Buizerd Buteo buteo brengt Havik Accipiter gentilis groot

On 27 april 2011, a Buzzard nest in the northern Netherlands was found to contain two Buzzard eggs (58.58x43.71 mm, 57.72x43.25 mm) and a single Goshawk egg (60.79x44.93 mm). An occupied Goshawk nest at some 100 m distance, checked on the same date, contained two eggs (59.07x44.97 mm, 58.82x44.33 mm). This latter nest turned out to have failed when checked on 3 June; both eggs were cold but contained a full-grown embryo. The Buzzard nest was climbed on 3 June, and held a Buzzard (18.2 days old, 566 g) and a male Goshawk chick (16.8 days old, backcalculated from wing length; 427 g). The chicks weighed respectively 782 and 572 g on 8 June. Both chicks fledged. Based on the age difference (and species-specific differences in incubation time), it is argued that the Goshawk egg was laid slightly in advance of the Buzzard eggs, the latter species apparently having taken over the nest some days later.