Common cuckoos (Cuculus canorus) do not rely on indicators of parental abilities when searching for host nests: the importance of host defenses

[EN]There is widespread evidence that individuals within and among host populations are not evenly parasitized by Common Cuckoos (Cuculus canorus). We first investigated whether the song and nest size of a host species, the Great Reed Warbler (Acrocephalus arundinaceus), reveal information on parental abilities and level of defense against Common Cuckoos. Second, we analyzed whether female Common Cuckoos’ preference for host nests is predicted by the degree of song expression and the nest size of the host. Earlier-breeding hosts built bigger nests, were more active singers, and had less rich syllable repertoires than late breeders. Host nestlings raised in a big nest received more feedings than those raised in a small nest. Host males that were active singers were paired with females that built bigger nests. All host pairs rejected nonmimetic artificial eggs, but those with a big nest were more prone to reject natural Common Cuckoo eggs. Thus, Great Reed Warbler pairs with a big nest were more willing to feed nestlings, but also had higher discriminatory abilities against Common Cuckoo eggs, than those with a small nest. These findings, and female Common Cuckoos’ inability to capture the information provided by Great Reed Warblers’ sexual signals, may explain why the females followed a simple rule of selecting the more visible host nests in the population.[ES]Existe abundante evidencia de que los individuos dentro y entre poblaciones hospederas no son parasitados de manera uniforme por Cuculus canorus. Primero, investigamos si el canto y el tamaño del nido de una especie hospedera, Acrocephalus arundinaceus, otorga información sobre las habilidades parentales y el nivel de defensa en contra de C. canorus. Segundo, analizamos si la preferencia de las hembras de C. canorus por los nidos hospederos es predicha por el grado de expresión del canto y el tamaño del nido del hospedero. Los hospederos que criaron más temprano construyeron nidos más grandes, fueron cantantes más activos y presentaron repertorios menos ricos en sílabas que los individuos que criaron más tarde. Los pichones de los hospederos criados en nidos grandes recibieron más alimento que aquellos criados en nidos pequeños. Los machos hospederos que fueron cantantes activos se aparearon con las hembras que construyeron nidos más grandes. Todas las parejas de hospederos rechazaron los huevos artificiales no miméticos, pero aquellas con nidos grandes fueron más propensas a rechazar los huevos naturales de C. canorus. Así, las parejas de A. arundinaceus con nidos grandes estuvieron más dispuestas a alimentar a los pichones de C. canorus, pero también presentaron mayores habilidades para discriminar sus huevos, que aquellas parejas con nidos pequeños. Estos resultados, y la incapacidad de la hembra de C. canorus de captar la información suministrada por las señales sexuales de A. arundinaceus, pueden explicar por qué las hembras siguieron una regla simple de seleccionar los nidos hospederos más visibles de la población.The study was supported by the Hungarian National Research Fund (OTKA, grant no. T48397 to C.M.) and by a bilateral grant from the Spanish and Hungarian governments (TéT, grant no. E-23/2005 to J.M.A. and C.M.)Peer reviewe

The VLQ Calorimeter of H1 at HERA: A Highly Compact Device for Measurements of Electrons and Photons under Very Small Scattering Angles

In 1998, the detector H1 at HERA has been equipped with a small backward spectrometer, the Very Low Q^2 (VLQ) spectrometer comprising a silicon tracker, a tungsten - scintillator sandwich calorimeter, and a Time-of-Flight system. The spectrometer was designed to measure electrons scattered under very low angles, equivalent to very low squared four - momentum transfers Q^2, and high energy photons with good energy and spatial resolution. The VLQ was in operation during the 1999 and 2000 run periods. This paper describes the design and construction of the VLQ calorimeter, a compact device with a fourfold projective energy read-out, and its performance during test runs and in the experiment.Comment: 32 pages, 25 figures, 2 tables (To be submitted to Nucl. Instrum. Meth. A

Eurasian Kurgan Database – a citizen science tool for conserving grasslands on historical sites

Eurasian steppes have an essential role in conserving biodiversity, but due to the huge habitat loss in the past centuries they are often preserved only in small refuges. Among such refuges are the ancient steppic burial mounds (the so called ‘kurgans’) which have a high cultural and historical importance and are also essential sites of nature conservation. Despite their high number (approximately half million) and conservational importance there is a huge lack of knowledge on the locality and conservational state of the kurgans in most regions of Eurasia. To fill this knowledge gap, we built a public database which allows to record and query basic information on their cultural values and factors (such as land cover type, threatening factors, cover of woody species) that might serve as a basis for their effective conservation. The database provides a transparent, public and easy-to-use source for conservation managers and landscape planners focussed on grassland conservation. In addition, it also provides background information for other associate disciplines and public agencies dealing with the protection of cultural heritage

A Doubly Nudged Elastic Band Method for Finding Transition States

A modification of the nudged elastic band (NEB) method is presented that enables stable optimisations to be run using both the limited-memory quasi-Newton (L-BFGS) and slow-response quenched velocity Verlet (SQVV) minimisers. The performance of this new `doubly nudged' DNEB method is analysed in conjunction with both minimisers and compared with previous NEB formulations. We find that the fastest DNEB approach (DNEB/L-BFGS) can be quicker by up to two orders of magnitude. Applications to permutational rearrangements of the seven-atom Lennard-Jones cluster (LJ7) and highly cooperative rearrangements of LJ38 and LJ75 are presented. We also outline an updated algorithm for constructing complicated multi-step pathways using successive DNEB runs.Comment: 13 pages, 8 figures, 2 table