Rufous-collared Sparrow - Ecology

Ecology

In the northern and western part of its range, this generally abundant bird is typically found at altitudes of 600–4,000 m (2,000–13,000 ft), but in the southern and eastern part it is commonly found down to near sea level. It can be seen in virtually any open or semi-open habitat, including cultivation, gardens, parks, grassland and scrubby second growth or cerrado. It copes well with urban and suburban environments, but is absent from the densely forested sections of the Amazon Basin.

It is also scarce on the Guiana Shield, occurring mainly on some tepuis and in the Pakaraima Mountains of Guyana.

Explaining the presence of this species in the island of Hispaniola and absence from the rest of the Caribbean basin, may be a similar theory to the one proposed for the Hispaniolan Crossbill (Loxia megaplaga). In that scenario, the bird's ancestors were present across the region during the much cooler climes of the last glacial period, but was left marooned in the highest Hispaniolan mountains once warming began.

The Rufous-collared Sparrow feeds on the ground on seeds, fallen grain, insects and spiders. It will sometimes join mixed-species feeding flocks and has been observed to pick termites from spider webs. It is usually seen in pairs which hold small territories, or in small flocks. Tame and approachable, it is common throughout its large range and not considered threatened by the IUCN.

The breeding season is limited by food availability and ultimately rainfall. In the subtropical yungas of NW Argentina, females begin to build nests around the end of October, when the wet season comes, but by early December most nesting activity has already finished. By contrast, 2,000 meters ASL in the Andes of Pichincha Province (Ecuador), eggs were being incubated in December, and nest-building activity recorded in March and April, suggesting extended breeding throughout the wet season. The open cup nest consists of plant material lined with fine grasses. It is constructed in matted vegetation on the ground, low in a tree or bush, or in a niche in a wall, perhaps 2 meters high at best but usually less than half a meter above ground.

The female lays two or three pale greenish-blue eggs with reddish-brown blotches. The eggs measure approximately 19–21 mm by 15–16 mm and weigh 2.6–2.8 g each. They are incubated by the female for 12–14 days, during which she spends about two-thirds of the daytime brood or attend the nest in some other way. The male helps in feeding the chicks however, which stay in the nest for about two more weeks. They are not very voracious, and even as they approach fledging the parents will only feed them every 10 minutes or so. Brood parasitism, e.g. by the Shiny Cowbird (Molothrus bonariensis), may occur, and breeding failure due to predation is very frequent during the incubation period. Predation on nestlings, on the other hand, does not seem to occur more often than in similar-sized Passeroidea.