Dissertations / Theses on the topic 'Turdus merula'

To characterise the habitat preferences of ring ouzel (Turdus torquatus) and blackbird (T. merula) in Switzerland, we adopt species distribution modelling and predict the species’ spatial distribution. We model on two different scales to analyse in how far downscaling leads to a different set of predictors to describe the realised habitat best. While the models on macroscale (grid of one square kilometre) cover the entire country, we select a set of smaller plots for modelling on territory scale. Whereas ring ouzels occur in altitudes above 1’000 m a.s.l. only, blackbirds occur from the lowlands up to the timber line. The altitudinal range overlap of the two species is up to 400 m. Despite both species coexist on macroscale, a direct niche overlap on territory scale is rare. Small-scale differences in vegetation cover and structure seem to play a dominant role for habitat selection. On macroscale however, we observe a high dependency on climatic variables mainly representing the altitudinal range and the related forest structure preferred by the two species. Applying the models for climate change scenarios, we predict a decline of suitable habitat for the ring ouzel with a simultaneous median altitudinal shift of +440 m until 2070. In contrast, the blackbird is predicted to benefit from higher temperatures and expand its range to higher elevations.
Unter Verwendung von Habitatmodellen beschreiben wir die Habitatpräferenz von Amsel (Turdus merula) und Ringdrossel (T. torquatus) in der Schweiz. Mit Hilfe verschiedener Klimaszenarien prognostizieren wir zudem die künftige potentielle Verbreitung beider Arten. Zur Beschreibung eines eventuell auftretenden Skalensprungs, d.h. einer Änderung in der Beschreibungskraft der Variablen auf verschiedenen räumlichen Ebenen, erstellten wir Modelle auf zwei unterschiedlichen Skalen. Während das Modell auf Makroskala mit einer Maschenweite von einem Quadratkilometer die gesamte Schweiz abdeckt, erstellten wir zudem eine Auswahl an Untersuchungsgebieten auf Revierebene. Ringdrosseln zeigen ihren Verbreitungsschwerpunkt in der subalpinen Lage, während Amseln vornehmlich das Tiefland und die Tallagen besiedeln und nur vereinzelt in hohe Lagen vordringen. In einem Gürtel von ungefähr 400 Höhenmetern siedeln beide Arten parallel.Trotz dieses auf der Makroskala erkennbaren Überschneidungsbereiches konnten wir in unserer Untersuchung auf Revierebene, von einer Ausnahme abgesehen, keine Koexistenz beobachten. Kleinräumige Unterschiede in der Habitatstruktur, insbesondere in der Vegetationsbedeckung scheinen demnach für die Habitatselektion von maßgeblicher Bedeutung zu sein. Auf Makroebene hingegen wurde der Einfluss klimatischer Variablen deutlich, die neben der Höhenlage auch dort typische Vegetationsstrukturen widerspiegeln. Wie die Klimaszenarien zeigen, nehmen geeignete Ringdrosselhabitate bei steigenden Temperaturen ab und die Art weicht im Mittel um 440 m in höhere Lagen zurück. Für Amseln scheint sich eine zunehmende Erwärmung jedoch positiv auszuwirken, während das Verbreitungsgebiet im Tiefland beibehalten wird, dringt sie von den Tälern ausgehend zunehmend in höhere Lagen vor.

