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A risk management model for deer population in the

Yakushima World Natural Heritage

H Matsuda*, A Ohta, S Tatsuzawa, H Takahashi, K Tokida,

* matsuda@ynu.ac.jp

http://risk.kan.ynu.ac.jp/matsuda/

NewsI am looking for 11 postdocs of a JSPS grant: Global Eco-Risk Management from Asian Viewpoints (http://risk.kan.ynu.ac.jp/gcoe/)

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Aims of this researchSika deer Cervus nippon yakushimae (endemic subspecies) damages on natural vegetation and endemic plants

A population dynamic model to propose a management plan

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What areas should we protect?

• Areas that include many rare plantshigh vegetation damage by deer– Logging roads may enhance deer dispersal and

outbreak throughout the island

• Areas that include many rare plants without heavily vegetation damage– Few chance of dispersal and high hunting

pressure

From Tet Yahara’s idea

2007/8/7

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＜ 1000 deer?

GPS points of deer by spotlight count (2005)

一湊

永田

大川林道

小楊子林道

栗生 モッチョム農道

安房林道

荒川林道

白谷線

宮之浦

安房線安房

長峰

小瀬田

Western

zone

林道

永田岬

中間林道

小瀬田林道

船行農道

湯泊林道 中瀬川林道

尾の間

4000-8000 deer?

3000-6000 deer?

Northeastern zone

Southern zone

Western zone

Data obtained & compiled by Tatsuzawa & Takahashi2007/8/7

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Increase of spotlight counts of deer (Tatsuzawa & Takahashi, unpubl. data)

•0.33 → 0.92 deer/km, from 1995 to 2005•Deer is overabundant in Western zone and Northeastern zone•Deer is relatively fewer in Southern zone

1995 2005

2007/8/7

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The number of removaljust 300 removal in Yakushima Island.

0

200

400

600

1 9 7 0 1 9 8 0 1 9 9 0 2 0 0 01 9 7 2 1 9 7 4 1 9 7 6 1 9 7 8 1 9 8 2 1 9 8 4 1 9 8 6 1 9 8 8 1 9 9 2 1 9 9 4 1 9 9 6 1 9 9 8 2 0 0 2

熊毛四島

上屋久町

屋久町

（含馬毛島）Kamiyaku Town

Yaku Town

　 2000199219801970

Kagoshima Pref. & Serow Tatsuzawa

4 Islands in Kagoshim Pref.

2007/8/7

Kamiyaku Town

Yaku Town

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Agricultural damage by wildlifein Yakushima Island.

0

2000

4000

6000

8000

10000

12000

14000

16000

サル

シカ

ヒヨドリ

カラス

19

87

19

92

20

02

19

97

（千円）

Yakushima cho

Monkey

Deer

}Birds

Dam

age

(tho

usan

d ye

n)

2007/8/7

8＜ 1000 deer?

Northeastern zone

Southern zone

Western zone

Zone-dependent deer management plan

2007/8/7

1) 3000-6000 deer?2) >300 s3) Depends on hunting effort

1) 4000-8000 deer?2) We need to

hunt >400-800 s

3) We give up to control!

1) 4000-8000 deer?2) We need to

hunt >400-800 s

3) We give up to control!

1) <1000 deer?2) 100-150 s3) We try to decrease deer

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Zoning planNortheastern zone

Southern zone

Western zone

■National forest■ Deforested area■ Orchard

Serow Tatsuzawa

一湊

永田

大川林道

小楊子林道

栗生 モッチョム農道

安房林道

荒川林道

白谷線

安房線安房

長峰

小瀬田

Western

zone

林道

永田岬

中間林道

小瀬田林道

船行農道

湯泊林道 中瀬川林道

尾の間

Aiko-dakeProtected

zone

http://www.rinya.maff.go.jp/sekaiisan/introduction/yakushima/001.html

World heritagearea (107km2)

1) 3000-6000 deer?2) >300 s3) Depends on hunting effort

1) <1000 deer?2) 100-150 s3) We try to decrease deer

2007/8/7

1) 4000-8000 deer?2) We need to

hunt >400-800 s

3) We give up to control!

1) 4000-8000 deer?2) We need to

hunt >400-800 s

3) We give up to control!

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A population dynamic model

3 habitat model with environmental stochasticity

# 0 year old

# adult femals

# adult males

Repro. Success. R(t)

Recruit from 0 yr old Adult survival Catch

Survival rate S

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Adaptive catch quotas

Hunting effort depends on the monitored population index

Pop. level

1 2 3 4 5

North-east zone

0-10001000-2000

2000-4000

4000-5000

5000-

Southern zone

0-200 200-500 500-700700-1000

1000-

Hunting %α 0 0.13 0.2 0.3 0.45

Catch limit 0 - - 1000 1000

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0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

0 2 4 6 8 10

Results when catch limit = 1000

0

100

200

300

400

500

600

700

800

900

1000

0 2 4 6 8 10

Year after present Year after present

NorthEast & South 95%CI>30% decline is expected 100

0

500

300

We might catch ca. 1000 deer for >10 yrs.

1

0.5

Pop

ulat

ion

inde

x N

(t)/

N(0

)

Cat

ch in

num

ber

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3 monitoring site plan Northeastern zone

Southern zone

Western zone

Aiko-dakeMountain

& catchment

Onoaidapathway

Seibu-rindo logging road

2007/8/7

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http://www3.ocn.ne.jp/~yakusima/eco2.tizu2/tizu2.htm

Aiko-dake Mountain Protection Area plan

• Villages including Onna-gawa riv. Catchment

• River boundary!

• Monitor Catch statistics of female deer

• Estimate deer population size

2007/8/7

Why do we use river boundaries?

• Deer dispersal is often limit by rivers.

• Villages are usually divided by rivers.

• Catch statistics by hunters are easily compiled by areas between rivers

• Therefore, a region between rivers is used as a relatively isolated deer habitat.

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Intensive Monitoring of Ono-aida path plan

• Villages between Taino-kawa Riv and Suzu-kawa Riv.

• Monitor Vegetation and Plant Species

• Monitor Catch Statistics of 9Female Deer

• Estimate Deer Population Size

2007/8/7

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Seibu-rindo logging road monitoring site

• Business as usual

• Monitor natural increase of deer by spotlight count and density estimation.

• Monitor damage on natural vegetation

• Monitor endemic threatened plant species.

2007/8/7

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Monitoring deer population

• Sex, stage, zone-dependent Catch statistics• Catch per unit effort (hunter sampling)

– Catch position (GPS), time, sex (CPUE in national forest)

• Spotlight count along routes 77-78 and logging roads

• Altitude-dependence in deer density– Automatic monitoring by night vision; – Line transect survey along Anbo-rindo logging road,

Onoaida path, Aiko-dake Mountain Prot. Area

2007/8/7

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Management plan

• Test effect of deer on natural vegetation– Vegetation recovery survey inside of fence

• Reducing agroforest damage– Hearing of farmers and citizens– Improving population dynamic model

• Promoting sustainable use of deer meet• 1000 catch is short for the Western Zone.

2007/8/7

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Routes of spotlight count (total length 202.9km)

30.22

30.27

30.32

30.37

30.42

30.47

130.37 130.42 130.47 130.52 130.57 130.62 130.67

舗装路未舗装路

宮之浦

小瀬田

安房

尾之間

栗生

永田

一湊

西部林道 大川林道

小楊子林道

中間林道湯泊林道

荒川林道

中瀬川林道

安房林道

白谷線小瀬田林道

船行農道

モッチョム農道

安房線

永田岬↓

→路幅変更

長峯

2007/8/7

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