During winter, Long-eared Owls (Asio otus) usually roost in groups in urban areas, but their noct... more During winter, Long-eared Owls (Asio otus) usually roost in groups in urban areas, but their nocturnal movement patterns are less known. The aim of our study is to provide insight into the local-scale urban movement habits of Long-eared Owls. Our study was carried out between 2015 and 2019 in the autumn and winter period, by observations in the early evening and by ringing and recapture of owls in the town of Sombor (NE Serbia). We observed owls when leaving the roosting site located in the town centre following the greenery of the larger avenues towards the outskirts. Owls were sporadically observed in densely built areas of the town, narrow streets with less greenery. Ringing and recapture data suggest that owls were closely linked to the green corridors. They probably used these corridors for easier orientation and to prey on birds roosting in trees in the town, such as sparrows (Passer domesticus, P. montanus), Common Blackbirds (Turdus merula) or Fieldfares (T. pilaris) appearing in harsh winters, and sometimes also pigeons.
In this study we explored the linkage between wing size of Great Reed Warbler males (Acrocephalus... more 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.
We studied the effects of roosting starlings, Sturnus vulgaris, on the nest defence behaviour of ... more We studied the effects of roosting starlings, Sturnus vulgaris, on the nest defence behaviour of great reed warbler, Acrocephalus arundinaceus, monogamous parents from 54 nests. A generalised linear mixed model was constructed to investigate the effects where the nest defence behaviour was the dependent variable and the independent variables were year (2011, 2014 and 2015), patch (roosting vs. non-roosting reed patches), sex and nest ID (as random effect). We found that the nest defence behaviour of great reed warblers was more intensive in years when starlings roosted. The significant interaction between year and patch indicated that the nest defence behaviour was more intensive in roosting reed patches. Similarly to previous studies, the females defended the nest more aggressively than the males. In conclusion, we suggest that nest defence behaviour of the great reed warbler in roosting areas might be influenced by various factors, e.g. the excessive noise of roosting starlings or the motion and density of birds in the vicinity of the nests.
Despite efforts on ecosystem restoration and management, biodiversity loss remains one of the maj... more Despite efforts on ecosystem restoration and management, biodiversity loss remains one of the major environmental concerns of our time. Beyond the focus on threatened species, animals that indicate regional biodiversity hotspots and population trends, such as brood parasites, should also be targeted by conservation actions. We studied how reed habitat quality and management influence brood parasitism rate and offspring survival in Common Cuckoos Cuculus canorus parasitizing nests of Great Reed Warblers Acrocephalus arundinaceus in six reed habitats in an intensive agricultural landscape. Data collected from 45 sites over 13 years showed that the brood parasitism rate was highest on large canals and was positively influenced by the availability of potential perches (Cuckoo vantage points) and the height where host nests were built. Cuckoo chick survival decreased with water depth and was not affected by other factors. Our results suggest that the habitat-dependent detectability of host nests was central in brood parasitism rate and that water level was central in Cuckoo chick survival. Our study shows that a maintenance of intermediate water levels is the most optimal for maintaining Cuckoo populations in intensive agricultural landscapes. Because brood parasites are excellent bioindicators as their presence predicts regional hotspots of taxonomic and functional diversity as well as population trends in bird communities, knowledge on their habitat requirements is relevant in management targeting diverse bird communities.
Knowledge of the effects of nest position with regards to distance from shore and vegetation stru... more Knowledge of the effects of nest position with regards to distance from shore and vegetation structure on the nest defence behaviour of Great Reed Warblers is lacking. Nest defence behaviour was investigated in the case of 110 monogamous breeding pairs during the breeding season of 2011. We found that nest distance from shoreline and from the reed edge adjacent to water, and reed density, influenced nest defence behaviour positively. However, time elapsed since hatching did not affect parental behaviour. Similar to what was found in previous studies, females defended nests more intensively. Previous papers reported higher predation pressure near both reed edge types (near shoreline and water) than in interior parts of the reed bed, and considering these and our results we suggest that the nest defence pattern of monogamous Great Reed Warblers may vary similarly near both edge types, while in the case of interior parts of reed beds further studies are required for proper conclusions.
