L.R. Griffen
Articles by this author
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L.R. Griffen, D. Skilling, R.T. Smith and J.G. Young The Rookeries of Dumfriesshire 2003. Including comparisons with the Surveys of 1908, 1921, 1963, 1975, 1993 and 2004 Ornithology, Zoology, Recent (Social) TDGNHAS Series III, 78 (2004), 1(4.91 MB)
Abstract
The 2003 Dumfriesshire Rookery census has revealed that since 1993, the number of nests has fallen from 25,489 to 17,853, a decline of 30%. Earlier surveys in 1908, 1921 and 1963 had indicated a relatively stable population. Subsequent censuses in 1973, 1 |
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L.R. Griffen, D. Skilling, R.T. Smith and J.G. Young The Rapid and Continued Decline of the Rook in Dumfriesshire - Results of the 2005 Census TDGNHAS Series III, 79 (2005), 186(4.05 MB)
Abstract
A survey of the entire county of Dumfriesshire in 1993 recorded a total of 25,489 rook nests. A repeat of the census in 2003 found only 17,853 nests, a decrease of 30%. This decline prompted a survey of a large part of the county in 2004, which confirmed |
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L.R. Griffen, D. Skilling, R.T. Smith and J.G. Young The Continuing Decline of the Rook in Dumfriesshire: Results of the 2008 Centenary Census Ornithology, Zoology, Agriculture TDGNHAS Series III, 82 (2008), 1(2.63 MB)
Abstract
During the complete county census of 2008 the total of 13,459 rook nests was recorded. Thus, in the five years since 2003, there has been a 25% decline in nest numbers. This continues to confirm the 5% per annum rate of decline extrapolated from the parti |
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L.R. Griffen, D. Skilling, R.T. Smith and J.G. Young The 2010 Dumfriesshire Rookery Census: Including comparisons with the surveys of 1908, 1921, 1963, 1973, 1975, 1993, 2003, 2004 and 2008 TDGNHAS Series III, 85 (2011), 9(3.42 MB)
Abstract
Completion of the whole-county 2010 census of Rook Corvus frugilegus nests in Dumfriesshire is the most recent in a series which began in 1908. The results confirm that the decline in the number of Rook nests, first noted in 20035 , continues and now at 12,350 is at the lowest level ever recorded. This number is less than 50% of that recorded in 1993 when 25,489 nests, the largest number for the area was counted, meaning that the number of breeding Rooks has more than halved in the 17 year intervening period since that survey. In 1993, 22 colonies each held more than 200 nests, in 2010 (as in 2008) only one colony (not the same one) had more than 200 nests, symptomatic of the unabated fragmentation of large rookeries that has occurred resulting in ever smaller average rookery size, now just 33 nests per rookery. |