White-tailed deer (Odocoileus virginianus) populations in the United States have
increased in recent years, particularly in urban and suburban landscapes where
traditional measures of population control are difficult to implement. As a result of rapid
urban development in the last several years, the Lyndon B. Johnson Space Center (JSC)
located southeast of the Houston, Texas metroplex has become a refuge for an
increasing, isolated urban white-tailed deer population. The use of the
immunocontraceptive SpayVac⢠has been proposed as a feasible measure in controlling
the JSC deer population; however, the potential effects of the vaccine on deer
movements are unknown. Furthermore, there is a need to estimate deer densities when
using intensive management practices (e.g., contraceptive program) which requires an
assessment of methods to estimate urban deer densities. The objectives of my study
were to (1) compare female movements and ranges between deer treated with
SpayVac⢠versus non-treated (control) deer, (2) determine if the timing of SpayVacâ¢
treatment affected efficacy, and (3) compare mark-resight and distance sampling
methodologies in estimating urban deer densities. I captured and radio-marked 59 adult
female deer at JSC. I found annual ranges between treated (mean 95% kernel = 82 ha, mean 50% kernel = 11 ha) and control (mean 95% kernel = 77 ha, mean 50% kernel =
11 ha) deer were similar (P > 0.05). Furthermore, I found daily movements between
treated (mean = 430 m) and control (mean = 403 m) deer also were similar (P > 0.05).
The use of SpayVac⢠did not alter movements and ranges of treated deer, and is
unlikely to increase deer-vehicle collisions due to increased movements. I found the
timing efficacy (i.e., time needed for vaccine to prevent pregnancy) of SpayVac⢠was
0% for does treated closer to the breeding season than previously believed. For JSC, this
expands the application time for SpayVac⢠treatment to a 5-6 month window rather
than the 2-3 month window as previously recommended.
I found mark-resight estimates (160-174 deer) were congruent with minimum
known alive estimates at JSC (158), whereas distance sampling estimates (83-114) were
biased low. The use of non-random road counts likely resulted in the low estimates
using distance sampling. I recommend that future efforts to monitor population densities
at JSC use mark-resight estimates along with the on-going contraceptive program.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/4671 |
| Date | 25 April 2007 |
| Creators | Hernandez, Saul |
| Contributors | Lopez, Roel R. |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | 361428 bytes, electronic, application/pdf, born digital |
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