Thomas Oliver Mérő

• PhD
• Research Fellow at Centre for Ecological Research

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 func...

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...

Freshwater wetlands and marshes with extensive reed beds are important hotspots of biological diversity, but in the absence of proper management, they are subject to biotic homogenisation. We assessed the impact of spatiotemporally variable management by cattle grazing (for 4 years) and late-summer burning (1 or 3 years before the study) on both so...

Clutch initiation date decreased with longitude, clutch size increased with latitude and decreased with maximum temperature, whereas the number of fledglings increased both with latitude and longitude, and decreased with maximum temperature in 19 European studies of the Great Reed Warbler. Our study confirmed previous findings about the increasing...

So far, much effort has been invested in the conservation of vulnerable freshwater habitats, yet their number still displays a decreasing tendency worldwide. Although many species have accepted man-made wetlands, their frequent disturbance may have a negative impact on these species. In this study, we examined the effects of human disturbance on th...

Freshwater wetlands and their biodiversity have suffered substantial losses globally, mainly due to the drainage of wetlands for agriculture. Recent studies suggest that small drainage and/or irrigation canals established in lowland areas can function both as partial replacement of wetlands lost and as biodiversity hotspots in agricultural landscap...

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 habi...

The decline of farmland bird populations starting in the 1980s has induced intense research on farmland biodiversity conservation in Europe. Although many studies assessing the effectiveness of agri-environmental schemes have concentrated on birds, farmland birds, surprisingly, have not yet been targeted directly by permanent, landscape-scale resto...

Here we report the first record of the Orange-flanked Bush-robin Tarsiger cyanurus in Serbia, the westernmost record of this species on the Balkan Peninsula. The individual aged as 2Y (in second calendar year) was ringed in Tara National Park, Western Serbia, on 7 October, 2020. The bird was caught in a mist net situated in a young open-canopy mixe...

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...

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 ear...

The degradation and loss of habitats are one of the major causes of the recent global decline of amphibian populations, and wetland ecosystems are increasingly restored to counter these effects. However, there is little information on how restoration of non-wetland habitats such as grasslands affect amphibians in wet-terrestrial habitat complexes....

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 aru...

Ecosystem restoration implies focusing on multiple trophic levels and ecosystem functioning, yet higher trophic levels, i.e., animals, are less frequently targeted by restoration than plants. Habitat diversity, the spatial heterogeneity between and within habitat patches in a landscape, is a well‐known driver of species diversity, and offers possib...

In this report, we present for the first time a detailed historical overview and documentation of 110 years of bird ringing in Serbia. The ringing of birds in Northern Serbia (Vojvodina) has a long tradition, starting in 1908. As far as we can establish, Károlyné Fernbach, née Dóra Karácson from Sombor, a further key figure who recognised the impor...

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 reus...

Between early December 2016 and late February 2017, we examined catfish (Silurus glanis) in Serbia to find the fish leech Piscicola fasciata Kollar, 1842. On December 26, 2016, we collected eight specimens from the head area of one catfish. As far as we know, this is the first published record of P. fasciata in Serbia and for the middle section of...

In Serbia, adult Sparrowhawks remain at their territories year-around while juveniles probably partially migrate. Sparrowhawk is regularly breeding in forest habitats, as well in parks and urban forests. The population size is estimated to 700-900 breeding pairs. In the period 1993-2016, 202 individuals were ringed (including 35 nestlings and 167 o...

While some previous investigations have been made into the effects of vegetation structure on the probability of brood parasitism in reed passerines, the effects of vegetation management remain unclear. Furthermore, we possess little information on how vegetation density influences the probability of brood parasitism in wide-surfaced reed-beds. The...

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 advantage...

We present a method for estimating nesting population size in a passerine bird based on counts of active nests, which can provide more accurate estimates on true population size than other methods. We surveyed five different reed habitat types in a region of Serbia in 2009-2011 to estimate the population size of the Great Reed Warbler. The estimati...

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...

A kétéltűek (Amphibia) globálisan az egyik legveszélyeztetettebb élőlénycsoport, ezért elterjedésük ismerete alapvetően fontos, különösen olyan védett területeken, ahonnan kevés a korábbi információ és aktív beavatkozások zajlanak. Jelen munkánkban összesítjük az Egyek-pusztakócsi mocsarak területén több korábbi vizsgálatban végzett felméréseink fa...

