Susceptibility of Spring-Flowering Garden Plants to Herbivory by Mule Deer

Many people look forward to spring flowers, only to discover that mule deer (Odocoileus hemionus) have eaten the sprouting plants and flower buds. One potential method to prevent this problem is to grow unpalatable flowering plants in gardens where deer herbivory is expected, but this requires knowledge about the relative palatability of plant species. We examined spring-flowering plants in gardens located in Cache County, Utah, USA (2010 through 2017), and recorded the proportion of leaves and flower buds browsed by mule deer. Mule deer browsing was greatest on tulips (Tulipa spp.), grape hyacinths (Muscari spp.), and crocuses (Crocus spp.) and lowest on iris (Iris spp.) and daffodils (Narcissus spp.) We hypothesized that the first plants to sprout in the spring experienced greater levels of deer herbivory because of the lack of alternate plants that deer can browse during that time of year. To test this hypothesis, we started plants in greenhouses so that they sprouted at the same time. We then placed these plants in locations throughout Cache Valley where there were deer trails and deer feces. Among these plants, tulip, liatris (Liatris spp.), and grape hyacinth were browsed heavily, suggesting that deer found these plants palatable. In contrast, crocus were rarely eaten, suggesting that deer damage on this plant results more from its early sprouting rather than its palatability. Planting unpalatable plants may be a viable approach to reducing homeowners' angst from finding that their spring-flowering plants have been browsed. Wildlife biologists and Cooperative Extension agents should find our results useful when guiding homeowners in selecting which spring-flowering plants to grow in areas where deer herbivory can be expected. (C) 2018 The Wildlife Society.