Taiga Bean Goose at Sarobetsu, Japan 45
©Wildfowl & Wetlands Trust
Wildfowl
(2013) 63: 40–55
Results
General goose use of the area
Taiga Bean Geese staging in the Sarobetsu
area used three main roost sites in autumn:
Lake Kabuto (zone A) especially at the
beginning of the season, Lake Penke (zone
C) during the whole season and oxbow
lakes along the Teshio River (Teshio
Oxbow Lakes) situated in zone E during the
whole season, albeit less frequently than
zone C (Fig. 3a). Almost all of the birds
feeding on Lake Kabuto and in adjacent
pasture in zone A in the daytime appeared
to roost on the lake whereas the birds
feeding in zone C roosted on Lake Penke
and in marshes nearby throughout. Some
geese that fed in zone B roosted on Lake
Kabuto until mid-season with others
roosting on Lake Penke. On 21 September
2002 for example, 1,554 Taiga Bean Geese
were counted in pasture situated in zone B
at 17:15 h, 329 birds of which flew away in
the direction of Lake Kabuto between
17:30–18:00 h and a large flock of geese,
presumably the rest, took off and flew away
in the direction of Lake Penke at 18:04 h.
On 12 September 2009, 280 Taiga Bean
Geese were counted in pasture situated in
zone B at 15:09 h, 245 birds of which flew
away in the direction of Lake Kabuto at
17:34 h. Zone D was used only in spring
during the study period: most of the birds
occurring in this zone roosted on Furaoi
Oxbow Lake, while some geese roosted on
the Teshio River itself. In spring, zone D
was used earlier than all the other roost
sites. (Fig. 3b). The majority of Taiga Bean
Geese feeding in zone E roosted on the
Teshio Oxbow Lakes. Geese were never
observed to roost on Lake Panke, despite its
close proximity to Lake Penke.
The migratory geese staging in this region
of northern Hokkaido feed primarily on
grass obtained from agricultural fields, and
aquatic plants available in the lakes: Water
Chestnuts
Trapa japonica
in Lake Kabuto and
Lake Penke and Water Chestnuts and Water
Oats
Zizania latifolia
in the Furaoi Oxbow
Lake. However, as the price of maize has
soared in recent years, and as the local
climate has become milder, an increasing
number of farmers in the study area have
begun to cultivate maize as cattle feed. The
post-harvest waste from this crop has
provided an additional food source for the
geese, and dense flocks of Taiga Bean Geese
can now be found visiting freshly harvested
maize fields in zone C in autumn.
Taiga Bean Goose numbers
Taiga Bean Goose numbers in autumn
Seasonal peak numbers of Taiga Bean
Geese ranged from 6,178 (2002) to 9,230
birds (2004), averaging 7,272 birds (s.e. =
267). Maxima recorded during each 10-day
period, were used to indicate the seasonally
changing pattern in numbers (Fig. 4a), as
numbers varied on a daily basis depending
on the birds’ behaviour. For instance, on
some days, a number of geese would remain
out of sight on Lake Penke rather than
flying to feed on the fields, and on other
occasions the birds were disturbed by
factors ranging from White-tailed Eagles
Haliaeetus albicilla
to ultra-light planes.
The lowest and highest peak counts
recorded during the 10-day observation
periods each autumn over the 10-year study
were, respectively: 409 and 6,500 (2002), 670
