LENSINK R (2021) Arrival of Great Egrets Ardea alba on roosts: difference between adults and juveniles. LIMOSA 94 (4): 169-173.

Great Egrets use common night roosts after the breeding season. In August-November incoming birds were checked on having wing moult (adults) or no wing moult (juveniles) on three different night roosts in the Dutch province of Gelderland. In October, the first adults have already completed their wing moult. Therefore only data on moulting status from August and September was used to distinguish juveniles from adults. In 2016-20 adults arrived on average 5 and 3 minutes earlier than juveniles, in August and in September, respectively (Fig. 1). Timing of arrival varied between years (Fig. 2), but the within year difference between the arrival of adults and juveniles (in September) was rather stable at 4.0 ± 1.22 minutes. The dominance of adults on feeding sites and their experience in gathering food, might explain why adults arrive earlier on night roosts, despite their need for more energy for moulting compared to the non-moulting juveniles.

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