Since 2006, we have conducted conservation-focused research on the breeding ecology of pallid and Montagu's harriers in central Asia in cooperation with the Naurzum Nature Reserve (North-central Kazakhstan) and with Todd Katzner www.katznerlab.com of the Division of Forestry and Natural Resources at West Virginia University www.forestry.wvu.edu. Click here to navigate to our project page.
The pallid harrier (Circus macrourus) is a migratory raptor that breeds from the Volga River eastwards through the Urals, southern Siberia, northern Kazakhstan and north-western China. Its main population strongholds are in southern-Asian Russia and northern Kazakhstan, which host c. 87 % of the world population. The population has declined in recent decades mainly on its western range distribution limits. Local declines have also been reported in Central Asia. The pallid harrier is classified by IUCN as a Near Threatened species.
Pallid harrier with satellite tag
Declines have been mainly attributed to breeding habitat degradation, leading to degradation of nesting habitat and reduction in prey availability, but migratory birds are also very sensitive to wintering conditions and it is known that the loss of high-quality wintering areas can influence breeding success during the following season. Wintering distribution of this species and the connectivity between breeding and wintering subpopulations is poorly known. Land-use transformations have also resulted in large-scale loss of dry grasslands and savannahs in Central Africa and India, the main wintering areas of this species. This project will identify the links between breeding and wintering populations, with the use of long-lived satellite-transmitters, and determine if the population dynamics of this species is affected by winter conditions.
In 2007, as a consequence of low vole abundance, breeding density of pallid harriers in the study area was very low (only 4 breeding pairs), and we could only fit one female with a satellite-transmitter. However, in 2008, harrier breeding densities were much higher and we were able to fit 8 more harriers with satellite tags.
We lost the signal of two birds prior to their migration. A total of 6 birds began their migration trip in September 2008. They all followed the same route from their breeding grounds in northern Kazakhstan to the eastern coast of the Caspian Sea in Russia, through Georgia, Turkey, Iraq, Saudi Arabia, and then crossed the Red Sea (2 of them passed by Egypt, see map below).
Map showing migration routes for pallid harriers
The blue line is the spring migration route of the pallid harrier we tracked from its wintering grounds in India (Satellite tracking of a pallid harrier that wintered in India). The other colours represent the autumn southern migration routes (from Kazakhstan to Africa) of the other 6 pallid harriers.
After arriving in Africa in early October 2008, the birds chose several different wintering areas. Two birds went to Ethiopia (where we lost the signal of one of them), two birds went to Sudan, including the female we captured in 2007, who also over-wintered in Sudan in that year (we have since lost transmission with one of the birds in November 2008) and interestingly, two birds took a more westerly route and spent the winter in Niger.
Three transmitters fitted to pallid harriers in Kazakhstan in previous years were still transmitting in spring 2009. Two birds seem to have bred in central Kazakhstan and one spent the breeding season in western Kazakhstan. We lost the signal of one of these birds during its post-reproductive prospecting phase in Russia, but the other two individuals initiated their autumn migration normally. Unfortunately, one of these disappeared during its southward migration, when it crossed Iraq.
The last individual, whose tag is still transmitting, reached its wintering grounds in eastern Africa (Ethiopia), and spent the whole winter there in a relatively constricted area, making no major movements during four months. In early April this bird began its northward migration, and in the two weeks since starting its migration it has crossed the Red Sea and Saudi Arabia, passed though Iraq and Iran and crossed the Caspian Sea. This bird entered south-western Kazakhstan in mid April, where it carried out it's pre-breeding prospecting phase (as observed in previous springs for other tracked pallid harriers). The aim of this phase is to locate and select suitable steppe habitats for breeding, characterized by high vole abundance. The bird has finally settled near Osmk, southwestern Siberia, Russia with recent flightlines showing lots of activity around a nest suggesting probable breeding. Pallid harriers usually start their autumn migration in late August however it is believed that before this journey they move away from the nest area, often quite far. The recent movements of the past 10 days are thought to be the post breeding dispersal. It is likely that the pallid harrier will now stop for a couple of weeks to have a break before pushing on with the southerly migration! For more maps and photos please click here.
This project formed part of Julien Terraube's PhD studies and was supervised by Bea Arroyo and Francois Mougeot.
Maps: F. Mougeot