumya Prasad and Jedediah Brodie for their help with illustrations and literature. The list of published articles was prepared with an extraction from the ISI Web of Knowledge, Thomson Reuters ®. The movie of Robbie and The Reindeer is available at YouTube, and other illustrations are from the web with link to source.