Abstract:The Barn Swallow (Hirundo rustica) is widely distributed in China, and the research on its reproduction ecology in different latitudes is helpful to reveal its adaptation to different environments. At present, the available records of the breeding ecology of the Barn Swallow is mainly focused on the subspecies of H. r. gutturalis, while data from other subspecies is lacking. From April to October in 2016 and 2017, we studied the H. r. mandschurica subspecies of Barn Swallow, which distributed only in Heilongjiang Province, in Northeast Forestry University in Harbin of China. At the same time, the reproductive ecology data were supplemented to explore whether there were differences in reproductive ecology among subspecies with different phenotypes. The reproductive behaviors were observed daily after immigrating. The morphology (including body weight, body length, wing length, tarsus length, bill length and tail length) of the nestlings were measured daily. The data was sorted and analyzed with SPSS 22.0. Our results showed that swallows arrived at the breeding areas in late April or early May and migrated southward in late September or early October. The clutch size was 4﹣6 (n = 19), long diameter of egg was 18.7 ± 1.4 mm (15.9﹣22.5 mm), short diameter of egg was 13.0 ± 0.5 mm (12.2﹣14.2 mm), egg mass was 1.6 ± 0.1 g (1.3﹣1.9 g, n = 35), and the incubation period was 16 ± 2 d (14﹣18 d, n = 19). The nestling-feeding period was 17 ± 1 d (16﹣18 d, n = 6). Nestlings’ growth curves (for body length, wing length and tail length) fitted well with a Logistic Growth Curve (Table 2). Body weight and tarsus grew the fastest at the age of 5 days, while body length and wing length increased the fastest at the age of 7 days (Table 1). The growth pattern of the nestlings conforms to the Energy Distribution Hypothesis. There are many differences in reproductive parameters between the swallows in the study area and other populations of H. r. gutturalis, including: eggs were smaller in size, lighter in weight, incubation period was similar to but feeding period was shorter than that of some southern populations of H. r. gutturalis. This may be caused by the differences of local food richness and parental feeding strategies among different populations.