Winter counts and phenology

Bean Geese tend to arrive on the Slamannan Plateau during late September or early October [1].

Roost counts
Since the late 1980s, when Bean Geese moved from the Carron Valley to the Slamannan Plateau area, the geese have primarily roosted on Loch Elrig (NS8874), East and West Fannyside Lochs (NS8073) and Fannyside Muir (NS8074). Since the early 2000s, roosting has mostly occurred on the Fannyside Lochs and the nearby Fannyside Muir. During periods of frost and snow, the flock will often remain out in their feeding areas and may not return to roost.

Roost counts have been carried out both on the morning flights and as birds return to the roost at dusk. The roost counts were often undertaken before or after field counts took place. At dusk, geese can sometimes arrive after dark, posing problems of identification and estimating numbers in flight. Arriving geese can split into two (or more) flocks, one landing on one of the Fannyside Lochs, the other landing on Fannnyside Muir. The arrival of geese can be staggered such that the counter may not be sure if all the geese have arrived to roost. On occasions birds will flight to either of the lochs and during darkness movements can occur between the loch and the muir [2].

Since winter 1997/98, 398 roost counts have been made (including days when no geese were counted coming to roost); a mean of 33 counts each season (range: three in 1997/98 to 111 in 2005/06). Season 2005/06 was exceptional due to extra roost counts being undertaken by ornithologists on behalf of Scotts UK Ltd., the company that owns part of Fannyside Muir (Maciver 2006).

Field counts
From 1997/98, non-standardised monitoring of field use has provided information on the distribution and abundance of Bean Geese in the Slamannan Plateau area. The route has varied from time to time (the entire plateau was not visited during every visit), depending on what time the counter had available and where the geese were thought to be. Field counts tended to take between four and six hours. Observations were made at different times of the day. Often, morning field counts were made after watching (and counting) birds flighting from the roost. Alternatively, field counts were made in the afternoon, before checking (and counting) geese flighting into roost at dusk. Duplicate counts could occur during field counting. The flock size and the field number were recorded and each observation was timed. Whilst the field counts can be considered non-systematic (the same route was not followed and the same fields were not checked each day) many fields in the Slamannan Plateau were inevitably checked for geese, either whilst driving between flocks or during scans from vantage points to locate the feeding flocks. Whilst the positive records of flocks were always recorded, checked fields that contained no geese were not. Within the regularly checked area, c.356 fields/land units have been coded, the field codes largely following those used by Smith et al. (1994) [2].

The mean number of days on which field counts were carried out each season was 64 (range 38-99, 1997/98 to 2014/15). In total, this has generated 1,890 records (separate flocks of Bean Geese), or a mean of 105 records per season.

From October to February, the geese begin to use more fields and, in addition, due to the nature of the landscape, the geese often disappear over contour lines and can therefore be hard to locate. The landscape of the Slamannan Plateau is one of rolling land mixed with forestry and woodland blocks. Locating the geese can prove taking. The geese can be relatively shy, especially during the hunting season (although Bean Geese are protected, Pink-footed Geese Anser brachyrhynchus and Greylag Geese A.anser, which also frequent the area, are legal quarry) adding to difficulties in locating feeding flocks.

During the 2000s, the birds were fairly consistent with their autumn arrival on the plateau and feeding at this time in the Luckenburn Farm area. The highest count of feeding birds, thought to represent the season maximum, was normally achieved early in the season at this area, before the flock split up and started to use new areas (see below). The number of new fields in which geese were seen, increased from the start of the season to the end. The geese had been recorded in a mean of less than twenty fields prior to the middle of December, but had been recorded in a mean of over thirty fields by the end of February (Figure 1).
Figure 1. The cumulative number of fields in which Bean Geese were recorded at the Slamannan Plateau from the first half of October (O1) to the first half of March (M1). Based on pooled data from 1997/98 to 2008/09. Standard errors shown.

From late October onwards, the geese begin to use more fields and, in addition, due to the nature of the landscape, the geese often disappear over contour lines and can therefore be missed. Field checking was a case of using the observer’s experience, gained over many years, assessing where the geese were likely to be. The main feeding areas of the Bean Geese have moved from east to west over the past ten years, however, eastern areas were still periodically checked when the observer counted Pink-footed Geese using this part of the plateau. Whilst no record was kept of the fields checked that contained no Bean Geese, large parts of the Slamannan Plateau area were checked for feeding geese. Once the geese arrived at the Slamannan Plateau (usually by the second half of October), the mean flock size recorded declined as the season progressed from c.120 birds to c.80 birds.

[1] Maciver, A. & Wilson, T. (2012). Population and distribution of Bean Geese in the Slamannan Area 2011/12. Report to the Bean Goose Action Group. 17pp
[2] Smith, T., Bainbridge, I. & O’Brien, M. (1994). Distribution and habitat use by Bean Geese in the Slamannan area. RSPB report to SNH. 71pp