We surveyed five reed habitats (mining pond, sand pit, large canal, small canal and lowland river... more We surveyed five reed habitats (mining pond, sand pit, large canal, small canal and lowland river) in northwestern Vojvodina (Serbia) between 2009-2011 to study habitat use and to estimate nest success in an understudied region of the breeding range of the Great Reed Warbler (Acrocephalus arundinaceus). Data from 174 nests showed that habitat use differed considerably between the habitat types, but was not related to the area of the study site or the reed bed. Higher-than-expected numbers of nests along the small canal and the river suggested that Great Reed Warblers preferred these to other habitats for nesting. Habitat use was closely linked to the availability of reed edges and the quality of the reed stand. Overall Mayfield nest success was 43%, slightly lower than in northern and western Europe. Nest success was low along the small and large canal, where brood parasitism by Common Cuckoos (Cuculus canorus) and nest predation were high due to nearby tree lines providing perching sites to cuckoos and predators. Nest success was intermediate at the mining pond due to very high predation pressure and adverse weather, and nest success was highest in the sand pit (despite high Cuckoo parasitism) and the river (despite relatively high predation). In conclusion, our results suggest that canals can function as ecological traps, which attract edge-preferring Great Reed Warblers but are highly accessible to predators and brood parasites. In contrast, sand pits can be perceptual traps because they provide good resources for nesting but were less attractive to Great Reed Warblers than other habitats. Habitat use in relation to habitat availability thus depends primarily on the availability of reed edges and the quality of the reed stand, whereas nest success also depends on the characteristics of the surroundings and weather conditions.
Although previous studies have reported on rare nesting behaviour such as nest reuse and/or unusu... more Although previous studies have reported on rare nesting behaviour such as nest reuse and/or unusual nest construction in open nesting passerines, very little is known about these rare phenomena. We found and monitored 1224 Great Reed Warbler nests between 2008 and 2017. In three nests, we found reuse of nests in the same season; two nests were reused after a Cuckoo chick had disappeared and one nest was reused after a damaged egg had been ejected. In two other nests, we observed that replacement nests were built directly under the original nest, using the same reed stems. These observations suggest that there may be cases when breeding Great Reed Warblers benefit from performing unusual yet adaptive behaviour, such as conserving energy and time when nests are reused, or recognizing the advantages of original nests, e.g. they may serve as cover and/or concealment.
This study provides preliminary findings related to whether and how the roosting of Starlings (St... more This study provides preliminary findings related to whether and how the roosting of Starlings (Sturnus vulgaris) in reedbeds influences the survival of clutches of the Great Reed Warbler (Acrocephalus arundinaceus). During the nesting seasons of 2014 and 2015, we surveyed the complete area of a mining pond in Serbia (south-eastern Europe) for Great Reed Warbler nests, and the presence of roosting Starlings was also recorded. Using the Mayfield method, we estimated the daily survival rate of Great Reed Warbler eggs and nestlings, and compared these rates between Starling roosting and non-roosting areas. Although both egg and nestling survival rates were lower in the Starling roosting than in the non-roosting areas, the differences were not significant, which was also reflected in overall nesting success. However, when only data from the time period when Starling roosting occurred, the overall Great Reed Warbler egg survival was significantly lower in roosting areas than in non-roosting areas. Our results suggest that Starling roosting did not influence the clutch survival of the Great Reed Warbler significantly, but that there can be a negative short-term or local effect. Our study implies that a larger number of Starlings and a longer roosting period could affect clutch survival more negatively.
Intersexual differences in habitat choice can arise if males and females differ in morphology, ph... more 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. Notre jeu de données, comportant 391 femelles nicheuses à 32 sites sur une période de 10 ans, a révélé que la longueur de l'aile était considérablement plus grande chez les femelles occupant les étangs miniers et les canaux de largeur moyenne, comparativement à celles occupant les grands canaux. La longueur de l'aile était négativement liée aux fluctuations du niveau d'eau et les femelles ont montré une forte philopatrie au type de milieu dans lequel elles avaient été capturées la première fois. Comparativement à notre étude précédente portant sur la sélection d'habitat chez les mâles, la présente étude a fait état de différences selon le sexe dans la sélection d'habitat. Même si les individus aux longues ailes chez les deux sexes ont préféré les milieux montrant un niveau d'eau stable et évité les petits canaux, les mâles aux ailes plus longues ont préféré les grands canaux peu ou non aménagés, tandis que les femelles aux ailes longues ont préféré les moyens canaux un peu aménagés. Bien que ces résultats corroborent jusqu'à un certain point une différenciation de niche fondée sur le sexe, il est aussi possible que les femelles aux longues ailes évitent les canaux larges, dans lesquels le parasitisme de nids par les coucous (Cuculus canorus) est fréquent, et/ou préfèrent les îlots de roseaux épars et aménagés, qui permettent de manoeuvrer plus facilement pour chercher la nourriture. Nos études laissent croire que les mâles sélectionnent peutêtre d'abord les milieux comprenant de nombreux vieux roseaux et des perchoirs desquels chanter, tandis que les femelles sont moins sensibles aux variations environnementales et sélectionnent sans doute des sites de nidification en fonction de la qualité du mâle ou du territoire. Aux fins de conservation, nous études indiquent que le maintien d'un niveau d'eau stable, l'aménagement à faible intensité et l'élimination des perchoirs de coucous sont vraisemblablement susceptibles de profiter tant aux mâles qu'aux femelles aux longues ailes.
