White-tailed Deer Population Status
2018
By Jennifer Stenglein and Beth Wojcik

Abstract
The statewide post-hunt white-tailed deer population estimate for 2018 was approximately
1,510,400 deer (95% Credible Interval: 1,365,400 – 1,666,700 deer) and the mean estimate was
10% higher than in 2017. Population estimates decreased 0.5% from 2017 to 2018 in the
Northern Forest Zone and 7% in the Central Forest Zone. Zonal estimates increased 12% in the
Central Farmland and 24% in the Southern Farmland.
Methods
Deer management units (DMUs) and deer management zones changed slightly from what was
used in 2017. The Central Forest Zone boundary was modified in Eau Claire and Clark counties,
and the Northern Forest Zone boundary was modified in Marinette and Chippewa counties. This
latter boundary modification split the Chippewa County DMU, so that the northern portion (305
square miles) of the county was removed from the Central Farmland Zone and added to the
Northern Forest Zone as the Chippewa Forest DMU. DMUs largely followed county boundaries
and units with similar deer season frameworks were combined into deer management zones
(Figure 1). Deer population size and density were estimated for 82 areas (61 entire counties, 10
counties split between 2 management zones, and Madeline Island as separate from Ashland
County). Estimates were not made for tribal reservation units or metro subunits due to lack of
harvest or aging data. Density was estimated based on total land area rather than estimates of
suitable deer habitat.
Population estimates for DMUs were calculated using the Sex-Age-Kill (SAK) formula. This
formula combines information on the age composition of the buck harvest with an estimate of the
percentage of adult buck mortality that is due to legal hunting (buck recovery rate) to estimate the
annual percentage of the adult buck population that is harvested (annual buck harvest rate). The
pre-hunt adult buck population size in each DMU is estimated by dividing the DMU’s registered
buck harvest by an estimate of annual buck harvest rate. Pre-hunt adult buck population
estimates are then expanded to the entire pre-hunt deer population by: 1) multiplying buck
population estimates by adult sex-ratios to estimate the adult doe population size, and 2)
multiplying doe population estimates by fall fawn to doe ratios to estimate fall fawn populations.
Post-hunt deer populations are estimated by subtracting total harvest from pre-hunt estimates
with allowance for 15% wounding loss/unreported harvest.
Annual inputs to the SAK formula for each DMU are: 1) registered harvests of antlered and
antlerless deer, 2) percentage of yearlings among harvested adult bucks, 3) percentage of
yearlings among harvested adult does, 4) buck recovery rate, and 5) early fall fawn to doe ratios.
Yearling buck and doe percentages by DMU were estimated from aging data from meat locker
and CWD sampling (see ‘Deer Ages and Conditions’ in Big Game Harvest Report on dnr.wi.gov)
including the previous 5 years of data to smooth temporally and use of a spatial smoothing model
to borrow information from neighboring DMUs and smooth spatially. Fawn to doe ratios were
estimated from a combination of Summer Deer Observation surveys (see ‘Summer Deer
Observations 2018’ on dnr.wi.gov), Operation Deer Watch roadside surveys, and Snapshot
Wisconsin as well as the previous 4 years of Summer Deer Observation survey data to smooth
temporally and a spatial smoothing model to borrow information from neighboring DMUs and

 smooth spatially. The spatial smoothing model provided an estimate of uncertainty for the aging
data and fawn to doe ratio inputs. Buck recovery rate was assumed to be 65 – 75% to allow for
uncertainty in this parameter. A hunter selectivity parameter of 5 – 10% was added to all DMUs in
Farmland Zones (Figure 1) to account for suspected hunter selection against yearling bucks in
areas with higher deer density.
The SAK formula was run in a Bayesian framework using a spatial smoothing model and uniform
distribution inputs which led to estimates of uncertainty and 95% credible intervals around point
estimates. A 95% credible interval can be defined as ‘given our observed data and the model
chosen for these data, there is a 95% probability that the true value falls in this range.’
Results and Discussion
Estimates of post-hunt deer populations during 2018 were made for 82 DMUs (Table 1; and ‘Herd
Abundance’ on dnr.wi.gov). Statewide, the 2018 post-hunt population estimate was approximately
1,510,400 deer (95% credible interval: 1,365,400 – 1,666,700) and the mean estimate was 10%
higher than in 2017. Mean post-hunt population densities by DMU in 2018 ranged from 3-61
deer/mi2 of land area and averaged 27 (95% credible interval: 25 – 30) deer/mi2 of land area
(Figure 2; and ‘Overwinter Deer Densities’ on dnr.wi.gov).
Population estimates decreased 0.5% from 2017 to 2018 in the Northern Forest Zone and 7% in
the Central Forest Zone. Zonal estimates increased 12% in the Central Farmland and 24% in the
Southern Farmland (Figure 3).
Post-hunt deer population estimates in the Northern Forest Zone have ranged from ~250,000
deer to >400,000 deer since 2002 and the 2018 post-hunt deer population estimate is close to as
high as we have seen the population since 2002 (Figure 3). Four mild to moderate winters in a
row and limited antlerless harvest help to explain the population growth in the northern deer herd
in 2018. The Central Forest Zone post-hunt population estimates have been largely stable since
2009 at 60,000 – 80,000 deer on average. The Central Farmland Zone deer population has
increased since 2008 and the 2018 post-hunt deer population estimate was the highest estimate
in the last 16 years. For a fourth year in a row, the 2018 post-hunt deer population estimate in the
Southern Farmland Zone exceeded 250,000. It also surpassed previous years estimates at over
300,000 deer (Figure 3).

