In this study we explored the linkage between wing size of Great Reed Warbler males (Acrocephalus arundinaceus) and their habitat selection and relate these linkages to differences in reed habitat quality. We measured the wing sizes of males nesting in 6 different reed habitats. To explain reed habitat selection, we modeled male wing size as a function of 7 predictor variables describing reedbeds: proportion of managed reed; densities of mixed, old, and fresh reed; reed stem diameter; water depth; and fluctuation of water level. Mean wing size was greatest for males at large canals, intermediate at mining ponds and smaller canals, and lowest at marshes and very small canals. The proportion of managed reed and fluctuation of water level were negatively related to wing size, and water depth was positively related to wing size, which suggests that males with larger wings preferred reed habitats with little management in deep water with little fluctuation in water level. We concluded that the availability of stable, deep water and lack of management are primarily important in attracting larger-winged (presumably dominant) males. Keywords: wing size, reed management, water depth, fluctuation of water level, male, habitat selection, Acrocephalus arundinaceus Selección de há bitat de carrizo con relación al tamaño del ala de machos de Acrocephalus arundinaceus RESUMENEn este estudio exploramos el vínculo entre el tamaño del ala de los machos de Acrocephalus arundinaceus y su selección de hábitat, y relacionamos estos vínculos con diferencias en la calidad del hábitat de carrizo. Medimos el tamaño del ala de machos anidando en seis hábitat diferentes de carrizo. Para explicar la selección del hábitat de carrizo, modelamos el tamaño del ala de los machos como una función de siete variables predictivas de los carrizales: proporción de carrizales con manejo, densidad de carrizo mixto, viejo o nuevo, diámetro del tallo del carrizo, profundidad del agua y fluctuación del nivel del agua. El tamaño medio del ala de los machos fue mayor en los canales grandes, intermedio en los estanques cavados y en los canales más pequeños, y menor en los pantanos y en los canales muy chicos. La proporción de los carrizales con manejo y la fluctuación del nivel del agua estuvieron negativamente relacionadas al tamaño del ala, y la profundidad del agua estuvo positivamente relacionada al tamaño del ala, lo que sugiere que los machos con alas más grandes prefirieron hábitats de carrizo con poco manejo en aguas profundas y con poca fluctuación del nivel del agua. Concluimos que la disponibilidad de agua estable y profunda y la falta de manejo son principalmente importantes para atraer a los machos (presumiblemente dominantes) con alas más grandes. Palabras clave: Acrocephalus arundinaceus, fluctuación del nivel del agua, macho, manejo del carrizo, profundidad del agua, selección de hábitat, tamaño del ala INTRODUCTION

ABSTRACT.---We surveyed five reed habitats (mining pond, sand pit, large canal, small 1 canal and lowland river) in north-western Vojvodina (Serbia) between 2009-2011 to study 2 habitat use and to estimate nest success in an understudied region of the breeding range of the 3 Great Reed Warbler (Acrocephalus arundinaceus). Data from 174 nests showed that habitat 4 use differed considerably between the habitat types, but was not related to the area of the 5 study site or the reed bed. Higher-than-expected numbers of nests along the small canal and 6 the river suggested that Great Reed Warblers preferred these to other habitats for nesting. 7Habitat use was closely linked to the availability of reed edges and the quality of the reed 8 stand. Overall Mayfield nest success was 43%, slightly lower than in northern and western 9 Europe. Nest success was low along the small and large canal, where brood parasitism by 10Common Cuckoos (Cuculus canorus) and nest predation were high due to nearby tree lines 11 providing perching sites to cuckoos and predators. Nest success was intermediate at the 12 mining pond due to very high predation pressure and adverse weather, and nest success was 13 highest in the sand pit (despite high Cuckoo parasitism) and the river (despite relatively high 14 predation). In conclusion, our results suggest that canals can function as ecological traps, 15 which attract edge-preferring Great Reed Warblers but are highly accessible to predators and 16 brood parasites. In contrast, sand pits can be perceptual traps because they provide good 17 resources for nesting but were less attractive to Great Reed Warblers than other habitats. 18Habitat use in relation to habitat availability thus depends primarily on the availability of reed 19 edges and the quality of the reed stand, whereas nest success also depends on the 20 characteristics of the surroundings and weather conditions.