Végvári 2016. Migration routes and stopover sites of the Eurasian Spoonbill (Platalea leucorodia)... more Végvári 2016. Migration routes and stopover sites of the Eurasian Spoonbill (Platalea leucorodia) between the Carpathian Basin and wintering areas.-Ornis Hungarica 24(1): 128-149.
The reproductive period in animals is a demanding part in their life history. In birds, environme... more The reproductive period in animals is a demanding part in their life history. In birds, environmental factors, such as adverse weather, predation, or brood parasitism; and/or anthropogenic disturbance, can limit breeding success, resulting in failure of clutches. The nest loss in open‐cup nesting passerines is usually replaced with a new nest with a new clutch, however, in some cases the clutch replacement may occur in unusual forms. In this study, we report on three cases of within‐season nest reuse in the Great Reed Warbler. In the first case, a nest was reused for two times in the same season after unsuccessful nesting attempts (two‐time nest reuse). After the nest was depredated the first time, the female laid new eggs that were depredated again, then again the female laid new eggs that produced four fledglings. In the second case, the first clutch was depredated, after which the female laid a new clutch in the same nest that was again depredated. In the third case, the female laid new eggs among the eggs that failed to hatch previously. Our observations tend not to be consistent with the predator avoidance hypothesis because the depredated nests were reused by the parents. The time/energy saving hypothesis or possible deterrence of nest parasitism could explain nest reuse in this study, but because of low number of nests reused compared to the total number of nests found, this phenomenon needs further clarification.
Long-eared Owls (Asio otus) frequently inhabit humanaltered landscapes, including residential are... more Long-eared Owls (Asio otus) frequently inhabit humanaltered landscapes, including residential areas in cities, where they usually breed in nests of corvids, and roost communally on trees during the autumn and winter (Pirovano et al. 2000, König and Weick 2008). Winter roosting sites are often located in urban/suburban areas (Makarova and Sharikov 2015) and can hold several hundred individuals (up to approximately 400 individuals; Ružić et al. 2009). Although Long-eared Owls have widely varying diets, they are considered specialist predators that prey primarily on small mammals (e.g., Microtus voles, Apodemus mice). Most studies conducted in Europe have concluded that small mammals are the most important prey of this species (Nilsson 1981, Escala et al. 2009, Dziemian et al. 2012) and can make up to 93% of the prey consumed (Birrer 2009). Pellet analyses usually document a very low proportion and occasional rather than regular occurrence of birds in the owls’ diet (e.g., Romanowski and Zmihorski 2008). In most cases, these were small-bodied passerines such as tits (Paridae), sparrows (Passeridae), and finches (Fringillidae), and larger birds were incidental (Sándor and Kiss 2008). Owls wintering in cities usually hunt outside the settlements in grasslands, agricultural areas, or shrubby habitats (Tulis et al. 2019). However, unfavorable weather conditions and/or rapid changes in small mammal prey communities may change the hunting behavior and strategies of owls (Canova 1989). We here report and discuss an observation of unusual prey selection and hunting behavior in the Long-eared Owl. Our observations took place in Sombor, a town in northwestern Serbia (southeastern Europe) with semicontinental climate and a human population of approximately 48,000 inhabitants (Mér} o and Žuljević 2010). During 27 February to 6 March 2018, temperatures were considerably colder than average, with lowest daily mean temperature around –108C (on average, mean lowest temperature is approximately –0.78C); the minimum temperature on 1 March was –258C. Approximately 15 cm of snow covered the region. Trees planted along avenues, in parks, and in gardens of private residences provide the major vegetative cover in the town; common deciduous species include common hackberry (Celtis occidentalis), London plane tree (Platanus 3 acerifolia), horse chestnut (Aesculus hippocastanum), and Japanese pagoda-tree (Sophora japonica). Gardens often contain coniferous trees (Mér} o and Žuljević 2010). In the gardens of the study site (banding locality) and the surrounding gardens, the most frequently planted tree species are pines (Pinus spp.), black locust (Robinia pseudoacacia), and elder (Sambucus nigra). Monitoring of Long-eared Owls wintering in Sombor started in winter 2014/2015. Every winter, between 120 and 150 Long-eared Owls roost in the center of Sombor (Mér} o and Žuljević 2010). We observed the behavior and movement of owls, captured them, and banded them with aluminum rings between November and March each winter. Our banding localities (n 1⁄4 8; Mér} o and Žuljević 2020) were in larger gardens with open areas in the urban and semi-urban regions of the town. We used mist nets to 1 Email address: [email protected]
