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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Vivendo na linha de fogo: história natural de Anthus nattereri (Aves: Motacillidae) nos Campos do Alto Rio Grande, Sul de Minas Gerais, Brasil / Living in the line of fire: natural history of Anthus nattereri (Aves: Motacillidae) in the Upper Rio Grande Grasslands, Southern Minas Gerais, Brazil

Lombardi, Vitor Torga 26 June 2017 (has links)
Submitted by Reginaldo Soares de Freitas (reginaldo.freitas@ufv.br) on 2017-11-08T15:05:10Z No. of bitstreams: 1 texto completo.pdf: 3526349 bytes, checksum: 439f28e5b6e1d484bf08aafe26e01502 (MD5) / Made available in DSpace on 2017-11-08T15:05:10Z (GMT). No. of bitstreams: 1 texto completo.pdf: 3526349 bytes, checksum: 439f28e5b6e1d484bf08aafe26e01502 (MD5) Previous issue date: 2017-06-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O caminheiro-grande Anthus nattereri é uma ave de hábito terrestre e especialista obrigatória em campos nativos de grande interesse conservacionista e de alta prioridade de pesquisa, sendo considerada globalmente e regionalmente ameaçada de extinção. Sua história natural ainda é pouco conhecida bem como seus requerimentos de área e habitat. Nesse contexto, este estudo se propôs a investigar aspectos da biologia reprodutiva e a estratégia territorial utilizada por A. nattereri, relacionando-os ao uso do habitat. Também se investigou sobre os efeitos em potencial do regime de queimadas atualmente empregado como manejo nos campos nativos locais sobre sua reprodução e seus territórios. O trabalho de campo ocorreu principalmente entre janeiro e dezembro de 2016 no setor nordeste dos Campos do Alto Rio Grande, situado no município de São João del-Rei, região sul de MG. Um ninho recém-queimado de A. nattereri foi oportunamente encontrado em setembro de 2014 e um recém-predado e outros três ninhos ativos foram encontrados entre outubro e novembro de 2016. Os ninhos possuíam um formato de cesto baixo, sendo construídos inteiramente com gramíneas secas e diretamente sobre o solo, assemelhando-se ao padrão documentado para outras espécies do gênero Anthus. O padrão de coloração dos ovos também se enquadrou dentro da variação conhecida para espécies congêneres, assim como o tamanho da postura (de dois a três ovos) para espécies de aves tropicais. Anthus nattereri utilizou locais com maior cobertura vegetal de gramíneas para nidificar, inclusive manchas não queimadas que remanesceram em meio aos campos cuja vegetação foi predominantemente comprometida em relação ao último evento de fogo. Entre janeiro e abril, A. nattereri se mostrou silencioso e de comportamento críptico. De junho até dezembro, os machos da espécie demarcaram e anunciaram territórios através de exibições aéreas e vocalizações. Anthus nattereri ocupou exclusivamente campos limpos, utilizando um amplo espectro de estágios de sucessão pós-queimada dessa vegetação. A espécie parece evitar terrenos fortemente inclinados, aparentemente preferindo grandes manchas de campo limpo em áreas com declividade mais amena. Com base nas localizações obtidas e no Estimador de Densidade Kernel delimitou-se o território de 21 machos. A área média ± DP (mín-máx) estimada a partir da isopleta de 95% foi de 2,04 ± 1,12 ha (0,46-5,26 ha), e a partir da isopleta de 80%, de 1,18 ± 0,61 ha (0,28-2,77 ha), com marcada sobreposição entre territórios adjacentes. Mesmo com uma baixa frequência de interações entre vizinhos, indivíduos estranhos, potencialmente flutuantes, são tenazmente excluídos dos territórios. Fêmeas raramente foram detectadas, nunca associadas aos machos em atividade de displays. Os indivíduos tenderam a permanecer em seus territórios ao longo do ano, exceto quando influenciados por queimadas severas, que provocaram a desestabilização dos territórios. Alguns dos indivíduos afetados permaneceram próximos dos territórios onde foram primeiramente detectados, inclusive se reestabelecendo com o avanço da regeneração da vegetação. Outros indivíduos estabeleceram novos territórios em áreas íntegras não ocupadas e não muito distantes (c. de 500 m) dos territórios de origem queimados. Indivíduos que tiveram seus territórios parcialmente queimados não abandonaram as áreas atingidas. Embora A. nattereri seja relativamente abundante na área de estudo, a maior incidência temporal de queimadas coincide com seu período reprodutivo na região, o que pode afetar a população local da espécie através da queima de ninhos e pela potencial eliminação de locais adequados para nidificação. Deste modo, urge a realização de estudos direcionados e de longo prazo para se avaliar o impacto de diferentes regimes de queimadas sobre seu desempenho reprodutivo, e, consequentemente, a conservação de A. nattereri. / The Ochre-breasted Pipit Anthus nattereri is a ground dwelling bird and an obligate grassland specialist of high conservation and research priorities, being considered globally and regionally Vulnerable to extinction. Its natural history is poorly known as well as habitat-area requirements. Here we studied the breeding biology, territorial strategy and habitat use by the Ochre-breasted Pipit. We also investigated the potential effects of the burning regime adopted by local cattle ranchers upon the territoriality and reproduction of the species. Field work was conducted mainly from January to December 2016 in the northeastern sector of the Upper Rio Grande Grasslands, municipality of São João del-Rei, southern state of Minas Gerais. One recently-burned nest was opportunistically found in September 2014 and one recently-preyed and three actives nests were found on October and November 2016. Nests are a low cup constructed with dry grasses and placed directly on the ground, in a pattern similar to that observed in other Anthus species. The egg color pattern fits within the known variation for congeners, and the clutch size (two to three eggs) is the typical for tropical birds. Anthus nattereri nests in sites with high and dense grass cover, usually in patches that have remained unburned since the last widespread fire event. From January to April 2016, A. nattereri was silent and showed cryptic behavior. From June through December, males demarcated and announced territories through aerial displays and vocalizations. Anthus nattereri inhabits pure open grasslands (campos limpos), using a wide spectrum of grassland types along the different stages of the post-burning succession. The species seems to avoid heavily sloping terrain, favoring large patches of open grasslands. We used the Kernel Density Estimator to delimit the territory of 21 males based on the locations obtained. The mean ± SD (min-max) area estimated from the 95% isopleth was 2.04 ± 1.12 ha (0.46-5.26 ha), and from the 80% isopleth, 1.18 ± 0.61 ha (0.28-2.77 ha), with marked overlap between adjacent territories. Even though agonistic interactions between neighbors were low, non-neighbor individuals, possibly floaters, were tenaciously excluded from the territories. Females were rarely detected and never associated with males in display activity. Individuals usually use year-round territories, except when burnings occur, what may lead to territory destabilization. Some of the affected individuals remain nearby, even reestablishing until the vegetation of their territory of origin regenerated. Others individuals established new territories in unoccupied areas not burned, not too far (c. 500 m) from their burned territory. Individuals who had their territories partially burned did not abandon the affected areas. Although A. nattereri is relatively abundant in the study area, the major temporal incidence of fires coincides with its breeding season, what may somewhat impact the local population of the species by burning some nests and/or eliminating suitable nesting sites. Thus, it is urgent to carry out long-term and targeted studies to evaluate the impact of different burning regimes upon the reproductive performance, and, consequently, the conservation of the species.
2

