Genetic tagging free-ranging white-tailed deer using hair snares

Ohio Journal of Science, The, Sept, 2007 by Jerrold L. Belant, Thomas W. Seamans, David Paetkau

The mean number of hair samples collected at SBDNL decreased from about 3.5 per snare in May to about one per snare during July (Fig. 5). Although the number of barbs available for snagging hair at PRNL was greater than at SBDNL, the mean number of hair samples collected in July was 1.4 per snare and then increased to 2.1 per snare in late August. The overall percentage of Category 2 samples at SBDNL was 72% during May-June and 27% during July; percentage of Category 2 samples at PRNL was 27%.

The mean number of hair samples collected at two-week intervals GINRA was 4.4 per snare, slightly greater than twice the rate samples were collected at PRNL at one-week intervals. Twenty-six percent of hair samples collected at GINRA were Category 2.

At several sites in Michigan study areas, slight cratering of the soil was observed apparently from deer attempting to ingest minerals from the attractant. Although no evidence of injuries was observed for deer or other wildlife entering snare sites, the wire from one side of a snare at PRNL was pulled from the tree. Barbed wire was bent on several occasions at hair snares at SBDNL and required straightening. Additionally, 19 samples at snares from SBDNL were collected from the ground.

DNA Analyses

Of the 53 winter hair samples analyzed from PBS, only one (2%) lacked adequate DNA for determining genotype. Degradation of this sample in the field was suspected as a suitable number of guard hairs (n = four) for extraction were collected. Twelve additional samples (23%) produced clear evidence of [greater than or equal to] 3 alleles, suggesting these samples contained hair from [greater than or equal to] 2 deer. The remaining 40 samples produced good genetic data and comprised 23 distinct genotypes. The most similar pairs of genotypes differed at four of the six markers (4MM pairs) with greatest [H.sub.E] (Table 1), suggesting it is highly unlikely that we sampled any single pair of individuals with identical six-locus genotypes.

The number of alleles for the 12 markers used to identify these 23 individuals ranged from five in marker OvH to 11 in Rt07; mean allelic diversity was 8.2 alleles per locus (Table 1). Mean observed heterozygosity (0.75) was similar to mean expected heterozygosity (0.77).

[FIGURE 2 OMITTED]

The number of samples obtained from individual deer ranged from one to six. Twenty-one deer were identified from one baited site and two deer were identified from the two baited sites located 1.0 km apart. This suggests that deer use of sites, and likely movements between sites, was low during the period that hair samples were collected.

DISCUSSION

Barbed wire snares were effective for non-invasively obtaining hair samples from free-ranging white-tailed deer under a wide range of densities (3-54/[km.sup.2]). We obtained many samples of sufficient quantity and quality for determining genotype. Several aspects of this technique could potentially be enhanced to improve efficacy. The attractant we used at SBDNL, PRNL, and GINRA was a combination of food scent and minerals. The premise was that deer would be attracted initially to the food scent and encounter the mineral component which would result in repeated use. An advantage of this type of attractant was that sites did not require reapplication of bait during each check session, in contrast to studies of other species where attractant was reapplied during each check session (e.g., Belant et al. 2005). Indeed, in some cases we did not reapply attractant for up to six weeks, yet deer continued using sites. This duration should be adequate for many field studies including population enumeration. However, numerous baits and scents are available to attract white-tailed deer, especially those developed by commercial manufacturers for sport hunting. Prebaiting sites until deer use is consistent may also facilitate obtaining hair samples. Improving attractiveness of bait used or bait delivery would increase deer activity at snare sites and consequently the number of hair samples obtained.