Thyroid hormones increase liver and muscle thermogenic capacity in the little buntings (Emberiza pusilla)

Thyroid hormones can increase energy expenditure and stimulate basal thermogenesis by lowering metabolic efficiency. In the present study, we examined the effects of thyroid hormones on basal heat production as well as on several physiological and biochemical measures indicative of thermogenic capacity to test our hypothesis that thyroid hormones stimulate increases in thermogenesis in little buntings. Little buntings that fed on thyroxine (T₄)–laced poultry food of 3 and 5 ppm concentrations showed increases in basal metabolic rate (BMR) during the 3-week acclimation. At the end, these buntings had lower body weights, higher levels of contents of mitochondrial protein, state 4 respiration and cytochrome c oxidase activity in liver and muscle, and higher concentrations of serum triiodothyronine (T₃) and T₄ compared to control buntings. These results support the argument that thyroid hormones play an important role in the regulation of thermogenic ability in buntings by stimulating mitochondrial respiration and enzyme activities associated with aerobic metabolism.     

黄喉鹀的羽色与雄鸟质量相关性分析

在国内首次利用光纤光谱仪对鸟类的羽色进行量化和分析.对黄喉鹀Emberiza elegans雌、雄鸟羽色的差异以及雄鸟羽色与雄鸟质量的相关性分析结果表明,黄喉鹀雌、雄鸟在人眼看来相同的黄色羽和白色羽部分,在紫外光色度上却存在显著差异,雄鸟紫外光色度高于雌鸟;雄鸟的质量与脸部黑色羽的亮度、可见光色度和色调呈显著正相关,雌...     

Reed bunting females increase fitness through extra-pair mating with genetically dissimilar males

Females of many socially monogamous species accept or even actively seek copulations outside the social pair bond. As females cannot increase the number of offspring with promiscuous behaviour, the question arises why they engage in extra-pair mating. We used microsatellite data to determine paternity, heterozygosity and genetic relatedness in the reed bunting (Emberiza schoeniclus), a species with high levels of extra-pair paternity (EPP). We found that extra-pair young (EPY) were more heterozygous than within-pair young (WPY). The high heterozygosity of the EPY resulted from a low genetic similarity between females and their extra-pair mates. EPY were heavier and larger when compared with their maternal half-siblings shortly before they left the nest. Recapture data indicated a higher fledgling survival of EPY compared with WPY. Our data suggest that reed bunting females increase the viability of their offspring and thus fitness through extra-pair mating with genetically dissimilar males.     

Control pattern of vocal center for vocalization in ruddy bunting (Emberiza rutila)

In recent studies, some progress has been made in the vocal mechanism of songbird by using both electrophysiological and acoustics technique[1—3]. High vocal center (HVC) is the highest center in the vocal control pathway in songbirds. Unilateral stimulating HVC may evoke bilateral electrical activity of HVC neurons[4,5]. The lesion of HVC critically affects the capacity of singing, and birds could produce only simple calls. In addition, the basic frequency decreases, rapid modulation o…     

栗斑腹鹀的栖息地和巢址选择

于1999到2001年5月至7月连续3a在吉林省镇赉县大岗林场,采用样地法和样方法,对栗斑腹鹀的栖息地选择和巢址选择进行了研究.结果表明此鸟的繁殖是在草甸草原+杏树环境下进行的,对栖息地样方和对照样方的对比分析得出,杏树最大高度、50 m半径圆内杏树数量、贝加尔针茅数量、大油芒数量、植物盖度、火绒草平均高度、贝加尔针茅最大高度、兴安胡枝子平均高度8个因子是影响其栖息地选择的主要因子.通过对46个巢的研究发现,大多数栗斑腹鹀把巢建在贝加尔针茅下面,巢出入口方向多为东南45°和西南45°.对46巢的27个因子的主成分分析,结果发现植物盖度、火绒草高度、鸢尾数量、巢出入口方向、10 m内杏树数量、30 m内杏树数量、裸地面积这6个因子是巢址选择的主要因子.对46巢26个巢址和非巢址因子进行判别分析,植物盖度、大油芒、乳浆大戟高度、石竹数量、线叶菊高度和30m内杏树数量等6个因子,为巢位选择的主要因子 .两种分析结果基本相似.总之,栗斑腹鹀喜欢在植被盖度大、杏树相对多、贝加尔针茅和大油芒的密度大、食物资源丰富的区域内营巢.     

A role for thyroid hormones in the development of premigratory disposition in redheaded bunting,Emberiza bruniceps

Excessive fat deposition and zugunruhe (nocturnal restlessness), two characteristics of premigratory disposition, are displayed in caged redheaded buntings. In earlier experiments thyroid ablation was found to inhibit premigratory fattening in this bird. Also, seasonal investigations on thyroid hormonal profiles indicated a distinct rise in circulating tri-iodothyronine just before spring migration, most likely as a result of increased peripheral monodeiodination of thyroxine. The physiological relevance of these findings has been assessed in the present paper. Results indicated that removal of thyroid gland completely prevented development of zugunruhe and fat deposition; replacement therapy with T4 or T3 restored both. Thyroxine-induced fattening in thyroidectomized birds was found to be dose responsive. In two experiments in thyroidectomized and intact birds each suppression of extrathyroidal conversion of thyroxine into triiodothyronine by iopanoic acid completely suppressed zugunruhe and fattening in thyroidectomized as well as intact birds, arguing for a role of triiodothyronine in migratory physiology. Blockage of thyroxine to triiodothyronine conversion, however, did not suppress feather regeneration, indicating that unlike effects on migratory parameters in the same individuals thyroxine-induced feather regeneration does not involve prior monodeiodination to triiodothyronine. Thus, contrary to the prevailing view that triiodothyronine alone is the finally active thyroid hormone (thyroxine being a precursor), both thyroxine and triiodothyronine may have specific roles to play in the physiology of seasonal events, and peripheral conversion of thyroxine to triiodothyronine may be one of the physiological devices to ensure that energetically incompatible events like migration and moulting do not occur simultaneously. Results also indicate that increasing spring daylengths which are known to trigger avian migration may influence peripheral conversion of thyroxine to triiodothyronine possibly imparting to this physiological process an adaptive value in the timing of seasonal events.Abbreviations IOP iopanoic acid - NS normal saline - RIA radioimmunoassay - T4 thyroxine - T3 triiodothyronine - Tx thyroidectomized     

