Nature reserves are crucial for whooper swans 

Whooper swans (Cygnus cygnus) spend their summers in subarctic Europe and Siberia, where they breed each year. But at the start of winter, they migrate many thousands of kilometers south to where the conditions will be less harsh. The estimated 16,000 whooper swans that overwinter in the United Kingdom come all the way from Iceland each year. Since their wetland habitats are threatened more and more, they rely heavily on protected areas for overwintering in the UK.

A new research study has investigated just how important these protected areas are for the survival of the Icelandic whooper swans. The team analyzed 30 years of data on swans from 22 UK sites, three of which are nature reserves managed by the Wildfowl and Wetlands Trust (WWT). In total, the study used observations of 10,000 whooper swans over the 30 years. 

The results, published in the Proceedings of the National Academy of Sciences, show that swan survival rates are 30 times higher in the nature reserves than they are in unprotected areas. Swans in the nature reserves had a lower annual probability of breeding, but the researchers stress that these birds have more lifetime opportunities to breed and will produce more offspring on average. Based on these findings, the research team project that nature reserves could help double the number of whooper swans wintering in the UK by 2030.

Not only were survival rates significantly higher at nature reserves, but population growth was so strong that many swans moved into non-protected sites as the density in the protected areas increased.These encouraging findings highlight the importance of nature reserves in terms of conservation, even when the areas protected are relatively small and are only used during short periods of a species’ life cycle. 

“Protected areas are the main tool being used to stem declines in biodiversity, and there is a growing consensus that 30 percent of the planet’s surface should be protected by 2030,” said Dr. Andrea Soriano-Redondo from the University of Exeter.

“However, the effectiveness of protected areas is not always clear – especially when species move between protected and non-protected areas throughout their lives. Our findings provide strong evidence that nature reserves are hugely beneficial for whooper swans, and could dramatically increase their numbers in the UK.”

Swans make use of the protected areas for many different reasons, and the WWT nature reserves in the study have implemented a range of measures to help wintering swans, including fox fences, supplementary food, managed roosting sites and hunting bans. These interventions have had a large impact on population growth that is crucial for this species that is listed as a species of conservation concern in the UK.

“The annual population growth rate inside nature reserves was 6 percent, compared to 0.2 percent outside reserves,” said Dr. Richard Inger from the Centre for Ecology and Conservation on Exeter’s Penryn Campus in Cornwall. “This population boost is not restricted to the nature reserves – it created a higher population density, which led some swans to move to non-protected areas. Young swans were most likely to do this, meaning the benefits of nature reserves spill over to other areas too.”

“Overall, our study demonstrates the huge benefits of localized protection for highly mobile animal species,” said Professor Stuart Bearhop. “It also shows that targeted measures during key periods of the life cycle can have disproportionate effects on conservation.”

“This research shows how safe havens for wetland wildlife, like those at WWT Caerlaverock, Welney and Martin Mere, can help a species survive and succeed when their traditional homes are under threat,” said David Pickett, Centre & Reserve Manager at WWT Caerlaverock Wetland Centre. “Many wild birds rely on our sites for food and shelter and we are committed to creating and restoring more of these healthy wetland habitats, which the U.K. has lost so many of in our recent history.”

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By Alison Bosman, Earth.com Staff Writer

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