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Full annual cycle tracking of a small songbird, the Siberian Rubythroat Calliope calliope, along the East Asian flyway
Abstract
We used light-level-based geolocation to study the spatio-temporal behaviour of Siberian Rubythroats Calliope calliope breeding in the Amur region of the Russian Far East. Three retrieved devices revealed long-distance migrations, with southwestward movement from Amur through Northeast China in autumn, with the tracked individuals reaching their wintering grounds in southern China and Indochina without major detours and apparently on a route slightly further west than that of the return migration in spring. A single stopover occurred in two of the three birds in both spring and autumn in China. Migration was faster in spring compared to autumn. The birds spent most of their time in seasonal habitats on their temperate breeding sites, and in less seasonal habitats on their tropical wintering grounds. Departure from and arrival at their breeding site coincided with decreasing and increasing vegetation greenness, respectively. This is the first study presenting year-round tracking data for a songbird migrating from mainland Eurasia to Southeast Asia along the East Asian flyway.
... In contrast, multiple ecological and life-history traits may place constraints on the timing of autumn migration, such that the selection pressure to adjust migration timing to weather conditions can vary according to species, sex and age (Newton, 2011;Wobker et al., 2021). Factors constraining migration timing potentially include the timing and duration of breeding (Sokolov et al., 1999;Chmura et al., 2020;Imlay et al., 2021), ability to raise multiple broods (Jenni and Kery, 2003), timing of moult (Stutchbury et al., 2011;Wobker et al., 2021), body size and morphology (La Sorte et al., 2013;Heim et al., 2018), dietary guild (Jenni and Kery, 2003;La Sorte et al., 2013;Heim et al., 2018), migration distance (Jenni and Kery, 2003;La Sorte et al., 2015;Barton and Sandercock, 2017), latitude of breeding and wintering sites (Boz o et al., 2021), conditions at stopover sites (Hasselquist et al., 2017;Boz o et al., 2018), and niche competition among related species . ...
... In contrast, multiple ecological and life-history traits may place constraints on the timing of autumn migration, such that the selection pressure to adjust migration timing to weather conditions can vary according to species, sex and age (Newton, 2011;Wobker et al., 2021). Factors constraining migration timing potentially include the timing and duration of breeding (Sokolov et al., 1999;Chmura et al., 2020;Imlay et al., 2021), ability to raise multiple broods (Jenni and Kery, 2003), timing of moult (Stutchbury et al., 2011;Wobker et al., 2021), body size and morphology (La Sorte et al., 2013;Heim et al., 2018), dietary guild (Jenni and Kery, 2003;La Sorte et al., 2013;Heim et al., 2018), migration distance (Jenni and Kery, 2003;La Sorte et al., 2015;Barton and Sandercock, 2017), latitude of breeding and wintering sites (Boz o et al., 2021), conditions at stopover sites (Hasselquist et al., 2017;Boz o et al., 2018), and niche competition among related species . ...
... Migrant birds in this region are not faced with barriers as significant as the Sahara Desert, which is known to influence migration patterns among European birds (Jenni and Kery, 2003;Newton, 2008), and may therefore not be subject to such strong selective pressures on migration. However, the migration of landbirds along the EAAF is relatively understudied compared to other parts of the world, and while there has been an increase in studies in recent years to increase the understanding of migration in Asia (e.g., Harris et al., 2013;Yamaura et al., 2016;Heim et al., 2018;Boz o et al., 2020Boz o et al., , 2021Dorzhieva et al., 2020;Wobker et al., 2021;Yong et al., 2021), still little remains known about the impact of climate change on the timing of migratory events along this flyway, especially in tropical and subtropical latitudes. Further studies are required to confirm whether the trends in migration phenology observed elsewhere also apply to the Asian flyways. ...
