**National Capital Region**

**National Park Service**

**Deer Survey Report**

**Fall 2005**

**Antietam National Battlefield**

**Catoctin Mountain Park**

**Chesapeake and Ohio Canal National Historic Park-Gold Mine Tract**

**Greenbelt Park (NACE)**

**George Washington Memorial Parkway-Great Falls**

**Manassas National Battlefield Park**

**Monocacy National Battlefield**

**Piscataway Park (NACE)**

**Prince William Forest Park**

**Harpers Ferry National Historic Park**

**Rock Creek Park**

**Scott Bates**

**Wildlife Biologist**

**NCRO**

**Center for Urban Ecology**

**4598 McArthur Blvd, NW**

**Washington, D.C. 20007**

**May 2006**

### ANNUAL REPORT CHECKLIST

### 

### X Cover page lists all authors and addresses.

### X Document has been reviewed for content, spelling, and grammar.

### X Abstract and keywords are provided on page three of final report.

### X Body of document includes introduction, description of study area, methods, results, and discussion.

### X Conclusion Section includes Public Interest Highlights.

### X Conclusion Section includes Management Recommendations.

### X Conclusion Section includes Research Recommendations.

### X Tables, figures, maps, and illustrations have descriptive titles and are sequentially numbered.

### X Document is supported by scientific literature.

### X Literature Cited has been checked against the text. 

### ABSTRACT

### 

### The results of the 6^th^ annual fall deer survey results are presented. The purpose of the survey is to assess densities and trends of white-tailed deer populations at natural and cultural resource parks. Distance Sampling is used at all parks except HAFE, where pellet-group counts are used. In 2005, 7 out of the 11 parks surveyed had decreases in density when compared to 2004. MONO, GREE, CATO, and ROCR had decreases that were 20% less than their 2004 densities. Four parks (GWMP, HAFE, CHOH, PISC) saw increases in 2005. HAFE and GWMP had significant increases over their 2004 densities. There were no significant trends at the 0.01 level. All parks except PRWI and GREE had deer densities over 40 deer per square mile. All parks with high deer densities have implemented or completed deer impact studies.

### 

### Keywords: Distance, white-tailed deer, sampling variation, and process variation. 

### TABLE OF CONTENTS

INTRODUCTION......................................................
..........1

METHODS............................................................
............1

RESULTS and
DISCUSSION...................................................2

REGIONAL DENSITY RESULTS..............................................2

SEX RATIO
RESULTS...........................................................4

PARK
RESULTS..................................................................5

CONCLUSIONS..................................................................16

LITERATURE
CITED...........................................................17

FIGURES

NCR FALL 2005 DENSITIES..........................................2

ANTI
.......................................................................5

CATO
......................................................................6

CHOH
......................................................................7

GREE
.......................................................................8

GWMP
.....................................................................9

MANA.....................................................................10

MONO
..................................................................\...11

PISC
.....................................................................\...12

PRWI
....................................................................\...13

ROCR.......................................................................14

HAFE.
......................................................................15

TABLES

NCR FALL DENSITIES........................................\.........3

BUCK:DOE RATIOS....................................................4

FAWN:DOE RATIOS...................................................4

### INTRODUCTION

Distance surveys and pellet-group surveys to determine densities of
white-tailed deer (*Odocoileus virginianus*) started in the fall of 2000
and spring 2001 within the National Capital Region (NCR). Distance
surveys were conducted at ANTI, CATO, CHOH, GREE, GWMP, MANA, MONO,
PRWI, and ROCR. Pellet-group surveys were conducted at HAFE. These
surveys are being conducted as part of a continuing effort to assess the
deer population and its effect on NCR parks. Density data will be used
in compiling deer management plans. This report summarizes the results
of these surveys from their inception through the fall of 2005.

