Seasonal altitudinal movements of birds in Brazil: a review

ABSTRACT Birds’ seasonal altitudinal movements in Brazil are poorly understood. The main source of information and has fostered interest since the 1980s. However, most of the available information is anecdotal, sources are repeatedly cited, and the information provided is quite superficial and speculative. Through bibliographic searches, we found 107 studies, 83 (77%) of which we consider valid, and only 63 (59%) were peer-reviewed. Most studies were carried out in southern and southeastern Brazil. Only 11 studies explicitly addressed seasonal altitudinal movements. Surprisingly, none of the studies simultaneously comprised a full year of study, standardized sampling methods, and encompassed the entire altitudinal range through which the birds might have moved. As a consequence, the quality of the data is questionable, and the expression “altitudinal migration” is unlikely to be accurate and has never been unequivocally demonstrated for birds in Brazil. Mention of “altitudinal migration” was found for 68 bird species, but these must be more clearly defined and appropriately tested.

摘要：巴西鸟类的季节性垂直海拔移动（seasonal altitudinal movements）目前尚缺乏充分研究。该领域的核心信息来源自20世纪80年代起便引发了学界关注。然而，现有信息大多为轶事性记载，研究来源被反复引用，且所提供的内容相当肤浅且带有推测性。通过文献检索，我们共检索到107项相关研究，其中83项（占比77%）被认定为有效研究，仅63项（占比59%）经过了同行评议。绝大多数研究均在巴西南部及东南部地区开展。仅有11项研究明确针对季节性垂直海拔移动展开。令人意外的是，尚无任何一项研究能够同时满足以下三项要求：开展为期一整年的持续观测、采用标准化采样方法，以及覆盖鸟类可能发生移动的全部海拔区间。因此，相关数据的质量存疑，"海拔迁徙（altitudinal migration）"这一表述大概率并不准确，且巴西鸟类的该行为从未得到明确证实。目前已有68种鸟类被提及存在海拔迁徙行为，但相关结论仍需进一步明确界定并经过恰当的验证。