Sources of variation for nutritional condition indices of the plasma of migratory lesser kestrels in the breeding grounds

Although published information on reference values for biochemical parameters in birds of prey has increased during the last years, little is known on their sources of variation. We used an insectivorous and small migratory raptor species, the lesser kestrel Falco naumanni, as a model. We looked for sources of variation of nutritional biochemical parameters (i.e. triglycerides, cholesterol, uric acid and urea) of both nestlings and adults. Reference values indicated that, as a rule, lesser kestrel showed more elevated triglycerides, urea and uric acid levels than other raptors. All analyzed factors except gender (i.e. year, colony, sampling time, presence/absence of a geolocator, body mass, laying date and capture date) reached significance for at least one biochemical parameter. In the morning, we found an important postprandial increase in the concentration of all biochemical parameters in nestlings, and uric acid and urea levels in adults. A positive relationship was detected between triglycerides and body mass in nestlings and adults. Although we did not find differences between blood biochemical parameters of the oldest and youngest chick of each brood, we found that cholesterol levels were lower in nestlings from larger broods. Coloration of tarsi (measured as brightness) was related to triglycerides and urea levels of nestlings and adults, respectively. The feeding habits of lesser kestrel probably explain the different levels and patterns of variation of metabolites in comparison to more carnivorous raptors eating mammals or birds.     

Can a ‘wintering area effect’ explain population status of Swainson's hawks? A stable isotope approach

It has been suggested that declines in breeding populations of Swainson's hawks ( Buteo swainsoni ) in California, Oregon, and Nevada may be due to differential mortality of hawks on their wintering grounds. Although massive mortality incidents reported on the wintering grounds partially support this suggestion, there are no data showing differential use of wintering areas by breeding populations of Swainson's hawks. We used stable-hydrogen isotope analysis of feathers to determine whether large flocks of hawks wintering in Argentina consisted of a mixture of individuals from across the North American breeding range or consisted of individuals from discrete breeding populations. We found that flocks of wintering Swainson's hawks consisted of a mixture of individuals. The lack of connectivity between populations of breeding and wintering hawks suggests that high wintering mortality, either natural or human-induced, is unlikely to have direct consequences on a single breeding area in North America. The demographic effects of winter mortality should be 'diluted' across the entire breeding range of Swainson's hawks.     

Hailstorms as a cause of mass mortality of Swainson's hawks in their wintering grounds

We describe a mass mortality event of wintering Swainson's hawks (SH, Buteo swainsoni) in central Argentina during November 2003. One hundred thirteen SH were found dead as a consequence of a single hailstorm. In addition, 14 hawks with severe injuries were recovered alive, but only 10 of these survived 1 wk later. Another 45 dead birds of 11 species were collected in the area. Interviews with local land-owners conducted in other areas of the SH wintering grounds provided further evidence of past hailstorm-related mortality involving SH, suggesting that such events commonly occur in the Argentine Pampas. This potential cause of mass mortality of SH wintering in agricultural areas of Argentina may be significant when added to the increased mortality associated with poisoning events during the last decade.     

Relations of serum interleukin 18 levels to serum lipid and glucose concentrations in an apparently healthy adult population

AIM: To investigate the associations between serum interleukin (IL) 18 concentrations and indices of lipid and carbohydrate metabolism in healthy adults. METHODS: Fasting serum concentrations of IL-18, glucose, total cholesterol, triglyceride, and high- and low-density lipoprotein cholesterols were measured in 570 apparently healthy adults. RESULTS: Univariate linear and partial regression analyses showed that the serum IL-18 concentration was positively correlated with serum triglyceride and glucose concentrations in both obese and diabetic subjects after controlling for the confounding effects of age, sex, and body mass index. CONCLUSION: IL-18 may be associated with obesity and glucose intolerance.     

