The water deer, Hydropotes inermis, is a small deer species native to East Asia, particularly China and Korea, though an established population also exists in the United Kingdom. This deer is easily recognized by the prominent, protruding canine teeth in males, which have earned it the nickname “vampire deer,” as antlers are absent in both sexes. Understanding the diet of the water deer provides insights into its ecological niche and how it thrives in various environments.
Primary Food Sources
Water deer are selective herbivores, primarily consuming tender, easily digestible plant parts. Their diet broadly includes graminoids, such as young grasses, sedges (Carex), and rushes (Juncus). Non-woody flowering plants, or forbs, are a significant component of their diet. Studies in China have shown that forbs can constitute a substantial portion of their intake, sometimes as much as 59% in captive settings, while grasses and sedges make up around 24%.
The preferred parts of plants include growing tips, leaves, and young shoots. In some regions, researchers found that about 46% of their diet consisted of leaves, 23% stems, 15% buds, and smaller percentages of flowers and fruits. While their diet is predominantly herbaceous, water deer also consume woody browse and even conifers. They readily feed on Salix species and can cause damage to such stands.
Seasonal and Habitat Influences on Diet
The diet of water deer changes considerably throughout the year and varies based on their specific habitat. During warmer seasons, when plant growth is vigorous, there is a greater availability and variety of forage. This period sees a higher consumption of fresh shoots, tender leaves, and a wider array of plant species. Studies indicate that forbs dominate their diet in spring (around 48%) and summer (around 50%).
As seasons shift, particularly into autumn and winter, the availability of herbaceous plants decreases. Water deer then adapt their diet to include more woody plants, constituting a larger proportion of their intake, sometimes reaching 59% in autumn and 61% in winter. This adaptation includes feeding on barks or twigs when fresh leaves are scarce. Different habitats also influence their food choices; deer in wooded areas tend to consume more woody plants than those in lowland areas, though seasonal changes often have a more pronounced impact than habitat alone.
Dietary Adaptations and Nutritional Needs
Water deer possess a ruminant digestive system, allowing them to process plant matter. Their four-chambered stomach, composed of the rumen, reticulum, omasum, and abomasum, facilitates the breakdown of cellulose through microbial fermentation. The rumen serves as a fermentation vat where microorganisms break down ingested plant material. Food is then regurgitated and re-chewed as cud before passing through the other stomach chambers for further digestion and nutrient absorption.
As selective feeders, water deer often prioritize foods low in fiber but high in soluble carbohydrates, proteins, and fats. This preference is linked to their high metabolic rate, which necessitates a diet of more digestible and nutrient-dense foods. Their daily dry matter requirement is approximately 500 grams. Water, protein, fat, carbohydrates, minerals, and vitamins are necessary, with protein and energy being particularly important for growth, reproduction, and overall body maintenance.