Breeding ecology of Kessler’s thrush (Turdus kessleri) in the western Sichuan plateau

The breeding of most high-altitude birds remains poorly known. We studied the breeding ecology of Kessler’s thrush (Turdus kessleri) and documented reproductive information throughout the nestling periods in the western Sichuan plateau. The data included natural nest sites, nest components, nest size, egg-laying dates, egg morphology, egg size, clutch size, egg incubation, nestling brooding and feeding, nestling morphology and growth, and reproductive outcome. The study found that T. kessleri used the old nest to breed. As the nestling grew, the female’s nestling brooding time decreased, and the feeding frequency of parent birds increased at first and then decreased. The frequency of clearing feces was positively correlated with the feeding frequency. The difference in the feeding frequency of both parents may be attributed to their division of labor, with a distinct difference between their investments. The parent birds’ cost of reproduction per nestling varies from one breeding period to the next. Predation by natural enemies is the main factor leading to reproductive failure in T. kessleri. This suite of life-history and behavioral strategies enables fledgling T. kessleri to cope with the harsh environments of mountains at higher altitudes.