Management of reed beds primarily includes controlling water levels and removing vegetation by mo... more Management of reed beds primarily includes controlling water levels and removing vegetation by mowing, burning, or grazing. Although recent studies have demonstrated increased diversity and abundance of wetland specialists after reed bed management, documenting demographic benefits to individual species would add additional support to the advantages of appropriate management. Here, we explore the effects of reed management on the philopatry of Great Reed Warblers (Acrocephalus arundinaceus) over 7 yr. Reed beds were managed in the winter by occasional burning at mining ponds and large canals, infrequent burning in marshes, and frequent mowing of small canals. Based on resightings and recaptures of 1,243 adult and 1,428 nestlings individually marked at 57 sites in 6 different reed habitats, we built Cormack-Jolly-Seber models to estimate the apparent annual survival and encounter probabilities of birds banded as nestlings or as adults. Apparent survival varied in time for both age groups and both sexes, suggesting annual fluctuations in survival, whereas encounter probability remained constant across years. The encounter probability of birds banded as juveniles was higher in reed beds with shallower water. The encounter probability of birds banded as adults was higher in reed beds with deeper water for females, and strongly increased with variation in reed management and less strongly with variation in water depth for males. We also found that the few returning juveniles displayed strong philopatry to the reed habitat occupied in their first breeding season. Our study provides evidence that reed management influences the return rates of juveniles and adult males and females in different ways. Spatially variable reed management by mowing or burning should be applied and water of varying depths should be maintained to maximize return rates of Great Reed Warblers.
Nesting parameters such as clutch size, hatching rate or nesting success have been extensively st... more Nesting parameters such as clutch size, hatching rate or nesting success have been extensively studied in birds in relation to biotic and abiotic factors. In this study we aimed to investigate the effects of air temperature, amount of precipitation, reed burning, and water depth (independent variables) on nest density, clutch size, hatching rate, and nesting success (dependent variables) of the Great Reed Warbler during a nine-year period. We found that neither the clutch size nor the hatching rate was influenced by any of the predictor variables. Nest density was positively influenced by the water depth, while the nesting success was negatively related to the amount of precipitation. Reed burning had no effect on any of the nesting parameters. Similarly, to our results, short-term studies reported a positive relationship between nest density and water depth, and a negative relationship between the nesting success and amount of precipitation, indicating that these two environmental ...
near Zrče, Pag Island (UTM VK93, N Dalmatia); no published records of the species for Pag or othe... more near Zrče, Pag Island (UTM VK93, N Dalmatia); no published records of the species for Pag or other Croatian islands Dne 29. 10. 2016 sva z Andrejem Sovincem obročkala ptiče v Zrčah na otoku Pagu. Mrežo sva imela postavljeno v borovem gozdu, glavni namen pa je bil obročkanje obeh vrst kraljičkov Regulus regulus/ignicapillus. Ko je bilo že vse skoraj pripravljeno za lov, sva v bližini zaslišala značilno oglašanje žalobne sinice. Ko sem vklopil posnetek petja omenjene vrste, sem, glede na izkušnje od drugod, predvideval, da jo bova tudi ujela. Čeprav se žalobna sinica zelo rada odzove na posnetek, je ni bilo blizu, še manj pa v mreži. Domnevala sva, da je bila v letu, in s posnetkom sva jo verjetno zamudila, tako da ni priletela v najino bližino. Podatek niti ne bi bil tako zanimiv, če bi vrsto med svojim dolgoletnim preučevanjem ptic otoka Paga zabeležil že kdaj prej. Tudi Rucner (1998) navaja, da žalobne sinice ni našel na nobenem jadranskem otoku. Znano pa je, da gnezdi v Nacionalnem parku Paklenica (Lukač 2011) v neposredni bližini otoka Paga. Dopuščava možnost, da je to žalobno sinico na otok Pag prinesla orkanska burja, ki je pihala prejšnji dan iz smeri Paklenice. Doslej se je na otoku Pagu že večkrat izkazalo, da je dan po burji najbolj primeren za opazovanje redkih in zanimivih vrst.
