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Crane numbers continue to climb

The 2019 breeding season has been one of mixed fortunes for the reintroduced cranes, but the overall trend is one of continued improvement in productivity.  This was the best year yet in terms of numbers of cranes fledged with the figure of nine new recruits an excellent acheivement.  Productivity can be measured in a number of ways - and it is usual to either use the number of fledged chicks divided by either the number of territorial pairs, or the number of pairs that made nesting attempts.  Both of these two figures 0.38 and 0.56 chicks per pair are given in the table below.                                                                                                         

  2013 2014 2015 2016 2017 2018 2019 5yr avg.
Territorial pairs 1 5 16 22 19  22 24 20.6
No. pairs making confirmed/prob nesting attempts 1 2 9 15 10 22 16 14.4
% of territorial pairs that made nesting attempts 100% 40% 44% 68% 53% 100% 67% 70%
Confirmed nesting attempts  - including re-lays 2 4 11 25 14 33 20  
No. known pairs reaching hatch stage 1 1 4 5 7 17 10  
% of confirmed and probable nesting attempt reaching hatch stage 100% 50% 44% 33% 70% 77% 62% 57%
Hatched chicks 1 2 06-Jul 7 11 20 19 12.8
Fledged chicks 0 0 4 3 4 7 9 5.4
PRODUCTIVITY RATE 1. 0 0 0.44 0.2 0.4 0.31 0.56 0.38
No. of fledged chicks per confirmed/probable pair
PRODUCTIVITY RATE 2. 0 0 0.25 0.14 0.21 0.31 0.38 0.26
No. of fledged chicks per total territorial pairs

This data can be compared with the non-reinrtroduced 'native' breeding crane population in the rest of the uk and you can see from the graph below - that even though the long term trend is improving - it is still short of the native populations productivity.  This is most likely caused by the reintroduced birds comprising a young population (none of the birds are over 9yrs old) and to date, most of the pairs comprising hand-reared birds that perhaps will never be quite as productive as wild, parent-reared birds.  

 

 

 

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Damon’s role is to act as the hub of the project - making sure everyone involved knows what is going on and that it is all running smoothly. He is also responsible for project community awareness work in Somerset, construction of the release enclosure, and running the post release monitoring work in Somerset.  Damon works alongside the RSPB reserve teams in Somerset.