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An audio recording of a house sparrow. The house sparrow (Passer domesticus) is a bird of the sparrow family Passeridae, found in most parts of the world. It is a small bird that has a typical length of 16 cm (6.3 in) and a mass of 24–39.5 g (0.85–1.39 oz).
Often parents change the level of parental care provided to manage the cost and benefits of parental care. Passerine species in North America have a large brood size containing 4–6 offspring and a 50% adult survival rate, and those in South America have a smaller brood size containing 2–3 offspring and a 75% adult survival rate.
The ruby-crowned kinglet is a very small bird, being 9 to 11 cm (3.5 to 4.3 in) long, having a wingspan of 16 to 18 cm (6.3 to 7.1 in), and weighing 5 to 10 g (0.2 to 0.4 oz). [17] It has gray-green upperparts and olive-buff underparts. [18] It has two white wingbars and a broken white eye ring.
Birds in captivity are often heavier than wild specimens. Migratory birds gain weight before the migratory period but lose weight during handling or temporary captivity. Dead birds tend to weigh less than in life. The weight can vary by 5 to 10%, even during the day. The male emperor penguin loses 40% of its weight during incubation. [12]
The male barn swallow returns to the breeding grounds before the females and selects a nest site, which is then advertised to females with a circling flight and song. [6] Plumage may be used to advertise: in some populations, like in the subspecies H. r. gutturalis , darker ventral plumage in males is associated with higher breeding success.
The southern cassowary is a solitary bird, which pairs only in breeding season, in late winter or spring. The male builds a nest on the ground, [6] a mattress of herbaceous plant material 5 to 10 centimetres (2–4 in) thick and up to 100 centimetres (39 in) wide. This is thick enough to let moisture drain away from the eggs.
Weight: 1.6–2.1 oz (45–60 g) Wingspan: 15.3–16.1 in (39–41 cm) Purple martins are sexually dimorphic. Adult males are entirely black with a glossy steel blue sheen, the only swallow in North America with such coloration. Adult females are dark on top with some steel blue sheen, and lighter underparts. Adults have a slightly forked tail.
Eggs are laid at 2- to 3-day intervals until the clutch of 1–3 eggs is complete. The elongated chalky bluish green or white eggs average 78 mm × 57 mm (3.1 in × 2.2 in) and weigh 130 g (4.6 oz). [24] Both parents incubate the eggs, starting as soon as the first egg is laid, but it is usually the female that remains on the nest overnight.