First case of overlapping broods for the Red-tailed Comet (Sappho sparganurus)

In Argentina the Red-tailed Comet (Sappho sparganurus) is present throughout the year in the NW mountains and the Andean region, although it descends to lowlands during the non-breeding season. Breeding occurs above 800 m elevation, from September to February and incubation period is 19 to 20 days, with chicks remaining in the nest for 28 to 32 days. On 19 September 2013 in Mendiolaza City, Córdoba, Argentina (31° 15’ S, 64° 17’ W) a female started to build a nest under the eaves of a house, attached to a creeper. On 4 and 6 October it laid two eggs and the chicks hatched on 22 and 25 October, and remained in the nest for 30 days. On 17 November, seven days before chicks from the first nest fledged, I observed this same female carrying material to build second a second nest. On 28 and 30 November, the female laid two eggs which were incubated for 18 and 19 days and the chicks remained in the nest for 29 to 30 days. Because the first nest required 16 days to be built, it is estimated that November 12 was the beginning of the construction of the second nest. Consequently, I presumed that the overlap between the two broods was 17 days. My observations are the first instance of rapid double brooding for a Hummingbird species in the Southern Hemisphere and also expands the altitudinal breeding limit for the Red-tailed Comet 260 m below the current known limit.