Behavioural ecology and conservation of two sympatric raptors in North-Central Kazakhstan: the pallid harrier (Circus macrourus) and the Montaguâ€™s harrier (Circus pygargus).
Pallid harrier chick
The pallid harrier is a rare and poorly understood migratory raptor that breeds across Eastern Europe and northern Asia. In winter, most pallid harriers move to the Afrotropics and the Indian subcontinent.
Substantial declines have been reported in many areas of the species' breeding range (Davygora & Belik, 1994), and the pallid harrier is now classified as Near-threatened globally (Birdlife International, 2000) and in certain countries is of even greater conservation concern. In spite of this situation, the species remains poorly studied.
Wetlands and other moist areas amidst grassland of steppe and forest-steppe are the typical breeding habitat of the pallid harrier (Birdlife International, 2003).Â Within these, in any given year they are thought to search for areas where densities of small mammals are high in early spring, though we donâ€™t know yet to what extent the distribution, breeding density and breeding success of this species is dependent on rodent abundance.
Female pallid harrier in moult
This project evaluates the behavioral ecology and conservation of pallid harriers in Kazakhstan, which is within its core breeding range. Indeed, there is an urgent need to understand the links between diet specialization, foraging and breeding habitat selection, local density dependence and breeding success in this species. As the breeding habitats of this species have deteriorated due to wide-scale transformation of steppe grasslands to agriculture this work will have implications for the conservation of this species, and will benefit steppe biodiversity at a larger scale.
Land-use transformations also have affected the wintering ground of this species and it is known that the loss of high-quality wintering areas can influence breeding success during the following season (Norris et al. 2004). This project will identify the links between breeding and wintering populations and determine if the population dynamics of this species is affected by winter conditions.
Female Pallid Harrier
In contrast to the pallid harriers, the behavioural ecology and population dynamics of Montaguâ€™s harriers is relatively well known. However, current knowledge about the species is based on the well-studied western European populations breeding in agricultural areas (review in Arroyo et al. 2004). The study of Asian populations breeding in natural habitats and comprising the bulk of the population in Eurasia may improve our understanding of the sustainability of Montaguâ€™s harrier populations in agricultural areas at a larger scale, and through comparative studies will help us to understand the ecological constraints of the Pallid harrier.
The project is being done in association with the North Kazakhstan Field Station near the Naurzum Natural Reserve, north-central Kazakhstan and Todd Katzner www.katznerlab.com of the Division of Forestry and Natural Resources at West Virginia University www.forestry.wvu.edu. The field station is an initiative supported the Wildlife Conservation Society. Pilot work in north Kazakhstan in 2000 showed this area to contain a high density of breeding harriers breeding. This project is one of the first international research projects to take place in the Field Station since its creation in 2006.
Click here to see movements of a pallid harrier from Kazakhstan that we have been tracking via satellite.
Division of Forestry and Natural Resources, West Virginia University, Morgantown, WV, USA
Photos: M. McGrady and J. Terraube
Nest of pallid harrier chicks with one egg
Congratulations to Julien! Julien Terraube has completed his PhD at IREC-University of Castilla-la-Mancha in Ciudad Real, Spain.Â His thesis was entitled â€œIntegrating foraging strategies, spatial movement patterns and reproductive success: implications for the conservation of sympatric avian predatorsâ€.
Julien's thesis is the result of a three-year research project funded by Natural Research that studied the population ecology of two sympatric harrier species, the pallid (Circus macrourus) and Montaguâ€™s harriers (C. pygargus), breeding in north-Central Kazakhstan. It aimed to better understand the causes of the decline observed in pallid harrier populations throughout their distribution, and gain some knowledge of the current conservation status of these two species in Central Asia.Â
Researcher in the field
The study confirmed that in the Narzum region pallid harriers specialized on small rodents, while the sympatric Montaguâ€™s harriers had a more generalized diet. Additionally, the research showed that foraging parameters of the specialist pallid harrier strongly varied with vole abundance, whereas foraging parameters of the generalist species were not variable and were independent of vole abundance.
One of the other main aims of this project was to gain knowledge on the migratory ecology of the pallid harriers and to find out where pallid harriers from north-central Kazakhstan winter. It seems that pallid harriers from Narzum winter from eastern Africa (mainly Sudan and Ethiopia) to western-central Africa (Burkina-Faso and Niger). Satellite tracking also revealed the great mobility of this species across the year, with important movements recorded during the pre-breeding and pre-migratory phases, probably aimed at prospecting for areas with high vole abundance.
The strong specialist foraging strategy of the pallid harrier implies a high level of vulnerability to global changes. Land use and climate change that induce a reduction in vole outbreak frequencies, or a higher spatial synchrony of vole population crashes could accelerate pallid harrier declines. Also, the high mobility of this specialist species highlights the need for implementing large-scale conservation actions across its global distribution.
Photos: Top: J. Terraube Bottom: F. Mougeot
Three pallid harriers were fitted with satellite transmitters in the spring of 2009 as part of a Natural Research funded PhD study by Julien Terraube.Â A blogÂ was set up to offer up-to-date viewing of the Pallid harrier movements throughout the year.Â Sadly, we lost signal from the last pallid harrier we were tracking in November 2011, to see maps and read more narrative about the movements of this bird, please click on the blog below: