Saffron-cowled Blackbirds' reduced nest success in Argentina's agricultural land highlights the importance of non-agricultural habitat for its conservation.

This article focuses on the breeding biology and nest survival of the globally endangered Saffron-cowled Blackbird (Xanthopsar flavus), an icterid endemic to southern South American grasslands, and assesses the impact of agricultural land use on its reproductive success. The study, conducted from 2015 to 2019 in northeastern Argentina, found an extremely low cumulative nest survival probability (0.06) with predation as the leading cause of nest failure, followed by brood parasitism and trampling by livestock and machinery. Nest survival was significantly higher in non-agricultural habitats such as marshes, which provide better concealment and act as breeding refuges, whereas grazed paddocks and other agricultural covers showed lower survival rates and higher brood parasitism by Shiny Cowbirds (Molothrus bonariensis). The findings highlight the negative effects of livestock ranching and agricultural practices on the species' reproduction and recommend conservation actions including the protection and restoration of marshes, management of brood parasitism, and the creation of non-productive breeding refuges within agricultural landscapes to support population maintenance.