Ducks Diving in Synchrony

Hundreds of Long-tailed Ducks and Greater Scaup, interspersed with White-winged Scoters, a few Lesser Scaup and one Black Scoter, were diving in synchrony (unison) in the channel at the bridge in Tommy Thompson Park in Toronto on 15 December 2019.

ACTION VIDEO: Diving ducks in Toronto

Abundant zebra and quagga mussels concentrate at the bottom of the deep channel at the bridge and attract diving ducks. Diving in synchrony is believed to be a strategy that helps prevent ducks from bumping into each other when they dive. It may also protect them from kleptoparasites like large gulls, which are waiting to steal their food. Tommy Thompson Park in Toronto on 15 December 2019.

The behaviour of the diving ducks was predictable. They dove in unison, stayed under for about 40-60 seconds, came to the surface, rested, then dove again. With each successive dive they arrived at the bridge, then they flew back several hundred metres and started diving again in the direction of the bridge. Tommy Thompson Park in Toronto on 15 December 2019.