Download Study Proposal - Natural Resource Ecology Laboratory

Study Proposal
Effects of chronic wasting disease on the fecundity on female mule deer
(from birth to weaning)
Jessie R. Dulberger
Graduate Degree Program in Ecology
Colorado State University
Dr. N. Thompson Hobbs
Natural Resource Ecology Laboratory
Colorado State University
Dr. Michael W. Miller
Colorado Division of Wildlife
Graduate Degree Program in Ecology
Colorado State University
Dr. Michael F. Antolin
Professor and Assistant Chair
Department of Biology
Colorado State University
Project Summary
The goals of this study is to understand to what extent chronic wasting disease
affects fecundity on female mule deer. The study will be conducted in a non-hunted
natural area in the foothills of Boulder, Colorado. Our objectives of this study are to
compare fecundity (i.e., potential reproductive capacity) rates for chronic wasting
disease infected and non-infected female deer during the first month of birth and
during weaning in the 3 month of birth. In order to meet these goals we will observe
forty-two radio-collared does and assess fawn presence or absence for three
summers after parturition (in June) and during weaning (in August). Twice a week
each animal will be monitored for mortality. Initial results from the pilot study
suggest that the fecundity of chronic wasting disease infected does is much lower
than non-infected does. This study is unique because the mule deer population is
not affected by hunting.
Introduction
Chronic wasting disease (CWD) is a natural, infectious and fatal prion disease that
negatively affects members of the deer family, mainly Mule Deer (Odocoileus
hemionus), Elk (Cervus elaphus nelsoni), and White-Tailed Deer (Odocoileus virginianus
(Miller et al. 2005). CWD causes neural degeneration and ultimately death (Williams et
al. 2002, Hobbs et al. 2002?). Wildlife managers in many states with wildlife recreation
based economies are concerned about the possible devastating effect of chronic wasting
disease on the state’s deer populations. Population models suggest that fawn survival is
key to maintaining deer population dynamics (Jensen et al. 1999).
We hypothesize that chronic wasting disease does have an affect fecundity in female
mule deer, and that effect is quite significant.
Objectives
Important factors that affect the stability of a healthy deer population are the fecundity of
does and fawn recruitment (Pojar and Bowden 2004). Therefore is important to study
how CWD affects both the fecundity and fawn recruitment up to weaning, in a freeranging mule deer population.
The specific objectives of this study are to:
(1) Compare the presence or absence of fawns during the neonatal period with
infected vs. uninfected does.
(2) Compare fawn survival of infected vs. uninfected does until weaning (16 weeks
after birth.
Background
In the last 39 years CWD has become a threat to states with wildlife recreation-based
economies and thus a concern to both the public and wildlife managers throughout the
country (Miller 2002, Williams et al. 2002, Hobbs et al. 2001). Currently CWD is not a
direct threat to humans. There have been no cases of human prion disease associated
with CWD (World Health Organization 2000, Belay et al. 2001), but a recent study has
shown that CWD specific prions ( PrPres) are in skeletal muscles. This raises the possibly
that through consumption of infected cervid meat, dietary exposure to prions could occur
(Angers et al, 2006). The disease is thought to be transmitted indirectly to deer
horizontally via prions in feces (Miller et al. 2004), but a recent study with captive deer
has shown that fawns orally given blood, saliva and chronic wasting disease infected
brain tissue, tested positive for the chronic wasting disease prions within 12 months of
age (Mathiason et al. 2006).
Models show that CWD epidemics drive populations to extinction, specifically when
prevalence rates reach 5% larger (Miller et al. 2000). The reduction of cervid populations
across North America may harm the balance within many ecosystems (Hobbs et al.
1996). Culling deer herds in CWD hotspot areas had been the practiced management
technique, until recently. The Colorado Division of Wildlife has halted the practice of
culling, since the prevalence of CWD in deer populations has not been reduced over the
past 5 years (Colorado Division of Wildlife, unpublished report). Further studies are
needed to understand how CWD spreads, how to stop it from spreading and how it affects
deer populations.
Declining mule deer densities have caused wildlife researchers to focus on studying fawn
survival and recruitment (Pojar and Bowden 2004). Population models for deer suggest
long-term population trends are most sensitive to the survival of fawns, (Jensen et al.