The oxidative costs of territory quality and offspring provisioning

The costs of reproduction are an important constraint that shapes the evolution of life histories, yet our understanding of the proximate mechanism(s) leading to such life‐history trade‐offs is not well understood. Oxidative stress is a strong candidate measure thought to mediate the costs of reproduction, yet empirical evidence supporting that increased reproductive investment leads to oxidative stress is equivocal. We investigated whether territory quality and offspring provisioning increase oxidative stress in male snow buntings (Plectrophenax nivalis) using a repeated sampling design. We show that arrival oxidative stress is not a constraint on territory quality or the number of offspring fledged. Nevertheless, owners of higher‐quality territories experienced an oxidative cost, with this cost increasing more rapidly in younger males. Males that provisioned offspring at a high rate also experienced increased oxidative stress. Together, these findings support the potential role of oxidative stress in mediating life‐history trade‐offs. Future work should consider that reproductive workload is not limited to offspring care, and other activities – including territory defence – may contribute significantly to the costs of reproduction.     

中国四种小型鸟类代谢产热的气候适应

采用封闭式流体压力呼吸计 ,分别在 5 - 35°C、 10 - 30°C和 10 - 35°C的环境温度范围内测定了黄眉(Emberizachrysophrys)、红胁绣眼鸟 (Zosteropserythropleura)、画眉 (Garrulaxcanorus)和红嘴相思鸟 (Leio thrixlutea)的耗氧量、热传导、体温等指标 ,探讨了其代谢产热特征。黄眉、红胁绣眼鸟、画眉和红嘴相思鸟的热中性区分别为 2 5 - 30°C、 2 5 - 2 7 5°C、 2 2 5 - 2 7 5°C和 30 - 32 5°C。在 5 - 30°C的温度范围内 ,黄眉和画眉能保持稳定的体温 ,分别为 4 0 5 8± 0 2 6°C和 4 1 6 8± 0 11°C ;红胁绣眼鸟和红嘴相思鸟的体温随环境温度的降低有下降的趋势。在热中性区内 ,黄眉、红胁绣眼鸟、画眉和红嘴相思鸟的平均基础代谢率分别是3 6 5± 0 14、 4 6 9± 0 2 7、 3 5 5± 0 14和 4 2 4± 0 17mlO2 / (g·h) ,分别是体重预期值的 12 8%、 2 30 %、 6 0 %和 12 0 %。在下临界温度以下 ,黄眉、红胁绣眼鸟、画眉和红嘴相思鸟的最小热传导分别是 0 2 4、 0 31、 0 2 1和 0 34mlO2 / (g·h·°C) ,分别是体重预期值的 14 9%、 14 9%、 2 15 %和 2 4 3%。这些小型鸟类的生理生态学特征是 :(1)黄眉和红胁绣眼鸟有高的基础代谢率和相对低的下临界温度 ,适应低温环境     

Control pattern of vocal center for vocalization in ruddy bunting (<Emphasis Type="Italic">Emberiza rutila</Emphasis>)

High vocal center (HVC) can produce single sound with one or two syllables by the single-type vocal control pattern in songbirds ruddy bunting (Emberiza rutila). It obviously shows left-side dominance in controlling double syllables, principal frequency (PF) and increasing sound intensity of the evoked calls. Meanwhile, the complex-type control pattern can produce complex calls with multisyllable, and also shows significant left-side dominance in controlling the number of syllables, tone changing and sound intensity. These indicate that left-side HVC controls higher frequency and complicated sentence structure. The basic vocal center, dorsomedial nucleus of the intercollicular complex (DM), controls the monosyllable sound in songbirds, and shows left-side dominance in controlling both the number of syllable and sound intensity. These results not only provide some direct evidence for left-side dominance in high vocal center, but also indicate that there is some internal connection between the high and basic vocal centers in songbirds.     

CHORUS HOWLING BY WOLVES: ACOUSTIC STRUCTURE,PACK SIZE AND THE BEAU GESTE EFFECT

ABSTRACT

A variety of structural parameters were measured from wolf choruses recorded in the Superior National Forest, Minnesota, USA. Mean duration of 60s did not vary with pack size or composition. Packs replied to simulated howling after an average of 40s, often interrupting the stimulus howls. Choruses began with simply-structured howls, which became increasingly modulated as the chorus progressed. Little difference in mean fundamental frequency or other howl parameters was found among the choruses from packs of various sizes and compositions. In particular, choruses produced by single adult pairs did not differ from those of larger packs accompanied by pups. The lack of relationship between chorus parameters and pack size or composition indicates there is little useful information concerning a pack's size to be found in its chorus howling.

The observation that chorus howling by adult pairs is often perceived as that of larger groups with pups suggests that chorus structure has evolved to exaggerate the apparent size of the pack, especially those newly-established or otherwise reduced in number. If so, wolf howling choruses may represent a mammalian example of the Beau Geste effect, made particularly viable because of the relative immunity of the signal to probing.