Tella José L, Sánchez-Prieto Cristina B, Romero-Vidal Pedro, Serrano David, Blanco Guillermo
Department of Conservation Biology Doñana Biological Station (EBD-CSIC) Sevilla Spain.
Department of Zoology University of Granada Granada Spain.
Ecol Evol. 2024 Oct 22;14(10):e70205. doi: 10.1002/ece3.70205. eCollection 2024 Oct.
With the exception of a few groups of birds, such as large raptors and colonial seabirds, direct counts of nests cannot be conducted over very large areas for most of the abundant and widely distributed species, and thus indirect methods are used to estimate their relative abundances and population sizes. However, many species of the Family Hirundinidae (swallows and martins) build their mud nests in discrete, predictable and accessible sites, which are reused across years. Therefore, the direct count of active nests could constitute a reliable method for estimating breeding population sizes and their changes at large spatial and temporal scales. We illustrate the feasibility of this monitoring approach through a single year survey of >2700 nests of three coexisting Old-World species, the barn swallow (), the red-rumped swallow (), and the crag martin (), distributed across Portugal and Spain. Our results revealed changes in the use of nesting substrates and increases in interspecific nest usurpation rates over recent decades. While 56% of the nests of were located in rocks five decades ago, almost 100% are nowadays located in anthropogenic substrates such as bridges, road culverts, and abandoned buildings, which could have favored the range expansion of this species. Nest occupation rates were surprisingly low (12% in , 21% in , and 37% in ), and the proportion of abandoned nesting sites was very high (65% in , 50% in , and 27% in ). Abandonment rates reflect the population decline reported for . Notably, the usurpation of nests of by house sparrows which is the main cause of breeding failure, has increased from 2.4% in 1976-1979 to 34.7% of the nests nowadays. The long-term monitoring of nests may constitute a reliable and affordable method, with the help of citizen science, for assessing changes in breeding population sizes and conservation threats of these and other mud-nest building hirundines worldwide.
除了少数鸟类群体，如大型猛禽和群居海鸟外，对于大多数数量众多且分布广泛的物种，无法在非常大的区域内直接统计巢穴数量，因此采用间接方法来估计它们的相对丰度和种群规模。然而，燕科（家燕和沙燕）的许多物种会在离散、可预测且易于到达的地点建造泥巢，这些巢穴会被多年重复使用。因此，直接统计活跃巢穴数量可能构成一种可靠的方法，用于估计大空间和时间尺度上的繁殖种群规模及其变化。我们通过对共存于旧大陆的三种物种（家燕、赤腰燕和崖沙燕）分布在葡萄牙和西班牙的2700多个巢穴进行为期一年的调查，来说明这种监测方法的可行性。我们的结果揭示了近几十年来筑巢基质使用情况的变化以及种间巢穴侵占率的增加。五十年前，崖沙燕56%的巢穴位于岩石上，如今几乎100%位于桥梁、道路涵洞和废弃建筑物等人造基质上，这可能有利于该物种的范围扩张。巢穴占用率出奇地低（家燕为12%，赤腰燕为21%，崖沙燕为37%），废弃筑巢地点的比例非常高（家燕为65%，赤腰燕为50%，崖沙燕为27%）。废弃率反映了崖沙燕种群数量下降的情况。值得注意的是，家麻雀对崖沙燕巢穴的侵占（这是繁殖失败的主要原因）已从1976 - 1979年的2.4%增加到如今巢穴的34.7%。在公民科学的帮助下，对巢穴进行长期监测可能构成一种可靠且经济实惠的方法，用于评估全球这些以及其他筑泥巢燕科鸟类繁殖种群规模的变化和保护威胁。
