Rook Rookery Survey Rookeries

Abundant resident breeder.

In the 19th century the Rook was resident and common, indeed Haines described it as 'undoubtedly too numerous in this district.' He recorded flocks of 400 around Uppingham. Browne recorded breeding at Knighton, Stoneygate and Westcotes within the city of Leicester. Both he and Haines commented on variants with pale plumage tracts, though these are more commonly found in Carrion Crows.

The first comprehensive census of the Rook population in Leicestershire was carried out in 1928. Hickling discussed local population trends of this species, noting that it increased from 1928 to 1944 by 44% (though he acknowledged that early counts using unsophisticated methods may have been too low). Between then and 1975 the population declined by over 50%, possibly as a result of changes in agricultural practice which may have reduced available food, increased disturbance and loss of nesting habitat. Since the 1970s, however, there has been a welcome recovery in numbers by over 60%.

This species remains abundant and widespread across the counties and the clamour of a rookery provides one of the quintessential sounds of spring. These conspicuous nesting colonies mean that Rooks are one of the easiest species to census in the breeding season and surveys have been carried out in 1928, 1944, 1964-65, 1975 and 1986-87. Consequently, we probably have more data on breeding numbers of this than any other species. Census results are given in Table 48:

Table 48: Rookery census results

Year(s)

County

No. of nests

No. of rookeries

1928

Leicestershire

9,381

No data

1944

Leicestershire

13,639

422

Rutland

3,657

83

Total

17,296

505

1964-65

Leicestershire

10,652

No data

1975

Leicestershire & Rutland

7,475

327

1976-85

Leicestershire

8,720

No data

Rutland

1,770

No data

Total

10,490

No data

1986-87

Leicestershire & Rutland

12,261

421

The current trend seems to be upward and the present breeding population is probably back up to, or around, the 1944 level.

The most recent full survey in 1986-87 showed that there were 242 rookeries of between one and 25 nests, 115 of between 26 and 50 nests, 51 of between 51 and 100 nests and 13 of between 101 and 200 nests. Rookeries were widely distributed across the whole of the counties but were absent from urban areas such as Leicester, Loughborough, Coalville and Market Harborough; it was also noticeably scarce in the extreme northeast. The highest densities occurred to the south and east of Leicester between Melton Mowbray, Oakham and

Corvus frugi/egus

Lutterworth and also in the Market Bosworth area (Holling 1988). Earlier surveys showed the highest nest density in east Leicestershire and Rutland, a region then dominated by pasture. During the recent recovery of this species, there has also been a shift towards larger rookeries. Most are small (fewer than 25 nests), but there has been an increase of 12% in the number of larger colonies (26 to 100 nests). The largest rookeries recorded during the 1986-87 survey were:

• 200 nests at Wharf Farm, Market Bosworth.

• 175 nests at Barrowden.

• 159 nests at Lubbesthorpe.

• 157 nests at Crossburrow Hill, Cranoe.

• 150 nests at Osbaston Hall.

The only rookeries larger than those recorded in 1986-87 were two counted in 1944: 300 nests between Barlestone and Osbaston and 284 nests east of Wing.

From 1991 to 2003 the RNHS carried out an annual survey of rookeries in Rutland. This shows that the population has been fairly stable in recent years, though it has been noted that, whilst there is little change in the number of large rookeries, Rooks in smaller rookeries regularly relocate to new sites in response to changes of land use (for example, from spring to autumn ploughing). In Charnwood, where there is a much smaller proportion of pasture, Webster (1997) recorded breeding in only 18% of 1-km squares.

Table 49: Numbers of rookeries and nests recorded in Rutland by RNHS from 1994-2003

Year 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

Rookeries 56 62 73 56 63 74 69 n/c 74 78

Nests 1,453 1,960 2,123 2,147 2,044 1,981 2,283 n/c 2,099 2,009

There were worries in the late 1970s that the loss of elms through Dutch Elm disease would cause a decline in Rook numbers, as a significant proportion of nests were built in these trees. This has not been borne out and they have successfully switched to other tree species. Although the vast majority of nests are built in trees (usually deciduous, but occasionally conifers), there are several records of small rookeries on electricity pylons.

Large flocks are maintained outside the breeding season and often number in the high hundreds; the largest flocks recorded are:

• 3,750 at Eastwell on December 6th 1982.

• 3,000 at a pre-roost gathering at Kirkby Mallory on January 28th 1991.

• 2,000 at Dadlington on February 7th 1986.

• 1,650 at Branston on February 26th 1995.

• 1,600 at Teigh on December 1st 1989.

• 1,500 at a pre-roost gathering at Bottesford during the second winter period of 1996.

In addition a mixed roost, with Jackdaws, of 15,000 to 20,000 was at Ambion Wood on October 29th 1954, with 13,000, again mixed, at the same site on November 20th 1955 and several thousand, also mixed with Jackdaws, were roosting between Twycross and Orton-on-the-Hill in December 1949. An aberrant bird shot at Noseley on May 20th 1942 was chocolate-brown in colour.

There are only six recoveries of ringed birds and just two had moved more than 10km: one ringed at Billesdon Coplow on April 5th 1990 was found shot 13km to the east-south-east at Stockerston on December 4th 1990 and one ringed at Market Bosworth on May 10th 1987 was found in similar circumstances 12km to the south-west at Atherstone (Warwickshire) on March 20th 1991.

Rooks are found from Europe and Asia Minor east to eastern Siberia, Japan, Korea and eastern China. The British breeding population was estimated at 853,000 to 857,000 pairs during 1988-91 (Gibbons et al. 1993) but a subsequent moderate increase has seen the latest estimate increased to 1,022,000 to 1,304,000 pairs (Baker et al. 2006).

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