Rapid advances in the timing of the spring passage migration through Israel of the steppe eagle Aquila nipalensis

Abstract

We examined phenological change in the spring migratory passage of the predatory steppe eagle Aquila nipalensis from 1977 to 2008. Data were collected at Eilat, Israel, a globally important site for migrating raptors. Changes in the observation dates of spring passage migration were examined using correlation and regression analyses to assess changes over time as well as potential relationships with temperature and with the Indian Ocean Dipole, an index of climate in the wintering area. Over the study period, the number of recorded steppe eagles decreased significantly, as did the proportion of juveniles. Despite the population decrease there was a rapid advance in first spring passage date. Although changes in passage dates were related to environmental conditions in wintering and en-route areas, we suggest that one possible additional reason for such a rapid advance is due to increasing competition between individuals for breeding territories due to dwindling habitats. In addition, changes to some aspects of the passage distribution may be a consequence of a changing age structure.

Crossing the desert barrier: Migration ecology of the Lesser Whitethroat (Sylvia curruca) at Eilat, Israel

“…Bluethroat (Luscinia svecica, Markovets et al, 2008), Red-throated Pipit and Tree Pipit (Anthus cervinus, Anthus trvialis, Yosef and Zduniak, in press). However, a similar strategy was also found for raptors crossing Eilat, such as Common Buzzard (Buteo buteo, Yosef et al, 2002), Levant Sparrowhawk (Accipiter brevipes, Yosef et al, 2003), and Steppe Eagle (Aquila nipalensis, Zduniak et al, 2010), and near-passerines such as Common Quail (Coturnix coturnix, Zduniak and Yosef, 2008), and Wryneck (Jynx torquilla, Yosef and Zduniak, in press). This could be the result of several options: (1) that the population leaves Africa synchronously but the more experienced adults are able to make the crossing more economically; or (2) adults leave the subSaharan wintering grounds earlier; or (3) juveniles winter separately from adults and initiate migration differently.…”

The Indian Ocean Dipole as an indicator of climatic conditions affecting European birds

“…The positive relationship between the IOD and variability in the timing of first clutches thus suggests that the IOD can possibly influence body condition of wintering birds. In the second study, the relationship between the passage time of steppe eagle Aquila nipalensis at Eilat, Israel and the IOD was examined (Zduniak et al 2010). They did not find any significant correlation between passage pheno logy and the IOD.…”

Climatic variation in Africa and Europe has combined effects on timing of spring migration in a long-distance migrant Willow WarblerPhylloscopus trochilus

“…Few studies have used the Sahel Precipitation Anomaly (SAH) (e.g., Zwarts et al, 2009;Tobolka et al, 2018) as a proxy for rainfall in the Sahel, where many European migrants stop over or stay for winter. The relationship between the timing of migration and the El-Niño-Southern Oscillation (ENSO/SOI) has been marginally explored (e.g., Stenseth et al, 2003;MacMynowski & Root, 2007;Miller-Rushing et al, 2008), as has the Indian Ocean Dipole (IOD) (e.g., Hušek et al, 2008;Zduniak et al, 2010;Tryjanowski, Stenseth & Matysioková, 2013;Tobolka et al, 2018). The SOI and IOD are continental-scale weather anomalies which are correlated with rainfall and temperatures in the southern hemisphere (Black, 2005;Marchant et al, 2006), thus they might serve as useful indices that reflect the conditions which migrant European birds experience in eastern and southern Africa.…”