Climate change impacts bird migration phenology, causing changes in departure and arrival dates, leading to potential mismatches between migration and other key seasonal constraints. While the impacts of climate change on arrival at breeding grounds have been relatively well documented, little is known about the impacts of climate change on post-breeding migration, especially at stopover sites. Here we use long-term (11 years) banding data (11,118 captures) from 7 species at Mai Po Marshes Nature Reserve in Hong Kong, a key stopover site for migratory birds along the East Asian–Australasian Flyway, to describe long-term changes in migration phenology and to compare observed changes to annual weather variation. We also examine changes in wing length over a longer time period (1985–2020) as wing length often correlates positively with migration distance. We found that observed changes in migratory phenology vary by species; three species had later estimated arrival (by 1.8 days per year), peak (by 2.6 days per year) or departure (by 2.5 days per year), one showed an earlier peak date (by 1.8 days per year) and two showed longer duration of passage (2.7 days longer and 3.2 days longer per year). Three species exhibited no long-term change in migration phenology. For two of the four species with shifting phenology, temperature was an important predictor of changing peak date, departure dates and duration of passage. Wing length was shorter in three species and longer in two species, but these changes did not correlate with observed phenological changes. The complex changes observed here are indicative of the challenges concerning the detection of climate change in migratory stopover sites. Continued monitoring and a better understanding of the dynamics of all sites in the migratory pathway will aid conservation of these species under global change.
... This may be due to the adequate food supply and similar prevailing wind directions for birds in both spring and autumn seasons, and the lack of obvious ecological barriers that have to be crossed during migration along the East Asian Flyway. Previously, Heim et al. (2018b) also found no indication of loop migration in the Siberian Rubythroat, but leapfrog migration (populations breeding further north overwinter further south) has been detected in this species using stable isotope analysis (Weng et al. 2014). However, in the case of Red-flanked Bluetail and Black-faced Bunting, it is conceivable that either males or females used different routes in spring and autumn. ...
... Some species migrate with high fat reserves and can thus travel longer distances (e.g., Marsh Warbler Acrocephalus palustris) (Csörgő, Gyurácz 2009), while others, such as Savi's Warbler Locustella luscinioides, have low fat reserves, which makes them stay longer at the stopover site and migrate faster over shorter distances (Neto et al. 2008). As the stopover ecology of birds can be studied at localised ringing sites without the need for a large geographical network, several studies on the East Asian Fly-way have been conducted earlier, however, the most intensive research on this topic also comes from East Russia from recent decades (Bozó et al. 2018b;Heim et al. 2018b;Bozó et al. 2019b;2019c;Sander et al. 2020) or China (Wang et al. 2006). Bozó et al. (2020) compared the stopover ecology of Yellowbrowed Warbler and Red-flanked Bluetail in the Muraviovka Park. ...
The East Asian-Australasian bird migration system is one of the most species-rich migration systems, nevertheless, we have very little information on the migration of the species that use the Asian-Australasian Flyway. Most knowledge is available about waterfowls (cranes, ducks). However, very little is known about songbirds, mainly due to the lack of large-scale, long-term ringing activities. Most of what we know about the migration of these species is based primarily on field observations and the results of the Migratory Animal Pathological Survey (MAPS) conducted in the 1960s and 1970s. In the 2010s, however, several local ringing projects started. They produced considerable knowledge about the migration of songbirds. More recently, geolocators have also aided researchers in their work, providing even more accurate data on the migratory routes and migratory habits of species. The present study summarises the data we have obtained over the past decade about the migration of long-distance migratory songbirds nesting in North Asia. The article is based primarily on the data collected at ringing stations in the Far Eastern Russia, complemented by research from other areas in East and Southeast Asia. This review highlights the need for further research to ensure long-term protection of species that, at times, show a drastic decline in numbers.