 Table 1. Deer post-hunt population size estimates and densities (deer per square mile of land
area; mean and 95% credible intervals [CrI]) for WI deer management units, 2018.
Deer management unit
Adams Farmland
Adams Forest
Ashland Forest
Barron Farmland
Bayfield Forest
Brown Farmland
Buffalo Farmland
Burnett Forest
Calumet Farmland
Chippewa Farmland
Chippewa Forest
Clark Farmland
Clark Forest
Columbia Farmland
Crawford Farmland
Dane Farmland
Dodge Farmland
Door Farmland
Douglas Forest
Dunn Farmland
Eau Claire Farmland
Eau Claire Forest
Florence Forest
Fond du Lac Farmland
Forest Forest
Grant Farmland
Green Farmland
Green Lake Farmland
Iowa Farmland
Iron Forest
Jackson Farmland
Jackson Forest
Jefferson Farmland
Juneau Farmland
Juneau Forest
Kenosha Farmland
Kewaunee Farmland
La Crosse Farmland
Lafayette Farmland
Langlade Forest
Lincoln Forest
Madeline Island Forest
Manitowoc Farmland

Post-hunt population size
Lower 95%
Upper 95%
Mean
CrI
CrI
6,300
5,400
7,300
19,900
16,500
23,800
14,900
12,300
18,100
21,100
17,600
25,000
33,100
26,400
41,900
11,600
9,800
13,600
24,200
20,300
28,600
22,600
18,500
27,400
5,300
4,400
6,200
17,200
14,600
20,200
7,600
6,300
8,900
21,900
18,300
25,900
10,800
9,000
12,900
31,300
27,200
36,000
21,100
17,800
24,900
22,300
19,300
25,500
17,700
15,200
20,500
18,100
14,400
22,400
32,600
26,200
40,900
23,300
19,800
27,300
10,900
9,200
12,700
5,400
4,500
6,400
15,600
12,500
19,400
16,100
13,700
18,700
17,500
14,700
20,700
31,600
26,500
37,200
11,600
9,800
13,700
14,800
12,700
17,100
26,700
23,200
30,700
6,900
5,600
8,400
19,000
16,300
22,100
10,300
8,600
12,200
10,900
9,200
12,700
14,000
12,100
16,300
12,700
10,700
15,000
1,600
1,200
2,100
12,300
10,200
14,800
17,100
14,500
20,000
12,400
10,400
14,700
24,000
20,200
28,300
22,900
19,400
26,800
500
400
600
15,700
13,000
18,700

Post-hunt population density
Lower 95%
Upper 95%
Mean
CrI
CrI
61
52
71
34
28
41
18
15
22
24
20
28
22
18
28
22
18
26
34
29
40
26
21
31
13
11
16
23
20
27
25
21
29
25
21
30
31
26
37
39
34
45
35
30
42
18
16
21
20
17
23
37
29
46
24
20
31
27
23
32
22
19
26
34
29
41
31
25
39
21
18
24
17
14
20
27
22
31
20
17
23
39
33
45
35
30
40
9
7
11
37
31
43
21
18
25
19
16
22
42
36
48
27
23
32
6
4
7
36
30
43
36
30
42
20
16
23
27
23
32
25
21
30
21
17
25
26
22
31

 Deer management unit
Marathon Farmland
Marinette Farmland
Marinette Forest
Marquette Farmland
Milwaukee Farmland
Monroe Farmland
Monroe Forest
Oconto Farmland
Oconto Forest
Oneida Forest
Outagamie Farmland
Ozaukee Farmland
Pepin Farmland
Pierce Farmland
Polk Farmland
Portage Farmland
Price Forest
Racine Farmland
Richland Farmland
Rock Farmland
Rusk Forest
Sauk Farmland
Sawyer Forest
Shawano Farmland
Sheboygan Farmland
St. Croix Farmland
Taylor Forest
Trempealeau Farmland
Vernon Farmland
Vilas Forest
Walworth Farmland
Washburn Forest
Washington Farmland
Waukesha Farmland
Waupaca Farmland
Waushara Farmland
Winnebago Farmland
Wood Farmland
Wood Forest
Total/Average

