Simulated Effects of Harvest Strategy on Reproduction in White-Tailed Deer

Abstract

A deterministic simulation model was used to examine the possible effects of harvest strategy on the temporal aspects of white-tailed deer (Odocoileus virginianus) reproduction in Mississippi. The timing of bucks-only and antlerless deer harvests affected reproductive parameters. Delaying the start of buck hunting from mid-November to mid-December increased the proportion of does serviced on their initial estrus of the season from 0.77 to 0.91 and resulted in a mean fawning date that was 4 days earlier. Harvesting antlerless deer prior to peak rut allowed the maximum number of does to be serviced on their first estrus of the season. Decreasing the harvest rate of bucks from 0.81 to -<0.61 increased the proportion of does serviced on their first estrus from 0.76 to 0.91 and increased the fecundity rate from 1.56 to 1.61. The model was sensitive to the timing of the rut and the number of does serviced per buck. J. WILDL. MANAGE. 48(2):535-541 The variation in breeding dates of adult ( 1/r years) white-tailed deer in Mississippi is extensive. Jacobson et al. (1979) reported that the rut ranged from 20 November to 15 March, with over 80% of breeding occurring between 21 December and 21 January. Additionally, mean breeding dates in north-central Mississippi shifted from 22 December during 196063 to 19 January during 1976-79 (Jacobson et al. 1979). Age and nutrition are known to affect the onset of estrus in white-tailed deer. Yearling does (11/? years old) tend to breed a few days later than the average for older animals, and doe fawns breed substantially later (Haugen 1975, Butts et al. 1978, McCullough 1979: 49-50). Verme (1965) reported that does on a high level of nutrition began breeding 15 days earlier than poorly fed animals. Teer et al. (1965), McGinnes and Downing (1977), and McCullough (1979: 50-51) also indicated that time of estrus must be controlled to some extent by nutrition. Other factors that may influence breeding periodicity are photoperiod (Severinghaus and Cheatum 1956, McDowell 1970), temperature (Cheatum and Morton 1946, Severinghaus and Cheatum 1956), and fawn survival rates the previous year (McGinnes and Downing 1977). None of these factors appear to account for the 4-week shift in mean breeding date observed in north-central Mississippi by Jacobson et al. (1979). They suggested that harvest of adult bucks prior to the peak period of estrus may have contributed to the delayed rut noted after 1963. Prior to the 1971 season, 20 days of bucks-only hunting with firearms were allowed between 20 November and 4 January with a limit of two antlered bucks/hunter. In 1971, gun hunting was increased to 32 days, a primitive weapons season of 16 days was initiated, and the limit increased to four antlered bucks/hunter. Length of the hunting season and bag limit remained essentially unchanged from 1971 to 1976. During the 1977 season, the regulations allowed one antlered buck to be taken per hunter daily. Traditionally, hunting pressure has been heavy and the IPresent address: Department of Range and Wildlife Management, Texas Tech University, Lubbock, TX 79409. 2 Present address: Department of Forestry, Clemson University, Clemson, SC 29631. J. Wildl. Manage. 48(2):1984 535 This content downloaded from 157.55.39.206 on Sat, 17 Dec 2016 05:25:22 UTC All use subject to http://about.jstor.org/terms 536 HARVEST STRATEGY AND DEER REPRODUCTION * Gruver et al. INPUT INITIAL CONDITIONS