... The East Asian flyway provides continuous stopover possibilities and lacks major ecological barriers for migrating songbirds (Yong et al. 2015), making seasonal detours and loop migration potentially unnecessary. However, a geolocation study found seasonal differences in stopover site locations among Siberian Rubythroats Calliope calliope, suggesting a more westerly migration route in autumn (Heim et al. 2018a). In a recent study in the Russian Far East, Bozó et al. (2018) found a positive effect of tailwind on the numbers of trapped Dusky Warblers Phylloscopus fuscatus and Yellow-browed Warblers P. inornatus in autumn. ...
... For Siberian Rubythroats, Weng et al. (2014) used stable isotopes and found that birds wintering in Taiwan originate from the southern part of the species's breeding range, which indicates that Siberian Rubythroat exhibits a leapfrog migration. Using geolocators, Heim et al. (2018a) found that the birds seem to follow rather straight paths without major detours towards their final winter destinations. These birds initiated migration in autumn by moving westward, far from the shore. ...
Loop migration, i.e. the use of different routes during spring and autumn migration, is a common migratory strategy among many long-distance migratory species. This migration strategy is most likely driven by the variation in food availability and/or prevailing winds en route between the spring and autumn seasons. Tracking studies and long-distance ring recoveries have revealed that many of the species that migrate along the American and Eurasian−African migratory flyways use different stopover sites in spring and in autumn. However, very little information is available on songbirds migrating along the East Asian flyway. In this study, we compared the wing lengths of six East Asian long-distance migratory passerines (Red-flanked Bluetail Tarsiger cyanurus, Siberian Rubythroat Calliope calliope, Taiga Flycatcher Ficedula albicilla, Arctic Warbler Phylloscopus borealis, Thick-billed Warbler Arundinax aedon and Black-faced Bunting Emberiza spodocephala) migrating through two different study sites in Russia. We examined whether these species show morphological differences between spring and autumn migration which could indicate the occurrence of different populations at different parts of the migratory cycle. Based on a dataset of 2,368 adult individuals, we found no differences in wing length between the two seasons for four studied species, suggesting the absence of loop migration. This might be explained by adequate food supply and similar prevailing wind directions for birds in both spring and autumn, or the lack of obvious ecological barriers along the East Asian flyway which have to be crossed during migration. However, the differing wing lengths of individuals captured in spring and autumn for two species, Black-faced Bunting and Red-flanked Bluetail, provide evidence for the possible use of different seasonal migratory routes. Further field studies are needed to better understand the migration ecology of passerine birds in the East Asian flyway.
... However, our data here is Overall, our data suggests that the tracked Arctic Warbler was almost constantly on the move, not a single site during the annual cycle has been used for more than two months. This differs strongly from other East Asian songbird migrants, for which long autumn stopovers of up to three months and very long stationary periods during the boreal winter ( ve-six months) were documented (Heim et al. 2018(Heim et al. , 2020 Fig. 1) might also relate to the constant movement of the tracked bird, but they could also stem from high levels of shading in the understorey of tropical forests which would affect the accuracy of the position estimation (Lisovski et al. 2012). ...
Little is known regarding the migration routes of songbird populations breeding in Siberia. Here we provide the first geolocator tracking data for an Arctic Warbler breeding in Central Siberia and compare its movements with eight long-distance ring recoveries of this species. In autumn, the tracked individual migrated eastward to a stopover site in eastern Siberia, before migrating southward through Taiwan to its non-breeding sites in the Philippines and Indonesia. During spring migration, the bird spent at least one month at stopover sites in Mongolia, before migrating to its breeding site in June. Ring recovery data confirmed the movement between the Central Siberian breeding grounds and stopover sites in northern Mongolia.
... In the EAF, very few studies of migratory connectivity in migratory forest breeding birds have been conducted. An exception is a recent study on the Siberian Rubythroat (Luscinia calliope), which is a shrubland breeding migratory species also seeming to show low migratory connectivity 40 . However, as such information is still largely lacking, this limitation further supports the need for more studies in the wintering range of migratory landbirds in the EAF. ...