Individuální akustický monotoring pěvců na příkladu lindušky lesní / Individual acoustic monitoring of songbirds - case study on the tree pipit

Pišvejcová, Iveta January 2014 (has links)
In field behavioural and ecological studies, it is often necessary to identify specific individuals. In birds, colour rings are often used as individual marks. However, rings might be difficult to observe, especially in small species and dense habitats. Thus recently, individual acoustic monitoring is becoming more commonly used to study of birds. This method is based on the recognition of individuals and often on the difference between temporal and spectral parameters of their vocalizations. However, in passerine species with more complex song these acoustic characteristics may not be reliable. In my thesis I used an alternative approach for the individual acoustic monitoring, based on differences in syllable repertoires of individual Tree Pipit males (Anthus trivialis). So far I have not found any study that would use a similar approach with other migratory passerine species with more complex song. The main aim of my study was to test the possibility of using syllable repertoires for recognition of specific individuals and to determine if this method is more efficient than identification by colour banding. From four years of research on the Tree Pipits population in the selected location in Brdy I received acoustic data from 59 males that I subsequently analyzed in a bioacoustic program. The...
3

Mezidruhová agresivita lindušky luční (\kur{Anthus pratensis}) a bramborníčka hnědého (\kur{Saxicola rubetra}) / Interspecific aggression in meadow pipit (\kur{Anthus pratensis}) and whinchat (\kur{Saxicola rubetra})

