L.R. Griffen

Articles by this author

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
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 Ornithology 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
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
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 Ornithology 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.
L.R. Griffen, D. Skilling and R.T. Smith with J.G. Young The 2015 Dumfriesshire Rookery Census: Including comparisons with the surveys of 1908, 1921, 1963, 1973, 1975, 1993, 2003, 2004, 2008 and 2010 Ornithology, Biology TDGNHAS Series III, 89 (2015), 9(4.65 MB) Abstract A total of 13,135 rook nests in 350 rookeries were counted in the 43 parishes of Dumfriesshire in April and May 2015. Although this represents a decrease of 20 rookeries compared to the number recorded in 2010, nest numbers increased by 785 in that period. The average number of nests per rookery increased to 38; something that has not been recorded during either the period of rook population growth from 1921 to 1993 or the period of population decline from 1993 to 2010. For the first time, no rookeries of more than 200 nests were recorded in 2015, the maximum count being 187 nests (cf. 217 in 2010). The number of rookeries containing over 100 nests increased from 20 to 24 from 2010 to 2015 — the first time an increase in this rookery size class has been recorded since 1993. Although it is of concern that the distribution of breeding colonies has again declined, the apparent increase in the breeding population and the cessation of the historic decline is perhaps a cause for optimism regarding the fortunes of the rook in this county.