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The Birds of Northcraig Reservoir

Fraser S Simpson  January 2000    | Map |

Published in Ayrshire Bird Report 1999 (SOC Ayrshire Branch 2000).

 

Introduction


In the 1985 edition of the Ayrshire Bird Report, Bill Davidson published an article entitled The Birds of Northcraig Reservoir in which he highlighted the importance of this small disused reservoir for wildfowl and passage waders. From his three and a half years intensive working of the site he recorded an amazing 125 species. The aim of this second article is to illustrate the factors which have led to several changes in the bird life of the reservoir and to provide an update on the growing list of species recorded by Bill and myself since then.  

Habitat and Land Use


Over the last two decades, since active use of the reservoir by Strathclyde Water Authority was halted, the site has been left to nature and is gradually developing into an attractive wetland site. Habitat developments have seen a change in the water level and an increase in plant colonisation on the north side in the form of emergent vegetation. A gradual eutrophication has enabled several species to breed along what was formerly a bare mud shoreline. Nutrient enrichment of the water in the form of nitrates draining in from an adjacent cereal field may also have contributed. Indeed, blue-green algal blooms produced by Cyanobacteria occurred in the hot summers of 1994, 1995 and 1996. Vegetation consists mainly of juncus rushes and carex sedges and their expansion has seen an increase in breeding passerines. The bare stone of the dam, which surrounds the reservoir on all sides but the north, has gradually been covered with rough grassland and therefore the landscape is not as bleak as it once was. The removal of grazing sheep from the reservoir in the last few years has resulted in a profusion of young oak, rowan, sycamore and willow trees appearing and this should provide song posts for more Reed Buntings. Around the three filter beds, which are rich in wild flowers, the development of scrub and small trees over the years has proved beneficial for nesting passerines. The only other trees present are the twenty or so mature trees, mainly oaks, forming a single line stretching along the north side behind the rushes. The surrounding farmland consists mainly of grazing and silage fields but the north-east side is the most interesting with unimproved grassland in the form of rushy pasture, tussocky grassland and young plantations grown for pheasant shooting. During the 1980's the reservoir was used for Brown Trout fishing and therefore disturbance was limited during this period. In the early 1990's, Rainbow Trout were introduced on a regular basis and this led to an increase in the numbers of anglers using the site. This has had both advantages and disadvantages. As house building has increased since the last article, the town of Kilmarnock is now only 300 metres away!

Waders


Perhaps the most important factor responsible for the changes in the reservoir's bird community has been the rise in the water level. From 1982, when operation of the reservoir was discontinued, until the early 1990's, exposed mud on the north side was a feature for much of the year. However, gradual blocking of the reservoir filters through a natural accumulation of deposits has been responsible for rising water levels. Coupled with the encroachment of rushes, the loss of mud has seen the numbers of passage waders drop to near zero. The reservoir was an important site in an Ayrshire context for the passage of Green Sandpipers, which were last recorded in 1992. Black-tailed Godwit last occurred in 1992, Wood Sandpiper and Spotted Redshank in 1993 and Ruff in 1994. These last three species were in fact recorded for the last time on a flooded field adjacent to the reservoir illustrating the magnetism of the site despite the loss of habitat. Twenty-four species of wader have been recorded including Temminck's Stint, Curlew Sandpiper, Turnstone and Knot. The status of other waders probably remains unchanged since they are not so reliant on the feeding opportunities provided by mud. Small numbers of Curlew and Oystercatcher stop over during the spring migration in late February and March as birds head inland to breed. These species feed on the grass-covered dams of the reservoir. At least one pair of the above attempt breeding in the surrounding area. Lapwings are restricted to feeding in the adjacent fields and between one and four pairs attempt breeding annually in the surrounding fields. Flocks of up to 100+ have occurred but 20 to 30 are more likely.

Common Sandpipers have always had a difficult time in breeding due to the fact that nests are created on the dam where anglers fish. Usually three or four pairs hold territories (five in 1991 and 1996) but only one or two pairs successfully rear chicks. The most productive years have been 1991 and 1996 when six birds were reared. The availability of suitable breeding habitat has probably decreased for this species due to the colonisation of the shores of the dam by rushes, and growth of long grass on the dam. Since 1996 a pair has attempted nesting in the gravel filter beds but have, disappointingly, been predated at the egg or chick stage. Small passage groups of 15-20 birds used to occur in late June or early July up until the early 1990's before the loss of the muddy shoreline. The average date of arrival is April 17th.