Stable isotopes of carbon (813C ), nitrogen (615N) and hydrogen (62H ) and microsatellite markers were used in conjunction with morphological data, to test whether breeding origins of two migratory passerines the Blackbird Turdus merula, and Redwing T iliacus, overwintering in the UK & Ireland could be predicted, based on data collected at European breeding sites. Geographical trends of feather 62H and 613C values of birds sampleda t Europeanb reeding sites were useful for determining breeding origins of Blackbirds at a broad geographical scale. Genetic markers were useful for discriminating between the two Redwing races iliacus and coburni. Conversely, no genetic structure was found within the nominate race iliacus and there was only weak genetic structure in Blackbird populations, suggesting relatively high gene flow. These results indicate that genetic markers are of limited value for population assigm-nenot f either species. Mean wing length of breeding Blackbirds differed significantly between breeding regions, and was positively correlated with latitude, suggesting that wing length is potentially a useful variable for discriminating between Blackbirds of different breeding origin. It was predicted that combining techniques would prove substantially more useful for assigning individuals to their most likely origin, than any one technique used in isolation. For Blackbirds, the combination of 62H and 813C values with wing length proved to be the most effective combination of variables (and was more effective than using either stable isotopes or wing length alone), allowing 72.2% to 76.3% of breeding Blackbirds to be correctly and consistently assigned to one of three broad geographic regions (UK, Fennoscandia and Continent). For Redwings, using DNA markers alone, 94.5% of birds were correctly assigned to either the coburni or iliacus; the addition of stable isotopes produced only a marginal improvement. Useful insights into the contrasting migratory strategies of Blackbirds and Redwings were revealed. The lack of genetic variation within the nominate Redwing race indicates a lack of migratory connectivity. In contrast, weak genetic population structure in the Blackbird, and differences in stable isotope i ratios and wing length between birds sampled at different wintering sites, suggests that different parts of the UK & Ireland may receive differing proportions of migrant Blackbirds originating from different breeding sites. This suggestst hat migratory connectivity might be strongeri n this species. The approach of using multiple techniques may prove useful for other species about which less is known regarding breeding origins, which may be particularly relevant for species of conservati on concern. However, the most useful variable/combination of different variables for a study of migratory connectivity will vary, both according to the species, its geographical range, and the scale of resolution required, and a clear understanding of the ecology and physiology of the study species is essential.

The aim of this thesis was to identify the factors determining reproductive success and breeding density in a rural population of blackbirds occupying contiguous woodland and farmland habitats. Once these factors were identified, an attempt was made to assess the quality of the two habitats in terms of reproductive success. Predation was the major factor affecting reproductive success. There were no significant effects of habitat on predation when habitat was defined as farmland, woodland and woodland edge. When defined in terms of nesting density, high density 'hot-spot' areas had significantly greater nesting cover and lower predation rates than territories in farmland or in the rest of the wood. Parents could adjust their provisioning rates according to chick demand. Consequently chicks in larger broods were not significantly different in weight to chicks in smaller broods. The seasonal change in clutch size is therefore well adapted to conditions for raising nestlings, although there was indirect evidence that female condition may limit clutch size early in the season. The nestlings were fed two main diet types, earthworms and caterpillars, the availability of the former being related to rainfall and temperature and the latter occurring in a seasonal peak. Nestlings fed on predominantly earthworm diets were significantly heavier, thus caterpillars are probably a lower quality prey. Starvation was a minor cause of nestling mortality. There was some evidence that farmland birds were more dependent on earthworms than woodland birds, and consequently only farmland broods showed a significant relationship between weight and rainfall. This conferred no disadvantage to farmland broods, although this may have implications for reproductive success in very dry years. Farmland breeders showed some characteristics of a population in a suboptimal habitat. Breeding density was low on farmland compared with woodland. This in part may have been due to lack of suitable nesting cover. An experiment with artificial nests indicated that predation would be proportionately higher on farmland if nesting density was increased. Year-to-year variations in density across the whole study site paralleled the relative harshness of the preceding winter. Food supplementation prior to the breeding season had no effect on subsequent breeding density or clutch size. It is concluded that farmland is potentially a sub-optimal habitat if subject to different conditions of weather or breeding density than those observed during the three years of this study.

L'incidence de l'anthropisation des habitats sur les populations naturelles est actuellement une préoccupation importante dans les domaines fondamentaux ou appliqués. Historiquement, la réaction des espèces face au milieu neuf et singulier que représentent les zones urbaines a été abordée au niveau communautaire. Cependant, si l'urbanisation a des conséquences au niveau des communautés, les pressions et contraintes s'exercent en premier lieu sur les populations et les individus qui les constituent. Le Merle noir Turdus merula est un oiseau originaire des forêts qui a colonisé les habitats urbanisés au XIXème siècle. Ce travail s'est intéressé à comparer des populations urbaines et forestières du Merle noir afin d'explorer leurs fonctionnements démographiques respectifs en liaison avec d'éventuelles contraintes propres aux différents habitats et en intégrant la dimension individuelle. En relation étroite avec ces préoccupations, la structuration génétique et morphologique a été envisagée
The consequences of human-induced disturbances on wild populations is a stimulating topic raising fundamental as well as applied questions. The effects of urbanization on wild life have been initially studied at the community level. However, even if urbanization influences communities, the selective pressures occur first on populations and individuals. Consequently, it is also crucial to consider the ecological problems at the population level. The Blackbird Turdus merula has colonized urban landscapes in Europe since the middle of the 19th century and provides good opportunities to explore the influence of urbanization on population biology. The aim of this work was to compare urban and forest Blackbird populations in terms of different population characteristics (survival, reproductive success and dispersal) and selective contraints (parasites). Direct (i. E. Capture and census of individuals) and indirect methods (i. E. Genetic) were used in order to assess the dynamics of these populations

