More than three million farmed mallards are released annually for hunting purposes in Europe. The ecological impact of these releases depends on how many birds survive to join the wild breeding population. We estimated annual survival in farmed-released and wild-caught Swedish mallards, using mark-recapture data. In 2011–2018, we ringed 13,533 farmed ducklings before release (26.5% recovered). Most recoveries were birds shot at the release site, while only about 4% were found >3 km away. In 2002–2018, 19,820 wild mallards were ringed in Sweden, yielding 1369 (6.9%) recoveries. Like in farmed-released birds, most recoveries were by hunting, but 91.1% of recovered wild mallards were >3 km away from the ringing site. Annual survival rate in farmed-released mallards (ringed as pulli) was 0.02. In wild mallards (ringed as fledged or fully grown), annual survival was lower in females (0.64) than in males (0.71). At two sites in 2018, farmed ducklings were released in two batches 3 weeks apart to study the effect of early versus late release date, while controlling for body condition (BCI). Ducklings released early had a higher BCI and were recovered earlier (lower longevity) than those released late. Individual BCI and longevity were not correlated in recovered ducklings. Based on our estimate of annual survival in farmed-released mallards, a substantial number, i.e., 5000 (95% CI, 3040–6960), join the wild population annually. Despite being fed, a large proportion of released ducklings does not survive until the hunting season. Early releases may maximize pre-hunting survival. Repeated releases may prolong hunting opportunities and increase hunting bags.

在欧洲，每年有超过300万种野鸭被释放以用于狩猎。这些释放物的生态影响取决于有多少鸟类能够生存并加入野生繁殖种群。我们使用标记捕获数据估算了养殖释放和野生捕获的瑞典野鸭的年生存率。在2011–2018年间，我们圈养了13,533只养殖小鸭，然后将它们放行（回收了26.5％）。回收率最高的是在释放地点射杀的鸟类，而距离> 3 km的地方只有约4％被发现。在2002–2018年间，瑞典圈养了19,820只野鸭，回收率达1369（6.9％）。像在农场释放的鸟类一样，大多数的恢复是通过狩猎实现的，但是91.1％的野生野鸭被恢复到距响点3公里以上。养殖释放的野鸭（称为普利犬）的年生存率为0.02。在野鸭（成年或完全成年）中，女性的年生存率（0.64）低于男性（0.71）。在2018年的两个地点，每隔3周分两批放养小鸭，以研究早释与晚释日期的影响，同时控制身体状况（BCI）。较早释放的小鸭的BCI较高，而且恢复得较早（寿命较低）。在恢复的小鸭中，个体BCI和寿命没有相关性。根据我们对养殖释放的野鸭的年生存率的估计，每年有相当数量，即5000（95％CI，3040-6960）加入野生种群。尽管被喂食，但大部分的放养的小鸭直到狩猎季节都无法生存。早期发行可以最大限度地提高狩猎前生存率。重复释放可能会延长狩猎机会并增加狩猎袋。