22 research outputs found
Influência do tamanho de ninhada no sucesso reprodutivo da andorinha-de-sobre-branco
No full textResumo: A teoria de seleção natural prevê que o tamanho de ninhada mais comum em uma população deve ser também o mais produtivo (ótimo). Além disso, restrições de energia e tempo geram um trade-off entre reprodução atual e futura dos indivíduos. Assim, a quantidade de energia investida em uma ninhada (determinada, por exemplo, pelo número de filhotes) deve ser resultado das chances de sucesso reprodutivo futuro de um adulto e das chances de sobrevivência da prole. Aqui, investigamos se o tamanho das ninhadas da andorinha-de-sobre-branco (Tachycineta leucorrhoa, Aves) é ótimo. Uma vez que sua distribuição abrange desde áreas tropicais até temperadas do hemisfério sul, a espécie deve ser, em geral, mais longeva e ter maior dificuldade em coletar alimento durante a estação reprodutiva do que aves do hemisfério norte temperado. Logo, o esforço em criar ninhadas maiores é alto e os adultos devem privilegiar sua própria sobrevivência frente à de seus filhotes. Para testar essa predição, manipulamos tamanhos de ninhada de casais reproduzindo em caixas-ninho às margens de duas represas no Paraná. Medimos o crescimento dos ninhegos até a idade de 12 dias e a taxa de visitação pelos pais, como forma de avaliar o benefício para os filhotes e os custos para os pais do cuidado parental, respectivamente. No ano seguinte, avaliamos a taxa de retorno, a condição corporal e a fecundidade dos jovens e dos adultos, para verificar se deficiências de crescimento dos ninhegos e se o esforço parental resultaram em custos para sobrevivência e reprodução futura, como previsto pela teoria. Verificamos que filhotes de ninhadas aumentadas e controle cresceram igualmente; e que adultos intensificaram o cuidado a proles aumentadas, mantendo a taxa de alimentação por ninhego igual à natural. Descrevemos também um comportamento de visitação dos pais a ninhadas alheias, que provavelmente tem o objetivo de explorar locais futuros para ninhos e que é exibido principalmente por adultos com ninhadas reduzidas e controle. Não observamos nenhum efeito residual dos tamanhos de ninhada à fecundidade, condição corporal e taxa de retorno dos filhotes ou adultos. Em conjunto, esses resultados indicam que a) o esforço empregado durante a criação dos filhotes não gera custos reprodutivos, b) adultos conseguem criar ninhadas maiores que as naturais, logo, ninhadas não tem tamanho ótimo. Nesse caso, discute-se que talvez outras fases do ciclo reprodutivo restrinjam os tamanhos de ninhada naturais (por exemplo, a fase de postura e incubação dos ovos), ou a restrição é temporal e não energética. Ainda, deve-se avaliar o impacto da seleção de lugares para ninho para o sucesso reprodutivo futuro e de inconstâncias climáticas no sucesso ao longo da vida dos indivíduos
New insights on the rarity of the vulnerable Cinereous Warbling-finch (Aves, Emberizidae) based on density, home range, and habitat selection
No full textWeather fluctuations are linked to nesting success and renesting decisions in saffron finches
No full textForaging behavior and diet of the vulnerable Cinereous Warbling-finch Poospiza cinerea (Aves, Emberizidae)
No full textDelayed plumage maturation explains differences in breeding performance of Saffron Finches
No full text<i>The web as a vehicle for constructivist approaches in language teaching</i>
No full textThe central question in this paper is whether Web technology has the potential
to add value to face-to-face language teaching in the form of activities that cannot be realized
fully in a traditional classroom. While arguments will be presented for and against e-learning,
our conclusion is that the latest human-machine interfaces offer an environment for interactive
learning that can foster the acquisition of communicative skills. The paper argues that one of the
great strengths of the Web is the potential to engage students in creative information gap activities
and real experiential learning in the form of meaningful, process-oriented projects in authentic
settings. Evidence will be drawn from three sources:[bull ] The current literature on new learning approaches.[bull ] The latest best-practice applications, such as Webquests, Voice Chat, MOOs and innovative
co-operative ventures.[bull ] The findings of two large research studies by the author on
students’ perceptions of Web-based language learning in school and tertiary settings.The paper emphasises the importance of creating connectivity rather than content.</jats:p
Delayed plumage maturation explains differences in breeding performance of Saffron Finches
