I have monitored the large gull species in the Banchory area, and in particular, the Crow's Nest amenity site (local map), depicted above, for the many years, having first visited on 19 July 1979 (aged 9) seeing 300 "seagulls" there. This page summarises details of some of the counts and observations.
Herring gulls
Overall numbers
Table 1 - Herring Gull numbers at Crow's Nest (including % of each age)
| Year | Date | Comment | Adult | 1st win | 2nd win | 3rd win | Total |
| 1988 | 7/1 | Underestimate - incomplete count; 80% to Skene | 4260 | ||||
| 1989 | 29/8 | Autumn count | 1160 | ||||
| 1990 | 10/1 | Plus 250 nearby at Maryfield | 3590 | ||||
| " | 29/3 | Spring count; 2 colour-ringed | 1500 | ||||
| " | 24/9 | Autumn count; leucistic 2nd win | 1020 | ||||
| 1991 | 24/12 | One with clear white head; one colour-ringed | 70 | 21 | 5.9 | 3.3 | 1600 |
| 1992 | 24/12 | 69 | 23 | 5.5 | 2.5 | 2000 | |
| 1993 | 24/12 | One colour-ringed | 60 | 30 | 6.8 | 3.4 | 2000 |
| 1994 | 29/12 | 2800 | |||||
| 1995 | 28/12 | 2000 | |||||
| 1996 | 28/12 | c. 70 | 1200 | ||||
| 1997 | 28/12 | 1100 | |||||
| 1998 | 26/12 | Site closed; hybrid x LBB present | 900 | ||||
| 2002 | 26/12 | Site closed; 75% to Skene | 810 | ||||
| 2003 | 22/12 | Daily bird scaring now used | 84 | 6.5 | 6.4 | 2.7 | 950 |
| 2004 | 20/12 | Daily bird scaring now used | 0* |
Numbers visiting the area have clearly declined since the 1980's, as shown in Table 1 and Figure 1. I was aware that large numbers of Herring Gulls used the Crow's Nest site daily in winter since my first interest in birds as a teenager (1984 onwards) as hundreds of birds could be seen moving to and from the site daily over our house in the N of Banchory. A site count was first made in 1988 when 4260 birds were observed leaving at dusk on 7/1/88 but this was incomplete as movement was in progress when counting commenced at 15.00hrs and there may well have been 5000+ birds in total. Thereafter the following peaks were recorded: 3840 on 10/1/90, 2800 on 29/12/94, and 2000 on 28/12/95. By the following year only 1200 were found on 28/12/96, with about the same total on 29/12/97 and new fences had been erected it was assumed that these and perhaps some form of bird scaring had contributed to the reduction in numbers.
In 2003 there were only 950 birds present on 22/12/03 and the site manager confirmed that bird scaring with falcons is now used on a daily basis to satisfy the requirements of SEPA. I subsequently learnt from another birder that he had witnessed birds being shot by an employee with an air rifle, so it seems that persecution at the site in now intense. This surely accounts for some, or all, of the drop in numbers.
In 2004 there were no birds on the site at all even though active tipping was taking place, though there were at least 1000 birds in the day roost nearby at Lochhead of Leys. The falcon had been used earlier that day, clearly to good effect.
It is also interesting to compare with counts of the Skene roost (by other observers, NESBR reports - reference 1). Between 1983 and 1986, 2500 to 3500 were recorded there at mid-winter. Counts have been fairly sparse in recent years but at the last national BTO survey (1993) only 890 birds were noted on 24/1. I found at least 2000 birds present at 15.15hrs on 27/12/03, but the final total was obscured by mist, and at least 3000 by 15:30hrs on 20/12/04.
Figure 1 - Herring Gulls numbers at Crow's Nest
Seasonal variation
The counts from 1989 and 1990 suggest that numbers peak in winter, with fewer present in spring and even lower numbers in early autumn.
Age distribution
On average, about 70% of birds have been adults with 20-30% 1st-winter individuals and progressively lower proportions of 2nd- and 3rd-winter birds. However, in 2003 the number of 1st-winter birds was abnormally low at 6.5%, with adults making up 84% of the total. The reason for this is unknown, but may be either due to a poor breeding season or the fact that 1st-year birds are more susceptible to scaring.
