The Yellow Cardinal Gubernatrix cristata is an ‘Endangered’ passerine from southern South America. For the past three years a management plan for Yellow Cardinals has been implemented in Argentina, in which rescued individuals from the illegal cage bird trade were released back into suitable habitats within their population of origin. We studied the reproductive success of a mixed population of released and wild Yellow Cardinals in La Pampa province, Argentina, during the reproductive season of 2019. The population was highly parasitized by the brood parasitic Shiny Cowbird Molothrus bonariensis. The frequency of parasitism was 100% and the intensity of parasitism was 4.5 ± 3.4 (mean ± SD) eggs per parasitized nest (range 1–13). No Yellow Cardinal chicks were recruited in the monitored nests, mainly as a consequence of Shiny Cowbird parasitism. The unusually high rate of parasitism led to a poor outcome of the reintroduction programme and indicates the need to update the conservation actions that have been carried out for the Yellow Cardinal so far. Shiny Cowbird abundance varies within the distribution of Yellow Cardinals, related to habitat modification and farming activities. Thus, further research on habitat suitability and assessment of Shiny Cowbird abundance should be incorporated into future strategies for the conservation of the Yellow Cardinal.

The Yellow Cardinal Gubernatrix cristata is a globally endangered passerine from the southern cone of South America. Because of its conspicuous plumage and very attractive song, it suffers considerably from illegal pet trade. The largest remaining populations are found in Argentina, but no coordinated efforts have been made thus far to understand better its current distribution and conservation status. During three annual surveys supported by a citizen science programme, more than 140 volunteers surveyed 644 geographical points during spring and detected 221 Yellow Cardinals. Based on the survey results, we evaluated the presence of cardinals within protected areas in Argentina and found that the species was only detected in four of them, two of which were private reserves with a low level of protection. We also found that the species was not restricted to the ‘Espinal’ ecoregion, but also inhabited ‘Monte’ and ‘Chaco’ ecoregions, which are generally drier. This citizen science programme allowed us to obtain up-to-date information on the remaining populations of the Yellow Cardinal and helped to increase public awareness about the conservation problems faced by the species. We propose some future strategies for monitoring Yellow Cardinals and taking informed conservation decisions.