During winter, Long-eared Owls (Asio otus) usually roost in groups in urban areas, but their noct... more During winter, Long-eared Owls (Asio otus) usually roost in groups in urban areas, but their nocturnal movement patterns are less known. The aim of our study is to provide insight into the local-scale urban movement habits of Long-eared Owls. Our study was carried out between 2015 and 2019 in the autumn and winter period, by observations in the early evening and by ringing and recapture of owls in the town of Sombor (NE Serbia). We observed owls when leaving the roosting site located in the town centre following the greenery of the larger avenues towards the outskirts. Owls were sporadically observed in densely built areas of the town, narrow streets with less greenery. Ringing and recapture data suggest that owls were closely linked to the green corridors. They probably used these corridors for easier orientation and to prey on birds roosting in trees in the town, such as sparrows (Passer domesticus, P. montanus), Common Blackbirds (Turdus merula) or Fieldfares (T. pilaris) appearing in harsh winters, and sometimes also pigeons.
In this study we explored the linkage between wing size of Great Reed Warbler males (Acrocephalus... more 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.
We studied the effects of roosting starlings, Sturnus vulgaris, on the nest defence behaviour of ... more We studied the effects of roosting starlings, Sturnus vulgaris, on the nest defence behaviour of great reed warbler, Acrocephalus arundinaceus, monogamous parents from 54 nests. A generalised linear mixed model was constructed to investigate the effects where the nest defence behaviour was the dependent variable and the independent variables were year (2011, 2014 and 2015), patch (roosting vs. non-roosting reed patches), sex and nest ID (as random effect). We found that the nest defence behaviour of great reed warblers was more intensive in years when starlings roosted. The significant interaction between year and patch indicated that the nest defence behaviour was more intensive in roosting reed patches. Similarly to previous studies, the females defended the nest more aggressively than the males. In conclusion, we suggest that nest defence behaviour of the great reed warbler in roosting areas might be influenced by various factors, e.g. the excessive noise of roosting starlings or the motion and density of birds in the vicinity of the nests.
Despite efforts on ecosystem restoration and management, biodiversity loss remains one of the maj... more Despite efforts on ecosystem restoration and management, biodiversity loss remains one of the major environmental concerns of our time. Beyond the focus on threatened species, animals that indicate regional biodiversity hotspots and population trends, such as brood parasites, should also be targeted by conservation actions. We studied how reed habitat quality and management influence brood parasitism rate and offspring survival in Common Cuckoos Cuculus canorus parasitizing nests of Great Reed Warblers Acrocephalus arundinaceus in six reed habitats in an intensive agricultural landscape. Data collected from 45 sites over 13 years showed that the brood parasitism rate was highest on large canals and was positively influenced by the availability of potential perches (Cuckoo vantage points) and the height where host nests were built. Cuckoo chick survival decreased with water depth and was not affected by other factors. Our results suggest that the habitat-dependent detectability of host nests was central in brood parasitism rate and that water level was central in Cuckoo chick survival. Our study shows that a maintenance of intermediate water levels is the most optimal for maintaining Cuckoo populations in intensive agricultural landscapes. Because brood parasites are excellent bioindicators as their presence predicts regional hotspots of taxonomic and functional diversity as well as population trends in bird communities, knowledge on their habitat requirements is relevant in management targeting diverse bird communities.
Knowledge of the effects of nest position with regards to distance from shore and vegetation stru... more Knowledge of the effects of nest position with regards to distance from shore and vegetation structure on the nest defence behaviour of Great Reed Warblers is lacking. Nest defence behaviour was investigated in the case of 110 monogamous breeding pairs during the breeding season of 2011. We found that nest distance from shoreline and from the reed edge adjacent to water, and reed density, influenced nest defence behaviour positively. However, time elapsed since hatching did not affect parental behaviour. Similar to what was found in previous studies, females defended nests more intensively. Previous papers reported higher predation pressure near both reed edge types (near shoreline and water) than in interior parts of the reed bed, and considering these and our results we suggest that the nest defence pattern of monogamous Great Reed Warblers may vary similarly near both edge types, while in the case of interior parts of reed beds further studies are required for proper conclusions.