Breeding experience affects condition: blood metabolite levels over the course of incubation in a seabird

In vertebrates little is known about causes and correlates of differences in individual body condition. This is, however, essential if we are to gain an understanding of environmental influences on wild populations. To track changes in individual physiological state we analysed blood metabolite concentrations in breeding common terns Sterna hirundo. We selected birds to contrast sex, breeding experience, sampling year and nutritional state and collected repeated samples from individuals during incubation. Unlike cholesterol, triglyceride and uric acid levels strongly correlated with nutritional state. While cholesterol levels in males remained stable throughout incubation, comparatively lower levels were measured in females directly after egg-laying. In 2006, only highly experienced females showed increased cholesterol concentrations by mid-incubation, whereas less experienced females maintained reduced levels and were apparently unable to recover. In 2007, all females showed an increase in cholesterol by mid-incubation. Triglyceride levels did not differ between sexes, but concentrations were significantly higher in more experienced birds and were overall higher in 2007 than in 2006. Uric acid concentrations did not differ significantly. The variation in cholesterol and triglyceride levels can be explained by differences in foraging conditions, as food abundance, onset of breeding and mean clutch size indicate 2007 to be the superior year. Thus, environmental conditions and breeding experience play an important role for cholesterol and triglyceride levels as well as the physiological state.     

Seasonal variation and sex differences in the nutritional status in two local populations of wild Japanese macaques

Seasonal variations and sex differences in the nutritional status in two local populations of wild Japanese macaques (Macaca fuscata fuscata) were examined. It was hypothesized that the ecological condition and/or reproductive strategies of each sex determine the nutritional condition and its seasonal fluctuation in each sex. Morphometric measures such as body mass, thoracic and femoris circumferences, skinfold thickness in four places (triceps, biceps femoris, subscapular, and abdomen), and wet mass of mesenteric and omental fat were used for comparisons between sexes, seasons, and populations. Animals of the Shimane population were larger than those of the Boso population in most morphometric measures, abdominal skinfold, and mesenteric and omental fat mass, suggesting environmental and/or genetic differences in the two populations. Females of both populations had larger skinfolds and mesenteric and omental fat mass than males, indicating that females had more fat than males. Females showed seasonality in most measures, having two peaks of body mass, thoracic and femoris circumferences, abdominal skinfold, and mesenteric and omental fat masses in early spring and late fall. In contrast, males exhibited no clear seasonal variations for most measurements, except for biceps femoris and subscapular skinfolds, which showed peaks in summer. Most morphometric measurements significantly correlated to each other, particularly in females, but most skinfolds had no correlation with other measurements. These findings suggest that sexual dimorphism in body composition and its fluctuation may be affected by the different reproductive strategies of males and females.     

Serum biochemical values in fallow deer (<Emphasis Type="Italic">Dama dama</Emphasis> L.) from different habitats in Croatia

Serum biochemical values were determined in blood samples collected from 48 shot fallow deer from the Brijuni islands and 45 sedated fallow deer (Dama dama L.) from hunting grounds in the continental part of Croatia. The parameters were compared with regard to age, sex and habitat. Statistically significant differences were found for serum total protein concentration, alkaline phosphatase, aspartate aminotransferase and alanine aminotransferase activity between young and adult island deer, as well as for total protein, triacylglyceride, cholesterol concentration and alkaline phosphatase activity between young and adult continental deer. In young animals, island males had higher albumin concentrations, while continental males had higher alkaline phosphatase values than females. In adult animals, island males had a higher blood urea nitrogen concentration, while continental males had higher albumin and cholesterol concentrations, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase and creatine kinase activities. In this group, males exhibited lower bilirubin and triacylglyceride concentrations than females. Our results indicate that besides age, sex and sampling method, nutritional and environmental factors should be considered when evaluating serum biochemical parameters of fallow deer     

IgA肾病合并高尿酸血症患者的危险因素分析

摘要 目的：探讨IgA肾病合并高尿酸血症患者的危险因素。方法：回顾性分析2018年1月至2021年1月于我院进行治疗的IgA肾病患者149例的病理资料,根据高尿酸血症发生情况分为高尿酸血症组（n=65）,正常尿酸组（n=84）。比较两组病理特征,收集患者年龄、性别、BMI、性别、高血压、血肌酐、尿素氮、血白蛋白、血胆固醇、甘油三酯、24 h尿蛋白定量、IL-6、IL-1及胱抑素C及CRP等资料,分析高尿酸血症发生的危险因素。结果：两组患者年龄、BMI、CRP差异无统计学意义（P>0.05）;性别、高血压、血肌酐、尿素氮、血白蛋白、血胆固醇、甘油三酯、24 h尿蛋白定量、IL-6、IL-1及胱抑素C与IgA肾病患者发生高尿酸血症相关（P<0.05）;高尿酸组患者球性硬化、节段硬化、新月体形成、小管萎缩、间质炎性浸润及间质纤维化发生率均显著高于正常尿酸组,差异显著（P<0.05）;多因素非条件Logistic分析显示,性别、高血压、血肌酐、尿素氮、血白蛋白、血胆固醇、甘油三酯、24 h尿蛋白定量、IL-6、IL-1及胱抑素C均是IgA肾病患者发生高尿酸血症的独立危险因素（P<0.05）。结论：患者性别、高血压、血肌酐、尿素氮、血白蛋白、血胆固醇、甘油三酯、24 h尿蛋白定量、IL-6、IL-1及胱抑素C均是IgA肾病患者发生高尿酸血症的危险因素,临床上对于具有危险因素的患者引起重视,提高治疗效果。     