Breeding Waterbirds


The loss of interesting waders, however, has been balanced by the gain of several breeding species of waterbirds. The first species to respond to the changing habitat was the Little Grebe which first bred in 1990, with two pairs in 1998 and three pairs in 1999.  Northcraig had always supported a small autumn population of up to eight birds through the 1980's, which has now increased to around 15 birds in recent Septembers. Next to arrive were Moorhen and Coot with single pairs breeding in 1993. Coots have been more successful with 2 pairs from 1996 rising to four pairs in 1998. At present there are two pairs of Moorhen. Interestingly, the status of these two species differs throughout the year. The adult Moorhens remain at the site for the entire year despite the weather whereas the Coots tend to have departed by mid-October, not returning before mid-January. The most exciting addition to the breeding community has been the Great Crested Grebe.  Recorded as "visiting the reservoir regularly" in the mid -1980's, it was rarely recorded during the 1990's. In 1998, a single bird appeared in March and remained for two weeks raising hopes the species was at least interested in the site. The following year, a pair arrived on 26 April. Courtship displays and nest building followed this. Three chicks were hatched and successfully raised. Hopefully this will not be a one-off occurrence and the pair will return again in 2000! The Water Rail has only been seen on two occasions with both records relating to passage birds in the autumn. The wetland habitat, which it requires for breeding, is not extensive enough.

Mallards have increased to four or five breeding pairs and a brood is usually first noted in early April. In addition to the preferred juncus rushes, nesting sites have also been recorded in nearby drainage ditches and in a large hawthorn hedgerow. The most unusual site has been in the water pipe at the end of the reservoir bridge where a melanistic female attempted laying during three years. No other duck species has been recorded breeding and this may be down to minor topological features such as the lack of islands or sheltered bays and corners. Despite this, a pair of Tufted Ducks often remains through June and July and together with the Teal, may breed in the future. The main threat to breeding productivity is the Carrion Crow with the nests of up to three pairs in the mature trees overlooking the rushes.

Other Breeding Birds


At least 46 species have been recorded breeding around the reservoir with several more in the surrounding area. The gradual extension of the rushes has seen Reed Buntings increasing to five pairs in the area and the breeding of Grasshopper Warbler and Sedge Warbler. One or two pairs of Whitethroat now breed due to the formation of scrub and overgrown hedgerow. In rough grassland, up to four pairs of Skylark and Meadow Pipits nest. Two or three pairs each of Linnet, Goldfinch, Greenfinch and Chaffinch nest in the trees around the cottage and in a nearby area of scrub. Willow Warblers formerly passed though on spring and autumn migration but up to five territories are now occupied. A pair of Pied Wagtails and up to three pairs of Swallows nest in the disused outbuildings, entering these relatively safe sites through open windows. A larger number of Swallows nest in the barns of North Craig farm. Only a single pair of Yellowhammers breed, usually in the perimeter hedgerow. In an area where Grey Partridges are relatively common, two pairs usually breed and nesting has been noted in the rushes on one occasion. Two or three Quail occurred in the area during 1997 and a pair may possibly have bred in an adjacent clover field.

Migrants, Wintering Species and other Visitors
Slavonian Grebes have occurred in two years with a single bird in April 1983 and two or three birds in October 1993.
Cormorant numbers have increased over the 1990's. This is a result of Rainbow Trout stocking. Immature birds predominate with up to three birds commuting between here and the Kay Park pond in Kilmarnock. The peak count has been 12 and birds have been observed flying high between the reservoir and the coast. Grey Herons regularly fish in the shallow corners with a family group in the summer months. Breeding has been recorded in nearby Moss Wood approximately 500 metres away. As mentioned in the first article, Mute Swans are still surprisingly scarce for some reason with only three records during the 1990's.  Whooper Swans continue to use the reservoir as an occasional roosting site during the winter months, the largest count to date being 22 during November 1994.  

Five species of geese have been recorded. Greylags are the most regularly encountered with most birds passing overhead, particularly during spring and autumn. Pink-footed Geese occur occasionaly in single figure numbers. Barnacle Geese have been recorded in five years since 1985. Of particular note were the 90 birds during September and October of 1994 in a year which saw record numbers of passage birds in Ayrshire. Single White-fronted Geese occurred in 1989 and 1991 but the rarest has been the Canada Goose with one bird in April 1998 which was either an escape or a local breeding bird. The status of the Shelduck has seen a contrast in the last two decades. In the 1980's up to five birds were recorded each year between March and May and one or two birds again in the autumn. The bird was last recorded in 1993 and this may again be due to loss of the mud.  

