Horoka Tomamu Forest Bat Survey 2012

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The Horoka Tomamu Forest Bat Survey was held from 4 to 15 August 2012.

Directed by Professor David Hill of the Kyoto University Primate Research Institute, it was the first full-scale survey of the conservation area.

Objectives

 

To manage the conservation area effectively we need to know which species live there. We originally intended to start with a plant survey, but for various reasons that didn't happen and we looked at other alternatives. 

 

Bats particularly interested us. Because they are nocturnal animals that are difficult to observe, they are still little understood compared to other animals, and this lack of information generally hinders their conservation. Woodlands support many bat species, which are not only indicators of biodiversity, but also an essential part of the ecosystem, helping to regulate the proliferation of insect life. 

 

We aimed to identify local species during the survey. Before we started we only knew that one bat, the Ussuri tube-nosed (Murina ussuriensis), existed in Horoka Tomamu. David Hill, the survey director, was hoping to obtain 10 to 20 samples of their DNA for a comparative study of the same species in Yakushima Island (in southern Japan).

 

Initial meeting

 

An initial meeting, with a series of talks, was held on Saturday, August 4 at the Ichikawa Imahashi Law Office, in Kami Tomamu (located close to the Tomamu Expressway IC). There were three speakers. Masumi Maruo Holledge gave 'A short introduction to the Horoka Tomamu Montane Forest'), Dr Hirakawa Hirofumi (Hokkaido Research Center Forestry and Forest Products Research Institute) explained about 'Monitoring wildlife in Hokkaido', and Prof David Hill (Kyoto University) talked about 'Surveying bats in woodlands'. David Hill also demonstrated the Autobat acoustic lure (originally developed by Hill and his colleagues at the University of Sussex in England, see below). (All the talks were in Japanese).

 

(See the leaflet that was produced and distributed before the survey.)

 

Duration of the survey

 

The survey took place on eight evenings (from about an hour before dusk to around midnight) between Sunday 5 August 5 and Wednesday 15 August. Surveying on three evenings was cancelled due to heavy rain.

 

Methods

 

Harp traps and mist nets were used to capture bats before releasing them. 'Autobat' devices, playing simulations of bat social calls, were used to attract the bats to the traps and nets. (Autobat speakers were put in front of all the traps and a majority of the nets.) 

 

Dual heterodyne/time expansion ultrasound bat detectors (Pettersson D240x) were used to listen to the echo-location, social and (post-capture) release calls of the bats. Four different areas were surveyed, with an unattended Pettersson D500 bat recorder placed in a fifth location on the ridge, near the top of the mountain. 

 

Captured bats were identified by species, sex, reproductive status, weight and forearm length, before being released. Small sample of wing tissue were taken from the Ussuri tube-nosed bat (Murina ussuriensis) for subsequent DNA analysis.

 

Before the survey started, we considered walking transects with bat detecters to identify bat 'hotspots', however significant numbers of bats were found in every area surveyed, so we never used this method.

 

Areas

 

 

batareas1.png

 

The five survey locations were: 1. northwest streamside, 2. lower north slope, 3. upper north slope 4. ridge (sound recorder only) and 5. southeast edge. Distances between the areas are indicated in the distance matrix on the map above, based on GPS waypoints. The lowest area was 5. (about 500 m above sea level), followed by 1. (520 m), 2. (600 m), 3. (620 m) and 4. (650 m). 

 

Results

 

Ten species were identified: eight by capture (see below) and two by recorded calls (Greater horseshoe bat (Rhinolophus ferrumequinum) and Birdlike noctule (Nyctalus aviator)). This compares with a total of 10 species identified in the conservation area for all other mammals. 

 

Capture and release

 

A total of 50 bats were captured and released.  (This number doesn't including the recapturing of two Ussuri tube-nosed bats.) By species, the bats were as follows:

 

Species

 

Total 

Female

Male

 

 

 

adult

juvenile

adult

juvenile

Ussuri tube-nosed bat

Murina ussuriensis

29

11

4

8

6

Ikonnikov's bat

Myotis ikkonikovi

7

1

3

3

 

Fraternal myotis

Myotis frater

5

3

1

 

1

Ussuri whiskered bat

Myotis gracilis

3

 

 

2

1

Northern bat

Eptesicus nilssoni

2

1

1

 

 

Japanese long-eared bat

Plecotus sacrimontis

2

1

1

 

 

Asian barbastelle

Barbastella leucomelas

1

 

 

1

 

Hilgendorf's tube-nosed bat

Murina hilgendorfi

1

 

 

1

 

 

By areas:

 

Areas

Nights

Harp traps 

Total bats 

Ussuri tube-nosed

Ikonnikov's

Fraternal myotis

Ussuri whiskered

Others

1

2

1

12

8

2

2

 

 

2

1

1

6

4

 

1

 

Japanese long-eared (1), 

3

1

1

7

6

 

 

 

Hilgendorf's tube-nosed (1)

5

4

2

27

13

5

2

3

Northern bat (2), Asian barbastelle (1),  Japanese long-eared (1)

 

DNA

 

A total of 28 small wing tissue samples of Ussuri tube-nosed bats (Murina ussuriensis) were obtained by Prof. Hill for future DNA analysis, with a view to determining kin relationships and population dynamics.

 

Bat calls

 

Many echo-location, social and (post-capture) release calls of the bats were recorded with the hand-held bat recorders. Using the unattended bat recorder (located on the ridge at 650 m) on the night of 12-13 August, we also obtained recordings of probably five individual bats (of Myotis species and either Eptesicus nilssonii or Vespertilio sinensis).

 

Red-listed species

 

Three of the species we discovered were on the Red List (Mammals) of the Ministry of the Environment 環境省レッドリスト (2007) (Japanese page): the Ussuri whiskered bat (Myotis gracilis) as 'endangered', Birdlike noctule (Nyctalus aviator) as 'near threatened', and Hilgendorf's tube-nosed bat (Murina hilgendorfi) as vulnerable. As of August, the first two species have been redesignated as 'vulnerable', and the third has been removed in a new Red List (2012). 

 

Other pages and video

 

See also Bat species at Horoka Tomamu (illustrated with photographs taken during the survey), the Species checklist (bats) and A video of the survey, taken at night with an infra-red camera (on Vimeo).

 

Simon Holledge, 18 October 2012