I studied the breeding biology and nesting ecology of the Altamira Oriole (Icterus gularis) and Northern Beardless-Tyrannulet (Camptostoma imberbe), two songbirds inhabiting remnant tracts of Tamaulipan brushland of the Lower Rio Grande Valley, Texas during 2002-2003. I found 76 active oriole nests, 7 of which were reused for second broods, for a total of 83 nesting attempts. I estimated that nearly 20% of the oriole breeding population were subadult, or second-year orioles, which is extremely rare for this species. Oriole breeding pairs were found in high densities and may be at their highest level at the study sites since the 1970s. Fifty-nine percent of oriole nests fledged, and 37% failed. Six nests produced Bronzed Cowbird (Molothrus aeneus) fledglings. Vegetation analysis suggests that orioles prefer the tallest trees at the sites in which to place their nests. A greater number of fallen logs near the nest was also a predictor of nest sites, which suggests that orioles prefer scattered woodlands, but also that many of the forests probably continue to shift to a more open, thorn-scrub climax stage. I monitored 28 Northern Beardless-Tyrannulet nests, which were restricted to a smaller number of study tracts than Altamira Orioles. Historical records are lacking for Northern Beardless-Tyrannulets at these sites, but my surveys indicated that there were similar seasonal numbers of tyrannulets at some of the study sites as there were during 1996-1998. Forty-three percent of nests were successful and 57% failed. Higher abundances of epiphytic Spanish moss (Bromeliaceae: Tillandsia usneoides) and ball moss (Bromeliaceae: Tillandsia recurvata) were the most important predictors of nest sites. The continued existence of these two species in South Texas will depend upon the preservation of tall forests, and in the case of the tyrannulet, forests rich in Tillandsia epiphytes.

I studied the breeding biology and nesting ecology of the Altamira Oriole (Icterus gularis) and Northern Beardless-Tyrannulet (Camptostoma imberbe), two songbirds inhabiting remnant tracts of Tamaulipan brushland of the Lower Rio Grande Valley, Texas during 2002-2003. I found 76 active oriole nests, 7 of which were reused for second broods, for a total of 83 nesting attempts. I estimated that nearly 20% of the oriole breeding population were subadult, or second-year orioles, which is extremely rare for this species. Oriole breeding pairs were found in high densities and may be at their highest level at the study sites since the 1970s. Fifty-nine percent of oriole nests fledged, and 37% failed. Six nests produced Bronzed Cowbird (Molothrus aeneus) fledglings. Vegetation analysis suggests that orioles prefer the tallest trees at the sites in which to place their nests. A greater number of fallen logs near the nest was also a predictor of nest sites, which suggests that orioles prefer scattered woodlands, but also that many of the forests probably continue to shift to a more open, thorn-scrub climax stage. I monitored 28 Northern Beardless-Tyrannulet nests, which were restricted to a smaller number of study tracts than Altamira Orioles. Historical records are lacking for Northern Beardless-Tyrannulets at these sites, but my surveys indicated that there were similar seasonal numbers of tyrannulets at some of the study sites as there were during 1996-1998. Forty-three percent of nests were successful and 57% failed. Higher abundances of epiphytic Spanish moss (Bromeliaceae: Tillandsia usneoides) and ball moss (Bromeliaceae: Tillandsia recurvata) were the most important predictors of nest sites. The continued existence of these two species in South Texas will depend upon the preservation of tall forests, and in the case of the tyrannulet, forests rich in Tillandsia epiphytes.