METHODS

Field methods for collecting Distance data and analyzing the data
followed NCR Distance Protocols described in the monitoring plan for the
region (NPS 2005) . All analyses were done at CUE. Spotlight data was
entered into Distance software. Most parks were surveyed for at least
three nights. Exceptions this year included GREE (4), ROCR (4), and MANA
(1). Each night was treated as a replicate and the data were pooled for
analysis. For the initial analysis, the detections were divided into
10-12 evenly-divided distance intervals. Intervals were expanded,
narrowed, or dropped from the analysis to produce a smooth shoulder as
the distance from the observer to the deer increased. Once a
satisfactory shoulder was produced, four models were fit to the data
(uniform, half-normal, hazard rate, and negative exponential). The three
criteria used to choose the best fitted model were: 1) percent
coefficient of variation (CV) less than 20; 2) the detection probability
variation was less than 30%; 3) lowest Akaike's Information Criterion
(AIC) score. Program Distance calculates all three measures.

Forty-five pellet-group plots were checked in the Maryland Heights
section of HAFE (one per every 15 acres). The plots are 44-inch circular
(1/1000 acre) plots. Deer pellets were removed in December and early
January. Plots were checked for deer pellet-groups (group ≥ 5 pellets)
90 or 91 days later.

Program TRENDS (Gerrodette 1987) was used to calculate the power of the
test to detect a trend in the deer population. TRENDS is a software
program that gives power estimates using appropriate tests. This is
important since we want to be able to guard against not being able to
detect a change in the population when it actually has occurred (a Type
II statistical error). At a minimum we would like to be able to have an
80% chance to detect a 10% increase or decrease in the deer population.
Wide variations in the number of deer groups encountered during the
survey are the main reason why a survey would have low power.

The mean fall CV from Distance was used as an input into Dr. Underwood's
Process and Power programs to account for temporal count (process
variation) and sampling variation. Temporal count variation is high when
there are wide variations in mean fall densities over time. Sampling
variation is high when there are wide count variations within a survey
year. Total CV was input into TRENDS. Other TREND parameters include: an
exponential model (changes in deer populations tend to be multiplicative
rather than additive); a 2-tailed test because we are interested in
decreases and increases in the population; an alpha level of 0.1; a 0.10
rate of change, and study duration (either 5 or 6 years depending on
whether or not data was gathered during the fall of 2000).

SYSTAT PC was used to perform linear regression of the logarithm of the
total population against time to check for significant population trends
over time. A p-value of 0.01 was used instead of 0.05. The 0.05 level is
typically used in scientific studies to guard against a Type I error
(rejecting the null hypothesis when it is actually true -- for our
purpose, stating that there is a population trend when it does not
exist). The p-value of a statistical significance test represents the
probability of obtaining values of the test statistic that are equal to
or greater in magnitude than the observed test statistic. A p-value
close to zero signals that your null hypothesis is false, and typically
that a difference (trend) is very likely to exist. Large p-values closer
to 1 imply that there is no detectable difference for the sample size
used (no trend exists).

There is a statistical and biological reason for using 0.01 instead of
0.05. When repeated measurements over time are collected from the same
area, the count data can be correlated from one year to the next (serial
or positive autocorrelation). The use of 0.01 can mitigate positive
autocorrelation (Hatfield et al. 1996).

The biological reason for using 0.01 is that it can take 5-10 years for
vegetation recovery to occur after deer densities have been reduced to
acceptable levels (Niewinski et al. 2006). A significant population
decrease at a significance level of 0.01 would be more congruent with
lower deer densities and vegetation recovery (but would not guarantee
vegetation recovery when densities remain above acceptable levels).

RESULTS and DISCUSSION

REGIONAL DENSITY RESULTS

Figure 1 shows the 2005 fall densities for all parks. All parks (except
GWMP and PRWI) have deer densities that exceed 16 deer per square
kilometer (40 deer per square mile). Densities above 40 deer per square
mile indicate negative effects on other wildlife species; densities
above 25 deer per square mile indicate a negative effect on vegetation
(Tilghman 1989; deCalesta 1997).

Individual park results will be discussed in the 'Park Results' section
below.

![](media/image1.wmf){width="4.428472222222222in"
height="3.2736111111111112in"}

Figure 1. Fall 2005 deer densities at NCR parks. Blue dots indicate the
mean; horizontal bars indicate the standard error of the mean.

SEX RATIO RESULTS

Table 2 contains buck:doe ratios from fall spotlight surveys. Buck:doe
ratios of 1:4 or more may indicate an overpopulation situation (Miller
and Marchinton 1995).