L-阿拉伯糖对尿酸的调节作用

转录因子是一类在生物生命活动过程中起到调控作用的重要因子,参与了各种信号转导和调控过程,可以直接或间接结合在顺式作用元件上,实现调控目标基因转录效率的抑制或增强,从而使植物在应对逆境胁迫下做出反应。 WRKY转录因子在大多数植物体内都有分布,是一类进化非常保守的转录因子家族,参与植物生长发育以及响应逆境胁迫的生理过程。众多研究表明,WRKY转录因子在植物中能够应答各种生物胁迫,如细菌、病毒和真菌等;多种非生物胁迫,包括高温、冷害、高光和高盐等;以及在各种植物激素,包括茉莉酸( JA)、水杨酸( SA)、脱落酸( ABA)和赤霉素( GA)等,在其信号传递途径中都起着重要作用。 WRKY转录因子家族蛋白至少含有一段60个氨基酸左右的高度保守序列,被称为WRKY结构域,其中WRKYGQK多肽序列是最为保守的,因此而得名。该转录因子的WRKY结构域能与目标基因启动子中的顺式作用元件W￣box( TTGAC序列)特异结合,从而调节目标基因的表达,其调控基因表达主要受病原菌、虫咬、机械损伤、外界胁迫压力和信号分子的诱导。该文介绍了植物WRKY转录因子在植物应对冷害、干旱、高盐等非生物胁迫与病菌、虫害等生物胁迫反应中的重要调控功能,并总结了WRKY转录因子在调控这些逆境胁迫反应过程中的主要生理机制。     

Seasonal changes in serum metabolites in free-ranging alpine marmots (<Emphasis Type="Italic">Marmota marmota</Emphasis>)

Circannual changes in serum parameters and body mass were studied in free-ranging Marmota marmota that had been shot in Switzerland (Grisons) for management reasons in May, July, and September of 1995, 1996, and 1997; and in April 1996. Markers of lipid (triglycerides, cholesterol), protein (total protein, urea-nitrogen) and mineral (calcium, inorganic phosphate) metabolism were evaluated in 111 haemolysis-free serum samples; the effects of sex, age, reproductive status, season and year were tested. Mean body mass was higher in adult males than in adult females in July and September, and serum cholesterol concentrations were lower in adult males in May. Pregnant females had lower concentrations of total protein than non-pregnant females, and triglyceride concentrations were negatively correlated with the number of uterine ampullae. Inorganic phosphate decreased and total protein increased with age. In adults, triglycerides, cholesterol and urea-nitrogen increased mainly from May to July and decreased between September and May. Total protein, calcium and phosphate did not change throughout the year. This suggests that, during the active season, ingested lipids and amino acids were utilised for metabolic needs or lipid storage, while in winter, lipids were catabolised and protein was spared. Quantitative differences between years, observed for triglycerides and total protein during the active season, were probably due to different climatic conditions in each year.     

Adaptations to fasting in a terrestrial mustelid, the sable (Martes zibellina)

The aim of this study was to investigate whether the actively wintering Palearctic sable Martes zibellina has evolved physiological adaptations to tolerate nutritional scarcity. Sixteen farm-bred male sables were divided into a fed control group and an experimental group fasted for 4 days. The rate of weight loss in the sable was similar to other medium-sized mustelids. Fasting led to hypoglycaemia and to a decreased lymphocyte percentage. The sable derived metabolic energy from both subcutaneous and intraabdominal white adipose tissues and the relative decrease in fat mass was the largest for the retroperitoneal and subcutaneous depots. Metabolic energy derived partly from body proteins indicated by the increased plasma levels of urea, uric acid and total essential amino acids. Triacylglycerols accumulated in the livers of the fasted sables and the increased plasma aminotransferase activities suggested hepatic dysfunction. The decreased plasma insulin concentrations and the elevated cortisol levels probably contributed to stimulated lipolysis and protein catabolism. Moreover, fasting increased the plasma ghrelin concentrations of the sables and down-regulated the thyroid activity.     

