The Greenland White-fronted Goose Anser albifrons flavirostris

Percentage of juveniles
Figure 6.1. Annual breeding success of Greenland
White-fronted Goose expressed as the proportion of
juvenile birds in the wintering flocks at Wexford and
on Islay for the years 1962-1999. Vertical arrow indicates
the point at which hunting on the wintering
grounds ceased (i.e. affecting both sites). Best fit least
squares regression models are shown for both sites (as
in following graph plots), the decline in proportion of
young at Wexford since protection is statistically significant,
although the decrease was not statistically
significant for the trend on Islay 4 .
Wexford, the mean proportion of young for the
years 1968-1999 inclusive was 16.3% (± 0.986 SE;
range 5.5% in 1999 to 32.5% in 1969 data courtesy
Oscar Merne, Dave Norriss, Alyn Walsh, Dúchas,
The Heritage Service, National Parks & Wildlife,
Ireland, Figure 6.1). On Islay for the years 1968-
1999 inclusive it was 14.9% (± 0.945 SE; range 6.7%
in 1992 to 27.3% in 1985 (data courtesy Malcolm
Ogilvie, Greenland White-fronted Goose Study,
Wildfowl and Wetlands Trust, Scottish Natural
Heritage, Figure 6.1). Until recently, flocks at
Wexford contained consistently higher proportions
of young than at other resorts, and the same
is true of the Islay birds compared to flocks in the
Percentage young on Islay
40
30
20
10
0
1960 1970 1980
Census year
1990 2000
40
30
20
10
0
pre-protection post-protection
Wexford
Islay
Wexford
Islay
0 10 20 30 40
Percentage young at Wexford
Figure 6.2. Patterns of annual breeding success (expressed
as percentage juveniles in the winter flocks)
at Wexford and on Islay for the period 1968-1999. The
diagonal line signifies the line of equal production.
Proportion of potential breeders
that are successful
0.3
0.2
0.1
0
1960 1970 1980
Census year
1990 2000
Wexford
Islay
Wexford
Islay
Figure 6.3. The proportion of potentially breeding adult
females (assuming birds could potentially breed in
their second summer) amongst the wintering flocks
on Islay and Wexford that have returned annually with
young during the period 1968-1999. The vertical arrow
indicates the point at which the population was
protected from hunting on the wintering grounds (i.e.
at both sites). There have been statistically significant
declines in these proportions at both sites since protection
5 .
rest of Britain (Pettifor et al. 1999). Overall, the
annual patterns of breeding success are highly
correlated between winter resorts (e.g. Figure 6.2).
Poor seasons are associated with late spring thaw
where thick snow cover in northern areas leads
to abandonment of breeding (e.g. 5.5% at Wexford
in 1999) or early snow in July which may
affect gosling survival (e.g. 6.4% at Wexford in
1996). The relatively low percentage of young,
returning in relatively large family units (see comparisons
in Table 6.1 above), means that far fewer
Greenland White-fronted Geese of potentially
reproductive age return with young to the winter
areas than is the case in other Whitefront populations.
Whether this is the result of geese attempting
to breed but failing, or simply not attempting
to breed is central to understanding why
recruitment is relatively low in this population.
There has been a significant decline in the overall
breeding success amongst the population wintering
at Wexford since protection, although there
was no significant trend on Islay (see Figure 6.1).
If it is assumed that birds can breed in their second
summer (although there is little evidence that
many do) there has been a significant decline in
the proportions of those birds of potential breeding
age which return to the wintering grounds
with young at both major resorts (Figure 6.3).
Hence, amongst both of the two major wintering
aggregations (Wexford and Islay), there has been
a decline in the proportion of potentially fecund
birds that reproduce successfully since 1982. Pro-
51