Montagu’s Harrier Circus pygargus
Background
Montagu’s Harrier is a highly migratory raptor. The species breeds from north-west Africa and Iberia north to southern Sweden, and eastwards to central Siberia. Western breeders winter in the northern tropics of Africa, south of the Sahara, whilst eastern breeders winter in India. The world population is thought to be at least 100,000 birds (BirdLife International 2010), with an estimated 35,000 to 65,000 breeding pairs in Europe, the largest numbers being in Russia, France and Iberia (BirdLife International 2004).
Montagu’s Harrier is a scarce summer visitor to the UK, returning to breed in small numbers between April and August. Parkin & Knox (2010) state that it appears to have been scarce in the 19th century, when probably rarely more than 20 pairs occurred. Persecution kept numbers low in the early 20th century, but this was followed by an increase in the mid 20th century, to an estimated 40-50 pairs in England & Wales, and a few also in Scotland and Ireland. Brown & Grice (2005) are perhaps a little more conservative, suggesting that is unlikely that the English population has ever exceeded about 30 pairs in any one year. This period was a followed by a decline, quite possibly related to pesticides, and there were no pairs proven breeding in 1974. Numbers then crept slowly upwards again towards the turn of the century. Virtually all breeding attempts in the late 20th century were in southern and eastern England.
The species is given the 2010 IUCN Red List status of Least Concern and was Amber-listed in Birds of Conservation Concern 3 (Eaton et al. 2009).
As a rare breeding bird, perceived to be at threat from a number of pressures (e.g. egg-collecting), detailed site-based information in this report is held in a Confidential Annex which is not to be generally distributed.
Reason for lack of SPAs
Montagu’s Harrier is listed on Annex I of the Birds Directive. To date, no SPAs have been classified within the UK for the species. Appendix 6.106 of Stroud et al. (2001) says:
“Montagu’s Harriers Circus pygargus nest largely on arable land in eastern England. No SPAs have been selected for this species because the only regular breeding area is largely comprised of intensively managed arable farmland within which precise nest locations vary considerably between years. This has prevented the identification of concentrations and delineation of suitable site boundaries. Nevertheless, Montagu’s Harriers are monitored in their regular nesting area and, as mechanisms are currently being developed to enable the classification of temporary and mobile habitats such as arable land, the species will remain under review.”
The species was not considered further by the SPARSWG between the 2001 review and the present review.
Current UK status
As a rare breeding raptor, Montagu’s Harriers are monitored by various local raptor enthusiastsand study groups, with the involvement of RSPB and Natural England; summary information is published annually by the Rare Breeding Birds Panel. Data have been provided by RBBP, as well as by Richard Saunders of Natural England who has been collating detailed information, and Paul Castle has provided helpful contextual information concerning birds in Wiltshire. The species is too scarce to feature on the Breeding Bird Survey (in 2009, the species was not recorded on any of the 3,243 BBS squares surveyed). A picture of the wider distribution of the species, especially of wandering (and probably non-breeding) individuals, can be gleaned from the ongoing Bird Atlas 2007-11 project, and from BirdTrack.
Figure 1 shows the recent status (1984-2008) of the UK breeding population as summarised each year by RBBP. Although there is year-to-year fluctuation, the trend appears to be one of relative stability, or at best only very slow increase. The number of confirmed pairs has not exceeded 13 in any single year, with an average of 11 confirmed pairs during the five-year period 2004 to 2008; widening the criteria slightly to “confirmed or probable” pairs increases this only slightly to an average of 12 pairs. Breeding productivity is more variable, but an average of 20 young have fledged in each of the five years 2004 to 2008. The mean number of localities reported in the same five year period has been 10, although the definition of a “site” for this species is not always clear-cut.
Figure 1: Confirmed pairs, localities and fledged young, source RBBP (1984-2008).
It should perhaps be noted that the data collated by Richard Saunders differs slightly from that held by RBBP. To a large extent this may involve differences of opinion regarding site definition or what constitutes a “pair”. Consolidation of data with RBBP to clarify these issues would be useful, but the discrepancies are not of a sufficient magnitude to alter the overall picture.
Key sites and links with existing SPA network
The majority of breeding Montagu’s Harriers in the UK occur in two broad areas in, respectively, eastern and south-west England. Sporadic breeding attempts have also occurred elsewhere in recent years. Virtually all of these have been in England, although a male displayed at a site in Wales in 2000. Montagu’s Harrier is currently only a scarce visitor to both Scotland and Ireland.
Area AThe most consistently occupied “site” is an extensive area of Lincolnshire and Norfolk. Much of this area is close to existing SPAs but most nests are outside the boundary. One nest site was nearly 40 km from the SPA boundary and perhaps it is arguable whether this should be considered as part of the same “cluster”. This area accounts for about 67% of nesting attempts over recent decades. An average of six pairs (range three to nine) was confirmed breeding between 2004 and 2008. The locations of individual nesting attempts can vary greatly between years, making site definition potentially problematic.
Area BOne area in south-west England has seen regular nesting attempts from at least 1993 (probably since 1982) to the present, with an apparently increasing level of occupancy in recent years. An average of three pairs were confirmed breeding annually between 2004 and 2008. This area overlaps an SPA, although many of the nesting attempts take place on farmland outwith the SPA boundary.
Area CA second area in south-west England has been regularly occupied by breeding birds with up to four territories per year from 1993 to the present, although only a single pair was present in most years between 2004 and 2008 (two in 2005). This area does not overlap with any SPA.
Area DA third area in south-west England was formerly regularly occupied, with breeding up to 2004, but it appears that breeding may now have ceased here, although birds regularly occur in the general area still.
Only sporadic breeding attempts have occurred in recent years away from the aforementioned areas. Since 2003, breeding has been confirmed once in Kent (Area E), once in Yorkshire (Area F) and once in Sussex (Area G), the latter two in (or close to) existing SPAs.
Discussion
To select SPAs for Montagu’s Harrier, consideration should first be given to the existing SPAs at, or close to, Areas A and B above, where birds make use of habitat within or adjacent to the existing SPA boundaries. Consideration might be given to boundary extensions in some cases. A third area (C above) may also be worthy of consideration for SPA designation but would require an entirely new site. Finally, if either the Yorkshire (Area F) or Sussex (Area G) sites prove to be occupied on more than an occasional basis, their existence within (or close to) an existing SPA also gives scope for designation for the species.
References
Birdlife International (2004). Birds in Europe: population estimates, trends and conservation status. BirdLife Conservation Series No. 12, BirdLife International, Cambridge UK.
BirdLife International (2010) Species factsheet: Circus pygargus. Downloaded from on 04/11/2010
Brown, A. & Grice, P. (2005). Birds in England. Poyser, London.
Eaton, M.A., Brown, A.F., Noble, D.G., Musgrove, A.J., Hearn, R.D., Aebischer, N.J., Gibbons, D.W., Evans, A. & Gregory, R.D. (2009) Birds of Conservation Concern 3: The population status of birds in the United Kingdom, Channel Islands and Isle of Man. British Birds, 102, 296-341.
Parkin, D.T. & Knox, A.G. (2010). The Status of Birds in Britain and Ireland. Christopher Helm, London.
Stroud, D.A., Chambers, D., Cook, S., Buxton, N., Fraser, B., Clement, P, Lewis, P., McLean, I., Baker, H. & Whitehead S. (eds.) (2001). The UK SPA network: its scope and content. JNCC, Peterborough.