Wigeon occur in single figures between September and November. The earliest arrival date has been 20th August and the peak count was 20 during November 1994. Teal numbers and occurrence resemble that of the Wigeon with which they often associate. Of the scarce dabbling ducks, Gadwall is an annual visitor with one or two birds noted during March and between August and October. Pintail are less than annual. Shoveler are the most regular with records spanning all months between March and November. Highest counts have been of six birds (August 1986, September 1998) and a pair was recorded in May 1990. Ferruginous Duck is the species for which Northcraig is most well known. An immature male was found in the Tufted Duck flock during 21st-26th October in 1987.  Numbers of wintering Pochard have declined from the 1980's when February peaks of 60 birds were recorded.  Typical wintering flocks during the 1990s numbered just 12-15 birds with a record number of 36 during November 1994. For its size, the reservoir supports a good moult flock of Tufted Ducks during the late summer and early autumn and, unlike the previous species, numbers have remained consistent over the two decades.  Up to 60 or 70 birds regularly build up in September or early October. Throughout the winter the flock numbers less than 20 with a peak again in April.  A pair regularly remains through the breeding season.  Scaup are annual and have been recorded in all months although September and October provide typical records of one or two birds. Long-tailed Ducks still occur but are probably less regular than they were in the 1980s. Goldeneye numbers are never impressive, usually less than 20 birds but a female has occasionally summered. Surprisingly, the Smew has only been seen once and October 1999 provided the first record. Red-breasted Mergansers have been noted in five years. The most exciting duck species is probably the Goosander and in the last few years the reservoir has become a locally important roost site for these birds. The bird was scarce in the 1980's but since the introduction of Rainbow Trout, several birds feed at the site between September and April. It is the hour before dusk, when birds have been seen arriving from the Irvine Valley, that numbers build up.  Up to 30 birds are regular with a peak count of 42 during January 1999. The Ruddy Duck has been sighted on three occasions: two females, Sep '91;  one female, Nov. '93;  one male in April '96. A total of 26 species of wildfowl has been recorded.

Six species of raptor have been recorded. Sparrowhawk and Kestrel continue to be the most obvious with pairs breeding in adjacent woods. Since the Buzzard has remarkably increased its range in Ayrshire in recent years it is perhaps not surprising that this species is now resident at the reservoir. One pair breeds less than 700 metres away and hunts the rushes and rough fields. Hen Harrier and Merlin occur every other winter and Peregrines are annual visitors. At least one or two Jack Snipe winter in the rushes with birds often arriving in mid-September. Woodcock can be seen 'roding' over nearby Moss Wood and have also occasionally been flushed from areas of rushes and rough grassland during autumn. The Red-legged x Chukar Partridge hybrids which, as explained in the first article, originated from a stocking programme in a nearby estate in the 1970's, were last recorded in 1991 after which the population was probably no longer self-sustaining.

Eight species of Gull have been noted. Late summer can see a large build up of Lesser Black-backed and Herring Gulls and in winter there are often a few hundred each of Common and Black-headed Gulls. Of the more interesting species, the Kittiwake has been recorded twice with single records of Little Gull and Glaucous Gull. All the regular terns in Ayrshire have been recorded: Sandwich Tern (23 birds in three years), Common Tern (4 in two years), Arctic Tern (2 in two years), Little Tern (2 in one year) and Black Tern (2 in two years).

Barn Owls roost at the reservoir each winter and Tawny Owls are regular visitors throughout the year. Short-eared Owls occur occasionally between September and December and all species, along with the raptors, are presumably attracted by the large rodent populations.

The Swift and hirundine flocks are a spectacular feature for much of the spring and summer months over this small area of water. In the spring, birds can be observed flying in over the surrounding fields either stopping to feed or continuing the journey north. Late evening is the best time, particularly for Swifts when numbers can build to over 200 birds in June and July. At times, counts of the four species have totalled over 400 birds.

Meadow Pipit passage is evident in March and September with flocks on the dam and rough grassland or as a steady movement of birds overhead. The Yellow Wagtail was a regular passage migrant at the reservoir in the 1980's and a pair even bred 1984. The bird was sadly last recorded in September 1987 as it gradually declined to extinction as a breeding species in Ayrshire. White Wagtails are annual migrants in small numbers in April and May and small flocks of Pied Wagtails often occur in September. Wheatears stop over in spring and autumn with the highest count being 12 in April 1996. Whinchats occasionally occur on the dam with the Wheatears. As with many species, the reservoir provides a good vantage point for watching birds moving through the surrounding countryside. Large movements of winter Thrushes can be observed and Redwing and Fieldfare are often resident in mid to late winter when berry supplies have been exhausted. Seven species of Warbler have been recorded. Large numbers of Corvids pass over the reservoir to winter roosts in adjacent woodland. In recent years, the occurrence of Ravens overhead has been notable with birds even feeding down on the dam. Local range expansion of the Magpie has seen birds breeding from 1995.
        
To date, around 147 species have been recorded which is notable for a small inland site in Ayrshire. Other species recorded on just one or a few occasions include the following:
Rock Pipit, Tree Pipit, Redstart, Stonechat, Spotted Flycatcher and Snow Bunting. Perhaps the highlight over the years was the occurrence of a Hoopoe for two days in 1999. It spent much of the time in the gravel filter beds providing hours of entertainment.

Conclusions


Clearly, the reservoir is still an important site as the diverse and increasing species list proves. While the passage of scarce waders no longer occurs, other birds are taking advantage of the change in habitat. While the activities of anglers have brought advantages and disadvantages, on the whole it would appear that both interests can co-exist at this site. As Kilmarnock's only freshwater site of this nature, it is locally valuable in the face of the expanding developments of an ever-growing town.

References


Ayrshire Bird Reports, 1982-1998 (SOC Ayrshire Branch).
Personal Field Notebooks 1990-1999.

 

 


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