Rapid high-intensity molt of flight feathers occurs in many bird species and can have several detrimental consequences, including reductions in flight capabilities, foraging performance, parental care, and plumage quality. Many migratory New World warblers (family Parulidae) are known to have intense remigial molt, and recent work has suggested that simultaneous replacement of the rectrices may be widespread in the family as well. However, the phylogenetic distribution of simultaneous rectrix molt, and high-intensity flight feather molt more generally, has not been systematically investigated in warblers. We addressed this issue by examining flight feather molt in 13 species, representing 7 different warbler genera, at Powdermill Avian Research Center in southwestern Pennsylvania, USA. All 13 species replaced their 12 rectrices simultaneously, with the onset of rectrix molt occurring in the early-middle stages of high-intensity primary molt. As expected, single-brooded early migrants molted earlier than double-brooded species whose nesting activities extend into late summer. However, our finding that late-molting species replaced their primaries more slowly and less intensively than early molting species was unexpected, as late-molting species are widely hypothesized to be under stronger migration-related time constraints. This surprising result appears to be at least partially explained by a positive association between the pace of molt and daylength; shorter late-summer days may mandate reduced daily food intake, lower molt intensity, and a slower pace of molt. In comparison to other passerines, flight feather molt in warblers of eastern North America is extraordinarily intense; at its peak, individuals are simultaneously replacing 50–67% of their 48 flight feathers (all 12 rectrices and 6–10 remiges on each wing) for 2–3 weeks or more. Because molt of this intensity is likely to present numerous challenges for flight, avoiding predators, foraging, and parental care, the period of flight feather molt for warblers constitutes a highly demanding phase of their annual cycle.

中文翻译：

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北美东部莺的高强度飞羽蜕皮及比较蜕皮生态

飞羽的快速高强度蜕皮发生在许多鸟类身上，并可能产生多种有害后果，包括飞行能力、觅食性能、父母照顾和羽毛质量的降低。众所周知，许多迁徙的新世界莺（Parulidae）具有强烈的迁徙蜕皮，最近的研究表明，同时更换直角莺也可能在该家族中普遍存在。然而，在莺中同时进行的反羽蜕皮和更普遍的高强度飞羽蜕皮的系统发育分布尚未得到系统的研究。我们在美国宾夕法尼亚州西南部的 Powdermill 鸟类研究中心检查了代表 7 个不同莺属的 13 个物种的飞羽蜕皮来解决这个问题。所有 13 个物种同时更换了它们的 12 个矩形，在高强度初级蜕皮的中早期阶段开始发生反式蜕皮。正如预期的那样，单孵的早期迁徙者比双孵的物种更早蜕皮，后者的筑巢活动一直持续到夏末。然而，我们发现晚期蜕皮物种比早期蜕皮物种更慢且更不密集地替换它们的初级物种是出乎意料的，因为人们普遍假设晚期蜕皮物种受到更强的迁移相关时间限制。这一令人惊讶的结果似乎至少可以部分解释为蜕皮速度与日长之间的正相关。夏末日数较短可能会要求减少每日食物摄入量、降低蜕皮强度和放慢蜕皮速度。与其他雀形目鸟类相比，北美东部莺的飞羽蜕皮异常强烈；在高峰期，个体同时更换 48 根飞羽中的 50-67%（所有 12 根飞羽和每侧翼上的 6-10 根飞羽）持续 2-3 周或更长时间。由于这种强度的蜕皮可能会给飞行、避免捕食者、觅食和父母照顾带来许多挑战，因此莺的飞行羽毛蜕皮时期构成了它们年度周期中要求很高的阶段。