Circus pygargus (Linnaeus, 1758)
Family: Accipitriformes > Accipitridae
Arguably our rarest breeding diurnal bird of prey, Montagu's Harrier is an exclusively summer visitor and one associated with drier habitats than our other breeding harrier species.
Britain is on the north-west fringe of the Montagu's Harrier's European breeding range, holding just a very small number of breeding pairs annually. This wider distribution suggests that we should be able to support more pairs, implying that lack of suitable habitat or other factors may be limiting.
While there are some areas within Britain that have held pairs over many years – for example the open arable farmland of Wiltshire and neighbouring counties – atlas data suggest a more fluent pattern of settlement.
Select a topic for more facts and statistics about the Montagu's Harrier
Montagu's Harrier identification is often difficult. The following article may help when identifying Montagu's Harrier.
Harriers are stunning, lithe and elegant birds of prey. Two species of grey harrier are regularly found in the UK, Hen and Montagu's - the males are relatively easy to separate, but the females and young birds can be more tricky.
Listen to example recordings of the main vocalisations of Montagu's Harrier, provided by xeno-canto contributors.
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Status and Trends
Population size and trends and patterns of distribution based on BTO surveys and atlases with data collected by BTO volunteers.
This species can be found on the following statutory and conservation listings and schedules.
The Montagu's Harrier is an extremely rare breeding species in the UK and the population has decreased strongly over the 25 years to 2019; in 2019 only two pairs were present and only one pair bred (Eaton et al. 2021). Breeding numbers have previously fluctuated: After having peaked at around 30 pairs in the mid-1950s they decreased and there were no pairs in 1974, before numbers improved again to a maximum of 13 pairs in the late 2000s (Balmer et al. 2013).
During Bird Atlas 2007–11
Occupied 10-km squares in UK
|No. occupied in breeding season||36|
|% occupied in breeding season||1.2|
European Distribution Map
|% change in range in breeding season (1968–72 to 2008–11)||-28%|
Montagu's Harrier is an increasingly rare summer visitor, arriving from April onwards.
Information about movement and migration based on online bird portals (e.g. BirdTrack), Ringing schemes and tracking studies.
An overview of year-round movements for the whole of Europe can be seen on the EuroBirdPortal viewer.
Lifecycle and body size information about Montagu's Harrier, including statistics on nesting, eggs and lifespan based on BTO ringing and nest recording data.
View number ringed each year in the Online Ringing Report
|Maximum Age from Ringing||13 years 0 months 5 days (set in 2017)|
|Typical Lifespan||6 years with breeding typically at 3 year|
|Field Codes||2-letter: MO | 5-letter code: MONHA | Euring: 2630|
For information in another language (where available) click on a linked name
Interpretation and scientific publications about Montagu's Harrier from BTO scientists.
Causes of change
Pesticides and a drought in the Sahel which began in 1968 may have driven the declines in the late 1950s and 1960s (Clarke 1996). Numbers have never recovered fully and, with Montagu's Harriers often nesting in agricultural crops, local action and monitoring can be important to support and protect nests and young (Clarke 1996, Balmer et al. 2013).
<p>Long-term effects of rewilding on species composition: 22 years of raptor monitoring in the Chernobyl Exclusion Zone</p>
Over 2,000 km² of Belarus previously given over to intensive agriculture and dense settlements was affected by the 1986 reactor meltdown at the Chernobyl Nuclear Plant in Ukraine.
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