| 1. |
- Andueza, Miren, et al.
(författare)
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Connectivity in Reed Warblers Acrocephalus scirpaceus between breeding grounds in Europe and autumn stopover sites in Iberia
- 2013
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Ingår i: Ardea. - : Netherlands Ornithologists' Union. - 0373-2266. ; 101:2, s. 133-140
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Tidskriftsartikel (refereegranskat)abstract
- We determined the degree of connectivity in the Eurasian Reed Warbler Acrocephalus scirpaceus between breeding regions in central and northern Europe and stopover sites in Iberia, during the autumn migration. We used both recovery data and wing length analyses to achieve this. Biometric data were obtained during 2009 at 11 sampling localities in Iberia, which we amalgamated into four major migratory areas within the region (Central, Western, Eastern and Southwestern Iberia, hereafter CI, WI, EI, SW). From the EURING database, we selected birds captured at their breeding sites in Europe and recaptured in Iberia during the autumn migration. Reed Warblers passing through WI had shorter wings than those in CI, EI and SW, suggesting that birds in WI migrated shorter distances, a fact also supported by recovery data. Although Reed Warblers showed some population overlap when passing through Iberia, we found that birds passing through EI and CI came from areas further to the east (continental Europe) than those passing through WI (mainly British Isles), thus supporting parallel migration. Reed Warblers tended to converge in southwestern Iberia, suggesting an effect of nearby geographical barriers.
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| 2. |
- Andueza, Miren, et al.
(författare)
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Geographic variation in body mass of first-year Reed Warblers Acrocephalus scirpaceus in Iberia
- 2014
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Ingår i: Ornis Fennica. - 0030-5685. ; 91:2, s. 88-99
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Tidskriftsartikel (refereegranskat)abstract
- On their route to tropical Africa, European trans-Saharan migrants must cross two major geographical barriers, the Mediterranean Sea and the Sahara Desert, which necessitates the accumulation of large fuel loads. While northern Africa is the chief region where most migrants gain fuel for the Sahara crossing, Iberia is a target area to gain fuel before the sea crossing existing between Europe and Africa. Despite the large body of studies approach- ing the question of fuel accumulation before geographic barriers, it is still poorly known which factors apart from distance to a certain barrier shape the geographical pattern of fuel reserves. To investigate this question in detail we used data of first-year Reed Warblers from 12 localities within Iberia during the autumn migration period of 2009. We run linear models to analyze the effects of location in Iberia, date, and body size on body mass variation at each migratory flyway (eastern, central and western Iberia). Flight ranges from each site were also calculated. Our results showed that Reed Warblers in Iberia had the necessary fuel needed to arrive in northern Africa but not to tropical Africa. However, body mass patterns varied depending on the geographical region (eastern, central or west- ern Iberia). Date did not affect body mass in central and western Iberia, but in eastern Ibe- ria heavier birds tended to pass later. Thus, the factors shaping body mass of Reed War- blers in Iberia before the sea crossing to Africa seemed to be more complex than just the distance to this geographical barrier, with underlying stopover quality-associated factors possibly playing a relevant role.
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| 3. |
- Lomas Vega, Marta, et al.
(författare)
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Migration Strategies of Iberian Breeding White-Rumped Swifts Apus caffer, Rufous-Tailed Scrub-Robins Cercotrichas galactotes and Bluethroats Cyanecula svecica
- 2019
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Ingår i: Ardeola (Madrid). - : Ardeola. - 0570-7358. ; 66:1, s. 51-64
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Tidskriftsartikel (refereegranskat)abstract
- The migration strategies of smaller, south European, Mediterranean birds are less well known than those of northern and central European birds. We used geolocators to map individual spatio-temporal migration schedules of three species breeding in the Iberian Peninsula: the White-rumped Swift Apus caffer, Rufous-tailed Scrub-robin Cercotrichas galactotes and Bluethroat Cyanecula svecica. The three species crossed the Sahara desert with a westward detour, to reach West African winter grounds in the Sahel (Bluethroats and Scrub-robins) or the rainforest belt (Swifts). Despite the proximity of the breeding grounds to the desert barrier, all but one individual stopped over before the desert crossing during autumn migration. After spending six months on average in sub-Saharan Africa with variable itinerancy, spring migration was faster overall and more direct than in autumn. Autumn migration was of similar duration to that found in related northern European migrants and therefore slower in southern birds. Spring migration was completed in less time than in the northern migrants (data only for Swifts and Scrub-robins). The shorter migration distance and proximity to the barrier potentially allow south European trans-Saharan migrants to migrate more slowly than northern migrants but only when less time-constrained in autumn.
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| 4. |
- Morrison, Catriona A., et al.
(författare)
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Covariation in population trends and demography reveals targets for conservation action
- 2021
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Ingår i: Royal Society of London. Proceedings B. Biological Sciences. - : The Royal Society. - 1471-2954. ; 288:1946, s. 20202955-20202955
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Tidskriftsartikel (refereegranskat)abstract
- Wildlife conservation policies directed at common and widespread, but declining, species are difficult to design and implement effectively, as multiple environmental changes are likely to contribute to population declines. Conservation actions ultimately aim to influence demographic rates, but targeting actions towards feasible improvements in these is challenging in widespread species with ranges that encompass a wide range of environmental conditions. Across Europe, sharp declines in the abundance of migratory landbirds have driven international calls for action, but actions that could feasibly contribute to population recovery have yet to be identified. Targeted actions to improve conditions on poor-quality sites could be an effective approach, but only if local conditions consistently influence local demography and hence population trends. Using long-term measures of abundance and demography of breeding birds at survey sites across Europe, we show that co-occurring species with differing migration behaviours have similar directions of local population trends and magnitudes of productivity, but not survival rates. Targeted actions to boost local productivity within Europe, alongside large-scale (non-targeted) environmental protection across non-breeding ranges, could therefore help address the urgent need to halt migrant landbird declines. Such demographic routes to recovery are likely to be increasingly needed to address global wildlife declines.
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