The Greenland White-fronted Goose Anser albifrons flavirostris

land White-fronted Geese in late winter and
spring are at least likely to affect the ability of an
individual to undertake the flight to Iceland successfully.
Furthermore, the levels of stores available
on departure from the wintering areas could
potentially influence the extent of stores available
for the onward flight to Greenland and ultimately
for investment in reproduction. Clearly, any contribution
that accumulated stores can make to
body maintenance, egg laying and incubation (in
the case of the female) and to territorial defence
and mate protection (amongst males) is likely to
contribute to the reproductive output of a goose
pair.
In the case of the Greenland White-fronted Goose,
there are three sources of proxy data that can be
used to follow the changes in body constituents
or in fat stores throughout the course of the winter.
The first is the use of catch data from Wexford
Slobs, where geese have been captured using
cannon nets each year since 1983/84. All have
been aged and sexed and weighed to the nearest
50 g before being fitted with individual marks and
metal tarsus rings (see MS7 for full details). Most
catching has taken place in the autumn, especially
in October/November, but some birds have been
caught in all months from October to April. Fitted
regression lines to the full data set of indi-
Body mass (g)
Body mass (g)
28
4000
3500
3000
2500
2000
Adult females
1500
1-Oct 20-Nov 9-Jan
Date of capture
28-Feb 18-Apr
4000
3500
3000
2500
2000
Juvenile females
1500
1-Oct 20-Nov 9-Jan
Date of capture
28-Feb 18-Apr
Body mass (g)
Body mass (g)
vidual weight regressed on date shows a polynomial
relationship between body mass and date
for all age and sex classes (Figure 3.1). These patterns
represent a slight decline in mass from arrival
until December followed by a gradual accumulation
until departure in early to mid April.
These data represent the cumulative data over
many years, but the general trend from January
onwards is confirmed by a second method. A series
of catches carried out throughout the spring
of 1999 specifically to assess within-winter patterns
of body mass change concentrated on late
winter/spring catches of small numbers of pairs.
The results are shown in Figure 3.2 and confirm
the general pattern of relatively slow accumulation
of body mass throughout the latter half of
the winter at Wexford.
The third proxy method of assessing body mass
is the use of field scores of abdominal profiles of
geese wintering at Wexford. Owen (1981) developed
the use of abdominal profiles as a non-consumptive
method of assessing the fat deposits of
geese in the field. The method depends upon the
fact that fat stored in the abdomen is a reliable
index of general fat stores accumulated throughout
the body (Thomas et al. 1983), and the levels
of abdominal fat storage can be assessed using a
4000
3500
3000
2500
2000
Adult males
1500
1-Oct 20-Nov 9-Jan
Date of capture
28-Feb 18-Apr
4000
3500
3000
2500
2000
Juvenile males
1500
1-Oct 20-Nov 9-Jan
Date of capture
28-Feb 18-Apr
Figure 3.1. Body mass determinations of Greenland White-fronted Geese caught at Wexford during the winters
1983/84-1998/99 combined, showing fitted polynomial regressions (see Appendix 1 for statistics relating to
figures 1 ).