NT
Pallid Harrier Circus macrourus



Justification

Justification of Red List Category
This species was previously thought to be undergoing a steep population decline in Europe, but more recently the European trend was re-assessed as stable. Trends are uncertain across the core of the breeding range in central Asia, however habitat loss and degradation is suspected to be causing slow, significant declines. The partly nomadic nature of the species and its fluctuating numbers make assessment of the overall trend problematic, but a moderately rapid decline continues to be suspected on a precautionary basis until better data are available from across the range, and consequently it remains categorised as Near Threatened.

Population justification
The global population is estimated at 9,000-15,000 pairs (Galushin et al. 2003), equating to 18,000-30,000 mature individuals. The European population is estimated at 1,000-2,200 breeding pairs, which roughly equates to 2,000-4,400 mature individuals (BirdLife International in prep.).

Trend justification
Assessment of population trends in this species is complicated by the fact that on breeding territories numbers fluctuate in response to environmental conditions, probably to changing numbers of small mammals. Thus, high or low territory numbers in any given year or two-year period may be indicative of change in demographics, or they may be indicative of change in local environment, while the birds may breed elsewhere without their population size changing. A 13-year data study in north-central Kazakhstan revealed that its numbers and reproductive success vary cyclically, peaking every c. 6 years, in response to interannual variation in local vole densities; these cycles were asynchronous between regions, suggesting a regional redistribution of birds between years (Terraube et al. 2012a). Large numbers of Pallid Harriers in Finland have also been associated with peaks in vole populations (Henry 2018).

A large decline occurred in Europe during 1970-1990 (Tucker and Heath 1994), when up to 30% of birds were lost (particularly from the key population in European Russia), and the species continued to decline in 1990-2000, when overall trends exceeded 30% over three generations (17 years) (BirdLife International 2004). More recently, the European population trend was assessed as stable in the 2021 European Red List of Birds (BirdLife International in prep.), partly due to an increasing breeding population in Northern Europe (Keller et al. 2020). Europe comprises about 40% of the species’ global breeding range, but holds a much smaller proportion of the global population, as the larger proportion is concentrated in Central Asia, especially in southern Russia and Kazakhstan (Galushin et al. 2003). When last assessed, surveys in the Kustanay Oblast region (northern Kazakhstan) from 1997 to 2004 indicated a fluctuating but ostensibly stable population of 1,500–2,000 pairs, nesting at a density of 9.4–25 pairs per 100 km(Bragin 1999, E. Bragin in litt. 2005). Anecdotal evidence from southern Kazakhstan (Almaty to Chockpack Bird Station) suggested that it was locally abundant (A. Corso in litt. 2005). A survey of harrier roost sites in India from 1985-2015 found a declining trend in the number of overwintering Pallid Harriers, although the trend was not statistically significant (Ganesh & Prashanth 2018). However, roost counts in southern India during 2015-2019 found a significant decline in male Pallid Harriers (Saravanan et al. 2021). 

The partly nomadic nature of the species and its fluctuating numbers make an assessment of the overall trend problematic. With the population estimated to be stable in Europe, but a potentially significant decline reported from overwintering sites in India, a moderately rapid decline of 10-20% continues to be suspected on a precautionary basis until better data are available from its core breeding range in Central Asia.

Distribution and population

This species breeds primarily in the steppes of Asiatic Russia, Kazakhstan and north-west China. Small populations breed in Azerbaijan, Romania, Turkey and Ukraine, however recent survey data suggest that these populations have almost disappeared (Keller et al 2020). A minority winter in south-east and central Europe, north Africa and the Middle East but most migrate to the Afrotropics and the Indian subcontinent (Thiollay 1994; Corso & Cardelli 2004). Records in northern and western Europe have increased in recent years, with regular breeding now taking place in Finland and passage/ wintering records in several other countries, suggesting a northwards range shift (Ollé et al. 2015; Henry 2018).

Reliable records from migration routes and wintering grounds are difficult to obtain owing to the rarity of the species, its broad-front migration strategy, and difficulties in field identification, although important concentrations of birds have been identified in parts of India and Africa (Galushin et al. 2003). Surveys in Europe during the last 20 years or more show an increase in numbers in most European countries, which may be influenced by drifting migration flyways due to climate-driven change in distribution of some breeding and/ or wintering populations (Corso & Cardelli 2004; Corso in litt. 2019; Réglade et al. 2015; Henry 2018). Migration monitoring surveys at Batumi on the Black Sea Coast of Georgia - the most important bottleneck for Western Palearctic raptors - show fluctuating numbers over the last 10 years but no obvious trend (Wehrmann et al. 2019). 

Ecology

It breeds in semi-desert, steppe and forest-steppe up to 2,000 m, where its favoured nesting sites are wet grasslands close to small rivers and lakes, and marshlands (Snow and Perrins 1998, Galushin et al. 2003). The species has also been found to breed in agricultural areas, at least when agriculture is non-intensive (Terraube et al. 2009). A minority of the population breeds in the boreal forest and forest-tundra zones, north of its main breeding range (Kuznetsov 1994, V. Morozov in litt. 1999), where it nests in clearings and other open areas (Galushin et al. 2003). Mosaics of forest/ shrubland and grassland and, to a lesser extent, agricultural land, are used in winter (Liminana et al. 2015). The species is migratory, with most birds wintering in sub-Saharan Africa or south-east Asia. They leave their breeding grounds between August and November and return in March and April (del Hoyo et al. 1994). Birds migrate on a broad front, with only minor concentrations at bottleneck sites (del Hoyo et al. 1994, Ferguson-Lees and Christie 2001). Record numbers during migration were counted at Batumi, along the Black Sea Coast of Georgia, where up to 2,500 birds were annually counted in autumn during 2008-2018 (Vansteelant et al. 2019). Although birds are most often seen singly, females and juveniles can form parties of 10-15 individuals on migration (Snow and Perrins 1998, Ferguson-Lees and Christie 2001). Birds fly at c.1-9 m above the ground when hunting (del Hoyo et al. 1994, Snow and Perrins 1998) and fly generally higher on migration, but tend to remain from c.1-15 m above the ground (Brown et al. 1982).

