74 Survival and dispersal in a new Barnacle Goose population
©Wildfowl & Wetlands Trust
Wildfowl
(2013) 63: 72–89
situated (Meininger
et al
. 1994; Ouweneel
2001; Voslamber
et al
. 2007). All birds were
fitted with steel leg-rings issued by the
Dutch ringing centre (Vogeltrekstation); all
adults and those juveniles large enough to be
colour-marked were additionally fitted with
two colour rings (each inscribed with a
unique code), one on each leg. Colour rings
can be read at distances of up to 500 m with
a telescope. Further information on
catching and marking procedures can be
found in Pouw
et al
. (2005) and van der
Jeugd
et al.
(2006, 2008).
Observations of marked geese, identified
by their engraved colour-rings or neck-
bands, can be added to a specially
designed website (
) by goose
researchers and also by members of the
public. This website is dedicated to tracking
individually marked geese and swans and its
primary objective is to encourage volunteer
observers by providing them with immediate
feedback on the birds reported. The website
is used by thousands of active observers in
many countries world-wide and facilitates the
gathering of large numbers of re-sightings
from a large geographical area. All sightings
in the
database of the 804
individuals colour-ringed in the Netherlands
were selected for analysis. Most sightings
were made in the Netherlands during late
winter, spring and summer (January–July),
but sightings from other months and outside
the Netherlands were also included.
Of the 804 birds selected, 55 were
reported as having died by June 2012. Any
sightings recorded for dates after the
reported date of death were checked.
Eleven of the 55 dead birds had, in total, 22
observations after the death date; these were
all removed from the dataset. One bird was
recorded on 26 occasions after its reported
death; these were retained as it was assumed
that the recovery details were incorrect.
Table 1
. Number of birds of each age and sex category ringed at different sites in the
Netherlands each year. Jan Durkspolder is in Fryslân; the other sites are in the Delta area.
Year
Location
Juvenile
Adult
Total
Female Male
Female Male
2004
Hellegatsplaten
77
77
87
64
305
2005
Hellegatsplaten
24
33
32
20
109
2007
Krammerse Slikken
20
20
19
26
85
2008
Krammerse Slikken
58
48
67
59
232
2009
Jan Durkspolder
8
11
8
6
33
2010
Krammerse Slikken
15
25
0
0
40
Total
202
214
213
175
804
