Mule Deer - 2005
Environmental Report Section 10.11.1.4
K. D. Hand and
J. A. Stegen
Population characteristics of mule deer on the Hanford
Site have been monitored since 1994. Roadside surveys
are conducted from mid-November to mid-January to assess
age and sex ratios and the frequency of testicular atrophy in
males. The survey route extends from near the 300 Area in
the south to the 100-B/C Area in the north and is divided at
the Hanford town site into north and south regions. Tiller and Poston (2000)
found that there is little overlap in the
home ranges of deer occupying these two regions.
Six surveys were conducted between mid-November 2005 and early-January 2006. A combined total of 559 deer observations were made over the six repeated surveys, which included multiple observations of the same animals in some cases. Individual animals were identified according to sex and age class (fawn or adult). For male deer, the presence of misshapen, velvet-covered antlers was used as an indicator of testicular atrophy.
Trends in the ratios of fawns to does over time can be used to monitor changes in mule deer population size and health. Data from the 2005â€"2006 surveys show a pattern of fawn to- doe ratios that was similar to that observed in 2004. In 2005, the north region fawn-to-doe mean estimate was 27 fawns per 100 does while the south region mean estimate was 22 fawns per 100 does (Figure 10.11.3). These estimates are similar to those from 2004 when the mean estimates were 20 and 24 fawns per 100 does for the north and south regions, respectively. Hanford fawn-to-doe ratios for all survey years (1994â€"2005) are weighted averages, using the total number of fawns and does seen per survey as the weighting factors.
In the early 1990s, testicular atrophy and sterility were
observed in some male mule deer on the Hanford Site (Tiller et al. 1997; PNNL-11518).
Extensive investigation found no
clear cause for these conditions (Tiller et al. 1997). Testicular
atrophy in male mule deer is associated with abnormal antler
growth manifest as misshapen, velvet-covered antlers, which
can be observed in field surveys. The frequency of misshapen
antlers in mule deer has ranged from a high of 17% in 1998
to a low of 0% in 2003 (Figure 10.11.4). The decrease from
1998 through 2003 was reversed in 2004 with 12.5% of the
north region and 5% of the south region male deer affected.
Data from the 2005â€"2006 surveys again show a decrease
with only 2.9% of male deer in both the north and south
regions affected. However, because small sample sizes may
not fully reflect population conditions, these frequency
estimates need to be interpreted with caution. Table 10.11.1
shows the total number of bucks observed and the number
with antler abnormalities observed during roadside surveys
between 1994 and 2005.
