44 Taiga Bean Goose at Sarobetsu, Japan
©Wildfowl & Wetlands Trust
Wildfowl
(2013) 63: 40–55
for the Tokachi or Sorachi regions, can
also be seen. In addition to observations
from the tower, fixed route surveys were
made repeatedly of the whole area by
vehicle.
Taiga Bean Geese were caught and fitted
with neck collars during the 1990s by
Russian researchers and members of the
Japanese Association for Wild Geese
Protection. A total of 159 birds were
marked in 1990, 98 in 1991, 36 in 1994 and
52 in 1999, all in Kamchatka, with four
marked in Niigata Prefecture in 1997 and
eight in 1999 (Japanese Association for Wild
Geese Protection 2012). The presence of
banded geese passing through Hokkaido
made it possible to follow individual
movements within and through the
Sarobetsu area. At peak, up to 52 banded
birds were found in a single season (autumn
2001), although numbers of marked
individuals had fallen to just one bird at
Sarobetsu by autumn 2012.
All observations in the Sarobetsu area
were made jointly by the two authors
using binoculars (10×), and tripod-
mounted telescopes (30×, 50× and 75×
magnification), typically at 200–400 m from
the geese. In autumn, geese flying out from
their roost site on Lake Penke were
observed from the tower in zone C at
daybreak (from 04:50 h in late September;
06:40 h by early November). After sunrise,
and once geese could be seen clearly feeding
on pasture, a fixed route was driven slowly
by vehicle along a combination of paved
roads and farm tracks, beginning in zone C,
then moving into zones B and A, before
finishing in zone E, during which geese were
counted, and any band codes read. The
survey from the observation tower to zone
E took 4–5 h each morning. In spring,
observations commenced at the Furaoi
Oxbow Lake (zone D) at 05:00 h, counting
geese still staying in the lake, then continued
along unpaved paths on riverside
embankments and on roads through zone D
to zones E, C, B and A, taking
c
. 4 h on each
occasion. The morning surveys used the
same methods in both spring and autumn,
followed the same route (albeit in reverse in
spring), and were undertaken promptly to
avoid duplicating counts.
Taiga Bean Geese sometimes formed
large flocks of > 1,000 birds in which a few
individual Tundra Bean Geese (1–10 birds
on each occasion, two or three times in a
season) were observed. As the identification
of individual Tundra Bean Geese in large
flocks of Taiga Bean Geese is difficult, we
counted them as Taiga Bean Goose unless
they formed discrete flocks and could be
identified as Tundra Bean Geese by their
stubbier bill, thicker lower mandible,
rounder head, strongly sloping profile and
contrasting exposed culmen/length of head
ratio (Kurechi
et al.
1983).
In autumn 2002–2011, 282 visits were
made to the Sarobetsu study area, at least
once in the last ten days of August and
thereafter twice or more during each 10-day
period until late November. In spring, 142
visits were made, at least once in late March
and in mid May and twice or more during
each 10-day period from early April to
early May. Mann-Whitney U tests assessed
differences in peak number of birds, staging
period and individual length of stay between
autumn and spring. Means are given ± s.e.
values throughout.
