The Watarase Retention Basin north of Saitama prefecture

Some bird observations by Fer-Jan de Vries.

On the south border of Tochigi prefecture with Saitama there is a large water reservoir (just north east of Koga, which has a railway station). The two water basins together with remaining marsh land area (roughly 1000 hectare) form the south most tip of a delta between two rivers just before they flow together in the large Tonegawa river which dominates the Kanto plane above Tokyo. The area borders on the west with Gunma prefecture, on the east with Ibaraki. The transformation of the marsh land into water reservoir must be recent (less than 5 years.) On the north-west and north-east there are still extensive reedlands (strong, 4 meter high!) remaining and a labyrinth of small rivers and or former rivers.

I believe that in principle this area is or could be a wetland area of high environmental value for birds. However, it is entirely open to the public and fully accesible by car. Many roads zigzag through the area, which people seem to use as an race circuit. At several places there are golf courses. The sky is full of motorized paragliders and radio controlled toy airplanes.


Visit: Februari 4, 1996, 14.00-18.00. The estimates are conservative lower bounds.
Weather: Bright dry winter weather, just above 0 degrees Celsius. Slightly warmer than the week before during the coldest attack of winter on Japan with strong winds and lots of snow in the North and along the Japan Sea. No snow, however, in this part of Japan. Due to the lack of rain and snow since September, the water level in the basin was rather low.
Participants: Stephan Shuichi Haupt and Fer-Jan de Vries.


Visit: at Februari 12, 1996, 12.30-18.00. No systematic counting. We did not visit the drinkwater basins, but checked out the river area on the east of Koga. Thus missing the Longtailed rosefinches that some japanese birdwatchers have seen in the centre area.
Weather: Bright dry winter/spring weather, around 10. Still very dry.
Participants: Stephan Shuichi Haupt and Fer-Jan de Vries.


Visit: at March 2, 1996, 12.30-18.00. Sunny day, with a very strong and very cold wind coming straight from the snow mountains of Nikko. No systematic counting. First we visited the drinkwater basins. Due to the high waves most ducks preferred the concrete banks of the basins. Next we checked out the muddy river/canal bed south and south west of the basins. Towards sunset we entered the marshland just on the northwest of the basins.
Weather: Bright dry winter/spring weather, around 3 Celsius. Strong north-western wind. Excellent view.
Participants: Stephan Shuichi Haupt and Fer-Jan de Vries.


Visit: at March 10, 1996. 12.30-18.00. Sunny day. First we visited mudfields in the canal just south of the drinkwater basins. Towards sunset we entered the marshland on the northwest of the basins.
Weather: Bright dry winter/spring weather, around 3 Celsius. North-western wind. Excellent view.
Participants: Stephan Shuichi Haupt and Fer-Jan de Vries.


Visit: at November 9, 1996. 10.00-18.00. Mild autumn day, first sunny, but lateron unexpectedly early and long dusk. First we checked the waterbasins and the canals south of the drinkwater basins. Incontrast to previous visits, no mudflats bust fast streaming water. Towards sunset we entered the marshland on the northwest of the basins.
Weather: Warm, mild windless autumn day. weather, around 20 Celsius. Good view.
Participants: Stephan Shuichi Haupt and Fer-Jan de Vries.

