The Greenland White-fronted Goose Anser albifrons flavirostris

during the period when the population was legal
quarry in Greenland, Iceland, Ireland and Britain,
although we have little idea of the precise
size and distribution of the harvest at that time.
By way of comparison, the survival rate for the
period 1990-1997 (using only the recovery data
generated from the collar-marking scheme) was
analysed using the Haldane methods and gave
an annual survival rate for the period of 81.7% (±
0.8 SE, H. Boyd, in litt.). The 5% difference in survival
rate is very similar to the mean hunting
mortality rate prior to protection (see Figure 8.1).
It was considered that the survival rate of Greenland
White-fronted Geese prior to protection was
too low to sustain the then level of hunting kill
(e.g. Owen 1978). For that reason much bureaucratic
and political effort was put into removing
the subspecies from the quarry list, especially on
the wintering grounds. As described earlier, this
led to the effective protection of the population
from hunting on the wintering areas from 1982
onwards (see MS14, Stroud 1992 and Fox et al.
1999 for full details). Evidence from counts of
birds at a number of wintering sites strongly suggested
that the increase in numbers that followed
the cessation of winter hunting was due to the
increase in return rate of birds, not to changes in
reproductive success (MS14). Indeed, we are now
aware that since protection, breeding success has
actually decreased amongst the Wexford and Islay
wintering elements of the population, which
provides more evidence that restriction on hunting
has increased annual survival.
There was no extensive visible marking programme
in effect before and after the implementation
of protection in winter. This would have
allowed a more sensitive monitoring of changes
in survival based on individual bird histories and
thus enable the interpretation of subsequent
changes in overall population size. The capturemark-recapture
study using neck-collared birds
initiated in Ireland only commenced after protection
had been implemented. Using the resightings
of neck-collared birds marked at Wexford during
1984-1989, Bell et al. (MS10) calculated annual
adult survival using SURGE4 models (Clobert et
al. 1987, Pradel et al. 1990) to generate maximum
likelihood estimates of 78.5% (± 1.4 SE). This compares
with 72.4% (± 7.3 SE) based on ringing recoveries
from the same ringing programme using
BROWNIE (Brownie et al. 1985). Using the
Haldane method on birds marked in the winter
period gives a survival estimate of 72.1% (± 1.1
Estimated annual adult survival rate
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
1982 1984 1986 1988 1990 1992 1994 1996 1998
Figure 8.3. Annual adult survival rate (+ 95% CL) for
Greenland White-fronted Geese caught at Wexford,
1983/84-1997/98 based on observations and recoveries
of neck-collared individuals using the MARK suite
of programs (see text and Appendix 1 for details) 12 .
Open symbols indicate those seasons when the hunting
season was opened at Wexford for a limited shoot.
The unusually low survival estimate and large confidence
intervals for 1983 probably reflect small sample
sizes in that year.
SE) for the period 1984-1989 (H. Boyd in litt.) The
SURGE models use much more fine-grained information
and provide year- and age-specific
maximum likelihood estimates, based on datarich
repeated resighting histories of individual
birds. The Brownie techniques utilise the geese
caught, ringed and never retrieved again to estimate
reporting and recovery rates in a more sophisticated
survival estimation than the Haldane
method. It is not possible to use the Brownie et
al. methods on the 1940s data, because some of
the original capture and ringing data do not exist.
More recent analysis has been carried out using a
combination of recoveries and resightings of collared
birds at Wexford using MARK (White &
Burnham 1999, based on the recovery-recapture
models of Burnham 1993 and multi-stage models
of Hestbeck et al. 1991). The selected model
was one of survival, which varied with year independently
for adults (weighted mean 78.5%,
see Figure 8.3) and juveniles (67.8%, but which
showed greater variability, Figure 8.4), with a
mean of 7% permanent emigration per year (M.
Fredriksen & A.D. Fox unpublished). There was
no effect of hunting on annual adult or juvenile
survival estimates in the two winters (1985/86
and 1989/90) when the moratorium was lifted at
Wexford, although the survival rates in the year
following 1989/90 were the lowest for adults and
juveniles (Figures 8.3 and 8.4). In 1990/91, only 7
out of a marked cohort of 33 first winter juve-
69