Observations at nest sites began in January-February, at which time most pairs had already occupied nesting territories and were exhibiting signs of courtship. Construction of nests was observed from 8 January through to 17 July. Nest construction was already underway by several pairs in early January, so the earliest nest building dates were not known. However, with nest construction ranging from 15 to 44 days (see below), and earliest eggs being laid on 15 January, it can be estimated that nest construction may have commenced in some pairs as early as the beginning of December.