Submitted by Edisangela Bastos (edisangela@ufpa.br) on 2013-08-23T15:39:48Z No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_VariacaoGeograficaZonas.pdf: 18570156 bytes, checksum: 1ea272ee8894a0800ddd66920fb7dc72 (MD5) / Approved for entry into archive by Ana Rosa Silva(arosa@ufpa.br) on 2013-08-30T14:39:18Z (GMT) No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_VariacaoGeograficaZonas.pdf: 18570156 bytes, checksum: 1ea272ee8894a0800ddd66920fb7dc72 (MD5) / Made available in DSpace on 2013-08-30T14:39:18Z (GMT). No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_VariacaoGeograficaZonas.pdf: 18570156 bytes, checksum: 1ea272ee8894a0800ddd66920fb7dc72 (MD5) Previous issue date: 2003 / O complexo Icterus cayanensis-chtysocephalus apresenta um intrincado padrão de variação em plumagem e tamanho corpóreo. São reconhecidos, tradicionalmente, para o grupo seis táxons: Icterus chtysocephalus, I. cayanensis cayanensís. I. cayanensis tibialis, I. cayanensis tibialis, I. cayanensis valenciobuenoi, I. cayanensis periporphyrus e I. cayanensis pyrrhopterus, que se substituem geograficamente ao longo de grande parte da América do Sul. Neste estudo foi feita a descrição dos padrões de variação geográfica. Foram diagnosticadas quatro espécies, à luz do conceito filogenético de espécie: Icterus cayanensis (Amazônia Meridional), Icterus chrysocephalus (Amazônia Setentrional), Icterus tibialis (Caatinga) e Icterus pyrrhopterus (Chaco); os táxons I. cayanensis valenciobuenoi e I. cayanensis periporphyrus foram sinonimizados. Entre as formas amazonicas (chrysocephalus e cayanensis) foi detectada a presença de uma zona híbrida mais extensa do que aquela reportada na literatura. No Brasil Central foi diagnosticada a maior zona de intergradação conhecida para aves, com aproximadamente 2.300 km de extensão, produto do intercruzamento entre Icterus tibialis e Icterus pyrrhopterus, formas distribuídas pela Caatinga e Chaco, respectivamente. Postula-se que as zonas de intergradação diagnosticadas neste estudo são produto do intercruzamento de populações previamente diferenciadas em isolamento geográfico. / The Icterus cayanensis-chrysocephalus species complex shows an intricate pattern of geographic variation in body measurements and plumage. Traditionally, six taxa have been recognized in this group: Icterus chrysocephalus, I. cayanensis cayanensis, I. cayanensis tibialis, I. cayanensis valenciobuenoi, I. cayanensis periporphyrus and I. cayanensis pynhopterus, which replace each other geographically in South America. In this work, the geographic pattern of plumage and size variation was described for this species complex, and inferences were made about the evolutionary processes behind those pattern. Under the phylogenetic species concept (PSC), four species are diagnosed; Icterus cayanensis (Southern Amazon), I. chrysocephalus (Northern Amazon), I. tibialis (Caatinga) and I. pyrrhopterus (Chaco). The taxa lcterus cayenansis vaienciobuenoi lhering (1902) and Icterus cayanensis periporphyrus (Bonaparte 1950) were synonymizied. A hybrid zone more extensive than hitherto reported in the literature was detected between two Amazonian taxa: I. chrysocephalus and I. cayanensis. In Central Brazil, it was recognized one of the widest zones of intergradations known for birds to date, approximately 2.300 km wide, between I. tibialis and I. pyrrhopterus. R is postulated here that those hybrid zones were formed by secondary contact, after a period of differentiation in geographic isolation.

No description available.