Effect of the amount of body condition loss from the dry to near calving periods on the subsequent body condition change, occurrence of postpartum diseases, metabolic parameters and reproductive performance in Holstein dairy cows

We investigated the effect of body condition loss from the dry to near calving periods on the subsequent body condition change, the occurrence of postpartum diseases, the serum metabolic parameters total cholesterol, triglyceride, glucose, and urea nitrogen and the number of days to first breeding after calving in Holstein dairy cows. Body condition scoring (using a 5-point scale with quarter-point divisions) was performed on 67 pregnant Holstein dairy cows. Cows were scored once for body condition during the dry period (prepartum day 35 +/- 16), near calving (postpartum day 5 +/- 4), and subsequently at months 1 (+/- day 4), 2 (+/- day 5), 3 (+/- day 5), and 4 (+/- day 4) of lactation. At the same time, blood samples were collected to evaluate serum total cholesterol, triglyceride, glucose and urea nitrogen concentrations. Cows were categorized based on body condition loss from the dry to near calving periods into two groups: the moderate condition loss group (0-0.75 points, n=41), or the marked condition loss group (1.0-1.5 points, n=26). Regular reproductive health examination was conducted by the same investigator once a week. The marked condition loss group lost more body condition (P<0.01) than the moderate condition loss group consistently until month 1 of lactation. The recovery of body condition in the marked condition loss group was more delayed (P<0.01) than in the moderate condition loss group from months 1 to 4 of lactation. The occurrence of metritis and metabolic diseases (including abomasal displacement, milk fever, ketosis) was greater (P<0.01) in the marked condition loss group (62 and 23%) than in the moderate condition loss group (27 and 2%), respectively. The total cholesterol concentration was lower (P<0.05) in the marked condition loss group (167 +/- 5.3 mg/dl) than in the moderate condition loss group (183 +/- 5.8 mg/dl) at month 1 of lactation, however, the cholesterol levels at the other periods were not different (P>0.05) between the two groups. The triglyceride, glucose, and urea nitrogen concentrations were not different (P>0.05) from the dry period to month 4 of lactation between the two groups. The number of days to first breeding after calving was longer (P<0.05) in the marked condition loss group (103 +/- 7.8 day) than in the moderate condition loss group (87 +/- 5.3 day). We conclude that marked body condition loss from the dry to near calving periods results in the increased occurrence of postpartum metabolic and reproductive diseases, decreased serum total cholesterol concentrations at month 1 of lactation and a longer interval to first breeding after calving in Holstein dairy cows, probably due to the more severe energy deficit reflected by unfavorable body condition score change during early lactation.     

七种圈养鹤的部分血液生化指标分析

为探索圈养鹤类的血液生化指标差异,本研究对白鹤(Grus leucogeranus)、丹顶鹤(G.japonensis)、黑冠鹤(Balearica pavonina)、黑颈鹤(G.nigricollis)、灰冠鹤(B.regulorum)、蓝鹤(Anthropoides paradiseus)和白枕鹤(G.vipio)的10项血液生化指标(总胆固醇、甘油三酯、总蛋白、白蛋白、球蛋白等)进行统计分析,并与国际物种信息系统(ISIS)提供的数据进行比较。结果表明,1)不同鹤类之间总胆固醇差异显著,而甘油三酯和血糖没有显著性差异,除了黑冠鹤和灰冠鹤的总胆固醇以及蓝鹤的血糖外,其余鹤类的常值均高于ISIS的平均值。2)不同鹤类之间的总蛋白、球蛋白和白蛋白的浓度差异显著,但总蛋白、球蛋白和白蛋白均在ISIS的正常范围内。3)不同鹤类间肌酐和尿酸不具有显著性差异,其中尿酸低于ISIS平均值,但仅尿素氮差异显著。不同鹤类之间血液生化指标存在差异,与圈养鹤的营养水平和环境有关。因此血液生化指标对于圈养鹤类营养状态和健康情况的判断具有重要参考价值,对圈养动物饲养管理具有重要的指导作用。     

Blood biochemistry reference values for wild juvenile loggerhead sea turtles (Caretta caretta) from Madeira archipelago