Race
Normally a small number of obviously dark-mantled argentatus-race birds from Scandinavia are present. In 2003 between 5 and 10 birds were found, including the adult and 4th-winter birds shown below, and a best-estimate ratio of 0.8% was determined from sample counts. This seems very low, particularly in comparison to some SE England sites, but may not be unusual for inland NE Scotland. The study of Coulson et al from 1978 to 1983 (Reference 2) included one sample count from Aberdeen in which 4 Scandinavian birds were caught amongst a total of 113 (i.e. 3.5%). See also the distribution map in the Coulson paper (Figure 3), which shows a very strong regional variation. The recent BTO Migration Atlas (Reference 3) also suggests that most immigration from Scandinavia is at the southern end of the North Sea (cf Figure 9 on p 372), birds presumably following the coast down the eastern side, though there definitely are some exchanges between NE Scotland and northern continental areas.
Hybrids
A presumed Herring Gull x Lesser Blackback was present on 26/12/98 with typical black back of ssp graellsi but pink legs. Similar or the same was reported from Terryvale piggery, Skene on 18 & 20/2/98. I was unable to obtain any pictures.
On 24/9/90 an extremely pale 2nd-year bird may have been a hybrid x Glaucous Gull or just a leucistic individual, but this could unfortunately not be confirmed either way.
Movements/roost sites Area map
By many observations along the route, over the years, it has been determined that the bulk of the birds commute to and from the Loch of Skene roost via a traditional path over Hirn, Red Moss, Cullerlie and Garlogie, a distance of about 8 miles. The normal flight-path runs approximately parallel with the B977 until Cullerlie when it swings more northwards parallel to the B9125. In timed observation on 27/12/03 a group of 140 birds completed the trip in 12 minutes, thus averaging 40mph with a gentle SW tail-wind.
Not all birds roost at Skene however. For example, of the 4260 departing Crows Nest on 7/1/88 about only 80% moved off directly towards Skene, whilst 75% of 240 birds leaving at 15.00hrs on 26/12/02 still went that way. The other birds move over north Banchory and sometimes gather near the Dee at Maryfield, or elsewhere in the Crathes-Park area. Similarly, from the A93 and B9077 road between Crathes and Cults, birds are often observed flying up the Dee Valley in the morning, and it is presumed that many come from coastal roosts near Aberdeen - a distance of about 17 miles. It seems that none, or very low numbers, roost at Inchgarth reservoir in Cults (at dusk, only 6 at 16.00hrs on 24/12/02 and 1, departing east at 16.20hrs, on 24/12/03). However, it is difficult to estimate numbers coming up the Dee valley and observation is complicated by that fact that these birds may stop off before Banchory, or continue beyond Banchory (very few counts have been published in NESBR for the Dinnet lochs roosts in recent years).
Birds have also been observed commuting via more direct routes to the coast, e.g. 50 SE through the valley between Cainshee and Craig of Affrusk (just W of Blairydryne on linked map above, at NO729932) at 13.30hrs on 25/12/02 would presumably have followed the route over the "Slug" to Stonehaven, and 30 NW over Upper Balfour and Denside on the NE side of Durris Forest at 8.50hrs on 26/12/02 would probably have come from the coast near Muchalls. Again in 2003 a small group was moving NW over Rickarton towards the "Slug" at 9.00hrs on 27/12/03. The distance to and from these parts of the coast is shorter than the route straight down the Dee valley at about 12-15 miles.
Observations are also complicated by the increased use of a relatively new site near Banchory - the various pig farms at Park. These are, of course, open every day (though evidence from other piggeries suggests that birds know when the pigs will be fed) so birds which may otherwise visit Crow's Nest may often go there instead when the latter is shut. There were for example 1100 there on at 12.30hrs on 25/12/01, 940 at 10.00hrs on 25/12/02 (of which 500 were arriving direct from the Skene direction, 100 E up the Dee valley and 100 W down the Dee valley having presumably already been to Crow's Nest) and 500 at 12.15hrs on 24/12/03. There may also of course be many other sites exploited by these birds about which I am unaware!
