Breeding biology of the pallid harrier Circus macrourus in north-central Kazakhstan: implications for the conservation of a Near Threatened species

We studied a breeding population of pallid harrier Circus macrourus in 2000 and 2006 in north-central Kazakhstan to evaluate the relationships between breeding parameters and breeding habitat in the species’ core breeding range. Pallid harrier nests were found in a wide variety of vegetation types and heights belonging to three main types: steppe, riverine and agricultural. The proportion of nests found in each habitat type (corrected for search effort) differed between 2000 and 2006, with agricultural habitats being more used in 2000, when fallow land was abundant, than in 2006. Highest densities were observed in riverine habitats but hatching success seemed to be lower there because of greater predation. There was apparently lower productivity (smaller broods) in agricultural than in other areas. Laying was spread over 2 months, with a bimodal pattern of laying dates. Birds laid earlier in agricultural and steppe habitats and later in riverine habitats. These differences may be linked to spatio-temporal habitat heterogeneity, and possibly to intra-population heterogeneity in wintering areas implying different arrival dates on the breeding grounds. We discuss the implications of the findings for the conservation of this Near Threatened species.