Standard biochemical parameters were determined in wild juvenile loggerhead sea turtles Caretta caretta living offshore Madeira Island, northeast Atlantic. We analyzed the influence of age, sex, sea surface temperature, and body condition index on biochemical parameters including uric acid, total bilirubin, total cholesterol, creatinine kinase (CK), glucose, total protein, urea nitrogen, lactate dehydrogenase, aspartate aminotranspherase (AST), gamma-glutamyl transferase (GGT), albumin, alkaline phosphatase (ALP), sodium (NA), potassium (K), chloride, calcium, phosphorus, and magnesium. Significant positive correlations were found between turtle body size and total cholesterol, total protein, and albumin. Total protein and the enzymes AST and CK were lower than reported levels in adults. Calcium levels were lower than those reported in adult or captive turtles, but similar to wild juveniles from Australian waters, and were interpreted as normal for this age category. These data may be useful to evaluate the health status of stranded or injured animals and to improve veterinary care at rehabilitation centers.     

Where do Swainson's hawks winter? Satellite images used to identify potential habitat

During recent years, predictive modelling techniques have been increasingly used to identify regional patterns of species spatial occurrence, to explore species–habitat relationships and to aid in biodiversity conservation. In the case of birds, predictive modelling has been mainly applied to the study of species with little variable interannual patterns of spatial occurrence (e.g. year‐round resident species or migratory species in their breeding grounds showing territorial behaviour). We used predictive models to analyse the factors that determine broad‐scale patterns of occurrence and abundance of wintering Swainson's hawks (Buteo swainsoni). This species has been the focus of field monitoring in its wintering ground in Argentina due to massive pesticide poisoning of thousands of individuals during the 1990s, but its unpredictable pattern of spatial distribution and the uncertainty about the current wintering area occupied by hawks led to discontinuing such field monitoring. Data on the presence and abundance of hawks were recorded in 30 × 30 km squares (n = 115) surveyed during three austral summers (2001–03). Sixteen land‐use/land‐cover, topography, and Normalized Difference Vegetation Index (NDVI) variables were used as predictors to build generalized additive models (GAMs). Both occurrence and abundance models showed a good predictive ability. Land use, altitude, and NDVI during spring previous to the arrival of hawks to wintering areas were good predictors of the distribution of Swainson's hawks in the Argentine pampas, but only land use and NDVI were entered into the model of abundance of the species in the region. The predictive cartography developed from the models allowed us to identify the current wintering area of Swainson's hawks in the Argentine pampas. The highest occurrence probability and relative abundances for the species were predicted for a broad area of south‐eastern pampas that has been overlooked so far and where neither field research nor conservation efforts aiming to prevent massive mortalities has been established.     

Sex determination of three raptor species using morphology and molecular techniques

ABSTRACT.   Accurate identification of sex is important for many raptor studies, but may be difficult to determine in the field for some species. Because of size differences between males and females, morphological measurements have often been used to sex raptors. However, few investigators have examined the accuracy of using measurements of individuals made at one location to sex individuals of the same species at another location. Our objective was to develop more accurate region-specific methods for determining the sex of Red-tailed Hawks ( Buteo jamaicensis ), Red-shouldered Hawks ( B. lineatus ), and Cooper's Hawks ( Accipiter cooperii ) migrating through and wintering in California. We determined sex using a polymerase chain reaction (PCR)-based genetic test and grouped individuals based on sex, age, and geographic area. We did not combine groups due to differences in measurements between age classes and geographic areas. We then compared a suite of morphological measurements between males and females of each combination, and developed both a discriminant function and a flowchart to determine the sex of Red-tailed and Red-shouldered hawks in the field. The flowcharts were more accurate than the functions for both species. We also confirmed the accuracy of the current flowchart used to determine the sex of Cooper's Hawks migrating along the California coast. These region-specific methods for Red-tailed and Cooper's hawks were generally more accurate than published methods, possibly indicating different populations of these species and highlighting the importance of validating sexing methods when using them in different locations.     