  ----------- ------------ ---------- ---------- ------------ ------------
              **2001**     **2002**   **2003**   **2004**     **2005**

  **ANTI**    1:9.00       1:5.22     1:3.06     1:3.54       1:8.12

  **CATO**    1:13.00      1:3.11     1:7.03     1:9.30       1:12.2

  **CHOH**    1:5.40       1:3.40     1:6.00     1:6.57       1:6.60

  **GREE**    1:3.61       1:3.47     1:8.00     1:2.76       1:9.00

  **GWMP**    1:4.92       1:5.23     1:2.33     1:23.00      1:5.90

  **MANA**    1:9.66       1:5.75     1:7.09     1:4.00       1:8.50

  **MONO**    1:11.40      1:5.22     1:6.13     1:7.12       1:6.50

  **PISC**    1:5.41       1:2.70     1:7.83     1:4.52       1:8.00

  **PRWI**    1:4.76       1:6.16     1:7.50     1:4.40       1:1.91

  **ROCR**    1:2.87       1:5.30     1:2.69     1:4.76       1:3.26
  ----------- ------------ ---------- ---------- ------------ ------------

**Table 2. 2001-2005 buck:doe ratios**.

Fawn: doe ratios (Table 3) of 0.3:1 or less indicate populations under
stress (Miller and Marchinton 1995) (not enough desirable food sources
for does to produce twins). Overall, 2005 had the lowest fawn:doe ratios
of any survey year -- 5 parks had their lowest ratios ever recorded.
CATO, PRWI, GWMP, CHOH, and ROCR had values of 0.3:1 or less in 2005.
PRWI and GWMP have had low fawn:doe ratios for 4 out of 5 survey years.
CATO has had low ratios for 2 consecutive years while CHOH has had low
ratios for 3 out of the 5 survey years. Poor visibility of fawns due to
vegetation may be a factor at PRWI.

  -------------- ---------- ---------- ---------- ------------ ------------
                 **2001**   **2002**   **2003**   **2004**     **2005**

  **ANTI**       0.74       0.91       0.86       0.80         0.41

  **CATO**       0.37       0.44       0.41       0.30         0.08

  **CHOH**       0.13       0.17       0.56       0.52         0.10

  **GREE**       0.25       0.22       0.63       0.46         0.56

  **GWMP**       0.23       0.28       0.76       0.26         0.03

  **MANA**       0.63       0.27       0.45       0.34         0.35

  **MONO**       0.66       0.93       0.87       0.59         0.38

  **PISC**       0.37       0.48       0.86       0.69         0.62

  **PRWI**       0.16       0.19       0.38       0.00         0.08

  **ROCR**       0.12       0.25       0.75       0.39         0.30
  -------------- ---------- ---------- ---------- ------------ ------------

**Table 3. 2001-2005 fawn:doe ratios**.

  -------------- --------------- ---------------- -------------- ---------------
                 \%              **F-RATIO^2^**   **P-VALUE**    **%POWER^3^**
                 **CHANGE^1^**                                   

  **ANTI**       21              1.55             0.30           70

  **CATO**       -61             8.49             0.04\*         100

  **CHOH**       36              1.01             0.37           60

  **GREE**       -49             0.03             0.85           34

  **GWMP**       40              0.04             0.84           21

  **HAFE**       11              0.01             0.92           16

  **MANA**       -16             0.43             0.54           97

  **MONO**       -1              0.61             0.49           95

  **PISC**       13              0.17             0.70           58

  **PRWI**       -39             7.63             0.06           18

  **ROCR**       -16             0.02             0.87           42
  -------------- --------------- ---------------- -------------- ---------------

**Table 4. Percent population change, linear regression f-ratio, and
p-value.**

1- First year density divided by last year density.

2- Linear regression test statistic.

3- 80% power to detect a ±10% trend.

\*- Significant p-value at the 0.05 level.

PARK RESULTS

![](media/image2.wmf){width="4.427083333333333in"
height="3.2944444444444443in"}

Figure 2. Antietam National Battlefield mean density data.

If bars overlap then there is no significant difference between years.
The 2005 deer density was the second decrease after two years of
increases. There was no significant population trend from 2001-2005
(Table 4). The park will have 80% power to detect a trend of ±10% after
the 2006 survey.

