Factors influencing summer habitat use of black-tailed deer on South-Central Vancouver Island

Use of seral stage, biogeoclimatic variant, aspect and elevation by 13 radio collared black-tailed deer (Odocoileus hemionus columbianus Richardson) was examined at the ‘within home range’ level of habitat selection. Pooled data sets were evaluated for patterns of habitat use in relation to time periods within the summer of 1991. The July/August period of peak clearcut use coincided with the period of peak fireweed (Epilobium angustfolium L.) use identified by other research. The percentage of locations within clearcuts was 67.9% in April/May/June, 78.2% in July/August and 69.2% in September/October. Fireweed, an early successional forb, has been shown by other research to be the most important black-tailed deer summer forage species. Similar trends in fireweed use and the percent of locations within clearcuts therefore, were predictable. The use of Montane variants of biogeoclimatic subzones was higher in the latter portions of the summer. The percentage of locations within Montane variants was 14.5% in Aril/May, 22.6% in June/July and 25.8% in August/September. Use of Montane habitat was lowest in the spring when forage species within the Submontane were more phenologically advanced and more nutritious. Shifts in elevation and changes in the use of aspect were not detected. Parturient deer did not change their use of seral stage within the fawning period. Home range size (minimum convex polygon) was greater in the fawning period than in any other period. Increases in home range size during the fawning period were caused by increases in the magnitude and/or rate of movements to the peripheries of the home ranges. This finding supports the idea that sites on the periphery of the dam’s home range are used for fawning, and is consistent with the ‘hider strategy’ model. Hiders are known to remove their young from the birth site to prevent predators from using olfactory cues to detect their young. If black-tailed deer were to give birth within their core areas of use, they would be forced to remove their fawns from the habitats they most IDrefer. Home range size was smaller in the immediate post-fawning period than in all other periods except the pre-natal period. This behavior is again consistent with the hider strategy. Immediately after fawning, the dam must remain close to her fawns, which are sedentary. Habitat use in the early summer was more concentrated in Submontane habitats where green-up occured first. Home range size in the pre-natal period therefore, should also have been small.