Are feeding preferences of white-tailed deer related to plant constituents?

Controlled feeding experiments can provide valuable insights into food selection of herbivores. We conducted cafeteria trials on captive yearling white-tailed deer (Odocoileus virginianus) during 2 years to determine feeding preferences in relation to plant chemical constituents, i.e., nitrogen and fibers. We simultaneously offered 8 species of cultivated and wild plants in monthly foraging trials conducted from June to October. We predicted that species preferences would be positively related to protein content from June to August and to digestible energy in September and October. As predicted, crude protein (CP) was positively related to feeding preferences, particularly as summer progressed. Feeding preferences were also negatively related to fiber content, especially in early summer. Our results indicate high protein needs over the complete growing season for yearling deer but a decrease in overall plant selectivity as summer progresses. Our results also suggest that deer browsing on cultivated plants might be due to higher CP content of cultivated plants than wild plants. To prevent deer impact on crops, managers should favor regeneration of plants rich in CP content in forests. © 2011 The Wildlife Society.     

Seasonal change in browsing by sika deer on hinoki cypress trees on Mount Takahara,central Japan

Browsing by sika deer (Cervus nippon Temminck) on hinoki cypress (Chamaecyparis obtusa (Sieb. et Zucc.) Endl.) was monitored for approximately 3years on 300 trees at three sites on Mount Takahara, central Japan. We investigated the seasonal change in browsing on hinoki cypress in relation to the availability of other food plants (dominated by Sasa nipponica Makino et Shibata) and preferred food plants (deciduous broad leaves). Browsing occurred mostly from November to April, while no browsing damage occurred from June to October. Browsing was observed in November, even when the amount of other food plants did not decrease. Therefore, the cause of browsing cannot be fully explained by a decreased availability of other food plants. Comparison of fecal composition and food availability showed that deer had a preference for deciduous broad leaves. The availability of these preferred plants decreased in November and increased in May. Chemical analysis of the hinoki cypress and deciduous broad leaves (crude protein and neutral detergent fiber) showed that the quality of deciduous broad leaves decreased in November, and as a result the quality of hinoki became higher than that of the deciduous broad leaves. Browsing on hinoki cypress occurred when the availability of deciduous broad leaves decreased, and vice versa. These results suggest that the availability of preferred food plants influences browsing on hinoki cypress by sika deer.     

Bark stripping of hinoki cypress by sika deer in relation to snow cover and food availability on Mt Takahara,central Japan

Bark stripping of hinoki cypress (Chamaecyparis obtusa (Sieb. et Zucc.) Endl.) by sika deer (Cervus nippon Temminck) was monitored for 4years on approximately 300 trees at three sites on Mt Takahara, central Japan. We investigated the effects of snow cover and food availability on seasonal and yearly changes in bark stripping. Bark stripping occurred during snowy periods (January and February) when less food was available because of the snow cover. The most serious bark stripping was observed in 1996 when the snow was the deepest and food resources were the poorest among the 4years of the study. In contrast, bark stripping did not occur in 1999 when the snow was thin and, consequently, more food was available. These results suggest that snow cover and food avail-ability influence the occurrence and intensity of bark stripping both seasonally and annually.     

Persistence of the threatened Knysna warbler Bradypterus sylvaticus in an urban landscape: do gardens substitute for fire?

Food resources can limit populations of insectivorous birds. Previous studies have shown strong correlations between bird population densities and their invertebrate food, with declining populations being attributed to loss of prey. This might also be the case for the threatened Knysna warbler (Bradypterus sylvaticus), which in the last 20 years has declined precipitously on the Cape Peninsula, South Africa. The bird is abandoning natural, protected forests, retreating to narrow belts of suburban, riverine woodland with dense, tangled understoreys. The potential invertebrate food availability in natural forests and suburban woodland was assessed against what is known of the bird’s preferred prey. The invertebrate food resource spectrum and abundance were determined using three sampling techniques in both natural forest and suburban woodland. Despite greater overall abundance of invertebrates in suburban woodland, the warbler’s preferred prey items were equally abundant in both habitats. This suggests that reduced food supply does not explain abandonment of natural forests by the warbler. Rather, it is concluded that the availability of suitable nesting substrata, which are more abundant in suburban woodland, has driven the biotope shift. This is an unusual case of a localized and threatened bird species faring better under transformed conditions than in natural habitats.