Scandinavian study reveals no crippling of three sea duck species 14th July 2023

European sea duck populations have been declining over the last decades, resulting in an increased focus on studies supporting conservation efforts and increasing our knowledge on factors affecting survival and breeding success of these species. An on-going study focusing on seaducks breeding in the Baltic Sea has revealed that crippling of females does not seem to pose an important threat to the studied populations.

By Iben Hove Sørensen, Waterfowlers' Network
Photo by Niklas Liljebäck

Most sea duck populations of Northern Europe are – or have been until recently – valued quarry species, and the negative population trends are causing concern among hunters as well as other conservation groups. International Single Species Action Plans for Velvet Scoter, Long-tailed Duck and Common Eider have all been adopted by the parties to AEWA during the last decade, and implementation of these plans will be guided by the AEWA International Seaduck Working Group.

The plans all point to important gaps in our knowledge on critical factors such as breeding success, migration ecology and causes of mortality. For several species, recent restrictions of hunting, including sex-specific (e.g. males only) or shortened open seasons, have been implemented to reduce any negative impacts caused by hunting. Apart from direct mortality, shooting may also result in crippling of birds, or birds may be exposed to lead poisoning through ingestion of lead pellets. Lead shots are now banned in several countries, but seaducks are long-lived species and pellets may be present in the environment for several years.

As part of an on-going study carried out in the Swedish Archipelago of the Baltic Sea, a total of 205 females of Common Eider (113), Velvet Scoter (57) and Red-breasted Merganser (35) were examined by x-raying individuals caught for ringing to detect prevalence of imbedded and ingested shot gun pellets. The study was carried out by a group of Swedish and Danish researchers during the breeding seasons of 2021 and 2022, and the results showed that none of the x-rayed females had any imbedded or ingested pellets.

Earlier studies have shown a much higher crippling rate, and the positive result presented here may be explained by a combination of factors such as reduced hunting pressure, remoteness of the study site, and improved shooting performance among hunters along the flyway. Future conservation efforts aimed at the studied populations can thus focus on other factors that may have a negative impact on the reproductive output and survival of breeding females.

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