Abstract Cities represent a new environment where organisms are exposed to different environmental conditions than the original natural habitats. This is essentially a noise and light pollution. The growing number of studies show that these factors can have a significant impact on voice activity of birds.Light pollution may alter the timing of vocalization.Urban noise can overlay the acoustic signals of birds, change the melody, volume, and the timing of singing. The main objective of this thesis was to investigate the influence of noise and light pollution to voice activity Blackbird (Turdus merula). In 2015 it was recorded vocalizations to 4 types of sites: a) on the site only with noise pollution (unlit busy road), b) on the site only with light pollution (Parks), c) on location with noise and light pollution (busy roads in cities), d) on the site without the noise and light pollution (forests). Recording was done with the help of voice recorders from early March until the end of May when the weather was good (no strong winds and storms) every week to thoroughly map the seasonal voice activity of the birds. Quiet location and localities with noise pollution have been in the woods near the town of Beroun near the D5 highway. Locations with light and noisy pollution is found in Hradec Kralove and Prague. In each locality they were searched individuals Blackbird and placed recorder into their territory. The recordings were taken 180 minutes before sunset, throughout the night and morning was the end of the recording 180 minutes after sunrise. The results showed the influence of the sites primarily on the morning vocalization when in the localities affected by light and noise vocalized significantly earlier than the quiet and noisy areas. In the evening times was vocalization without significant differences. The greatest intensity of vocalizations Blackbird was light-noisy areas, opposite to others. The evening was the greatest intensity of the sound recorded in quiet locations. Finally, the night vocalization has been demonstrated only in localities light-noisy.

Widespread anthropogenic invasions have prompted concerns that naturalized organisms could threaten biodiversity. In particular, invasive weeds can negatively affect native biota through a variety of means, including disrupting mutualisms. This thesis was designed to observe and test dispersal mutualisms in a native forest during autumn when the majority of plant species are fruiting. In this thesis I examined whether the invasive plant barberry (Berberis glaucocarpa) was influencing the behaviour of a native frugivore bellbird (Anthornis melanura) and a range of dispersal related services in a native forest, Kowhai Bush near Kaikoura. To test these 18 banded bellbirds were followed through autumn 2011. These observe bellbirds were split between control and test bird. Barberry fruit was removed from the test bird territories. I recorded whether bellbirds changed their territory sizes, foraging and daily behaviours. During 52 hours of observations, bellbirds were never observed feeding on barberry fruit. No significant changes to bellbird behaviour or territories were observed after the removal of barberry fruit. Bellbird diet overall was dominated by invertebrates (83% of foraging observations), with smaller contributions from fruit (16%, nearly all on Coprosma robusta), nectar and honeydew. Since bellbirds did not eat barberry fruit, removal of this weed is unlikely to negatively affect bellbirds during autumn. Which other bird species were dispersing barberry was recorded. I recorded 242 hours of videotape footage on 24 fruiting plants. A total of 101 foraging events were recorded of 4 different bird species: silvereyes (Zosterops lateralis) 42 visits, blackbirds (Turdus merula) 27 visits, song thrush (Turdus philomelos) 29, and starlings (Sturnus vulgaris) 3 visits. The species differed in the mean length of time they spent in plants, so the overall contribution to barberry fruit removal was 32.6% silvereyes, 24.3% blackbirds, 42.9% song thrush and 0.1% starlings. To find out the relative contribution of exotic and native birds to dispersal of fruits in Kowhai Bush, I mist-netted 221 birds of 10 species and identified any seeds in the 183 faeces they deposited. A total of 21 plant species were observed fruiting in Kowhai Bush during this time. A total of 11 different plant species were identified from 1092 seeds. Birds were further observed feeding on 3 other plant species which were not observed in faecal samples. This left 7 plants with unobserved dispersal vectors. There were likely four main dispersers, bellbirds, silvereyes, song thrush and blackbirds and five minor, brown creeper (Mohoua novaeseelandiae), tui (Prosthemadera novaeseelandiae), fantails (Rhipidura fuliginosa), dunnock (Prunella modularis) and starlings. However there was considerable variability between these bird species dispersal abilities. Introduced birds’ song thrush and blackbirds were observed dispersing naturalized plant seeds at higher than expected rates in comparison to native frugivores bellbirds and silvereyes. I also measured the gape sizes on mist netted birds and on samples of fruit from Kowhai Bush. Both silvereyes and bellbirds were found to be eating fruit larger than their gape, but despite this two native (Hedycarya arborea and Ripogonum scandens) and three exotic plants (Vitis vinifera, Taxus baccata and Crataegus monogyna) had large fruit that were probably mainly dispersed by song thrush and blackbirds. Hence, introduced birds were important seed dispersers for large fleshy fruited seeds in Kowhai Bush. Demonstrating that interactions among native and exotic flesh fruited plants and frugivores is important within forest communities.