Blood values of Bald Ibis ( Geronticus eremita) in captivity: comparative ranges and variability with age, sex and physical condition

The Bald Ibis (Geronticus eremita) is one of the worlds most threatened species of birds. The number of individuals in captivity is several times greater than the number of individuals in the wild, so that the re-introduction of individuals from captive breeding into their natural habitat may be vital for the recovery of the species. A knowledge of the health problems associated with the handling of captive individuals and the improvement of their veterinary care could have great importance in determining the success of these captive breeding programs. Haematology and blood chemistry are very useful complementary tools in the diagnosis and treatment of diseases in birds, and provide valuable information about the individuals nutritional status and physical condition. The present work reports haematocrit and blood chemistry values for individuals belonging to a captive population of this species, and analyses their variability with respect to age, sex, and physical condition of the animals. Adults presented greater values of haematocrit, uric acid, total proteins, cholesterol, and aspartate amine transferase than the young. With respect to sex differences, adult female birds had higher concentrations of alkaline phosphatase than males, contrary to previous results for captive individuals of this species. The condition index of adults was positively correlated with triglycerides, glucose, and alkaline phosphatase levels, and negatively with urea and lactate dehydrogenase levels. These results may be very useful as a complementary diagnosis tool during the veterinary care of individuals of this species included in re-introduction programs.     

Variation in plasma biochemical parameters in captive adult red-legged partridges (Alectoris rufa) during daylight hours

Blood biochemical parameters may provide useful information about the physical condition of the individual, making them a useful tool in ecological studies. However, to avoid biases, factors affecting circulating levels of plasma metabolites must be investigated. In this paper, we analyse the effect of daytime sampling hour on seven plasma metabolites in adult red-legged partridges (Alectoris rufa) with free access to food during the breeding season. We found that sampling hour affected circulating levels of glucose and triglycerides but not those of cholesterol, total protein, uric acid, urea or albumin. A sex effect was found only for glucose, uric acid, urea and triglycerides. Repeated sampling affected all the parameters studied. These results suggest that the effect of sex, sampling hour and repeated sampling should be carefully controlled for (methodologically or by statistical procedures) to avoid undesirable sources of error at least in some blood parameters.     

Differential effects of dietary flaxseed protein and soy protein on plasma triglyceride and uric acid levels in animal models

The effect of dietary soy protein and flaxseed meal on metabolic parameters was studied in two animal models, F344 rats with normal lipid levels and obese SHR/N-cp rats with elevated levels of cholesterol and triglyceride. The rats were fed AIN 93 diet differing only in the source of protein. The rats were fed either 20% casein, 20% soy protein or 20% flaxseed meal. Plasma was analyzed for cholesterol, triglyceride, uric acid, blood urea nitrogen (BUN), creatinine and total protein. In both strains of rats, flaxseed meal significantly decreased plasma cholesterol and triglyceride concentrations. The effect of soy protein on lipids was not as striking as that of flaxseed meal. Flaxseed meal also lowered uric acid in F344 rats and BUN in SHR/N-cp rats. Since cholesterol, triglyceride and uric acid are independent risk factors for cardiovascular disorders, our data show that both flaxseed meal and soy protein may have beneficial effects. Which chemical constituent(s) of flaxseed meal or soybean is (are) responsible for the beneficial effects need to be identified.     

Non-breeding song rate reflects nutritional condition rather than body condition

Numerous studies have focused on song in songbirds as a signal involved in mate choice and intrasexual competition. It is expected that song traits such as song rate reflect individual quality by being dependent on energetic state or condition. While seasonal variation in bird song (i.e., breeding versus non-breeding song) and its neural substrate have received a fair amount of attention, the function and information content of song outside the breeding season is generally much less understood. Furthermore, typically only measures of condition involving body mass are examined with respect to song rate. Studies investigating a potential relationship between song rate and other indicators of condition, such as physiological measures of nutritional condition, are scant. In this study, we examined whether non-breeding song rate in male European starlings (Sturnus vulgaris) reflects plasma metabolite levels (high-density lipoproteins (HDL), albumin, triglycerides and cholesterol) and/or body mass. Song rate was significantly positively related to a principal component representing primarily HDL, albumin and cholesterol (and to a lesser degree plasma triglyceride levels). There was only a trend toward a significant positive correlation between song rate and body mass, and no significant correlation between body mass and the abovementioned principal component. Therefore, our results indicate that nutritional condition and body mass represent different aspects of condition, and that song rate reflects nutritional rather than body condition. Additionally, we also found that intra-individual song rate consistency (though not song rate itself) was significantly positively related to lutein levels, but not to body mass or nutritional condition. Together our results suggest that the relation between physiological measures of nutritional condition and song rate, as well as other signals, may present an interesting line of future research, both inside and outside the breeding season.