Breeding ecology of the Twite Carduelis flavirostris in northern Tibet

Abstract

The breeding ecology of the Twite was studied during 2004-2007 in a meadow environment at 4,300 m elevation, in northern Tibet. Twite laid eggs between late May and mid-August in response to ripeness of seed food. Nests were located in firewood stacks, trees and marshes, with average inter-nest distances less than 15 m. Pairs formed monogamously and males used both proximity and frequent copulations to guard their paternity. Clutch size averaged 4.2 (± 0.7 SD; 3-7), seasonally increasing or remaining unchanged according to year. Incubation by the female only lasted 12.2 days (± 1.2 SD; 10-15) and provisioning of chicks in the nest was continued by both parents for 14.7 days (±1.1 SD; 7 13-17). Males performed courtship feeding when their mates were engaged in egg-laying, incubating and brooding. Breeding success, measured as the percentage of nesting attempts from which at least one nestling fledged, was 64%. Compared to their lowland counterparts, Tibetan Twite produced smaller clutches and larger eggs, suggesting a life history strategy to cope with the harsh high-elevation environment.