The rufous-collared sparrow or Andean sparrow (Zonotrichia capensis) is an American sparrow found in a wide range of habitats, often near humans, from the extreme south-east of Mexico to Tierra del Fuego, and the island of Hispaniola in the Caribbean. It has diverse vocalizations, which have been intensely studied since the 1970s, particularly by Paul Handford and Stephen C. Lougheed (UWO), Fernando Nottebohm (Rockefeller University) and Pablo Luis Tubaro (UBA). Local names for this bird include the Portuguese tico-tico and mariquinha, the Aymara Pichitanka the Spanish copetón ("tufted") in Colombia, as well as chingolo and chincol, comemaíz "corn eater" in Costa Rica, chincol in Chile and Cigua de Constanza in the Dominican Republic.
Description The rufous-collared sparrow is 13.5–15 cm (5+1⁄4–6 in) long and weighs 20–25 g (0.71–0.88 oz). The adult has a stubby grey bill, and a grey head with broad black stripes on the crown sides, and thinner stripes through the eye and below the cheeks. The nape and breast sides are rufous, and the upperparts are black-streaked buff-brown. There are two white wing bars. The throat is white, and the underparts are off-white, becoming brown on the flanks and with a black breast patch. Young birds have a duller, indistinct head pattern, with brown stripes and a buff ground colour. They lack the rufous collar and have streaked underparts. There are 27 subspecies of the rufous-collared sparrow. In general, the smaller forms occur in coastal mountains, intermediate birds in the Andes, and large, darker, forms breed on the tepuis. The largest of the tepui subspecies, Z. c. perezchincillae, has grey underparts, and the rufous collar extends as a black band of freckles across the breast. This form might be separable as a distinct species, or it might just be a particularly distinct population due to genetic bottleneck effects.
Distribution and habitat In the northern and western parts of its range, this generally abundant bird is typically found at altitudes of 600–4,000 m (2,000–13,100 ft), but in the southern and eastern parts, it is commonly found down to near sea level. It can be seen in virtually any open or semi-open habitat, including cultivations, gardens, parks, grasslands, 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. The species was likely more widespread across the Caribbean region during the much cooler climes of the last glacial period, but was left marooned in the highest Hispaniolan mountains (the highest in the Caribbean) once warming began. This pattern is mirrored in the population of the Hispaniolan crossbill (Loxia megaplaga), a sympatric bird. However, it is also known to exist in Aruba and some other Caribbean islands.
Diet 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.
Breeding
The breeding season is limited by food availability and ultimately rainfall. In the subtropical yungas of north-west 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, at 2,000 m (6,600 ft) ASL in the Andes of Pichincha Province (Ecuador), eggs were being incubated in December, and nest-building activity was 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 a niche in a wall, perhaps 2 m (6.6 ft) high at best but usually less than 0.5 m (1.6 ft) above ground. The female lays two or three pale greenish-blue eggs with reddish-brown blotches. The eggs measure approximately 19–21 mm (0.75–0.83 in) by 15–16 mm (0.59–0.63 in) and weigh 2.6–2.8 g (0.092–0.099 oz) each. They are incubated by the female for 12–14 days, during which she spends about two-thirds of the daytime brooding or attending to 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.
Physiology
Osmoregulation/ionoregulation The rufous-collared sparrow relies entirely on its kidneys for osmoregulation and ionoregulation. It is able to tolerate a wide range of salt intake despite lacking a salt gland, however, the metabolic cost in energy is too great to maintain the necessary osmoregulatory processes for an extended period of time. As a result, the Rufous-collared sparrow tends not to inhabit marine environments such as salt marshes. Under conditions of higher salt intake, the mass of the kidney and heart can increase up to 20%. This response in organ size causes an increase in basal metabolic rate (BMR) by up to 30%. Kidney size is also affected by the amount of water available in the environment. In arid environments, the urine is more highly concentrated, and the kidneys tend to be smaller than in wetter environments.
Thermoregulation In association with its non-migratory behavior, and its tendency to be found at a wide range of elevations, the Rufous-collared sparrow experiences significant fluctuations in temperature throughout its range each year. Strategies used to acclimate to changing seasonal temperatures include limiting the amount of evaporative water loss (EWL) and increasing metabolic rate. Total evaporative water loss (TEWL) increases during summer months, which may help prevent overheating, and remains lower during winter months. In response to cold temperatures, both basal metabolic rate (BMR), and maximum metabolic rate (MMR) will increase.
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