In hierdie studie word die etiologiese verband tussen verstadigde neurologiese integrasie en latere leerproblematiek by kinders met klinies betekenisvolle neonatale bilirubienmetings ondersoek. Resente navorsing dui aan dat kinders met klinies betekenisvolle bilirubienmetings tydens die neonatale fase ‘n groter risiko loop om later verstadigde neurologiese integrasie te vertoon, veral weens die kwesbaarheid van die neonatale brein vir toksiene. Hierdie navorsingsresultate suggereer ‘n verband tussen klinies betekenisvolle neonatale bilirubienmetings en latere leerproblematiek, aangesien spesifieke breinareas wat deur neonatale bilirubien aangetas word ook vaardighede medieer wat belangrik is vir prestasie in sekere leerareas, te wete lees, skryf en reken. Neonatale fisiologiese geelsug is nie altyd met die blote oog sigbaar nie, en derhalwe word simptome soos oormatige slaperigheid en ingekorte behoefte aan voeding dikwels deur onervare moeders geïgnoreer, omdat die baba nie opmerklik “geel” is nie. Verder word neonatale fisiologiese geelsug nie altyd as sodanig gediagnoseer nie, weens verskeie faktore soos ontoereikende primêre gesondheidsorgdienste op die afgeleë platteland, tuisgeboortes en vroeë ontslag van moeders en babas uit klinieke en hospitale, veral gesien in die lig daarvan dat neonatale geelsug piekvlak tussen dag drie en dag sewe bereik. Bilirubienmeting is nie standaard prosedure by afgeleë klinieke nie, en waar ‘n rowwe skatting deur die klinieksuster op ‘n klinies betekenisvolle bilirubientelling dui, word moeders dan dikwels aangeraai om natuurlike fototerapie (sonlig) toe te pas. Verdermeer vind opvolgkonsultasies by ‘n klinieksuster dikwels eers plaas nadat die baba ongeveer een maand oud is, en voorligting aan die moeder rakende moontlike kwesbaarhede wat verband hou met klinies betekenisvolle neonatale bilirubienmetings is gebrekkig. Sodanige ouers kan dus heeltemal onbewus wees van die potensiële skade wat aangerig kan word aan die ontwikkelende brein, en intervensie vind gevolglik nie tydig plaas nie. Betekenisvolle duidinge wat uit hierdie navorsingsprojek mag voortvloei, kan derhalwe benut word ten einde spesifieke kwesbaarhede in kinders met klinies betekenisvolle neonatale bilirubienmetings tydig te kan identifiseer; en hoë-risiko leerders se moontlike latere leerproblematiek deur tydige intervensie tydens die voorskoolse jare te ondervang, voordat pobleme in die grondslagfase manifesteer. ‘n Empiriese ondersoek is uitgevoer waarby 37 deelnemers betrek is. Gebaseer op die resultate van die data-analise en interpretasie van die resultate word die hipotese aanvaar. Relevante aanbevelings met betrekking to praktykverbetering en verdere navorsing word gemaak. ENGLISH: With this study the etiological link between delayed neurological integration, high neonatal bilirubin measures and learning difficulties were investigated. Recent research findings suggest that children with high neonatal bilirubin measures are at a greater risk for delayed neurological integration later on, especially because of the susceptibility of the neonatal brain for toxins. The results of this research project suggest an etiological link between neonatal hyperbilirubinemia and learning difficulties at a later stage, since specific brain-areas which are affected by the bilirubin do mediate skills important for performance in certain learning areas, e.g. reading, writing and arithmetic. It is not always possible to notice neonatal physiological jaundice; hence, inexperienced mothers tend to ignore symptoms like sleepiness and lack of appetite, merely because their babies do not appear “yellowish”. Neonatal physiological jaundice is often misdiagnosed due to various factors like inadequate primary health care services in rural areas, home births and early discharge from hospitals - particularly in light of the fact that jaundice peaks between day three and day seven after birth. Measurement of neonatal bilirubin levels is not a standard procedure at rural clinics, and mothers are often advised to make use of natural phototherapy (sunlight) when the baby appears “yellowish”. Follow-up consultation often occurs when the baby is already one month old; hence mothers often receive inadequate information concerning neonatal hyperbilirubinemia. Parents might therefore be totally unaware of the potential vulnerability and harm to the developing brain, and intervention often does not take place. Significant indicators of this research project can be used to identify well in advance specific vulnerabilities in learners with neonatal hyperbilirubinemia, as well as potentially high-risk learners during the pre-school years, before such vulnerabilities escalate during the foundation phase. An empirical study with 37 participants was conducted. Based on the data analyses and interpretation of the results, the hypothesis was accepted. Relevant recommendations concerning best practice and further research were done. / Thesis (PhD)--University of Pretoria, 2008. / Educational Psychology / unrestricted