We surveyed five reed habitats (mining pond, sand pit, large canal, small canal and lowland river... more We surveyed five reed habitats (mining pond, sand pit, large canal, small canal and lowland river) in northwestern Vojvodina (Serbia) between 2009-2011 to study habitat use and to estimate nest success in an understudied region of the breeding range of the Great Reed Warbler (Acrocephalus arundinaceus). Data from 174 nests showed that habitat use differed considerably between the habitat types, but was not related to the area of the study site or the reed bed. Higher-than-expected numbers of nests along the small canal and the river suggested that Great Reed Warblers preferred these to other habitats for nesting. Habitat use was closely linked to the availability of reed edges and the quality of the reed stand. Overall Mayfield nest success was 43%, slightly lower than in northern and western Europe. Nest success was low along the small and large canal, where brood parasitism by Common Cuckoos (Cuculus canorus) and nest predation were high due to nearby tree lines providing perching sites to cuckoos and predators. Nest success was intermediate at the mining pond due to very high predation pressure and adverse weather, and nest success was highest in the sand pit (despite high Cuckoo parasitism) and the river (despite relatively high predation). In conclusion, our results suggest that canals can function as ecological traps, which attract edge-preferring Great Reed Warblers but are highly accessible to predators and brood parasites. In contrast, sand pits can be perceptual traps because they provide good resources for nesting but were less attractive to Great Reed Warblers than other habitats. Habitat use in relation to habitat availability thus depends primarily on the availability of reed edges and the quality of the reed stand, whereas nest success also depends on the characteristics of the surroundings and weather conditions.
Although previous studies have reported on rare nesting behaviour such as nest reuse and/or unusu... more Although previous studies have reported on rare nesting behaviour such as nest reuse and/or unusual nest construction in open nesting passerines, very little is known about these rare phenomena. We found and monitored 1224 Great Reed Warbler nests between 2008 and 2017. In three nests, we found reuse of nests in the same season; two nests were reused after a Cuckoo chick had disappeared and one nest was reused after a damaged egg had been ejected. In two other nests, we observed that replacement nests were built directly under the original nest, using the same reed stems. These observations suggest that there may be cases when breeding Great Reed Warblers benefit from performing unusual yet adaptive behaviour, such as conserving energy and time when nests are reused, or recognizing the advantages of original nests, e.g. they may serve as cover and/or concealment.
This study provides preliminary findings related to whether and how the roosting of Starlings (St... more This study provides preliminary findings related to whether and how the roosting of Starlings (Sturnus vulgaris) in reedbeds influences the survival of clutches of the Great Reed Warbler (Acrocephalus arundinaceus). During the nesting seasons of 2014 and 2015, we surveyed the complete area of a mining pond in Serbia (south-eastern Europe) for Great Reed Warbler nests, and the presence of roosting Starlings was also recorded. Using the Mayfield method, we estimated the daily survival rate of Great Reed Warbler eggs and nestlings, and compared these rates between Starling roosting and non-roosting areas. Although both egg and nestling survival rates were lower in the Starling roosting than in the non-roosting areas, the differences were not significant, which was also reflected in overall nesting success. However, when only data from the time period when Starling roosting occurred, the overall Great Reed Warbler egg survival was significantly lower in roosting areas than in non-roosting areas. Our results suggest that Starling roosting did not influence the clutch survival of the Great Reed Warbler significantly, but that there can be a negative short-term or local effect. Our study implies that a larger number of Starlings and a longer roosting period could affect clutch survival more negatively.
Intersexual differences in habitat choice can arise if males and females differ in morphology, ph... more 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. Notre jeu de données, comportant 391 femelles nicheuses à 32 sites sur une période de 10 ans, a révélé que la longueur de l'aile était considérablement plus grande chez les femelles occupant les étangs miniers et les canaux de largeur moyenne, comparativement à celles occupant les grands canaux. La longueur de l'aile était négativement liée aux fluctuations du niveau d'eau et les femelles ont montré une forte philopatrie au type de milieu dans lequel elles avaient été capturées la première fois. Comparativement à notre étude précédente portant sur la sélection d'habitat chez les mâles, la présente étude a fait état de différences selon le sexe dans la sélection d'habitat. Même si les individus aux longues ailes chez les deux sexes ont préféré les milieux montrant un niveau d'eau stable et évité les petits canaux, les mâles aux ailes plus longues ont préféré les grands canaux peu ou non aménagés, tandis que les femelles aux ailes longues ont préféré les moyens canaux un peu aménagés. Bien que ces résultats corroborent jusqu'à un certain point une différenciation de niche fondée sur le sexe, il est aussi possible que les femelles aux longues ailes évitent les canaux larges, dans lesquels le parasitisme de nids par les coucous (Cuculus canorus) est fréquent, et/ou préfèrent les îlots de roseaux épars et aménagés, qui permettent de manoeuvrer plus facilement pour chercher la nourriture. Nos études laissent croire que les mâles sélectionnent peutêtre d'abord les milieux comprenant de nombreux vieux roseaux et des perchoirs desquels chanter, tandis que les femelles sont moins sensibles aux variations environnementales et sélectionnent sans doute des sites de nidification en fonction de la qualité du mâle ou du territoire. Aux fins de conservation, nous études indiquent que le maintien d'un niveau d'eau stable, l'aménagement à faible intensité et l'élimination des perchoirs de coucous sont vraisemblablement susceptibles de profiter tant aux mâles qu'aux femelles aux longues ailes.