![](media/image3.wmf){width="4.550694444444445in"
height="3.2944444444444443in"}

Figure 3. Catoctin Mountain Park mean density data.

The mean fall density decreased significantly for the second straight
year. This may be due to a combination of factors: poor habitat
conditions from 25 years of an overpopulation condition, disease,
increased hunting/depredation pressure outside of the park, and
predation by coyotes (primarily) and black bears (rarely). Similar
decreases occurred after the winters of 1993-1994 and 1995-1998; the
population quickly rebounded.

The decrease in the population during the period of study (2000-2005,
Table 4) was not significant at the 0.01 level but is significant at the
0.05 level. If the density remains under 37 deer/square kilometer
(95/square mile) in 2006, the decrease in the population will be
significant at the 0.01 level.

![](media/image4.wmf){width="4.550694444444445in"
height="3.2944444444444443in"}

Figure 4. CHOH (Goldmine Tract) mean density data.

Densities at C&O have been fairly stable when compared to other parks (a
range of 16 between the lowest and highest densities). There was no
significant population trend during the study period (2000-2005, Table
4). The park will have 80% power to detect a ±10% trend in 1 year.

![](media/image5.wmf){width="3.09375in" height="3.2916666666666665in"}

Figure 5. Greenbelt Park mean density data.

There has not been any significant trend at Greenbelt during the study
period (Table 4). The park has low power to detect a trend (Table 4).
Year-to-year variation (55% of the total variation) was the primary
factor. It will take 3 more years of surveys before the park reaches 80%
power to detect a trend.

![](media/image6.wmf){width="4.427083333333333in"
height="3.2944444444444443in"}

Figure 6. Great Falls mean density data.

There was no significant trend in the deer population (Table 4). The
park also has low power to detect a trend (Table 4). Year-to-year count
variation was responsible for 89% of the total variation. This can be
seen looking at the mean fall densities from 2001-2005 (33, 27, 36, 9,
and 47). It will take another 5 years of surveying before 80% power is
achieved. Deer may have moved away from Great Falls during the Riverbend
Park culling operation in 2004. Future spotlight surveys have to be
conducted before culling begins in order to achieve accurate results or
another method (digital camera surveys) may have to be used to assess
the approximate deer density.

![](media/image7.wmf){width="4.550694444444445in"
height="3.2944444444444443in"}

Figure 7. Manassas National Battlefield Park mean density data.

Manassas experienced slight non-significant decreases in 2004 and 2005.
No significant trend was detected during the study period (2000-2005,
Table 4). MANA has achieved 100% power to detect a ±10% trend.

![](media/image8.wmf){width="4.550694444444445in"
height="3.2944444444444443in"}

Figure 8. Monocacy National Battlefield mean density data.

Monocacy's deer density decreased slightly from 2004. The park had the
second highest density in the region in 2005. It has been one of the top
3 high-density parks in each year of the survey. There was no
significant population trend during 2001-2005 (Table 4). The park has
95% power to detect a ±10% trend after the 2005 surveys.

![](media/image9.wmf){width="4.550694444444445in"
height="3.2944444444444443in"}

Figure 9. Piscataway Park mean density data.

The deer density at Piscataway continued to exhibit a zigzag, up-down
pattern. There was no significant population trend from 2001-2005. Power
to detect a trend is now 58% and should be over 80% after the 2006
survey (Table 4).

![](media/image10.wmf){width="4.550694444444445in"
height="3.2944444444444443in"}

Figure 10. Prince William Forest Park mean density data.

Density at Prince William decreased slightly in 2004 and 2005. With the
exception of 2003, the deer population has been less than 16 deer/square
kilometer (40 per square mile). No discernible trend was detected though
power to detect a trend remains low (Table 4). Sampling variation and
year-to-year variation account equally for the total count variation. It
will take another 5 years of surveying before the park reaches 80%
power. The relatively high amount of variation in 2003 has kept the
power to detect a trend quite low. Increasing the number of spotlight
surveys to increase the power to detect a trend would be easier than
using digital camera surveys. It would take 150 digital cameras to
conduct an accurate deer density survey at the optimal density of one
camera per 160 acres throughout the park.

