16/03/2005
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Black-necked Grebes in the Lower Derwent Valley NNR

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Black-necked Grebe: North Duffield Carrs, Yorks. This front-on shot shows how stunning these birds are in full summer plumage. (Photo: Steve Huddleston) Black-necked Grebe: North Duffield Carrs, Yorks. This side profile illustrates the intense eye-colour and golden ear-tufts. (Photo: Steve Huddleston)

Black-necked Grebes appear to have a long history with the Lower Derwent Valley with the first documented occurrence referred to by Nelson (1907), who listed a record of an adult male in 'splendid plumage' at Bubwith in the year 1854. It would seem likely, given the plumage of the bird, to relate to the breeding season or at least summer months. The details surrounding the next published record are also rather vague, but Smith (1912) describes it as an 'accidental visitor', referring to a single specimen found in Captain Dunnington-Jefferson's collection at Thicket Priory. It is believed to have been obtained by the great Yorkshire wildfowler and punt-gunner Snowden Slights, but there are no other details.

The first record of recent times for this delightful but rather secretive small grebe was a single at Ellerton Ings from 23rd March to 4th April 1969. Another at Aughton Ings on 17th January 1970 was presumably the same individual at Bubwith Ings on 24th January 1970. The species went unrecorded for the next eleven years before two pairs attempted breeding, unsuccessfully, at Wheldrake Ings in 1983. They appeared to fail during incubation and although the cause is unknown it has been suggested that fierce inter-specific aggressive encounters that were noted between the adult grebes and nearby breeding Coots may have been responsible.

The next appeared at Wheldrake in 1987 and birds were subsequently recorded there in three of the following four years, with records falling between 1st April and 19th May, the exception being a single on 14th June 1987.

It was 1992 that proved to be a turning point for this species' fortunes within the valley with the colonisation of the site. A pair arrived at Wheldrake Ings on 13th April and had built a mating platform by 27th April. On 14th June the adults appeared with two small young, both of which fledged before departing on 14th August. A second pair is also thought to have bred at the same site. The breeding population then expanded rapidly with five pairs at Wheldrake Ings in 1993 fledging six young birds and 14 pairs there in 1994 producing a total of 24 young. A clear pattern of occurrence had emerged by this time with birds appearing in late March or the first few days in April and quickly settling down to breeding activity within a few days of arrival. The first newly fledged young generally appeared during mid- to late-May with most birds leaving the site in late June and early July; the adults apparently leaving before the young had fledged.

In 1995 an early bird appeared on 14th March although the next was more typical on 29th March. Two pairs from 1st April increased to a total of nine pairs by the end of the month. A total of 15 young including three broods of three chicks were found following the first on 29th May. A rather late juvenile finally left the site on 4th August.

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A full survey in 1996 located 15 pairs at Wheldrake Ings following the first arrivals on 4th April and two adults present later in the month on 16th April 1996 were seen to be carrying BTO rings and as such are almost certainly to have been ringed as chicks at this site in either 1993 or 1994.

Black-necked Grebe: North Duffield Carrs, Yorks. Juvenile present in May 2004. (Photo: Steve Huddleston)

Since 1997 there has been a change in water level management at Wheldrake Ings. This has lead to a decrease in the number of birds using the site and productivity of those remaining pairs. Whether this is directly due to the loss of open water from the site during the breeding season, or the loss of the Black-headed Gull colony with which the grebes closely associated with as a result of lowering water tables, is unclear. Breeding has been more sporadic and opportunistic since 1997 with five pairs breeding at North Duffield Carrs in 1998 producing nine young and three pairs breeding there again in 2001 producing at least six young. Although pairs occurred during 1999, 2000 and 2002 no breeding is thought to have taken place and it would appear likely that spring flooding experienced during 1998 and 2001 allowed birds to find suitable habitat on North Duffield Carrs in which to breed. Even here, as water levels fall, birds are forced to congregate on the larger ditches which continue to hold water into mid May and early June. Two juveniles found on a small ditch were caught, BTO-ringed and released onto a larger ditch on this site on 27th May 2001 where they remained until 11th June before departing.

Table 1: Black-necked Grebes in the Lower Derwent Valley NNR – 1998-2004

Year Possible Probable Confirmed Total Young reared
1998 - 2 4 4-6 11
1999 5 - - 5 1
2000 4 - - 4 -
2001 - 4 3 3-7 9
2002 3 - - 3 -
2003 - - - - -
2004 5 3 4 4-12 11

With the present water level management in the Lower Derwent Valley it is likely that spring passage birds may be more likely to be encountered in late March and early April than breeding birds later in the season, although perhaps with opportune birds remaining to breed during wetter years or periods, perhaps as they did in 1854. That appears to have been exactly what happened in 2004, when extensive spring flooding left suitable conditions at North Duffield Carrs on the birds arrival. Following the first pair on 29th March, numbers increased to a total of 14 pairs during April and May.

Black-necked Grebe: North Duffield Carrs, Yorks. The colour ring combination can be easily seen when the birds roll-preen or climb onto vegetation. (Photo: Steve Huddleston) Black-necked Grebe: North Duffield Carrs, Yorks. Conditions in 2004 allowed excellent opportunities for studying the grebes. (Photo: Steve Huddleston)

Four birds were caught and ringed during the year, bringing the total ringed in the Lower Derwent valley NNR to 12. However, the four birds (three adults and a unfledged chick) were also fitted with colour-rings in 2004 to try and increase the chances of subsequent sightings of these birds. Birds are fitted with a single colour repeated on both legs and we would be most interested to hear about any sightings of these birds. One bird has already been reported, just five days after leaving the area in late May 2004, already providing valuable information of movements. With low water levels present in the Lower Derwent Valley during March 2005, it is looking likely that the grebes will not remain and breed at the site this year, so we would encourage those birdwatchers monitoring breeding sites elsewhere to keep look for colour-ringed birds this year. We would of course ask everyone fortunate enough to find themselves watching Black-necked Grebes this spring to spend a bit more time giving them a closer inspection. These sightings can be forwarded to the BTO ringing office or direct to craig.ralston@english-nature.org.uk.

Written by: Craig S Ralston, Assistant Site Manager – English Nature