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Andrzej Dyrcz – One of the best experts on this subject based on the ideXlab platform.

  • Prolonged copulation, sperm reserves and sperm competition in the Aquatic Warbler Acrocephalus paludicola
    Ibis, 2008
    Co-Authors: Karl Schulze-hagen, Bernd Leisler, Tim R. Birkhead, Andrzej Dyrcz

    The Aquatic Warbler Acrocephalus paludicola has a quasi-promiscuous mating system with high levels of multiple paternity and, thus, intense sperm competition. The duration of copulation in the Aquatic Warbler is unusually long. In hand-reared, captive birds the duration of mounting was 23.7 ± 11.8 min (mean ± s.d.). On average, six cloacal contacts (inseminations) occurred during each copulation. Between inseminations the male remained in contact with the female, either on top of or directly behind her. Protracted copulation may be a form of contact mate guarding, a behaviour not previously recorded in birds. Copulation was most frequent during the evening and early morning. Male Aquatic Warblers also exhibit extreme morphological adaptations of their reproductive system compared with other Acrocephalus species and other birds: their testes, cloacal protuberance and seminal glomera (which contain 198 × 106 spermatozoa) are all relatively large. Frequent insemination during protracted copulation and contact mate guarding may be alternatives to paternity guarding found in other birds.

  • Great reed warbler Acrocephalus arundinaceus and reed warbler Acrocephalus scirpaceus respond differently to cuckoo dummy at the nest
    Journal of Ornithology, 2006
    Co-Authors: Andrzej Dyrcz, Lucyna Halupka

    A cuckoo Cuculus canorus dummy was exposed at 24 nests of great reed warbler Acrocephalus arundinaceus (GRW) and 34 nests of reed warbler Acrocephalus scirpaceus (RW) during the egg-laying stage. The eight GRW pairs attacked the cuckoo directly, striking the dummy, but such a behaviour was not recorded in RWs. Also, other behavioural measures (closest distance from the model, duration of distress calls and number of excitement calls) indicated a lower level of defence by RWs compared to GRWs. In the study area, the parasitism rate was much lower in GRWs (1.7% of nests) than in RWs (11.3%). We suggest that one of the reasons for the lower level of cuckoo parasitism on GRWs is its stronger nest defence and hence higher risk of injury or even death for the cuckoo during egg dumping.

  • Potential food resources and nestling food in the Great Reed Warbler (Acrocephalus arundinaceus arundinaceus) and Eastern Great Reed Warbler (Acrocephalus arundinaceus orientalis)
    Journal für Ornithologie, 2000
    Co-Authors: Andrzej Dyrcz, Heiner Flinks

    The main ecological difference between the Great Reed Warbler (Acrocephalus arundinaceus arundinaceus) and Eastern Great Reed Warbler (Acrocephalus Acrocephalus orientalis) lies in the density of breeding population, which in the Eastern subspecies studied in Japan is on average 10 times higher than that of European populations of the Western subspecies. In this study it is shown that potential food resources of the Great Reed Warbler in Japan are more than ten times more abundant than those in Poland, with respect both to the number of potential prey items (invertebrates) and to their total biomass. This strongly suggests that such high densities of Great Reed Warbler in Japan are at least partly due to more plentiful food supply. Other factors which could explain the difference between breeding densities in Japan and Poland are the predation by Marsh Harrier (Circus aeruginosus) in Poland and lack of competition with Reed Warbler (Acrocephalus scirpaceus) in Japan. The abundance of food on the sample plot in Japan resulted primarily from outbreaks of dipterans of the suborder Nematocera, the most common of which were Chironomidae. Although Chironomidae were not the preferred prey, they made up a substantial proportion of the diet of nestlings. In both studied areas, apart from dipterans, the greatest proportion of nestlings’ diet constituted arachnids. Differences in nestlings’ diet between study sites resulted mainly from a greater proportion of Nematocera and lower proportion of Coleoptera and Odonata in Japan.

Staffan Bensch – One of the best experts on this subject based on the ideXlab platform.