![](media/image11.wmf){width="4.677083333333333in"
height="3.2944444444444443in"}

Figure 11. Rock Creek Park mean density data.

Rock Creek experienced a slight decline in 2004 and 2005. There have
been no significant trends in the population. Power to detect a trend
remains low (42%) because of the increase in the survey in 2003 of
sampling variation and temporal count variation. The breakdown of their
contribution to the total variation was 53% and 47%, respectively. The
park will reach 80% power to detect a trend in 3 more years.

![](media/image12.wmf){width="4.550694444444445in"
height="3.4298611111111112in"}

Figure 12. Harpers Ferry National Historic Park mean density data.

Deer density increased to a 6-year high after decreasing for 4
consecutive years. Power to detect a 10% change in the population is low
(16%). The reason for this is extremely high sampling variation which
comprised 98% of the total variation. This is typical for an indice
technique. Either the number of plots should be increased or another
technique (digital camera stations) should be considered.

In 2006 the park will be using SPIN funding to use the pellet-group
indice throughout the park. Regeneration plots will also be established
throughout the park. The number of pellet-group plots will be increased
to a density of one plot per 10 acres to decrease the sampling
variation. The current density is one plot per 15 acres.

CONCLUSIONS

Deer Density

All but two of the parks surveyed had overabundant deer populations
(\>40 per square mile). Only GREE and PRWI had densities less than 40
per square mile, and PRWI exceeded this in 2003. All of the parks in the
survey have completed or implemented deer impact studies except for
GREE.

Power to Detect Population Trends

Three parks (MANA, CATO, and MONO) have achieved high power to detect
small trends after five years of surveying. The remaining parks are
listed in ascending order of additional years of surveying: ANTI, PISC
and CHOH (1); ROCR (2); GWMP and PRWI (5); GREE (7), and HAFE (13).
GWMP, GREE, and HAFE failed to increase their power to detect trends
when compared to the 2004 survey. After 5 years of conducting DISTANCE
at GWMP and GREE and 6 years of conducting pellet-group surveys at HAFE,
it may be time to consider using digital cameras to calculate population
density.

Public Interest Highlights

• Nine of the eleven parks surveyed have deer populations deleterious to
other native plant and animal species.

• PRWI and GWMP (Great Falls) have densities less than 40 deer per
square mile.

Management Recommendations

• HAFE should increase the number of pellet-group plots or use a
mark-recapture method utilizing remote cameras.

Research Recommendations

• The first year of data collection for the DISTANCE road bias project
has been completed at ANTI and CATO.

• The first year of data collection for the Potomac Gorge deer impact
project has been completed.

LITERATURE CITED

deCalesta, D. S. 1997. Implications of feeding preferences for
management of white-tailed deer on Cuyahoga Valley National Recreation
Area. USDA Forest Service. 30 pp.

Gerrodette, T. 1987. A power analysis for detecting trends. Ecology
68:1364-1372.

Hatfield, J.S., W.R. Gould IV, B.A. Hoover, M.R. Fuller, and E.L.
Lindquist. 1996. Detecting trends in raptor counts: power and Type I
error rates of various statistical tests. Wildlife Society Bulletin
24(3): 505-516.

McShea, W. J. 2005. The impacts of white-tailed deer foraging on
agricultural and woodlots in the Chesapeake and Ohio Canal National
Historical Site, Antietam National Battlefield Park, and Monocacy
National Battlefield Park. Unpublished report. 16 p.

Miller, K.V. and R.L. Marchinton. 1995. Quality whitetails. Stackpole
Books, Mechanicsville, PA. 322 pp.

Niewinski, A.T., T.W. Bowersox, and R. L. Laughlin. 2006. Vegetation
status in selected woodlots at Gettysburg National Military Park pre and
post white-tailed deer management. Technical Report NPS/NER/NRTR --
2006/037. USDI-NPS Northeast Region, Philadelphia, PA. 311 pp.

NPS. 2005. Monitoring plan for the National Capital Network of the
National Park Service. Unpublished report. 225 pp.

Tilghman, N. 1989. Impacts of white-tailed deer on forest regeneration
in northwestern Pennsylvania. Journal of Wildlife Management 53:524-532.