New research shows that spoonbill parents continue to care for their young for months after they have fledged. However, once the autumn migration starts, the young birds are expected to care for themselves.

Using GPS trackers and smart movement sensors, researchers followed 15 spoonbill families long after the chicks had fledged. A young spoonbill can fly about a month after hatching. The tracking data revealed that it then takes another three weeks or so before they leave the colony and begin exploring their surroundings. The frequency and duration of contact between fledglings and their parents during this period varied greatly between families. While some parents stop caring for their chicks as soon as they can fly, others maintain contact for weeks, sometimes right up until their departure to the south. Part of this variation is explained by the sex of the parent bird: mothers have slightly more contact with their fledged young than fathers.

Tracking an adult spoonbill (left) and a nearly fledged chick (right) - Photos: Jan Reint Lok & Tamar Lok

This contact occurs within several tens of kilometers from the colony. By following their parents, the young birds presumably learn where suitable places are to rest and forage. The movement sensors show that during 3% of the contact moments, the young birds beg for food, during 5% they forage for themselves, and for the majority (92%) they rest. Contact with the parents becomes less frequent as the young birds grow older and ceases entirely once the autumn migration begins. This pattern was confirmed by visual observations of color-ringed young birds being fed by a parent.

This research demonstrates that parental care in spoonbills often continues long after the chicks have fledged, but that the young birds must manage without their parents from the start of the autumn migration. However, they often fly in large groups with other adult birds, from whom they can still learn a great deal.

The study was published in Behavioural Ecology and Sociobiology (open access) and a nice article about it was written in Trouw (unfortunately behind a paywall).

Young spoonbill (NA2B) begging for food from parent bird (aYfR/ LYG) at Balgzand, 27 km from its natal colony at Vooroever. Photo: Kees Venneker.