Post-hunt population size
Lower 95%
Upper 95%
Mean
CrI
CrI
49,500
42,000
57,900
23,900
19,800
28,700
25,200
20,900
30,300
26,300
22,700
30,400
800
700
1,000
28,700
24,600
33,300
5,100
4,300
6,000
28,100
23,700
33,000
10,700
9,000
12,600
25,800
21,900
30,400
16,000
13,500
18,700
3,700
3,000
4,400
7,200
6,000
8,500
13,700
11,200
16,500
26,000
21,500
31,100
26,000
22,300
30,000
30,500
25,900
35,800
2,200
1,700
2,700
32,300
27,800
37,400
8,900
7,400
10,600
27,000
22,800
31,700
37,100
32,200
42,800
25,500
21,700
30,000
42,300
35,900
49,400
11,400
9,500
13,600
12,800
10,600
15,300
30,200
25,300
35,600
26,300
22,400
30,700
34,700
29,500
40,500
17,500
14,400
21,500
5,800
4,800
7,000
21,000
17,600
24,800
9,900
8,200
11,800
9,200
7,700
10,900
38,500
32,900
44,700
25,000
21,500
28,800
9,600
8,200
11,100
13,400
11,300
15,700
9,200
7,700
10,900
1,510,400
1,365,400
1,666,700

Post-hunt population density
Lower 95%
Upper 95%
Mean
CrI
CrI
31
27
37
36
30
44
33
27
39
57
49
66
3
3
4
42
36
49
39
32
46
43
36
50
30
25
35
21
18
25
25
21
29
16
13
19
29
24
34
23
19
28
27
22
32
32
27
37
24
20
28
6
5
8
55
47
63
12
10
15
29
24
34
44
38
51
21
18
24
46
40
54
22
18
26
17
14
21
31
26
36
35
30
41
42
36
50
19
16
24
10
8
12
25
21
29
23
19
27
16
13
19
50
43
58
39
34
45
17
14
19
29
24
33
27
23
32
27
25
30

 Apostle Islands 0 Deer Management Zone

Red Cliff .
Reservation . Metro SUb-Ul?llt
made'me Wand Deer Management Unit
Bad Rlver
Reservation
Bayfield
Douglas Lac du Flambeau
eservation
Lac Courte lron
Oreilles Ashland
Res ation
Vllas
Burnett WaShbum Sawyer Price Florence
Polk one'da Forest
Barron Mannette

Central Rusk Northern Forest Zone Tay  or meom Langlade oconto Parkway 

32 64 Road

 2 64  . El Mal?inette .

 

 

 

Cl l'k
St Cr0lx a Marathon Oconto
Pierce Dunn Shawano Door
I mm Kewaunee
Clark entral Outagam'e Brown
Buffalo Jackson Wood 13
2, Central 73 Farmland
Jackson .t
Forest  2 CI anlowoc
aume
Trempealeau La Crosse 1 Wtaushara 
nne ago
94 Adams Marquette Green
Monroe Lake Fond du Lac Sheboyga
Fort McCo Juneau 82
vernon SaUk Columbia
Richland DOdge Wash. Ozaukee
Southern Farmland Zone 2
Crawford
Iowa Jefferson Milwaukee
Grant Dane Waukesha
ROCK Racine
Lafayette Green Walworth
Kenosha

 

Figure 1. Wisconsin?s deer management units and zones in 2018.

Figure 2. Estimated 2018 mean post-hunt deer density (deer per square mile of total area) for
Wisconsin’s deer management units.

 Northern Forest zone Central Forest Zone

   

   

I150
Im II
350'
a 
TTaoo 

Annual estimate Annual estimate
?3-I,rr average _3'Vr ?Erase


JIW1 Jim; 3W5 JWI PM ?a11; ??15 201} 2501 2003 2005- Im? moo 2011 ZUIEI IUI5 201? 3019
Year Tear
ILientral Farmland zone Southern Farmland Zone
100

5-D
1'30 Annua1e5tlmate 0 Annual estimate
average ?3-Irr average
0
m1 m3 ME- 3011 2013 2915 2?01? 301'? 2003 2005 :00? 2ND 21311 H313 2'315 Ilill'il
?l'ear ?l'ear

Figure 3. White-tailed deer population trends in Wisconsin?s deer management zones, 2002-
2018.