The East Asian Flyway (EAF) is the most species diverse of global flyways, with deforestation in its migratory landbird’s non-breeding range suspected to be the main driver of population decline. Yet range-wide habitat loss impact assessments on EAF migratory landbirds are scarce, and seasonal variation in habitat preference of migratory species further increases the complexity for conservation strategies. In this study, we reviewed population trends of migratory forest breeding birds in the EAF along with their seasonal habitat preference from the literature and assessed the impact of forest cover change in species’ breeding and non-breeding ranges on population trends. We found that 41.3% of the bird species with trend data available are declining, and most have higher forest preference in the breeding season. Despite 93.4% of the species experienced deforestation throughout their annual cycle, forest cover change in the non-breeding range was not identified as the main driver of population trend. However, forest cover change in species’ regional breeding range interacts positively with the degree of breeding season forest preference in predicting population trends. We therefore stress that regional breeding habitat protection may still be important while following the call for cross-border collaboration to fill the information gap for flyway conservation.
... Other recent studies also demonstrated that northern populations of the species are migratory (Choi, Nam, Kim, et al., 2020;Choi, Nam, Park, & Bing, 2020;Zhang et al., 2023). All individuals migrated south-westward during autumn to nonbreeding sites on the East Asian mainland, a pattern observed in the majority of migratory East Asian songbird species (Bensch et al., 2022;Heim, Heim, Beermann, et al., 2020;Heim, Pedersen, et al., 2018;Yamaura et al., 2017). An exception to this pattern is the Blue-and-white Flycatchers Cyanoptila cyanomelana co-occurring with yellow-throated buntings at our study site, which TA B L E 2 Migration timing and nonbreeding locations estimated based on light-level geolocation data for six individual yellow-throated buntings breeding at Khingansky state nature reserve, Russia. ...
Basic information on the ecology of species is key for their conservation. Here we study the ecology of the little-known yellow-throated bunting Emberiza elegans based on a multi-year study on its breeding grounds in the Russian Far East. For the first time in this species, we quantified breeding habitat parameters, calculated sex-specific apparent survival, and determined individual nonbreeding locations using light-level geolocation. We found that the habitat around song posts of male yellow-throated buntings is characterized by tree and shrub layers on richly littered moist ground. Habitat use overlaps with co-occurring Tristram's Buntings Emberiza tristrami and Black-faced Buntings E. spodocephala, but territories differ especially in tree cover and litter cover. Based on 4 years of color-ringing data of 72 individuals, we calculated an apparent survival rate of 36%, with higher survival estimates for male than for female yellow-throated buntings. We found no effect of carrying a geolocator on survival. We retrieved six geolocators from males. All birds migrated south-westward during autumn and spent the nonbreeding season at locations in China 700-1700 km away from their breeding sites. At least two individuals spent the boreal winter outside of the known range in northern or central China. Birds left the breeding area between early October and early November and returned between mid-March and mid-April. Our data on habitat use, survival rate, and migratory connectivity will help to assess threats to the populations of this enigmatic species, which might include habitat loss due to forest fires on the breeding grounds, and unsustainable harvest for consumption during the nonbreeding season.
... Because Bluethroats spend most of their time in dense vegetation, shading makes it challenging to obtain migration tracks using light-level geolocators, as previously has been seen in other species with similar life styles (Heim et al. 2018). It was therefore not possible to obtain more precise information of the route. ...
The Bluethroat subspecies Cyanecula svecica svecia occurs throughout the northern Palearctic. European C. s. svecia has been shown to follow a route west of the Himalaya to winter quarters in southern Asia. Out of 30 Bluethroats tagged with geolocators in eastern Siberia, we obtained one track suggesting that it migrated east of the Himalaya to a wintering area located in Myanmar. The different routes of western and eastern C. s. svecia implicate the presence of a migratory divide in Siberia, either formed in situ during the post-glacial colonization process or resulting from a secondary contact between different refuge populations.
