Current status: Answered by Roseanna Cunningham on 18 December 2017
To ask the Scottish Government how many hen harrier nests there were on (a) RSPB and (b) non-RSPB reserves in each of the last five years, and what information it has regarding how many failed to have any chicks fledge, broken down by the reason for the failures.
The Scottish Government does not hold information on hen harrier nests broken down by nature reserves on which the nests are located, or on reasons for nest failure.
The Scottish Raptor Monitoring Scheme (SRMS) and RSPB have provided the data in Table 1 for RSPB reserves. The data is from 2011-2015. Data for 2016 will be available in early 2018.
Table 1
|
Year |
No of pairs monitored |
Successful |
Failed/Outcome unknown |
|
2011 |
42 |
13 |
29 |
|
2012 |
37 |
15 |
22 |
|
2013 |
37 |
12 |
25 |
|
2014 |
37 |
13 |
24 |
|
2015 |
43 |
15 |
28 |
Around 80% of the records in Table 1 are from RSPB Orkney reserves. The Orkney harrier population is well known for high levels of polygyny with males often breeding with 2 or 3 females. Most of these additional females either fail or produce very few young, as normally males struggle to feed more than one female and brood. This affects the failure rate overall and the proportion of successful nesting attempts is higher on non-Orkney RSPB reserves compared to Orkney reserves.
Table 2 provides data on breeding hen harriers across Scotland from the SRMS. It does not include the data included in Table 1.
Table 2
|
Year |
No of pairs monitored |
Successful |
Failed/Outcome unknown |
|
2011 |
204 |
98 |
106 |
|
2012 |
180 |
92 |
88 |
|
2013 |
210 |
97 |
113 |
|
2014 |
256 |
164 |
92 |
|
2015 |
233 |
105 |
128 |
The SRMS annual report for 2015 includes an article on Patterns of Breeding and Causes of Failure in 2015 (see http://raptormonitoring.org/wp-content/uploads/2016/11/SRMS_Report15.pdf). It shows the regional variation in both the success/failure rates and stage of nesting attempt when failure occurred for hen harriers, as well as providing a summary of causes of failure for all species reported in 2015. It highlights the difficulty in accurately assigning causes of failure, with the majority of failures being in the unknown reason category.