Si les parasites sont étudiés depuis très longtemps, la plupart des connaissances concernent des parasites présentant un intérêt médical ou vétérinaire. Ainsi, malgré leur omniprésence au sein du monde vivant, le rôle des infections parasitaires sur les populations naturelles est encore très mal maîtrisé.
Un objectif de ce travail était d'étudier la pathogénicité de deux groupes de parasites (tiques et Haemosporidae) au sein de populations de Merles noirs. Ces deux groupes de parasites se sont révélés associés aux indices de condition corporelle et de réponse immunitaire des individus. Cependant, l'étude d'une population urbaine ne nous a pas permis de confirmer un effet des Haemosporidae sur la survie et la dynamique de la population de Merles.
L'incidence du milieu de vie (structuration spatiale) sur le fonctionnement de la relation hôte-parasite a été également abordée. En effet, le Merle est une espèce ubiquiste. Nous avons montré que les populations de milieu urbanisé présentent des infections parasitaires plus faibles que celles vivant en milieu forestier. Ce résultat pourrait expliquer en partie les fortes densités de Merles en zones urbaines, même si d'autres interprétations restent bien sûr envisageables.
Enfin, divers travaux récents suggèrent le rôle des caroténoïdes comme lien entre l'immunité des mâles et l'intensité de leur signaux colorés. Cependant, ces études utilisent des mesures de l'immunité par challenge immunitaire pour « mimer » les infections parasitaires. Cette démarche a été récemment discutée car les challenges pourraient ne pas toujours refléter la résistance parasitaire. Nos résultats vont dans ce sens. De plus, nos travaux semblent montrer que le contexte social module la relation entre immunité et signaux colorés. Ceci pourrait remettre partiellement en cause l'idée selon laquelle les caroténoïdes constituent un mécanisme universel garant de l'honnêteté des signaux.

Birds are a major pest in vineyards both in New Zealand and overseas. There is a need for new behavioural research on birds' foraging habits and feeding preferences in vineyards, as much of the literature to date is anecdotal. Research on cues to birds' feeding will provide a basis on which new deterrent and control strategies can be devised. Spatial-and temporal bird damage in a small vineyard block was mapped to find if damage was correlated with grape maturity and environmental factors. Vineyard and field observations of bird behaviour using video technology combined with preference experiments aimed to establish the relative roles of grape sugar concentration and colour in avian selection. Proximity of vineyards to bird roosts affects damage levels, regardless of differing maturity between locations. The rate of damage tends to increase exponentially once grape maturity has passed a threshold of 13 °Brix. Bunches positioned closest to the ground receive more damage if blackbirds or song thrushes are the predominant pests. Both sugar concentration and grape colour were found to affect birds' feeding preference, but the importance of the two factors varied between years. Black and green grape varieties were differentially preferred by blackbirds (Turdus merula) and song thrushes (Turdus philomelos) while silvereyes (Zosterops lateralis) appeared to have no strong colour preference. It was apparent that there were other, not assessed, grape factors that also affect selection. In small unprotected vineyards that are adjacent to bird roosts the entire grape crop can be taken by bird pests. Besides removing the roosts, which can be beneficial shelterbelts in regions exposed to high winds, growers currently may have no alternative other than to use exclusion netting to keep crops intact. The differential preferences between bird species for variety characteristics suggest that any new deterrents and other strategies to deflect birds from grape crops may need to be species-specific.

