Most Emberizids are monogamous. However, a few are polygynous. Even among the socially monogamous species, extra-pair copulation (when birds mate with individuals other than their mate) is common. Smith’s longspurs (Calcarius pictus) are polygynandrous (promiscuous, males and females have multiple mates). Saltmarsh sharp-tailed sparrows (Ammodramus caudacutus) exhibit what is called scramble competition polygyny. In this mating system, which is common in frogs, males are not territorial and more than one male will try to mate with a single female at once. In most species, males defend breeding territories using song and by chasing intruders.
Mating System: monogamous ; polyandrous ; polygynous ; polygynandrous (promiscuous)
Breeding in Emberizids usually takes place during the summer or rainy seasons. Breeding usually occurs during the season with the maximum abundance of invertebrates, the favored food source for parents to feed their young. Many species have more than one brood per year and will re-nest if their initial nest is lost due to depredation. Nests are built between 0 and 6 meters above the ground, however, usually on the ground or in shrubs within one meter of the ground. Sparrows and buntings usually build open cup nests (a few species build domed nests) made of grass and stems, lined with fine roots, grass and hair. Nests are not re-used year after year and take from 2 to 12 days to build (usually 3 to 4).
Females lay 3 to 5 eggs on average. Eggs are white, bluish or tan with very few spots to a lot of spotting. They measure between 17 by 13 mm to 25 by 19 mm. Females incubate the eggs and may be fed occasionally by their mates during this period. Incubation lasts 11 to 14 days and the eggs hatch synchronously. Young are fed primarily insects by both parents and usually fledge between 9 to 12 days after hatching. If the nest is disturbed, chicks will fledge earlier. Young reach sexual maturity in one year.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); fertilization (Internal )
Females incubate the eggs and may be fed occasionally by their mates during this period. Incubation lasts 11 to 14 days and the eggs hatch synchronously. Young are altricial and are fed primarily insects by both parents. Chicks usually fledge between 9 to 12 days after hatching. If the nest is disturbed, chicks will fledge earlier. Young receive parental care for 21 to 35 days after hatching. Males often take a greater part in raising fledglings than females so that females can begin a second brood.
Parental Investment: altricial ; male parental care ; female parental care
- Rising, J., D. Beadle. 1996. A Guide to the Identification and Natural History of the Sparrows of the United States and Canada. San Diego: Academic Press.
- Byers, C., J. Curson, U. Olsson. 1995. Sparrows and Buntings, A Guide to the Sparrows and Buntings of North America and the World. Boston: Houghton Mifflin Company.
- Dunning, J. 2001. New World Sparrows. Pp. 516-535 in C Elphick, J Dunning, D Sibley, eds. The Sibly Guide to Bird Life and Behavior. New York: Alfred A. Knopf.