Autumn Migration Speed of Juvenile Reed and Sedge Warblers in Relation to Date and Fat Loads (original) (raw)
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Ostrich, 2005
Ecological barriers are the riskiest phases of the annual migrations for migratory birds. Comparatively little field data exists pertaining to the ability of migratory birds to prepare for the challenges of crossing ecological barriers, or their ability to recuperate afterward. Migrating Reed Warblers (Acrocephalus scirpaceus) were captured in Eilat, Israel, during their spring and autumn migrations. Data on spring and autumn body masses, their inter-annual variation, and the pattern of body mass increase were analysed. The birds show a significant inter-annual variation in their body mass and body condition index in both seasons, which is consistent with the data from other sites and for other passerine species. During stopovers, mass gain occurred in both seasons. Birds in poor initial condition, and those that stop over for a longer period of time, gained more body mass faster. In spring, but not in autumn, the progress of the season was also an important factor; late-arriving birds gained more fuel faster. The average rate of fuel gain was 0,157g·day -1 ± 0.018 SE.
Ring, 2007
Autumn Migration Dynamics, Body Mass, Fat Load and Stopover Behaviour of the Willow Warbler (Phylloscopus trochilus) at Manyas KuşcennetI National Park (NW Turkey) Turkey is located on one of the major migratory routes between Palearctic and Afrotropical regions. Despite its importance for many species, few studies exist on bird migration over Turkey. In this study, autumn migration dynamics and stopover behaviour of the Willow Warbler, a passage migrant in Turkey, was documented and analysed at Manyas Kuşcenneti National Park (NW Turkey). Birds were mist-netted, ringed, measured, weighed and fat scored from mid-August in 2002 and end of August in 2003 to end of October in both years. Totally, 543 and 929 Willow Warblers were ringed in 2002 and 2003, respectively. For 2002 and 2003 respectively, fat score values (mean ± SE) were 4.63 ± 0.06 and 3.84 ± 0.05, while body mass reached 11.38 ± 0.07 and 10.37 ± 0.05 g for birds captured for the first time. Fat scores in 2003 showed a bimo...
The European Zoological Journal, 2020
The great reed warbler Acrocephalus arundinaceus is a common migrant through the Western Palearctic. However, its migration strategy, especially the spatiotemporal pattern of accumulation and utilisation of energy stores en route, is poorly known. Using ringing data collected at distant stopover sites located from Central Europe to Asia Minor, we observed that pattern in juvenile great reed warblers migrating along the eastern European flyway in autumn. We analysed body condition and stopover duration and estimated potential flight ranges for this species, taking into account two large ecological barriers-the Mediterranean Sea and the Sahara Desert-which it crosses during its southward migration. In Central and SouthEastern Europe the seasonal trends in body condition were similar and non-linear, with low values in August (i.e., during intensive migration of Acrocephalidae), and then a significant increase from the beginning of September until the end of the month. Estimated potential flight ranges showed that individuals migrating through Central and SouthEastern Europe might generally reach only the northern coast of the Mediterranean Sea. On the other hand, those flying from Asia Minor were able to reach the northern edge of the Sahel zone, crossing two large ecological barriers without refuelling. Therefore, it seems that great reed warblers change their autumn strategy en route: first, they migrate in short steps with low energy reserves through continental Europe; and then, after intensive refuelling before the Mediterranean Sea, they reach sub-Saharan Africa in a long flight. Based on the analysis of ringing data from several stopover sites, we show the complex pattern of how a longdistance migratory species accumulates and utilises its energy stores en route.
Naturwissenschaften, 2010
The migration strategies of birds may vary strongly between species and also between age and/or sex groups. We studied the autumn migration and body condition of molecularly sexed Reed Warblers Acrocephalus scirpaceus and Sedge Warblers Acrocephalus schoenobaenus (211 and 208 ind., respectively) at a stopover site on Lake Druzno, Northern Poland, in 2008. Immature male Reed Warblers were caught significantly later than females (median dates 9 days later), but in the Sedge Warbler, both sexes of immatures migrated at about the same time. Adult males and females of both species did not differ in their time of migration. Adult and immature males of both species were larger (wing length and body mass) than females. In both species, fat reserves were similar in both sexes of both age classes. Adults of both sexes of Reed and Sedge Warbler were generally caught earlier than immatures. In both species, the body mass and fat reserves of immatures were generally less than in adults. The autumn protogyny of immature Reed Warblers may allow smaller females to limit competition with bigger males during migration and at the wintering grounds. In the Sedge Warbler, which tends to match its migration to peak of occurrence of superabundant food at stopover sites, both sexes gain an advantage from migrating at the same time. Since part of the measured wing length variation in both species was explained by sex differences, temporal trends in wing length recorded at stopover sites should be interpreted with caution.