Végvári 2016. Migration routes and stopover sites of the Eurasian Spoonbill (Platalea leucorodia)... more Végvári 2016. Migration routes and stopover sites of the Eurasian Spoonbill (Platalea leucorodia) between the Carpathian Basin and wintering areas.-Ornis Hungarica 24(1): 128-149.
The reproductive period in animals is a demanding part in their life history. In birds, environme... more The reproductive period in animals is a demanding part in their life history. In birds, environmental factors, such as adverse weather, predation, or brood parasitism; and/or anthropogenic disturbance, can limit breeding success, resulting in failure of clutches. The nest loss in open‐cup nesting passerines is usually replaced with a new nest with a new clutch, however, in some cases the clutch replacement may occur in unusual forms. In this study, we report on three cases of within‐season nest reuse in the Great Reed Warbler. In the first case, a nest was reused for two times in the same season after unsuccessful nesting attempts (two‐time nest reuse). After the nest was depredated the first time, the female laid new eggs that were depredated again, then again the female laid new eggs that produced four fledglings. In the second case, the first clutch was depredated, after which the female laid a new clutch in the same nest that was again depredated. In the third case, the female laid new eggs among the eggs that failed to hatch previously. Our observations tend not to be consistent with the predator avoidance hypothesis because the depredated nests were reused by the parents. The time/energy saving hypothesis or possible deterrence of nest parasitism could explain nest reuse in this study, but because of low number of nests reused compared to the total number of nests found, this phenomenon needs further clarification.
Long-eared Owls (Asio otus) frequently inhabit humanaltered landscapes, including residential are... more Long-eared Owls (Asio otus) frequently inhabit humanaltered landscapes, including residential areas in cities, where they usually breed in nests of corvids, and roost communally on trees during the autumn and winter (Pirovano et al. 2000, König and Weick 2008). Winter roosting sites are often located in urban/suburban areas (Makarova and Sharikov 2015) and can hold several hundred individuals (up to approximately 400 individuals; Ružić et al. 2009). Although Long-eared Owls have widely varying diets, they are considered specialist predators that prey primarily on small mammals (e.g., Microtus voles, Apodemus mice). Most studies conducted in Europe have concluded that small mammals are the most important prey of this species (Nilsson 1981, Escala et al. 2009, Dziemian et al. 2012) and can make up to 93% of the prey consumed (Birrer 2009). Pellet analyses usually document a very low proportion and occasional rather than regular occurrence of birds in the owls’ diet (e.g., Romanowski and Zmihorski 2008). In most cases, these were small-bodied passerines such as tits (Paridae), sparrows (Passeridae), and finches (Fringillidae), and larger birds were incidental (Sándor and Kiss 2008). Owls wintering in cities usually hunt outside the settlements in grasslands, agricultural areas, or shrubby habitats (Tulis et al. 2019). However, unfavorable weather conditions and/or rapid changes in small mammal prey communities may change the hunting behavior and strategies of owls (Canova 1989). We here report and discuss an observation of unusual prey selection and hunting behavior in the Long-eared Owl. Our observations took place in Sombor, a town in northwestern Serbia (southeastern Europe) with semicontinental climate and a human population of approximately 48,000 inhabitants (Mér} o and Žuljević 2010). During 27 February to 6 March 2018, temperatures were considerably colder than average, with lowest daily mean temperature around –108C (on average, mean lowest temperature is approximately –0.78C); the minimum temperature on 1 March was –258C. Approximately 15 cm of snow covered the region. Trees planted along avenues, in parks, and in gardens of private residences provide the major vegetative cover in the town; common deciduous species include common hackberry (Celtis occidentalis), London plane tree (Platanus 3 acerifolia), horse chestnut (Aesculus hippocastanum), and Japanese pagoda-tree (Sophora japonica). Gardens often contain coniferous trees (Mér} o and Žuljević 2010). In the gardens of the study site (banding locality) and the surrounding gardens, the most frequently planted tree species are pines (Pinus spp.), black locust (Robinia pseudoacacia), and elder (Sambucus nigra). Monitoring of Long-eared Owls wintering in Sombor started in winter 2014/2015. Every winter, between 120 and 150 Long-eared Owls roost in the center of Sombor (Mér} o and Žuljević 2010). We observed the behavior and movement of owls, captured them, and banded them with aluminum rings between November and March each winter. Our banding localities (n 1⁄4 8; Mér} o and Žuljević 2020) were in larger gardens with open areas in the urban and semi-urban regions of the town. We used mist nets to 1 Email address: [email protected]
