This discussion was first published as part of the 2015 Red List update. At the time a decision regarding its status was pended, but to enable potential reassessment of this species as part of the 2017 Red List update this post remained open and the date of posting was updated.
Pallid Harrier Circus macrourus breeds from Ukraine and SW Russia east through Kazakhstan to NW China and NW Mongolia (and irregularly farther N and W in Europe), and winters mainly in sub-Saharan Africa and S Asia (Orta & Christie 2015). It is currently listed as Near Threatened, because when last assessed it was considered likely to be experiencing a moderately rapid population decline overall.
Globally, it has an extremely large range in both the breeding season (>5 million km2) and in winter (>16 million km2), and hence does not approach the thresholds for Vulnerable under the range size criteria (B and D2). Its population size is poorly known, but was estimated at 9,000–15,000 pairs more than a decade ago (Galushin et al. 2003); this is moderately small, but does not approach the thresholds for Vulnerable under the population size criteria (C and D1). Therefore, the only potentially relevant criterion is A, which relates to reductions in population size. Until recently, the global population was thought to be declining moderately rapidly, at a rate approaching the threshold for listing as Vulnerable under criterion A (at least a 30% decline over ten years or three generations, whichever is longer).
New data collated from across Europe for the European Red List of Birds (BirdLife International 2015) resulted in the species being classified as Near Threatened at regional level, owing to its moderately small European breeding population (300–1,100 breeding females). However, no recent trend data were available from European Russia (with >99% of the European population) or from several other countries, although the species has established a small but growing breeding population in Finland (see data).
Europe comprises about 40% of the species’ global breeding range, but holds a much smaller proportion of its global population, which is concentrated in Central Asia, especially in S 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 km2 (Bragin 1999, E. Bragin in litt. 2005). No other detailed surveys were known from its Asiatic range, although anecdotal evidence from southern Kazakhstan (Almaty to Chockpack Bird Station) suggested that it was locally abundant (A. Corso in litt. 2005).
Assessing the status of this nomadic species is complicated by the fact that numbers on breeding territories fluctuate in response to environmental conditions. Recently, 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). Other 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).
At present, however, no evidence is available to suggest that the species has recently or is currently declining at a rate approaching 30% over three generations (18 years, based on a generation length estimated by BirdLife to be 6 years). Indeed, the fluctuations evident in its Kazakh stronghold, along with its colonisation of Finland and the increasing frequency of records in W Europe (e.g. Ollé et al. 2015), suggest that its global population may be shifting or even increasing overall, but seems unlikely to be decreasing.
Therefore, the limited information available implies that globally the species is no longer declining sufficiently rapidly to be listed as Near Threatened, and hence should be reclassified as Least Concern.
Comments on this proposal are welcome, along with any data regarding the recent trend of its breeding populations, especially in Russia and Kazakhstan, and of its wintering populations in Africa and Asia
BirdLife International (2015) European Red List of Birds. Luxembourg: Office for Official Publications of the European Communities. http://www.birdlife.org/datazone/info/euroredlist
Bragin, E. 1999. The changes of fauna and number of birds of prey in Kustanay Oblast (North Kazakhstan). Kazakhstan Zoological Journal: 99-105.
Galushin, V., Clarke, R. & Davygora, A. (2003) International Action Plan for the Pallid Harrier (Circus macrourus).
Limiñana, R., Arroyo, B., Terraube, J., McGrady, M., & Mougeot, F. (2015). Using satellite telemetry and environmental niche modelling to inform conservation targets for a long-distance migratory raptor in its wintering grounds. Oryx, 49(02), 329-337.
Ollé, A. Trabalon, F. & Bertran, M. (2015) Occurrence of the Pallid Harrier Circus macrourus in the Western Mediterranean revisited: a new migrant and wintering species. http://revistacatalanaornitologia.blogspot.co.uk/2015/03/i-am-no-longer-rarity.html
Orta, J. & Christie, D.A. (2015) Pallid Harrier (Circus macrourus). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.) (2015). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. www.hbw.com
Terraube, J., Arroyo, B. E., Bragin, A., Bragin, E., & Mougeot, F. (2012a). Ecological factors influencing the breeding distribution and success of a nomadic, specialist predator. Biodiversity and Conservation, 21(7), 1835-1852.
Terraube, J., Mougeot, F., Cornulier, T., Verma, A., Gavrilov, A., & Arroyo, B. (2012b). Broad wintering range and intercontinental migratory divide within a core population of the near‐threatened pallid harrier. Diversity and Distributions, 18(4), 401-409.
EDIT 4 August 2015:
Yoav Perlman and colleagues at Israel ornithological Center / Society for the Protection of Nature in Israel have provided a summary of the status of Pallid Harrier in Israel – see link below.