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Intersexual differences in habitat choice can arise if males and females differ in morphology, physiology, niche partitioning, or resource use, and can be influenced by variation in habitat structure, quality, and management. To better understand such intersexual differences, we studied habitat choice in female Great Reed Warblers (Acrocephalus arundinaceus), a long-distance migrant flagship species of lowland Palearctic reed (Phragmites australis) habitats. We compared wing length, a widely used proxy for individual quality in passerines, of females nesting in six types of differently managed reed habitats. Our dataset on 391 females nesting in 32 sites over 10 years showed that wing length was significantly greater in mining ponds and medium-sized canals than on large canals. Wing length was negatively related to water level fluctuation and females showed strong philopatry to the habitat type in which they were first captured. In comparison to our previous study on male habitat choice, this study found differences in habitat choice between the sexes. Although long-winged individuals in both sexes preferred habitats with stable water and avoided small canals, longer-winged males preferred large canals with little or no management, whereas long-winged females preferred medium-sized canals with some management. Although these results provide some support for intersexual niche segregation, it is also possible that long-winged females avoid large canals, in which nest parasitism by Cuckoos (Cuculus canorus) is frequent, and/or prefer managed, sparse reed beds with better maneuverability for foraging. Our studies suggest that males may primarily choose habitats with abundant old reed and singing perches, whereas females are less sensitive to environmental variation and may choose nest sites based on male quality or territory quality. For conservation, our studies imply that the maintenance of stable water levels, a low intensity of management and the elimination of Cuckoo perches are likely to benefit both long-winged males and females. Sélection d'habitat lié à la longueur de l'aile chez les Rousserolles turdoïdes femelles : le rôle de la qualité de l'habitat et de l'aménagement RÉSUMÉ. Des différences dans la sélection d'habitat liées au sexe peuvent s'observer si les mâles et les femelles diffèrent en termes de morphologie, de physiologie, de différenciation de niche ou d'utilisation des ressources, et peuvent être influencées par la variation de structure, de qualité et de l'aménagement de l'habitat. Pour mieux comprendre ce type de différences intersexuelles, nous avons étudié la sélection d'habitat chez la femelle Rousserolle turdoïde (Acrocephalus arundinaceus), espèce-phare migratrice de longue distance occupant des milieux paléarctiques de basses terres dominées par le roseau (Phragmites australis). Nous avons comparé la longueur de l'aile, un indicateur très utilisé pour attester de la qualité individuelle des passereaux, de femelles nichant dans six types de milieux de roseaux aménagés de façon différente....

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Nest-site characteristics and breeding density of Magpie Pica pica in Sombor (NW Serbia) In March 2009, active Magpie Pica pica nests were censused in the town of Sombor (Vojvodina, NW Serbia) to study nest-site characteristics, breeding density and spatial distribution. The area of the town can be divided into two parts according to different urban landscapes, i.e. the town centre (150 ha) and the residential area (2,224 ha). In total, 222 Magpie nests were found and their height, tree species and nest-site type determined. Nests were found in 25 tree and two shrub species, the most of them (31.1%) being placed in the commonest tree species in the town, the Common Hackberry Celtis occidentalis. The majority of the nests were found in tree avenues (39.6%) and groups of trees (31.5%). Nests in the town centre with a mean height (± SD) of 15.2 ± 4.05 m were significantly higher than those in the residential area with a mean height (± SD) of 11.4 ± 5.13 m. The mean distance of nests from the top of the canopy (± SD) was 1.5 ± 1.33 m, demonstrating the Magpie's tendency to place its nests in the very tops of trees in the urban areas. In the residential area, nests were present in every height class, while in the town centre they were not found lower than 5 m. This difference can be explained by denser human population in the town centre and hence greater disturbance (e.g. pedestrians), as found in several other studies, but also by the negative effect of high buildings that prevail there. Thus, the height of surrounding buildings, too, might play an important role in nest-site selection in Magpies breeding in urban habitats, especially in densely built-up areas. Breeding density of Magpie in Sombor was 0.94 pairs/10 ha, with almost twice as high in the town centre as in the residential area. The findings of this study are compared to those obtained in other studies in Serbia and abroad.

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Clutch size generally decreases with latitude from the poles towards the Equator (Bell 1996, 38 Sanz 1999, Cardillo 2002, Cooper et al. 2005, Jetz et al. 2008, Griebeler et al. 2010, Winkler 39 et al. 2014. Griebeler et al. (2010) and Jetz et al. (2008) The Great Reed Warbler Acrocephalus arundinaceus, a western Palearctic species breeding in 57 reed Phragmites australis habitats, is suitable for such investigations because its breeding 58 biology is well described from several locations in Europe (Fig. 1). Latitudinal gradient found 59 in avian clutch size (Jetz et al. 2008, Griebeler et al. 2010 The results of the analyses showed that the best one-term model for mean clutch initiation 109 date contained the term Longitude, whereas four of the five best two-term models also 110 included Longitude (Table 1) The two best one-term models for mean clutch size were either with Maximum Temperature 118 or Latitude, and these variables were part of a number of two-term models for mean clutch 119 size ( Table 1). The effect of Latitude was positive (Table 2) (Table 1). Again, the effects of Latitude and Longitude were positive 128 (Table 2), indicating more fledglings at more northern and eastern localities, whereas that of 129 Maximum Temperature was negative, indicating fewer fledglings in localities with higher 130 maximum temperatures in the hottest month (Fig. 4, linear regression, F 1,15 = 8.9, p < 0.01). 131Maximum Temperature was frequent in the best models (appearing in 9 of 10 best models, In conclusion, we found that clutch initiation date was earlier in more eastern sites and that its