O mercúrio é um elemento não essencial que tem a capacidade de biomagnificação e bioacumulação nas teias tróficas. No entanto, pouca atenção tem sido dada à acumulação em aves terrestres, especialmente espécies insetívoras ou omnívoras. Estas espécies podem estar expostas a grandes concentrações de mercúrio, através da ingestão de insetos aquáticos, de insetos predadores ou pelo consumo de frutos com fungicidas. Deste modo, o presente trabalho teve como objetivos: a) estudar a dieta de aves insetívoras, os andorinhões (Apus sp.) e aves omnívoras, os melros (Turdus merula); b) estudar a concentração de mercúrio em diferentes tecidos destas aves; c) avaliar o efeito da idade e do sexo das aves na concentração de mercúrio. Nos tratos gastrointestinais dos andorinhões foram encontrados fragmentos de presas das Ordens Hymenoptera, Coleoptera e Hemiptera e nos melros das Ordens Coleoptera, Hymenoptera e Pulmonata. Os tecidos das aves recolhidos para análise do mercúrio foram o bico, unhas, penas, músculo, fígado, cérebro, rins, pulmões, trato gastrointestinal, coração e pele. Ambas as espécies apresentaram as concentrações mais altas nas penas, rins, unhas e fígado e as mais baixas foram registadas no músculo e na pele. Nos andorinhões todos os tecidos demonstraram uma forte correlação entre si, enquanto nos melros as penas não demonstraram correlação com todos os tecidos internos, o que significa que não serão bons indicadores da presença de mercúrio nesta espécie. A idade revelou ser um fator significativo, verificando-se uma maior acumulação nos indivíduos adultos de ambas as espécies. Por outro lado, o sexo das aves não foi determinante na acumulação de mercúrio. As diferenças entre as duas espécies verificaram-se apenas nas unhas e na pele, sendo que as aves omnívoras registaram uma maior acumulação de mercúrio nesses tecidos. No presente estudo a dieta insetívora ou omnívora não pareceu influenciar a concentração de mercúrio.
Mercury is a non-essential element which has the ability to biomagnify and bioaccumulate through the food webs. However, terrestrial birds have received little attention, especially insectivorous or omnivorous species. These may be exposed to high mercury concentrations, either by the ingestion of aquatic insects, predatory insects or fruits which have been treated with fungicides. So, the main goals of the present work were: a) to study the diet of the insectivorous swifts (Apus sp.) and the omnivorous blackbirds (Turdus merula); b) study the mercury concentration in different tissues of these birds; c) evaluate the effect of age and gender of the birds on mercury concentrations. Fragments of preys belonging to Hymenoptera, Coleoptera and Hemiptera Orders were found in the swifts’ gastrointestinal tracts, while the Coleoptera, Hymenoptera and Pulmonata were present in the blackbirds’ tracts. Birds’ tissues collected for analysis were beak, claws, feathers, muscle, liver, brain, kidneys, lungs, gastrointestinal tract, heart and skin. Both species showed the highest mercury concentrations in feathers, kidneys, claws and liver while the lowest were found in the muscle and skin. In swifts all tissues showed a strong correlation between them, the same did not occur in blackbirds, in which feathers didn’t show any relation with the internal tissues. This suggests that feathers are not good indicators of mercury contamination in this specie. Age proved to be a significant factor, with greater accumulation in adults of both species. However, gender was not determinant in the accumulation of mercury. The differences in mercury accumulation between the two species were only present in claws and skin, with omnivorous birds presenting a higher accumulation in these tissues. In the present study insectivorous or omnivorous diet did not seem to influence mercury concentration.
Mestrado em Ecologia Aplicada