The ongoing study of Sparrowhawks in the province of Groningen located 37 territories in 2016. Repeated surveys in two municipalities indicated a slight increase since 2012, when the survey started: resp. 12, 12, 14, 16 and 17 territories in 2012-16. Nests in 2016 were more often constructed in deciduous trees (20x) than in coniferous trees (13x). Breeding success of 28 pairs was recorded, of which 16 failed to produce fledglings (mainly due to predation by martens and Goshawk Accipiter gentilis). Mean start of laying was 28 April (range 18 April-8 May, N=13). In 6 out 13 nests chicks carried louseflies. The aggressive behaviour of females at 24 nests was also recorded: 4 females were silent or absent, 12 alarm-called from a distance, 7 fake-attacked and 1 physically attacked. Combined for 2012-16, 7 out of 24 breeding males were in firstyear plumage (29%), as were 15 out of 74 females 20%).