Management of reed beds primarily includes controlling water levels and removing vegetation by mo... more Management of reed beds primarily includes controlling water levels and removing vegetation by mowing, burning, or grazing. Although recent studies have demonstrated increased diversity and abundance of wetland specialists after reed bed management, documenting demographic benefits to individual species would add additional support to the advantages of appropriate management. Here, we explore the effects of reed management on the philopatry of Great Reed Warblers (Acrocephalus arundinaceus) over 7 yr. Reed beds were managed in the winter by occasional burning at mining ponds and large canals, infrequent burning in marshes, and frequent mowing of small canals. Based on resightings and recaptures of 1,243 adult and 1,428 nestlings individually marked at 57 sites in 6 different reed habitats, we built Cormack-Jolly-Seber models to estimate the apparent annual survival and encounter probabilities of birds banded as nestlings or as adults. Apparent survival varied in time for both age groups and both sexes, suggesting annual fluctuations in survival, whereas encounter probability remained constant across years. The encounter probability of birds banded as juveniles was higher in reed beds with shallower water. The encounter probability of birds banded as adults was higher in reed beds with deeper water for females, and strongly increased with variation in reed management and less strongly with variation in water depth for males. We also found that the few returning juveniles displayed strong philopatry to the reed habitat occupied in their first breeding season. Our study provides evidence that reed management influences the return rates of juveniles and adult males and females in different ways. Spatially variable reed management by mowing or burning should be applied and water of varying depths should be maintained to maximize return rates of Great Reed Warblers.
Nesting parameters such as clutch size, hatching rate or nesting success have been extensively st... more Nesting parameters such as clutch size, hatching rate or nesting success have been extensively studied in birds in relation to biotic and abiotic factors. In this study we aimed to investigate the effects of air temperature, amount of precipitation, reed burning, and water depth (independent variables) on nest density, clutch size, hatching rate, and nesting success (dependent variables) of the Great Reed Warbler during a nine-year period. We found that neither the clutch size nor the hatching rate was influenced by any of the predictor variables. Nest density was positively influenced by the water depth, while the nesting success was negatively related to the amount of precipitation. Reed burning had no effect on any of the nesting parameters. Similarly, to our results, short-term studies reported a positive relationship between nest density and water depth, and a negative relationship between the nesting success and amount of precipitation, indicating that these two environmental ...
near Zrče, Pag Island (UTM VK93, N Dalmatia); no published records of the species for Pag or othe... more near Zrče, Pag Island (UTM VK93, N Dalmatia); no published records of the species for Pag or other Croatian islands Dne 29. 10. 2016 sva z Andrejem Sovincem obročkala ptiče v Zrčah na otoku Pagu. Mrežo sva imela postavljeno v borovem gozdu, glavni namen pa je bil obročkanje obeh vrst kraljičkov Regulus regulus/ignicapillus. Ko je bilo že vse skoraj pripravljeno za lov, sva v bližini zaslišala značilno oglašanje žalobne sinice. Ko sem vklopil posnetek petja omenjene vrste, sem, glede na izkušnje od drugod, predvideval, da jo bova tudi ujela. Čeprav se žalobna sinica zelo rada odzove na posnetek, je ni bilo blizu, še manj pa v mreži. Domnevala sva, da je bila v letu, in s posnetkom sva jo verjetno zamudila, tako da ni priletela v najino bližino. Podatek niti ne bi bil tako zanimiv, če bi vrsto med svojim dolgoletnim preučevanjem ptic otoka Paga zabeležil že kdaj prej. Tudi Rucner (1998) navaja, da žalobne sinice ni našel na nobenem jadranskem otoku. Znano pa je, da gnezdi v Nacionalnem parku Paklenica (Lukač 2011) v neposredni bližini otoka Paga. Dopuščava možnost, da je to žalobno sinico na otok Pag prinesla orkanska burja, ki je pihala prejšnji dan iz smeri Paklenice. Doslej se je na otoku Pagu že večkrat izkazalo, da je dan po burji najbolj primeren za opazovanje redkih in zanimivih vrst.
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