1999). Andelt et al. 2004 showed that mule deer fawn:doe ratios in December had
declined by 0.015 fawns/doe/yr from 1972 through 1995 in Colorado. Many hypotheses
have been offered to explain fawn:doe declines including: failure to breed, decreased
fecundity, resorption/abortion of fetuses, low summer and fall fawn survival, habitat
deterioration, increased predation, drought, hunting, disease or a combination of these
factors ( Pojar and Bowden 2004, Andelt et al. 2004, Unsworth et al. 1999). Andelt et al,
2004 concluded that failure to breed or maintain pregnancy through at least early January
or February was not the cause of low f:d ratios observed in Colorado, since 90-93% of
deer in the study were pregnant. Predation, specifically coyotes has been questioned as a
significant mortality factor for fawn numbers (Jensen, 1999), but it has since been shown
that coyotes and mountain lions appear to kill fawns in very poor condition (Bishop,
2005). Mortality rate of fawns were not directly related to population levels of coyotes
(Hamlin, 1984).
This study will evaluate the effects of CWD on the fecundity of adult does in the foothills
of Boulder, CO. An ongoing mule deer survival study with the City of Boulder’s Open
Space and Mountain Parks and the Colorado Division of Wildlife has thus far shown a
relatively high prevalence rate (50% in bucks and 30 % in does). When animals were
retested a year later 25% of the does that were not infected had contracted chronic
wasting disease (unpublished data). Models forecast population declines once CWD
prevalence exceeds about 5% (Miller 2000). Therefore the deer population along the
Front Range in the City of Boulder is in jeopardy, and will be a good example of how
CWD affects a non hunted free-ranging mule deer population.
The City of Boulder Open Space and Mountain Parks has had several mule deer
population studies using the Lincoln-Peterson estimator. From 1983 to 1990 there was an
increase in the mule deer population from 783 to 1,238 in a 17 square mile area (Kelsey,
1990). The study area for this past study was twice as large as the current study and it
ranged North of El dorado Springs Dr to just south of Lee Hill Road. The 2005 markresight population count of mule deer averaged 270 using the Bowden estimator. The
study area ranged North of El dorado Springs Dr. and South of Baseline Rd. Even though
the 2005 study is half the size of the study done in 1983-1990, if doubled it would only
average around 540, which is the lowest City of Boulder population seen in many years.
The Pilot Study Summer 2006
From June to September in 2006, a pilot study was conducted. The power calculation
performed from this initial data set showed that we will need twelve infected and equal
numbered non-infected does to detect a difference of 0.9 in fecundity rates. Figures 2,3
and 4 demonstrate that sample sizes of seven and ten were too small, while fifteen is not
needed. The methods during the pilot were not as rigorous as the methods will be for the
following two summers, due to lack of time. There were seven matched pairs of does in
the study for the summer of 2006. Extra non-infected does were also observed for
presence or absence of fawns, mainly in August/September, (please see figure 1.). Using
Likelihood and Akaike’s information criterion corrected for small sample bias (AICc) for
model selection, we were able to detect a difference using a two parameter comparison.
The two parameter model had more support in the data than the one parameter model.
The limiting factor for this study is the sample size of chronic wasting disease infected
does, since only one out of three female deer sampled tested positive for CWD.
Number does with
Number total does
Fawns
Observed
CWD Positive
3
7
23
32
CWD Negative
Figure 1. Pilot study data from summer 2006.
total # of does (7)
1.2
1
wr
0.8
0.6
0.4
0.2
0
0
1
2
3
# of does w ith faw ns
4
5
6
1 parameter
2 parameters
Figure 2. One versus two parameters for seven does.
Total # of does 10
1.2
1
wr
0.8
0.6
0.4
0.2
0
0
1
2
3
4
5
# of does with fawns
6
1 parmater
2 parmaters
Figure 3. One versus two parameters for ten does.
Total # of does 12
1.2
1
wr
0.8
0.6
0.4
0.2
0
0
1
2
3
4
5
# of does with fawns
6
1 parameter
2 parameters
Figure 4. One versus two parameters for twelve does.
Total # of does 15
1.2
1
wr
0.8
0.6
0.4
0.2
0
0
1
2
3
4
# of does with fawns
5
6
1 paramter
2 paramters
Figure 5. One versus two parameters for fifteen does.
Material and Methods
Study Area: The study area in Boulder will focus on low-elevation mule deer winter
range. The study’s boundaries are as follows: Baselines Rd on the north, Broadway Rd
and the east, El dorado Springs Dr. on the south and the Flatiron Mountain range to the
west. (please see figure 7.)
Figure 7. Study area in Boulder, Colorado
Approach: Adult does have been previously marked with unique numbered ear tags and
collars with mortality-sensing radio transmitters. Twelve CWD infected and thirty noninfected does will be paired at the beginning of the summer on the basis of infected or not
infected with chronic wasting disease, age, location and genotype.