Movement away from the Banchory area towards the roost sites commences about 1 hour before sunset and continues until well after dark. Return passage must commence well before sunrise as birds are sometimes seen/heard over N Banchory before dawn. 100 arriving at Park from down the Dee valley at sunrise on 21/12/04 must have departed about 30mins before dawn.
Colour-ringed birds
The following colour-ringed adults were observed:
These birds were apparently all ringed by a team from Durham and Glasgow Universities in their UK study area between 1978 and 1983 (see report). The ringers confirmed that these would have been birds rung in NE England but have not provided me with any more precise details on origin.
Great Blackback
Numbers were very low in the late 1980's (2 on 26/12/86, 5 on 23/9/87) but steadily increased through the early 1990's - e.g. 11 on 24/9/90, 22 on 24/12/91, 28 on 23/12/92 with 80 through the Maryfield roost on 29/12/82 (may include birds from Deeside), 46 on 28/12/96, 126 on 29/12/97 and c. 150 on 29/12/98. However, in 2002, only 5 adults were noted amongst 600 Herring Gulls leaving the site on 26/12/02 whilst in 2003 there were at least 19 birds in the area on 22/12/03. Only 6 were present nearby on 20/12/04.
With much smaller numbers than Herring Gull, counts of this species are prone to much more random variations. Nevertheless, it does seem that there was a genuine large increase through the 1990s but that mid-winter numbers have now fallen again in-line with overall gull numbers.
Lesser Blackback
Observations of this species at Crow's Nest have always been of low numbers, e.g. 2 on 23/9/87, 1 on 29/3/90 and a single mid-winter sighting on 24/12/91. There was also a presumed hybrid HG x LBB on 26/12/98.
Other gull species
Common Gulls are often present at the site in very low numbers. Similarly, Black-headed Gulls visit the site in small numbers, though perhaps more frequently when they bred at Loch of Leys. Surprisingly, the only white-winged gull unearthed was a 2nd-winter Iceland Gull in the nearby dayroost by the Dee at Maryfield on 10/1/90. The white-winged species are certain to occur more regularly in the area and indeed a Glaucous Gull was once reported from Aboyne dump further inland.
Corvids
The site is always attended by good numbers of corvids. Peak counts have been as follows:
It is interesting to note that the crows (Carrion and Hooded) normally assemble with the gulls at their roost site at Lochhead of Leys to the east. By contrast to the gulls, the crows are normally active in the roost.
Passerines
Whilst numbers of Herring Gulls visiting the Banchory area seem to have declined significantly since the mid 1980's, perhaps associated with changes in the way that the Crow's Nest amenity site is managed, significant numbers, probably well in excess of 1000 individuals, still visit daily during the winter months. These still come predominantly from the Skene roost (8 miles), though a significant proportion commute up the Dee valley (17 miles) or more directly from other parts of the coast between Aberdeen and Stonehaven (12-15 miles). Latest observations suggest that the number of 1st-winter birds at the Crow's Nest is now much lower than it was historically but the reasons for this are unknown. More birds may now be exploiting other food sources, such as the local pig farms. Colour-ringing shows that some of the birds originate from NE England and relatively low numbers of argentatus-type birds are observed.
Great Blackback numbers seem to have followed an opposite trend, starting with very low numbers in the mid 1980's, peaking at c. 150 individuals by 1998, but then dropping again recently in-line with the fall in overall gull numbers.
The Crow's Nest amenity site is also a locally important feeding site for five corvid species and some passerines.
References
1. NESBR North-East Scotland Bird Reports, published by Aberdeen University Bird Club (1974-1982) & North-East Scotland Bird Club (1983 to date)
2. Coulson, J. C., Monaghan, P., Butterfield, J. E. L., Duncan, N., Ensor, K., Shedden, C. & Thomas, C. "Scandinavian Herring Gulls wintering in Britain", Ornis Scand. 15: 79-88
3. Wernham, C., Toms, M., Marchant, J., Clark, J., Siriwardena, G. & Baillie, S. (eds.) "The Migration Atlas - Movements of the birds of Britain and Ireland", Poyser, 2002
Updated 3/1/05
