Department of Forest Ecosystems and Society, Oregon State University, Corvallis, United States of America.
FitzPatrick Institute of African Ornithology, DST-NRF Centre of Excellence, University of Cape Town, South Africa.
PLoS One. 2019 Jan 17;14(1):e0210756. doi: 10.1371/journal.pone.0210756. eCollection 2019.
Annual movements have been widely described for birds migrating across the Americas and between Eurasia and Africa, yet relatively little information exists for intra-African migrants. Identifying the areas used throughout a species annual cycle by understanding migratory patterns and settlement areas during breeding and non-breeding seasons is essential for conservation initiatives. Here, we describe for the first time, the migratory patterns and settlement areas of an endangered raptor endemic to Southern Africa, the Black Harrier (Circus maurus). From 2008 to 2015, thirteen breeding adult Black Harriers were trapped in south-western South Africa and fitted either with a GPS-GSM or with a PTT tracker device. Adults were monitored for 365 ± 198 days (range: 56-819 days) revealing great individual variability in annual movements. Most Black Harriers performed an unusual West-East migration from their breeding areas, but routes of all migrating individuals covered the entire southern land area of South Africa and Lesotho. The distance travelled averaged 814 ± 324 km, but unlike many other species, migrants travelled faster during post-breeding (i.e. austral summer) (207.8 ± 113.2 km.day-1) than during pre-breeding (i.e. austral winter/spring) migrations (143.8 ± 32.2 km.day-1). Although most marked individuals displayed movements similar to those that bred following pre-breeding migrations, only two of thirteen were confirmed as breeders the year after being tagged. This suggests that individuals may sometimes take a sabbatical year in reproduction, although this requires confirmation. Most tagged birds died on migration or during the non-breeding season. Adults frequently returned to the same non-breeding settlement areas, and often used up to 3 different locations an average of about 200 km apart. On the other hand, there was wide variation in distance between subsequent reproductive events. We discuss the implications of our study for the conservation of Black Harriers and more broadly for intra-African bird migrants.
鸟类在美洲和欧亚非大陆之间迁徙的年度活动已被广泛描述，但关于非洲内部迁徙者的信息相对较少。通过了解繁殖季节和非繁殖季节的迁徙模式和定居区，确定一个物种在其年度周期中使用的区域，对于保护倡议至关重要。在这里，我们首次描述了一种濒危的南非特有猛禽——黑腹隼（Circus maurus）的迁徙模式和定居区。2008 年至 2015 年，我们在南非西南部捕获了 13 只繁殖期的成年黑腹隼，并为它们配备了 GPS-GSM 或 PTT 跟踪器设备。这些成年个体被监测了 365 ± 198 天（范围：56-819 天），显示出个体在年度活动中存在巨大的差异。大多数黑腹隼从繁殖地进行了不寻常的西向东迁徙，但所有迁徙个体的路线都覆盖了南非和莱索托的整个南部陆地。平均迁徙距离为 814 ± 324 公里，但与许多其他物种不同的是，迁徙者在繁殖后（即南半球夏季）（207.8 ± 113.2 公里/天）的迁徙速度比繁殖前（即南半球冬季/春季）（143.8 ± 32.2 公里/天）更快。尽管大多数标记个体的迁徙模式与繁殖前迁徙后繁殖的个体相似，但在被标记后的第二年，只有 13 只中的 2 只被确认为繁殖者。这表明个体有时可能会在繁殖中休一年假，尽管这需要确认。大多数被标记的鸟类在迁徙或非繁殖季节死亡。成年个体经常回到相同的非繁殖定居区，并且经常使用多达 3 个不同的地点，平均相隔约 200 公里。另一方面，随后的繁殖事件之间的距离差异很大。我们讨论了我们的研究对黑腹隼保护以及更广泛的非洲内部鸟类迁徙者保护的影响。