Grasslands host a high diversity of plant and animal species. In Serbia, most alkali grasslands are located in the province of Vojvodina. The majority are not subject to conservation. The aim of the study was to investigate the relationship between the proportion of croplands and (1) the number of breeding species and (2) the number of breeding pai...

Marsh Warbler vocally imitates Great Reed Warbler

Upravljanje prirodnom baštinom u Vojvodini, Natural Heritage Management in Vojvodina edited by Puzović, S. & Panjković, B.; authors: Puzović, S., Panjković, B., Tucakov, M., Stojnić, N., Sabadoš, K., Stojanović, T., Vig, L., Marić, B., Tešić, O., Kiš, A., Galamboš, L., Pil, N., Kicošev, V., Stojšić, V., Timotić, D., Perić, R., Bošnjak, T., Delić, J...

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, a...

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 y...

In the spring of 2011,an individual of the rotan, Perccottus glenii Dybowski 1877, was found in the stomach of a European perch, Perca fluviatilis L., captured in a drainage-irrigation channel in eastern Hungary. This is the first recording of the rotan found in the diet of the European Perch in Central Europe.

Pozvetek Objavljanje in osnovna analiza obročkovalskih podatkov sta sicer pogosti temi člankov, redko pa so objavljeni podatki iz posameznega mesta, kot je denimo Sombor v premalo raziskani regiji Srbije. Predstavljamo podatke o obročkanju in ponovnem ulovu plavčkov Cyanistes caeruleus in velikih sinic Parus major za obdobje 32 let. Dodatno smo pre...

We surveyed five reed habitats (mining pond, sand pit, large canal, small canal and lowland river) in north-western Vojvodina (Serbia) between 2009–2011 to study habitat use and to estimate nesting success in an understudied region of the breeding range of the Great Reed Warbler (Acrocephalus arundinaceus). Data from 174 nests showed that habitat u...

Previous attempts to determine the age of the great reed warbler, Acrocephalus arundinaceus, after the complete moult have exposed a number of uncertainties. The present study provides evidence that the age of adult birds of this species cannot be determined precisely by using the colours of the iris and the tarsus as well as by the presence or abs...

Faunistical study on odonates was carried out in the Natura 2000 area of Lake Velencei, with a main focus on the species of community interest. In 2013 at 58 sampling sites 2270 individuals (133 larvae, 638 exuviae and 1499 adults) representing 24 species were collected or observed. The number of species per sampling site ranged from one to 15, wit...

Ecosystem/habitat restoration has become a major goal of international biodiversity policy. However, restorations are often limited in space or time, and we know little on whether and how restoration and management affect vertebrates. Here we assessed the local and landscape-scale effects of habitat restoration and management on small-mammal commun...

In autumn 2011 and spring 2012, the diet of pike (n = 112) captured in a backwater in eastern Hungary were examined. Eight species of prey-fish were found in the stomachs of 31 of the 112 pike individuals. 71.9% of the prey-fish, found in the stomachs of 16 of the 31 pike individuals, were European weather loach, Misgurnus fossilis. This first reco...

The migration of tits has been the subject of a number of studies, whereas very little is known as concerns their movements in their wintering areas in urban habitats. This study presents the effects of weather variables (the air temperature, the number of days with a snow cover and the amount of precipitation) on the distances moved by the Great T...

The effects of physical variables of the reed (e.g. the diameter and density of the reed stems) on the breeding success of the Great Reed Warbler were studied in the cases of the nest-supporting reed stems and the stems in the surroundings of 124 nests in three different reed habitats (mining ponds, small canals and large canals). The mean diameter...

The appearance of spider (Araneae) and beetle (Coleoptera) assemblages found in nests of great reed warbler Acrocephalus arundinaceus was studied, firstly to investigate breeding success and the amount of precipitation as potential factors which might affect the abundance and species richness of both groups. In addition, we compared the diversity o...

We possess little information on diet of the pike (Esox lucius L.) in nearly natural water habitats in the Balkans. Between 2006 and 2010, 528 pike were captured at 20 locations in three different water habitats. The capture of pike was done with an angling system a minimum of four times a month. Pike were mainly caught in autumn with the highest n...

Although the Danube is the largest river in Hungary, its Odonata fauna is scarcely known, especially that of the river section in Budapest. In this paper new data on the Odonata fauna of the latter Danube section are presented. In 2013 the collections of exuviae and observations on adults were made at five sites along the Danube in Budapest. During...

