Chilean populations of the Diuca diuca breed between September and February and may have multiple broods (Bullock 1940). In Argentina, the breeding season occurs from November to January and these birds only have one brood. The nest of Diuca diuca are an open cup consisting of thorny Acacia and Trevoa sticks, dry grass, and vegetable fibers, often lined with soft vegetation, wool, horsehair, rabbit hair, or other bird feathers (Lazo and Anabalón 1991, Marin 2011). Nests are most often 1.64 m above the ground (0.4-4.0 m), with an internal diameter of 71.5 mm (64-78 mm; Marin 2011). The nest have been reported to be most common in second-growth Acacia caven, but can be found in various locations, including bushes, dense thornless trees, or conspicuously in thorny trees with little foliage but constructed with thorny twigs (Marin 2011). They tend to prefer thornless and high leaf density, perhaps for crypsis against predators. Alternatively, thorny settings could also potentially protect against predation (Lazo and Anabalón 1991). Diuca diuca has also been known to use old nests of other birds, like the Short-billed Canastero (Asthenes baeri) and other Furnariidae species (Mezquida 2003). The clutch usually consists of 2-4 eggs, with an average of 3 (Lazo and Anabalón 1991, Jaramillo 2011, Marin 2011). Egg coloration is greatly variable, with a base of pale blue to pale glossy green, which is overlayed with densely mottled dark brown, lavender-grey, and olive green spots (Marin 2011). The spotting may vary from streaky to so dense that the green is barely visible (Ogilvie-Grant 1912, Marin 2011, Jaramillo 2011). Egg measurements are given in Table 3 below. The incubation period lasts 13-14 days and both parents participate (Marin 2011). At hatching, body mass is about 2.7 g, and nestlings don’t exceed 29.5 g. Nestlings fledge 9-10 days after hatching (Marin 2011). Diuca diuca nests are frequently parasitized by the Shiny Cowbird (Molothrus bonariensis), a species that expanded into Chile from Argentina in the 1800s (Jaksić 1998, Marin 2011, Jaramillo 2011).