Long-distance migratory birds often face major geographical barriers on their journey. While some species are able to cross them, others use longer routes to avoid such barriers. Little is known about the strategies of Siberian landbird migrants, which either cross or circumvent the deserts and mountain ranges of Central Asia en route to their non-breeding sites in South-East Asia. Here we compare data on migration phenology and morphology from two bird ringing stations in eastern Russia, situated at similar latitudes but with a longitudinal difference of 1500 km, to hypothesise migration patterns. We found significant differences in timing between the two sites (birds migrated significantly earlier in spring and significantly later in autumn in the east), suggesting longitudinal migration as a result of migration detour. However, morphological differences show a less clear pattern. We argue that most Siberian landbirds might opt for a detour through the Russian Far East instead of a direct route in order to avoid unfavourable stop-over habitat in Central Asia. However, tracking studies will be necessary to prove this.
Each year, billions of birds migrate across the globe, and interpretation of weather radar signals is increasingly being used to document the spatial and temporal migration patterns in Europe and America. Such approaches are yet to be applied in the East Asian-Australasian Flyway (EAAF), one of the most species-rich and threatened flyways in the world. Logistical challenges limit direct on-ground monitoring of migratory birds in many parts of the EAAF, resulting in knowledge gaps on population status and site use that limit evidence-based conservation planning. Weather radar data have great potential for achieving comprehensive migratory bird monitoring along the EAAF. In this study, we discuss the feasibility and challenges of using weather radar to complement on-ground bird migration surveys in the flyway. We summarize the location, capacity and data availability of weather radars across EAAF countries, as well as the spatial coverage of the radars with respect to migrants' geographic distribution and migration hotspots along the flyway, with an exemplar analysis of biological movement patterns extracted from Chinese weather radars. There are more than 430 weather radars in EAAF countries, covering on average half of bird species' passage and non-breeding distributions, as well as 70% of internationally important sites for migratory shorebirds. We conclude that the weather radar network could be a powerful resource for monitoring bird movements over the full annual cycle throughout much of the EAAF, providing estimates of migration traffic rates, site use, and long-term population trends, especially in remote and less-surveyed regions. Analyses of weather radar data would complement existing ornithological surveys and help understand the past and present status of the avian community in a highly threatened flyway.
Estimating how much long‐distance migrant populations spread out and mix during the non‐breeding season (migratory connectivity) is essential for understanding and predicting population dynamics in the face of global change.
We quantify variation in population spread and inter‐population mixing in long‐distance, terrestrial migrant land‐bird populations (712 individuals from 98 populations of 45 species, from tagging studies in the Neotropic and Afro‐Palearctic flyways). We evaluate the Mantel test as a metric of migratory connectivity, and explore the extent to which variance in population spread can be explained simply by geography.
The mean distance between two individuals from the same population during the non‐breeding season was 743 km, covering 10–20% of the maximum width of Africa/South America. Individuals from different breeding populations tended to mix during the non‐breeding season, although spatial segregation was maintained in species with relatively large non‐breeding ranges (and, to a lesser extent, those with low population‐level spread). A substantial amount of between‐population variation in population spread was predicted simply by geography, with populations using non‐breeding zones with limited land availability (e.g. Central America compared to South America) showing lower population spread.
The high levels of population spread suggest that deterministic migration tactics are not generally adaptive; this makes sense in the context of the recent evolution of the systems, and the spatial and temporal unpredictability of non‐breeding habitat.
The conservation implications of generally low connectivity are that the loss (or protection) of any non‐breeding site will have a diffuse but widespread effect on many breeding populations. Although low connectivity should engender population resilience to shifts in habitat (e.g. due to climate change), we suggest it may increase susceptibility to habitat loss. We hypothesize that, because a migrant species cannot adapt to both simultaneously, migrants generally may be more susceptible to population declines in the face of concurrent anthropogenic habitat and climate change.