  1. Great crested grebe Podiceps cristatus, Kanmuri-aitsuburi. A: 1 ex. , D 10
  2. Little grebe Kaitsuburi, Podiceps ruficollis. A 5 ex. B, D, E 10 ex.
  3. Great Cormorant Phalacrocorax carbo, Kawa-u. A: at least 25. B, D 130, E 25
  4. Goose Anser, gan. A: at least 600. Towards sunset, a large group of unidentifiable geese (Probably Bean goose or White fronted goose) were flying round in the area north east of Koga (in Ibaraki). Probably flying to their nearby sleeping place; apparently not in the water reservoir. Not seen during the second visit.
  5. Mallard Anas Platyrhynchos, Ma-gamo. A: at least 1000. , D: at least 500, E at least 3500
  6. Spot-billed duck Anas poecilorhyncha, Karu-gamo.A: at least 100. , D at least 50, E at least 2000
  7. Northern Shoveler Anas clypeata, Hashibiro-gamo. A, D, E several
  8. Green-winged teal Anas crecca, Ko-gamo. A: at least 300 , D, E at least 20
  9. Gadwall Anas strepera, Okayoshi-gamo. A: at least 8, D at least 10
  10. Pintail Anas acuta, Onaga.A: at least 200, D, E at least 3000
  11. (Eurasian) Wigeon Anas penelope, Hidori-gamo.A: at least 200, D: at least 200, E at least 50 LI> Pochard Aythya ferina Hoshi-hajiro E, few.
  12. Tufted duck Aythya fuliula, Kinkuro-hajiro. A: at least 50. No Pochards.
  13. Smew Mergus albellus, Miko-aisa. Aat least 80. One third of them were white males
  14. Herring gull Larus argentatus, Seguro kamome. A: 1 ex., D
  15. Black-headed Gull Larus ridibundus, Yuri-kamome. A: 2 ex. E 1 ex.
  16. Black-Crownded Night heron Nycticorax nycticorax, Goi-sagi. A: 1 ex.
  17. Little egret Egretta garzetta, Ko-sagi. A: 1 ex. B, D, E
  18. Great egret Egretta alba, Dai-sagi. A: 1 ex. Large, black feet and yellow bill.B, D: 1 ex, E
  19. Gray heron Ardea cinerea, Ao-sagi. A: at least 5. B, D: at least 22, E
  20. Common Gallinule Gallinula chloropus, Ban. A: 2 ex.
  21. Little ringed plover Charadrius dubius Kochidori : D 4 ex.
  22. Long-billed ringed plover Charadrius placidus Ikaru-chidori : D 2 ex.
  23. Snowy plover Charadrius alexandrinus Medai-chidori : C 1 ex.
  24. Lapwing Vanellus vanellus Tageri : D, at least 300 ex
  25. Common Sandpiper Tringa hypoleucos Isoshigi : D, 2 ex E 1 ex.
  26. Common snipe Gallinago gallinago Ta-shigi : D, 1 ex
  27. Black Kite Milvus migrans, Toni. A: 6 ex: 2 females and 4 males if size is distinctive. B
  28. Common buzzard Buteo buteo, Nosuri. 1 ex B, D, E 20 ex.
  29. Northern harrier Circus cyaneus, Hajiro-chuuhi. A: 1 female.B: 4 females only , D, E one female
  30. Eastern marsh harrier Circus spilonotus, Chuuhi. A: 1 female B: Several males and females. According to authorities like Sibley and Monroe this is not the same species as the Marsh harrier seen in Europe. Indeed the female has not the clear yellow edge and light head as the European species has. And the head of the male is rather dark while the breast is whitish. And light shoulder tips., D, E 10 ex.
  31. Northern Goshawk Accipiter gentilis, Ou-taka. 1 female B
  32. Japanese lesser sparrowhawk Accipiter gulariss, Tsumi. E 1 ex. Fast passing small hawk. Few gliding moments compared to Sparrow hawk. Rather streaked dark bird.
  33. Merlin Falco columbarius, Ko-chougenbou. 1 ex B Active hunting just before sunset., D: at least 5 searching for sleep tree.
  34. Short eared owl Asio flammeus, Komimi-zuku. A: 1 ex. Flying around after sunset. I could see the rather pied upper wing pattern of the Short eared owl.
  35. Ural owl ?? Strix uralensis, Fukurou. E: 1 ex. Flying around after sunset. Rather determined flyer, with a steady fast wingbeat. Whitish plumage, rather heavily streaked with blackish. Boldly barred, as the book says. Size small buzzard.
  36. Common pheasant Pasianus colchicus, Kiji. A: 1 male calling.B Several calling. E several calling just after sunset.
  37. Rufous turtle dove Streptopelia orientalis, Kiji-bato. D, E
  38. Common Kingfisher Alcedo atthis, Kawasemi. A: 1 ex. E at same spot.
  39. Skylark Alauda arvensis, Hibari. A: 2 ex. B Singing at many places, D, E one ex. singing
  40. Water pipit Anthus spinoletta, Tahibari. A: 3 ex, D
  41. White wagtail Haku-sekirei, Motacilla alba. A: at least 5 ex. B, D, E
  42. Japanese wagtail Seguro-sekirei, Motacilla grandis. A: at least 5 ex, D, E
  43. Brown-eared bulbul Hypsipetes amaurotis, Hiyodori.A: several. BPlenty in the reedlands. E, 2 ex.
  44. Bul-headed shrike Lanius bucephalus, Mozu.A: 1 ex.B, D, E 8 ex.
  45. Daurian redstart Joobitaki [Phoenicurus auroreus.] E, males and females at various places.
  46. Pale thrush Turdus palidus , Shirohara. D 2ex. , D
  47. Dusky thrush Turdus naumanni, Tsugumi. A: several.B Everywhere, often in pairs. , D, E at most 40 ex.
  48. Siskin Carduelis spinus [Ma-hiwa] E group of about 80.
  49. Oriental greenfinch Kawarahiwa, Carduelis sinica. B , D at least 60, E at least 500
  50. Tree sparrowSuzume, Passer montanus. A B, D,E
  51. Gray starling Sturnus cineraceus, Mukudori. A B, D
  52. Siberian meadow bunting Emberiza cioides, Houjiro. B: everywhere in the reedlands.B, D, E
  53. Rustic bunting Emberiza rustica, Kashira-daka. A: at least 4 ex.B, D
  54. Lapland longspur bunting Emberiza lapponicus, Tsumenaga-hoojiro. A: 2 ex! At close range. Winterplumage, no crest. Dark feet and legs. Bright contrastful coloration on back. Brown neck and black dots on whitish breast. I forgot to look at the white wingbars. Walking on the concrete sides of the water reservoir. When disturbed it went for hiding in the few dry plants sticking out the concrete. Sometimes hiding behind these, sometimes sitting against the stem.
  55. Azure winged magpie, Onaga, Cyanopica cyana.B, E
  56. Carrion crow Corvus corone, Hashiboso-garasu. A: several.D: several. E
  57. Jungle crow Corvus machrorhynchos, Hashibuto-garasu. D: several. E

  1. Japanese weasel (Mustela itatsi): visits B,C D
  2. Bats flying around at sunset: visit E. area north of drinkwater basins. Seemed large, with pointed snout looking downwards. Noisy. Rhinolophus ??
  3. Also smaller Pipistrelli like bats in Konusu, two ex, hunting from wooden ledge in wall, quickly returning after each single sweep hunt... Like a pendulum.
  4. Tanuki: 1 ex dead, visit E. Strange green color in neck. Covered by flies.

Back to previous page Last modified: November 10, 1996. Fer-Jan de Vries,