CONICET | Buscador de Institutos y Recursos Humanos

The White-throated Cacholote Pseudoseisura gutturalis is a little studied,socially monogamous furnariid, endemic to arid Argentina. Here we providenovel information to characterize the breeding biology of the northernsubspecies ochroleuca in the Monte Desert, Argentina, and discuss the similari-ties and differences with other Pseudoseisura species. Nests were bulkyenclosed structures constructed with thorny sticks and twigs of native plantspecies (n = 15) and 47% of them had objects used as external decorations.Nests had an entrance tube oriented preferentially towards the northeast, prob-ably to avoid the prevailing south-southeast winds at the study site, and wereplaced at a mean height of 2.1 m above the ground (n = 13). Most of the activenests (93%) were built in columnar cacti Trichocereus atacamensis that werehealthier and with fewer branches than nearby available conspecifics. Meanclutch size was 3.2 white eggs (n = 9) and the incubation period was c. 1820days. Brood size ranged from one to three hatchlings (n = 12) and nestlingsremained in the nest for 2426 days until fledgling. Nests with complete clutcheswere found between 29 October and 1 February and nestlings were foundbetween 1 November and 5 February. Nestlings were attended by both parentsand were fed with arthropods (n = 63) and vertebrates (n = 7). Nest visitationrate per nestling was similar among nests with three and two nestlings and lowerthan for a nest with one nestling. The breeding success was high during theincubation (73%) and nestling rearing (82%) stages. Our data show thatPseudoseisura species are similar in some aspects of their breeding biology(e.g. nest dimensions, nest decorations, mating system, clutch size), whereasother aspects, such as nest-site selection, nestling period and nest attendancerate, are more variable among species.

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