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Satellite tagging of young kestrels
Annual kestrel summaries - Scotland
Annual Report 2012
Despite the open winter and good weather in March territory occupation was low at 60%. Several of the traditional ‘banker’ territories were empty which was unusual. From March onwards the weather deteriorated, April and May being mixed erring on the wet and June had one of the highest rainfall figures on record. It was difficult to assess whether the low territory occupation was due to local conditions or part of the kestrel’s general decline. Certainly the weather was a major factor on the production of young and this was compounded by the scarcity of voles.
The first egg laying dates were all in the second half of April, but those pairs which did breed produced reasonable sized clutches. Productivity was poor, even lower than in the last really low vole year of 2009. Brood survival was the poorest for many years probably due to the continuous rainfall with broods in crows’ nests and other exposed sites being in particularly poor condition. Thirteen of the successful pairs reared either two or three young, a low productive rate for the study area.
The 2012 breeding statistics are as follows :-
|
|
2012 | 2011 | 2010 | 2009 | 2008 | 2007 |
2006 |
|
Number of territories
checked |
46 | 38 | 37 | 39 | 41 | 34 |
35 |
|
% occupation |
60 | 63 | 73 | 49 | 73 | 59 |
72 |
|
Number of clutches
known |
11 | 11 | 15 | 10 | 18 | 12 |
16 |
|
Average clutch
size |
5.2 | 5.45 | 5.2 | 4.6 | 5.3 | 5.25 |
4.75 |
|
% of eggs which
hatched |
73 | 67 | 89 | 91 | 83 | 95 |
84 |
|
Number of results
known |
26 | 24 | 25 | 19 | 26 | 17 |
25 |
|
Average young per
breeding pair |
2.4 | 2.8 | 3.8 | 2.8 | 3.81 | 4 |
3.2 |
|
Average young per
successful pair |
3 | 3.5 | 4.4 | 3.4 | 4.3 | 5.15 |
3.8 |
|
Number of breeding
attempts failed |
5 | 5 | 3 | 4 | 3 | 3 |
4 |
|
% failed |
19 | 21 | 12 | 21 | 11 | 17 |
16 |
|
% brood
survival |
83 | 89 | 89 | 90 | 96 | 93 |
98 |
|
Number of young ringed |
15 | 20 | 34 | 23 | 46 | 44 |
46 |
Number of field days: 32
Two failures occurred at the prelaying stage, two at the clutch stage and one pair lost its brood. Only fifteen young kestrels were ringed and there were no ringing recoveries from previous years’ birds.
GORDON RIDDLE September 2012