The yellow cardinal (Gubernatrix cristata) is a passerine bird endemic to southern South America. At present, the species is threatened with extinction, in part because of the capture of wild birds to supply the illegal caged‐bird market. Previous genetic evidence supports the existence of 3 management units for the species in Argentina, where the largest populations are currently found. Our objectives were to guide the reintroduction of these animals to their respective management units by determining the origin of seized specimens from illegal trade using 2 molecular markers, mtDNA and microsatellites, and to monitor the success of the released birds through radio‐telemetry. We compared the performance of different molecular markers and assignment approaches to optimize a technique capable of assigning the origin of confiscated yellow cardinals in a reliable way. Five of 10 released radio‐tracked individuals were predated shortly after liberation; however, 3 were successful in finding a mate and starting reproductive activities. Individual success was independent of the time spent in captivity, the liberation with a partner, the settlement type (semi‐open or closed), and the maximum distance traveled from the point of release. Cardinals that survived had higher individual heterozygosity. Our findings contribute a robust genetic assignment technique to be used in future yellow cardinal seizures and identify factors that might improve subsequent releases. © 2019 The Wildlife Society.

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Breeding outcome in birds can be influenced by both intrinsic and extrinsic factors, which may contribute differentially to each stage of the breeding cycle. Island raptors are relatively threatened species that rely on simplified food webs and usually co‐occur with invasive species. Here, we studied a population of Striated Caracara Phalcoboenus australis in Isla de los Estados (Argentina) to understand the relative contribution of food availability, topographical features and territoriality to breeding parameters. Caracaras in the area depend on the short seasonal (i.e. pulsed) availability of seabirds for feeding their chicks. On the other hand, the recent introduction of non‐native ungulates may have led to a suboptimal breeding environment by reducing Caracara nest‐site availability within the seabird colonies via disturbance of the grassland. Using data from seven breeding seasons we analyse the abundance, the proportion of breeding individuals, the spatial structure of breeding events and the population‐level breeding performance, including chick sex ratio, to study whether the breeding ecology of this species is still shaped by marine food web pulses or could be associated with invasive herbivore disturbance. The breeding adults represented only 6–15% of the population. The spatial pattern of nest‐sites did not differ from random arrangement after considering the heterogeneous distribution of food availability. Territory identity accounted for most of the variation in clutch size and productivity, and penguin availability explained part of the variability in territory occupancy and hatching rate. The chick sex ratio was biased towards females and varied according to brood size, with the more productive territories producing 91% of males. The breeding cycle of this population is still mainly dependent upon the Rockhopper Penguin Eudyptes chrysocome food pulse and presents mixed evidence of being disrupted by invasive herbivores. The studied factors contributed differentially to the output of each reproductive stage, with territory identity accounting for most of the variation. Our results suggest that individual‐level, long‐term data could be relevant to understanding the dynamics of this species in the Fuegian archipelago, and thus a broad‐scale research programme is warranted to assess the conservation status and propose future management scenarios for this species.