In this study, we present the effects of reed burning and precipitation on the breeding success of Great Reed Warblers on a mining pond (2008–2011). Breeding success, i.e. the probability that an egg would produce a fledgling, was 0.43. Clutch survival was lowest in 2010, due to the precipitation and high water level during the season. Breeding suc...

We monitored the breeding success of the Common Cuckoo (Cuculus canorus) in four reed habitats (e.g. clay pits, marsh and fishponds, small canals and large canals) in northwestern Vojvodina (Serbia) between 2009 and 2011 (three breeding seasons). A total of 596 Great Reed Warbler (Acrocephalus arundinaceus) nests were found and monitored. The overa...

We studied small mammal assemblages on croplands, and restored and natural grasslands of the Egyek-Pusztakócs marsh system by live trapping in 12 grids of 36 traps covering 1 hectare in the spring and autumn of 2011. In the spring, we captured only 20 individuals of three species during 2160 trap-nights, while in the autumn we caught 359 specimens...

Abstract Understanding the diverse responses of animal groups to grassland restoration is vital for restoration planning. Here we summarise responses of seven animal taxa (orthopterans, bees, carabid beetles, spiders, amphibians, birds, mammals) to grassland restoration in Hortobágy National Park (E-Hungary). Species richness did not vary but abund...

During migration and wintering 2010/2011, Eurasian Tree-creeper Certhia familiaris was recorded 94 times in 21 villages and towns of Vojvodina, mostly in parks, groups of planted trees, and other man-made green areas. One to five individuals were recorded per site per day. It was obviously more common than in the winter periods of previous years.

This study presents the periodical but irregular appearance of pike (Esox lucius L.) in the Danube River and its inundated ponds. During 14 years, 1076 pike were captured at nine sites. The fish appeared in large numbers in years when the average water level was high in spring (R = 0.738, P < 0.01, n = 14). During the study, there were two periods...

Between 1 April and 15 May 2009 Rook Corvus frugilegus colonies were mapped in Bačka (the area between the Danube, Tisa and Hungarian border). This article data analyses the number, size, distribution and abundancy of colonies, the number of nesting pairs, nesting habitats and threats.

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...

Breeding birds of shelterbelts near Sombor (NW Serbia) In 2008, breeding birds were studied in the shelterbelts surrounded by arable land NW of Sombor (Vojvodina, NW Serbia). Seven 500 m long sections of wooded shelterbelts were selected and surveyed for birds six times between May and July. Sampling plots differed in tree species composition and d...

Sombor has a long tradition of pigeonry, waterfowl husbandry and other activites with bird species. However, there are hardly any information about observations and studies of wild bird species. The richness of the town’s ornithofauna is poorly known among the citizens of Sombor. One probable reason is that birdwatching is not as popular as in some...

In 2009 five breeding of Great Reed Warbler Acrocephalus arundinaceus was studied at five sites(man-made ponds, canals and small rivers) around Sombor (Bačka). Sample for this research were 40 nests which were controlled in five day intervals during the breeding season. The breeding density and breeding success were predsented and discussed in this...

Number of active pairs of European Bee-eaterMerops apiaster was censused in 2008 using different field methods in three colonies of different sizes situated around Sombor (Bačka): A – counting of all circular entrances 7-12 cm in diameter; B – counting of adult birds in horizon when observer stands in the colony area and division of this number by...

Many continual water habitats are excellent stop-overs for migrating birds, but temporary ponds can potentially be an important resting place, too. Some studies have shown that temporary ponds in the Mediterranean are of great importance to many species. Last but not least, they are important environments for many migratory birds that use these spo...

The Central European Great Reed Warbler (GRW) (Acrocephalus arundinaceus) population spends the winter in Africa south of the Sahara. Studies showed that, during migration, the great number of Central European GRWs pass the Carpathian basin and Dinaric Mountains. During their journey they often use Adriatic wetlands as stopover sites (Kralj et al....

Density of territories of Great Reed-Warbler Acrocephalus arundinaceus, Common Reed Warbler A. scirpaceus and Sedge Warbler A. schoenobaenus were studied during 2007 on an isolated 1.4 ha large and 130 cm deep pond situated on the outskirts of Sombor (Bačka). Reed Phragmites australis covers almost 80% of the pond’s surface, while the rest of the s...

At the meander of the former flow of the Zapadna Mostonga River which lies on the western outskirt of Sombor (Baèka), the research of the waterbirds was conducted. At the beginning of the 2006 a temporary pond was formed there. During August and September the number and dynamics of 21 waterbirds was studied.