No full textTheory predicts that, even within the same population, birds may vary their breeding investment with age. This may be due to an improvement in individual quality of old birds in body condition, foraging and in nesting experience. Birds commonly signal age and individual quality to potential mates and competitors through plumage colour. Young male and female breeders of Saffron Finches (Sicalis flaveola) have dull plumages that change to yellow with age. We asked whether older, yellow birds are in better condition and invest more in breeding than dull, younger birds. In southern Brazil, we monitored Saffron Finches breeding in nest-boxes over three breeding seasons. We found that yellow birds were in better condition: females had more furcular fat and males were heavier. Yellow parents bred earlier, had larger clutch sizes, shorter incubation periods, re-nested more and ultimately fledged twice as many offspring as dull parents. Egg mass, nestling mass and nest survival probability were similar between plumage colours. Female colour predicted clutch sizes and incubation periods better than male colour. Our results highlight the importance of accounting for female quality and reproductive investment decisions within the context of sexual selection.</p
The effectiveness of suggestopedia in the light of research data
No full textObwohl die Suggestopädie weltweit Beachtung gefunden hat, sind die Forschungsergebnisse widersprüchlich: Sie reichen von nicht-signifikanten Einflüssen auf das Lernergebnis (Knibbler 1982) bis hin zu Behauptungen über fünfzigfache Steigerung der Lernfähigkeit (Ostrander & Schroeder 1979). Es fehlt eine detaillierte Analyse und umfassende Darstellung vorliegender Befunde. Der Beitrag gibt im Anschluß an einen kurzen geschichtlichen Abriß über die Ursprünge und Prinzipien der Suggestopädie sowie wichtiger Adaptionen einen ersten systematischen Überblick über vorliegende empirische Untersuchungen, sowohl was die untersuchte Auswirkung einzelner Elemente - Musik, Entspannung, Suggestion - betrifft, als auch zur Wirksamkeit der Methode ingesamt. Den Abschluß bildet die Darstellung der Ergebnisse dreier empirischer Studien der Verfasserin, in denen die Auswirkungen der suggestopädischen Methode auf Variablen wie Problemlöseverhalten, Einstellung und Selbsteinschätzung sowie auf quantitative und qualitative Ergebnisse des Spracherwerbs untersucht wurden. Die besonderen Leistungen der Suggestopädie im Hinblick auf eine Verbesserung affektiver Variablen im Fremdsprachenunterricht wird dabei bestätigt. (DIPF/Orig.)Although Suggestopedia has already been widely used all over the world, reports of research results have been rather inconsistent, ranging from no signiflcant effects on achievement (Knibbler 1982) to Claims of learning being improved by fifty times (Ostrander & Schroeder 1979). Findings have not yet been analysed in detail and in a comprehensiveform. The following article begins with a brief historical account of the origins and principles of Suggestopedia and important adaptations. The literature review looks at the reported effects of individual elements - music, relaxation, and suggestion - as well as effects of the methodas a whole. The final section summarises the results of the author\u27s own empirical work, three studies which investigate effects of the approach on variables such as on-task behavior, attitude andself-concept, and on quantitative and qualitative measures of language learning. The studies confirm that Suggestopedia appears to have the potential to enhance affective variables in the context o fa regular language class. (DIPF/Orig.
BREEDING BIOLOGY OF PASSERINES IN THE SUBTROPICAL BRAZILIAN ATLANTIC FOREST
No full textInformation on breeding biology of birds is fundamental for the understanding of life history evolution and conservation. This information is only beginning to accumulate for Neotropical birds but the southern subtropics are still overlooked. Here we describe the breeding biology of passerines in subtropical Brazilian Atlantic Forest. We monitored 265 nests of 38 species during the 2012–2013 breeding season. Breeding began in September, but some species started as late as December. Average breeding season length was 64 days, but varied broadly across species. Average clutch sizes ranged from two to five eggs. The breeding season phenology, clutch sizes, and nesting periods were similar to other two communities at the same latitude in Argentina. Our data contribute to the debate that the combination of small clutch sizes and short breeding seasons seen in subtropical South America challenges the tropical-temperate paradigm of life-history theory