Journal of Field Ornithology, 2003
Body mass and fat reserves of Sedge Warblers (Acrocephalus schoenobaenus) on nocturnal departure and arrival were studied by two methods (capture in high nets and playback of songs) on the Courish Spit (Eastern Baltic, Russia) in spring 1998-2000. The average body mass of departing Sedge Warblers was 13.7 g, and the average body mass of arriving birds was 13.1 g. The difference between arrival and departure masses was not significant. The calculated flight range of departing Sedge Warblers in still air varied from 19 to 665 km, with a mean of 295 km. The high fuel loads of Sedge Warblers on departure and on arrival may be explained by the necessity for Scandinavian populations to cross the Baltic; the risk of drifting out to sea for birds migrating over land; or the general vernal migratory strategy of Sedge Warblers, involving a series of short (4.5-6.2 h) flights on several consecutive nights.
Changes in migration phenology and biometrical traits of Reed, Marsh and Sedge Warblers
Open Life Sciences, 2012
Global environmental processes like climate change could severely affect population level migratory behaviour of long range migrant birds. We analyzed changes in migration phenology and biometrics of three closely-related long-distance migrant Acrocephalus species. We used the records of 12 063 Sedge, 12 913 Reed, and 5 409 Marsh Warblers caught and ringed between 1989–2009, at a Hungarian stopover site. Quantile regressions were used to analyse the changes in spring and autumn migration phenology. Median spring arrival date of Sedge and Reed Warblers shifted 6.5 and 7.5 days earlier, respectively. Autumn arrival of all species shifted one (Reed and Marsh Warblers) or two (Sedge Warbler) weeks later. Mean body mass of adult Reed and Marsh Warblers decreased in spring (by 0.3 and 0.2 grams, respectively) and in autumn (by 0.8 and 0.2 grams, respectively) while body mass of adult Sedge Warblers decreased only in autumn (by 0.4 grams). Mean wing length of all species increased signific...
Ringing and Migration, 1991
Previous data from Llangennech, a reedbed in west Wales, indicated that Sedge Warblers with pre-migratory weights typical of fattening birds were as common as at established fattening sites in southern England or France. Data from the British Trust for Ornithology's ringing scheme were thus used to see whether any Sedge Warblers moved into Wales during the fattening period. They showed that many Welsh Sedge Warblers take typical routes from Britain, stopping off in the established fattening areas of southern England or France. Nevertheless, some from other parts of Britain and Ireland move into Wales at this time. Further weight data were collected from Llangennech to assess if heavy birds occurred in all years, while weights from two other Welsh sites (Kenfig Pool and Ffrwd Wen) were examinedfor heavy birds over 2-9 years. Mean weights in juveniles at all three sites were low in the pre-migratory periods of 1989 and 1990, with few individuals (4-9%) over 13 g. Densities of Reed Áphids were much lower at these sites during 1990 than at south coast sites during good fattening years. Long-term data (1982-90) on Sedge Warblers from Kenfig showed that the years 1985-88 were characterised by significantly greater weights than earlier or later years; 12.1% of pre-migratory juveniles were heavier than 13 g, comparable with earlier data from sites in southern England. The previous data showing heavy birds at Llangennech had involved this period, and trends here and at Kenfig were almost identical between 1987 and 1990. Mean weight at Kenfig for the years 1982-90 declined significantly with increasing summer temperatures, and birds also passed through the site significantly earlier in hotter years. Increases in the local density of Sedge Warblers may also have depressed individual weight, but the effect was moderate. It is concluded that Sedge Warbler fattening in south Wales is facultative and does not occur in all years, with Welsh birds clearly using established routes from Britain. Nevertheless, fattening can occur under some conditions, and Welsh reedbeds are of potential importance to birds from a large area of Britain and Ireland. The extent to which reed aphids, or other insects, supports this fattening remains unclear. There are also gaps in our knowledge about whether Sedge Warblers fatten at single sites, or whether they gain weight at several locations on their migratory route.
Annales Zoologici Fennici, 2015
Related species showed different strategies when migrating south towards wintering grounds in the Sahel and southern Africa: the garden warbler steadily increased fuel reserves along the migration route, the blackcap showed mixed fattening strategy with high fat reserves just before the Sahara crossing, the common whitethroat accumulated large fat reserves well in advance (North Mediterranean) before crossing this barrier, while the lesser whitethroat starting from the northern part of the Mediterranean showed a stable level of fat reserves. Results of this study support the hypothesis that species-specific ecology, rather than phylogenetic relationships, plays the major role in the evolution and form of bird migration. There were also population-specific differences in the strategy of species based on migration distance (blackcap), as well as individual differences where some individuals of the same species were potentially able to cover larger distance than conspecifics (blackcap, common whitethroat).
Erciyas K., Gürsoy A., Özsemir A.C., Bar2º Y.S. 2010. Body mass and fat score changes in recaptured birds during the autumn migration at the Cernek ringing station in Turkey. Ring 32, 1-2: 3-15. The fat level and the body mass of recaptured birds ringed at the Cernek Ringing Station are presented in this study. Data from autumns of 2003-2005 were analysed. Species of different migratory and feeding habits are compared. A total of 351 recaptures of the Blackcap (Sylvia atricapilla), Garden Warbler (S. borin), Reed Warbler (Acrocephalus scirpaceus), Marsh Warbler (A. palustris) and Cetti's Warbler (Cettia cetti) were mist-netted and handled according to the South-East European Bird Migration Network (SEEN) standards.