  • Prevalence and diversity of Plasmodium and Haemoproteus parasites in the globally-threatened Aquatic Warbler Acrocephalus paludicola.
    Parasitology, 2015
    Co-Authors: Júlio M. Neto, Antón Pérez-rodríguez, Martin Haase, Martin Flade, Staffan Bensch

    The diversity and prevalence of malaria parasites of the genera Plasmodium and Haemoproteus were determined in the globally-threatened Aquatic Warbler Acrocephalus paludicola. Birds were sampled during migration in Portugal and at the wintering quarters in Senegal and parasites were detected using molecular methods. Only three generalist parasite lineages (Plasmodium) were found. There were no significant differences in the prevalence of parasites between sexes in Europe, but adults had higher prevalence than first-year birds, and birds in Europe had higher prevalence than those captured in Africa. When comparing with other Acrocephalus species and taking sample size into account, Aquatic Warblers had the lowest prevalence and, together with another threatened species, the Seychelles Warbler Acrocephalus sechellensis, the lowest diversity of malaria parasites. We hypothesize that the low diversity of parasites and absence of specialist lineages of Aquatic Warblers are caused by its small population size and fragmented distribution. Furthermore, Aquatic Warblers’ extreme habitat specialization may decrease their exposure to malaria parasites, but other explanations such as high mortality (which would constraint the sampling of infected birds) or, in contrast, very efficient immunological system in clearing the infections cannot be ruled out. This study contributes to explain variation in prevalence and diversity of malaria parasites among hosts.

  • Lost and found: the enigmatic large-billed reed warbler Acrocephalus orinus rediscovered after 139 years
    Journal of Avian Biology, 2007
    Co-Authors: Philip D. Round, Bengt Hansson, David J. Pearson, Peter Kennerley, Staffan Bensch

    We present compelling evidence of the continued existence of the large-billed reed warbler Acrocephalus orinus, hitherto known only from the unique type specimen collected in NW India 139 years ago. Morphological and genetic analyses of an unusual Acrocephalus warbler mist-netted south-west of Bangkok, Thailand, on 27 March 2006, confirmed its identity as A. orinus, and revealed that it was heterozygous at four out of eight microsatellite markers, indicating the continued existence of a viable population whose breeding and wintering areas are still unknown.

Eivin Røskaft – One of the best experts on this subject based on the ideXlab platform.

  • egg phenotype differentiation in sympatric cuckoo cuculus canorus gentes
    Journal of Evolutionary Biology, 2010
    Co-Authors: Anton Antonov, Eivin Røskaft, Bård G. Stokke, Johan Reinert Vikan, Frode Fossøy, Peter Sjolte Ranke

    The brood parasitic common cuckoo Cuculus canorus consists of gentes, which typically parasitize only a single host species whose eggs they often mimic. Where multiple cuckoo gentes co-exist in sympatry, we may expect variable but generally poorer mimicry because of host switches or inter-gens gene flow via males if these also contribute to egg phenotypes. Here, we investigated egg trait differentiation and mimicry in three cuckoo gentes parasitizing great reed warblers Acrocephalus arundinaceus, marsh warblers Acrocephalus palustris and corn buntings Miliaria calandra breeding in close sympatry in partially overlapping habitat types. The three cuckoo gentes showed a remarkable degree of mimicry to their three host species in some but not all egg features, including egg size, a hitherto largely ignored feature of egg mimicry. Egg phenotype matching for both background and spot colours as well as for egg size has been maintained in close sympatry despite the possibility for gene flow.

  • breeding success of common cuckoos cuculus canorus parasitising four sympatric species of Acrocephalus warblers
    Journal of Avian Biology, 2004
    Co-Authors: Oddmund Kleven, Eivin Røskaft, Bård G. Stokke, Arne Moksnes, Geir Rudolfsen, Marcel Honza

    We investigated the level of parasitism, egg mimicry and breeding success of cuckoos parasitising four sympatric species of Acrocephalus warblers in southern Moravia, Czech Republic. The parasitism rate was highest in the marsh warbler Acrocephalus palustris (44.8%) followed by great reed warbler A. arundinaceus (33.8%), sedge warbler A. schoenobaenus (26.5%) and reed warbler A. scirpaceus (11.6%). Although the cuckoo eggs showed a high level of mimicry the eggs of the marsh warbler this host species rejected 72% of the cuckoo eggs, resulting in a cuckoo breeding success of only 4.3%. Cuckoo eggs laid in great reed warbler and reed warbler nests showed a similar hatching success, but the cuckoo chicks survived better in great reed warbler nests, resulting in a breeding success of 30.4%, as compared to 16.4% in nests of the reed warbler. The relationship between the level of parasitism, host rejection of cuckoo eggs, cuckoo chick survival and breeding success is discussed for the four host species.