LINHART, Pavel January 2007 (has links)
Interspecific aggression of meadow pipit (Anthus pratensis) towards treepipit (A. trivialis), whinchat (Saxicola rubetra) and skylark (Alauda arvensis) and interspecific aggression of whinchat towards meadow pipit was tested in playback experiments at the beginning of breeding cycle (both species) and during the brood feeding period (whinchat only). Neither meadow pipits nor whinchats responded aggressively to the playback of the heterospecific songs. Whinchats, however, chased or attacked meadow pipits that approached it in response to the meadow pipit songs in the brood feeding period. I suggest that the aggressive behaviour in whinchat is triggered rather by visual than acoustic cues. Another series of playback experiments with meadow pipits was carried out to investigate the effect of the sensitisation caused by previous playback of the conspecific song on performance during the playback of the tree pipit song 30 minutes later. No clear effect was discovered, but some of meadow pipits reacted in a way more characteristic for the intraspecific experiments.
4

From relict to future model? Common pastures as biodiversity refuges in the pre-alpine agricultural landscape

Schwarz, Cinja 10 May 2022 (has links)
Wir befinden uns inmitten einer globalen Biodiversitätskrise mit steigender Aussterberate, die die natürliche Hintergrundrate bereits jetzt um das Tausendfache überschreitet. In terrestri-schen Lebensräumen geht vom Landnutzungswandel die größte Gefahr für die Biodiversität aus. Besonders die ursprünglich hohe Vielfalt im mitteleuropäischen Grünland ist seit der In-dustrialisierung durch Nutzungsintensivierung und -aufgabe stark zurück gegangen. Traditionell genutztes, beweidetes Grünland ist in Mitteleuropa selten geworden. Dennoch deuten einige aktuelle Studien auf seine große Bedeutung für den Erhalt der Biodiversität in der Agrarland-schaft hin. Allerdings fehlen umfassende, systematische Untersuchungen für viele traditionelle Grünlandsysteme. Um diese Wissenslücke zu verringern, untersuchte ich in meiner Dissertation die Relevanz voralpiner, traditionell bewirtschafteter Allmendweiden als Refugium für bedrohte Zielarten (Baumpieper [Anthus trivialis], Blaukernauge [Minois dryas]) sowie für arten- und individuenreiche Zoozönosen (Heuschrecken [Orthoptera]) der mitteleuropäischen Agrarlandschaft. Gepaarte Vergleiche von Allmendweiden und angrenzenden Flächen mit identischen Standortbedingun-gen (Referenzflächen) ermöglichten den Vergleich der Arten bzw. -gruppe anhand von Umwelt-parametern in den Vegetationstypen Grünland auf Mineralboden und offenen Mooren. Der Un-tersuchungsraum in Südbayern stellt den Verbreitungsschwerpunkt für Allmendweiden und intakte bis naturnahe Moorökosysteme in Deutschland dar. Meine Analysen zeigen, dass sich der Landnutzungswandel drastisch auf die Referenzflä-chen, die früher überwiegend Teil der Allmendweiden waren, auswirkte: Im Vergleich zu den Weiden weisen sie (i) homogene Strukturen auf Landschafts- und Habitatebene, (ii) geringe Anteile nährstoffarmer Habitate und (iii) eine geringe Besiedlung von Vögeln und Insekten auf. Somit sind sie weitgehend ungeeignet für den Erhalt der Biodiversität. Die einzige Ausnahme innerhalb der Referenzflächen bilden traditionell genutzte Heu- und Streuwiesen. In den Allmendweiden sorgt die traditionelle Beweidung (0.5–2.0 Großvieheinheiten/ha von Mai–Oktober) für eine hohe strukturelle Vielfalt mit nährstoffarmen Habitaten und fließende Übergänge zwischen Wald und Offenland. So können saisonal bzw. innerhalb des Lebenszyklus wechselnde Ansprüche vieler typischer Agrarlandschaftsarten im eng verzahnten Mosaik wert-voller Habitate erfüllt werden. Der Erhalt der Allmendweiden ist für das Überleben von Agrar-landschaftsarten im Untersuchungsgebiet essenziell. Eine Ausdehnung der Allmendweiden-Nutzung auf angrenzende Flächen ist unbedingt zu empfehlen.

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