Birds migrating across the Himalayan region fly over the highest peaks in the world, facing immense physiological and climatic challenges. The authors show the different strategies used by birds to cope with these challenges. Many wetland avian species are seen in the high-altitude lakes of the Himalayas and the adjoining Tibetan Plateau, such as Bar-Headed Geese. Ringing programmes have generated information about origins and destinations, and this book is the first to present information on the bird's exact migratory paths. Capitalising on knowledge generated through satellite telemetry, the authors describe the migratory routes of a multitude of birds flying over or skirting the Himalayas. The myriad of threats to migratory birds and the wetland system in the Central Asian Flyway are discussed, with ways to mitigate them. This volume will inform and persuade policy-makers and conservation practitioners to take appropriate measures for the long-term survival of this unique migration.
In their 2015 Current Biology paper, Streby et al. [1] reported that Golden-winged Warblers (Vermivora chrysoptera), which had just migrated to their breeding location in eastern Tennessee, performed a facultative and up to “>1,500 km roundtrip” to the Gulf of Mexico to avoid a severe tornadic storm. From light-level geolocator data, wherein geographical locations are estimated via the timing of sunrise and sunset, Streby et al. [1] concluded that the warblers had evacuated their breeding area approximately 24 hours before the storm and returned about five days later. The authors presented this finding as evidence that migratory birds avoid severe storms by temporarily moving long-distances. However, the tracking method employed by Streby et al. [1] is prone to considerable error and uncertainty. Here, we argue that this interpretation of the data oversteps the limits of the used tracking technique. By calculating the expected geographical error range for the tracked birds, we demonstrate that the hypothesized movements fell well within the geolocators’ inherent error range for this species and that such deviations in latitude occur frequently even if individuals remain stationary.
Daily records of bird observations were obtained from the Wild Bird Society of Japan bird sanctuary at Lake Utonai, Hokkaido, from 1982 to 2002. We analysed the daily records of four species thought to be experiencing declines: Brown Shrike Lanius cristatus, Black-browed Reed Warbler Acrocephalus bistrigiceps, Chestnut-eared Bunting Emberiza fucata and Yellow-breasted Bunting E. aureola. The detection rates of Brown Shrike and Yellow-breasted Bunting declined drastically during the two decades, whereas the detection rates of Black-browed Reed Warbler and Chestnut-eared Bunting remained stable. In 2002 and 2003 we conducted line transect censuses, and detected very few Yellow-breasted Buntings and no Brown Shrikes, both of which had been abundant as recently as 1977. The accumulated data from annual bird watching surveys showed similar declines in the same two species. These observations suggest that whereas the Brown Shrike had been common prior to the early 1980s, it declined drastically in 1986. The Yellow-breasted Bunting remained common until 1997, but declined seriously thereafter. There were no clear trends for Black-browed Reed Warbler or Chestnut-eared Bunting from 1982 to 2002, although the latter appeared to decline from 2011 onwards. Large-scale habitat destruction is unlikely in the study area, since the lake and its surrounding area have been a designated a wildlife protection area since before the study began. We discuss potential causes, together with previous studies.
Migratory birds track seasonal resources across and between continents. We propose a general strategy of tracking the broad seasonal abundance of resources throughout the annual cycle in the longest-distance migrating land birds as an alternative to tracking a certain climatic niche or shorter-term resource surplus occurring, for example, during spring foliation. Whether and how this is possible for complex annual spatiotemporal schedules is not known. New tracking technology enables unprecedented spatial and temporal mapping of long-distance movement of birds. We show that three Palearctic-African species track vegetation greenness throughout their annual cycle, adjusting the timing and direction of migratory movements with seasonal changes in resource availability over Europe and Africa. Common cuckoos maximize the vegetation greenness, whereas red-backed shrikes and thrush nightingales track seasonal surplus in greenness. Our results demonstrate that the longest-distance migrants move between consecutive staging areas even within the wintering region in Africa to match seasonal variation in regional climate. End-of-century climate projections indicate that optimizing greenness would be possible but that vegetation surplus might be more difficult to track in the future.