The location and body condition of each doe has been determined at least once a month,
since their original capture date. They are also monitored twice weekly for survival
status. When an animal dies it is found via the mortality emitting radio transmitter and
telemetry. The cause of death is recorded and samples are taken to retest for chronic
wasting disease, and if the cause is unknown the body is submitted for a necropsy to the
Colorado Division of Wildlife laboratory.
Beginning in the last week of May each doe will be observed 1x/week for 2 hours after
sunrise or before sunset to determine the presence or absence of fawn/s. Does that show
behavioral and physical characteristics, such as moving alone, udder development and
sunken flanks, are prime candidates for having fawns (Pojar and Bowden 2004, Huegel et
al. 1985). When observing doe productivity, a search in the first two weeks after
parturition is necessary, since mothers associate very little with fawns and periods of
contact are brief, occurring predominantly at sunrise and sunset. It is also crucial to detect
presence or absence of fawns after in during the neonatal period because in June the
probability of survival is lowest, 0.33 in June compared to 0.9 in September (RaganellaPelliccioni, 2006). We hypothesis that chronic wasting disease affects infected does
which in tern can not keep their fawns alive, whether it is due to the fawn/s being born
weak or due to a lack of parenting. Mothers also keep the shortest distances during the
first two weeks (Schwede et al. 1994). During this time does can also be approached
closely before flushing (Huegel et al. 1985). Huegal et al. 1985 found that does always
remained in the general vicinity of their fawns while the crew search. The search will
consist of marking the original location of the doe upon first approach and then searching
out from that point 200 meters in a circle around that original point. If searches were
unsuccessful, follow-up searches were made 1-2 days later if the doe had remained in the
original search area. When fawns and does are seen together, fawn less than 20 meters
away will be considered associated with the doe (Schwede et al, 1994). Once the
presence of fawns is established, does will be observed twice a month until weaning
when fawns are 16 weeks of age, or the end of September. At each observation the body
condition, location of the doe and fawn, presence or absence of fawn/s and vegetation
type will be recorded.
Analysis
Model Selection will be used to evaluate the relative strength of models predicting
female fecundity. Several factors that will contribute to these models are: location,
genotype, age and CWD status. We will create a candidate set of models via a priori
knowledge and use likelihood inference and AICc to select the model that has the most
support in the data.
Budget
June 2006-September 2006
Research Assistantship ($/month * 4 monthes) (first field season)…$(OSMP)
Field Equipment (scope, digital camera, logbook, binoculars, miscellaneous)………..$2,000.00
Tom’s Salary ?
Mike’s Salary ?
1st Field Season Subtotal……………………………………………………………….$2,000.00
+ Ten Percent…………………………………………………………………………..$200.00
1st Field Season total…………………………………………………………………..$2200.00
October 2006-September 2007
Research Assistantship ($1500/month * 12 months + fringe) (first field season)……..$14,400.00
Tuition (two semesters)………………………………………………………………...$3,073.98
Field Assistant (2 monthes at $1760/month+fringe)..………………………………….$3,520.00
Materials and Supplies…………………………………………………………………$300.00
Travel and Conferences……………… ………………………………………………$500.00
Tom’s Salary ?
Mike’s Salary ?
Year 1 Subtotal……………………………………………………………………….$21,793.98
+ Ten Percent…………………………………………………………………………$2,179.39
Year 1 Total…………………………………………………………………………..$23,973.37
October 2007-September 2008
Research Assistantship ($1500/month * 12 months + fringe) (first field season)……..$14,400.00
Tuition (two semesters)………………………………………………………………...$4,810.90
Mileage (,000 miles/week at 36 cents/mile...…………………………………………..$?
Field Assistant (2 monthes @$11/hr 40hr/wk +fringe)………………………..………$3,520.00
Materials and Supplies………………………………………………………………….$300.00
Tom and Mike’s Salary ?
Year 2 Subtotal…………………………………………………………………………$23030.90
+ Ten Percent…………………………………………………………………………..$2,303.09
Year 2 Total……………………………………………………………………………$25333.99
October 2008-September 2009
Research Assistantship ($1500/month * 12 months + fringe) (first field season)……..$14,400.00
Materials and Supplies…………… ………………………………………………….$300.00
Tom and Mike’s Salary ?
Year 3 Subtotal……………………………………………………………………….$14,700.00
+ Ten Percent…………………………………………………………………………$1,470.00
Year 3 Total…………………………………………………………………………..$16170.00
3 ½ YEAR PROJECT TOTAL……………………………………………………….$63,904.27
Budget for Jessie Dulberger for 2 ½ years. 3 field seasons, 5 semesters of classes, 1 semester to write thesis.
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