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Research article - Peer-reviewed, 2022

Quantifying effects of wetland restorations on bird communities in agricultural landscapes

Kacergyte, Ineta; Part, Tomas; Berg, Ake; Arlt, Debora; Zmihorski, Michal; Knape, Jonas


Restoring wetlands to improve habitats for birds has become an important conservation tool as many wetlands have deteriorated and wetland bird populations declined. To what extent such restorations are effective is not well known because surveys usually either lack data before the restoration or means of correcting for background population trends. We identified wetland restorations made in agricultural landscapes in Sweden and retrieved all available Before-After survey data of breeding birds. From the resulting heterogeneous surveys, we quantified the effectiveness of restorations for eight bird groups comprising 72 bird species from 30 wetlands. We used national survey data to correct for background population trends. We estimated that island breeder populations have increased by between 62 % and 315 % (95 % confidence intervals) following restorations. Deep water foragers, shallow water foragers and short meadow breeders also mainly increased following restoration. The direction of effect was uncertain for tall meadow breeders, reed breeders and predators. Shrubland breeder populations declined between-55 % and-4 % following restorations. While restoration measures seemed to generally benefit about half of the breeding wetland bird community, estimated species-and site-specific re-sponses varied greatly and were associated with large uncertainty. Such heterogeneity in responses can arise due to biotic and abiotic interactions, varying management actions and survey methods between wetlands. Thus, to improve the effectiveness of future wetland restorations, funding bodies and environmental agencies should require standardised Before-After bird surveys at both restored and non-restored reference sites. Such improved survey designs would facilitate the development of more efficient restoration efforts.


Management; Aves; BACI; Eutrophic lakes; Wetland overgrowth; Freshwater ecosystem

Published in

Biological Conservation
2022, Volume: 273, article number: 109676