When Swans Choose to Fight not Rest

Image credit Noel Donaldson

A  study, by the University of Exeter and the Wildfowl & Wetlands Trust (WWT), into the behaviour of mute and whooper swans revealed that they’d give up time they should be resting to quarrel over the best feeding spots.

Dr Paul Rose, from the University of Exeter and WWT, explained:

“These swans use aggression if there’s competition over foraging areas. Our findings show this this requires a trade-off, and that both species reduce resting time to allow for this aggression.

“This was the strongest trade-off we found, but there was also a trade-off for both species between foraging and resting. However, there was no apparent trade-off between some behaviours, such as aggression and foraging, and aggression and maintenance.”

The swans were observed via a live-streaming webcam at WWT Caerlaverock nature reserve in Scotland. Whooper swans are migratory, and those observed in the study spend their winters at Caerlaverock.

Mute swans live there all year round, and Dr Rose said this means they can be more “flexible” in their behaviour because they don’t share the whooper swans’ urgent need to store fat ahead of migration.

“By providing enough foraging spots for the birds, we can reduce the need for aggression around desirable feeding spots, giving them more time to rest,” Dr Rose said.

“This can help to ensure that migratory species don’t ‘push out’ non-migratory species when they mix in the same wintering locations.

“Our study also demonstrates how remotely collected data can be used to investigate fundamental questions in behavioural research.”

Dr Kevin Wood, of WWT, said:

“At WWT we get lots of questions from our visitors about the aggressiveness of swans.

“This new study helps us to understand how swans’ behaviour changes when they engage in their disputes.”

The paper, published in the journal PLOS ONE, is entitled: “Assessing trade-offs in avian behaviour using remotely collected data from a webcam.”

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