Breeding

The most comprenhive information on the breeding of Saffron-billed Sparrow is from northwestern Argentina (Auer et al. 2007); the following summary is based on that research, unless otherwise specified.

Seasonality: The average date of the first nest was 21 October, and the breeding season averaged 60.2 days (n = 72).

Nest: Saffron-billed Sparrow builds an enclosed nest, sited 0-0.9 m above the ground, with a mean height of 0.0 m ± 0.0 SE (n = 54).

Eggs: Eggs in Argentina are buff or blue-gray, with dark and light brown speckles and scrawls (Jaramillo 2011). The mass of eggs averaged 2.90 ± 0.14 g, with a length of 22.3 mm ± 0.5 SE and a width of 15.8 mm ± 0.2 SE (n = 4).

Clutch size: Clutch size of 2.8 ± 0.1 SE. Another study found the average clutch size to be 2.5 (n = 58) (Martin et al. 2000).

Incubation: The incubation period averages 15.3 d ± 0.3 SE. The females incubate the eggs and the male brings her food.

Parental care: The nestling period is 12.2 d ± 0.2 SE (n = 23). Nest attentiveness, measured as the proportion of daylight hours when one or both parents were present at the nest, was 61.8% ± 3.1% SE (n = 24) in one study (Auer et al. 2007) and 65% in another (Martin 2002). The nestling feeding rate was 4.9 hr-1 ± 0.3 SE (n = 19), with both parents feeding the nestlings (Auer et al. 2007).