Threats

Within its breeding range, the species is primarily threatened by the destruction and degradation of steppe grasslands through conversion to arable land, burning of vegetation, intensive grazing of wet pastures and the clearance of shrubs and tall weeds (Galushin et al. 2003, E. Bragin in litt. 2007). Fires are started by farmers, arsonists and dry thunderstorms (E. Bragin in litt. 2007).

On its wintering grounds, the species is thought to be negatively affected by the loss and degradation of grassland due to conversion to agriculture, burning, cutting, overgrazing, excess harvesting of trees and shrub encroachment as a result of changes in pastoral activities (Galushin et al. 2003; Limiñana et al. 2015). The species's nomadic nature may allow them to find alternative areas, however suitable habitat is fragmented, therefore this may be energy intensive (Limiñana et al. 2015). The species may also be affected by the use of harmful pesticides, rodenticides and other toxic chemicals (R. Simmons in litt. 1999, Galushin et al. 2003), although this requires more research. The distribution of overwintering Pallid Harriers is associated with climatic variables (particularly rainfall), therefore climate change may also pose a threat (Limiñana et al. 2015).

On migration, one of the main threats is illegal bird shooting - over 10% of the European population of Pallid Harriers may potentially be illegally killed each year in North and Central Europe and the Caucasus region, representing over 1% of the global population (Brochet et al. 2019). For example at Batumi on the Black Sea Coast and south to Eastern Turkey, where the largest numbers of migrating birds are counted annually, a large number of birds are regularly killed (Batumi Raptor Count; A. Corso Terra 2019).

Conservation actions

Conservation and research actions underway
It is listed in Appendix II of CITES, Annex II of the Bonn and Bern Conventions, Annex I of the EU Birds Directive, Annex II of CMS and Category 1 of the Raptors MOU. It is also listed in the Red Data Books of Belarus, Ukraine, Russia and Turkey (Galushin et al. 2003, Kiliç and Eken 2004). It occurs in five state nature reserves in Russia as well as in Naurzum and Korgaljin Nature Reserves in Kazakhstan (Galushin et al. 2003). The most suitable wintering areas in the Sahel region are relatively well represented by the current network of Protected Areas (Limiñana et al. 2015). An International Action Plan for the species was produced in 2003 (Galushin et al. 2003). Recent studies have used ring recovery data, satellite tracking data and environmental niche modelling to improve understanding of the species’ migration routes and wintering areas (Terraube et al. 2012b), and to inform conservation planning in its wintering grounds in Africa (Limiñana et al. 2015).

Conservation and research actions proposed
Encourage conservation of wetlands and ponds in typical steppe grassland and semi-desert. Support moderate grazing and conservation of grasslands. Develop survey methodology (including GIS) and carry out surveys, primarily in the core breeding range and, secondarily, to establish its northern and southern range limits as well as to search for new nesting places outside core breeding grounds. Carry out research into diet and foraging range size, and their role in the movement of populations. Lobby for enactment and enforcement of legislation banning the use of harmful pesticides in the winter range, and in the recovering agricultural economy in the breeding range. Survey grassland and thorn-forest areas in African and Indian winter range for significant roosting concentrations, including tracking birds by means of satellite telemetry as soon as feasible. Review roost site and catchment area management at winter roosts, most urgently in areas where agriculture is changing due to new irrigation schemes, and pursue any necessary conservation action. Carry out research into pesticide residues in corpses, and pesticide use in winter roost catchment areas. Encourage full legal protection and education in countries on migration routes and in the winter range (Galushin et al. 2003).

Identification

40-48cm. Narrow winged, lightly built harrier, with similar structure and flight to C. pygargus and females and juveniles closer to C. cyaneus in structure and plumage details. Adult male unmistakeable, with pale grey and white plumage, relieved only by black wing-tips. Adult female dark brown above, streaked below, with barred tail. Similar spp. Adult female can be distinguished from C. pygargus by lack of solid dark trailing edge to inner primaries when seen in flight from below combined with duller secondaries, lack of dark bar along mid-secondaries on upperwing, and a series of subtle characters. Juvenile differs from C. pygargus in having almost white ruff-collar rather than dark neck shawl, same primary pattern as for female and other subtle characters. Female and juvenile C. macrourus also resemble C. cyaneus, but the latter species is larger, with proportionately shorter and broader wings. Voice Little known, but said to be similar to that of C. pygargus and C. cyaneus. Usually silent in winter.

Acknowledgements

Text account compilers
Haskell, L.

Contributors
Bragin, E., Brouwer, J., Corso, A., Katzner, T., Morozov, V., Simmons, R.E., Benstead, P., Capper, D., Khwaja, N., Symes, A., Taylor, J., Ashpole, J, Temple, H., Pilgrim, J., Peet, N., Hermes, C. & Derhé, M.


Recommended citation
BirdLife International (2022) Species factsheet: Circus macrourus. Downloaded from http://www.birdlife.org on 06/07/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 06/07/2022.