Avian Diets Research Articles

A framework and review of evidence of the importance of coral reefs for marine birds in tropical ecosystems.

As global heating and other anthropogenic influences alter tropical marine environments, it is unclear how marine bird populations will be impacted and whether their current roles in tropical marine ecosystems will change. Although marine birds roost and breed on tropical islands in large numbers, the direct trophic interactions between these birds and their prey across the tropics are poorly documented. We present a first framework for evaluating the dependence on and contributions of marine birds to tropical coral reef ecosystems and use it to examine the evidence for different kinds of interaction, focusing primarily on avian diets. We found 34 publications between 1967 and 2023 that presented a total of 111 data sets with enough detail for quantitative dietary analysis of tropical marine birds. Only two bird species out of 37 (5.4%) had diets of >50% coral reef fishes and only one, the Pacific Reef Egret, appeared to depend almost entirely on reef-based production. Marine birds are also prey for other marine organisms, but insufficient data are available for quantitative analysis. Evidence for indirect effects of birds in tropical marine environments is stronger than for direct dependence on coral reefs, particularly in relation to nutrient concentration and the fertilisation impacts of guano on corals. Dispersal of propagules (e.g. seeds, spores, invertebrate eggs) by bathing, drinking, resting or foraging birds is under-studied and poorly documented. Although the degradation of coral reefs appears unlikely to have a significant direct impact on food availability for most marine bird populations, indirect effects involving marine birds may be disrupted by global environmental change.

Sulfur isotopic discrimination factors differ among avian tissues and diets: Insights from a case study in Gentoo Penguins

Abstract The use of stable isotopes of sulfur (δ34S) to infer avian diets, foraging habitats, and movements is relatively uncommon, resulting in a lack of information on patterns of δ34S incorporation in avian tissue. In a controlled study of Gentoo Penguins (Pygoscelis papua), we found that diet-tissue isotopic discrimination factors (Δ34Sdiet-tissue) differed among egg components and feathers synthesized from a common diet, ranging from –0.4 to –1.7‰. We also found that methodical choices such as lipid extraction and prey tissue selection influenced calculated Δ34Sdiet-tissue values. Specifically, Δ34Sdiet-tissue values were lower (i.e., more negative) when calculated using whole fish relative to fish muscle and lipid-extraction biased egg yolk, but not fish tissue, δ34S values. The Δ34Sdiet-tissue values obtained for Gentoo Penguins fed a marine fish diet were generally lower than those reported for freshwater fish consumption by Double-crested Cormorants (Phalacrocorax auritus), the only other bird species in which Δ34Sdiet-tissue has been quantified. We found support for the hypothesis that tissue Δ34Sdiet-tissue values are inversely related to dietary δ34S values in birds, similar to what has been observed in mammals. Given this relationship, the discrimination factors reported here for Gentoo Penguins may be broadly applicable to other avian species with a similar marine diet. Finally, we provide recommendations for future studies seeking to quantify Δ34Sdiet-tissue in avian tissues and guidance to allow for greater application of sulfur stable isotope analysis in ornithological research.

Web-sourced photographic methods reveal dietary composition and shifts in resident and migrant Coracias rollers in southern Africa

Closely related species coexisting in the same niche often have dietary overlap and interspecific competition can result in resource partitioning e.g., dietary shifts, migration or phenological changes. Traditional methods to study avian diets are typically costly, difficult, and invasive. Using web-sourced photographs is an emerging, non-invasive method to study avian foraging ecology. We used this approach, along with photographic road surveys, to study prey composition of migratory European Rollers Coracias garrulus and resident Lilac-breasted Rollers Coracias caudatus where they co-occur in southern Africa. These insectivorous sister species are frequently photographed with prey in their bills because of their conspicuous perch-and-wait foraging behaviour and bright plumage coloration. We collated over 250 photographs of rollers holding prey and identified prey items representing 15 animal orders. Lilac-breasted Roller diet contained six unique orders of prey during the Austral summer (when the European Roller is present), and only one during winter (when the European Roller has migrated north). This suggests that Lilac-breasted Rollers may broaden their diet seasonally to alleviate competition with European Rollers during summer. Additionally, Lilac-breasted and European Rollers had an 84% overlap in dietary composition, potentially representing high interspecific competition - even during wet savanna summers when resource abundance is high - that might have originally driven the evolution of migratory behaviour in the European Roller. Our findings expand the current knowledge of roller diets and highlighting the growing role of social media in ecological studies.

Current methods and future directions in avian diet analysis

AbstractIdentifying the composition of avian diets is a critical step in characterizing the roles of birds within ecosystems. However, because birds are a diverse taxonomic group with equally diverse dietary habits, gaining an accurate and thorough understanding of avian diet can be difficult. In addition to overcoming the inherent difficulties of studying birds, the field is advancing rapidly, and researchers are challenged with a myriad of methods to study avian diet, a task that has only become more difficult with the introduction of laboratory techniques to dietary studies. Because methodology drives inference, it is important that researchers are aware of the capabilities and limitations of each method to ensure the results of their study are interpreted correctly. However, few reviews exist which detail each of the traditional and laboratory techniques used in dietary studies, with even fewer framing these methods through a bird-specific lens. Here, we discuss the strengths and limitations of morphological prey identification, DNA-based techniques, stable isotope analysis, and the tracing of dietary biomolecules throughout food webs. We identify areas of improvement for each method, provide instances in which the combination of techniques can yield the most comprehensive findings, introduce potential avenues for combining results from each technique within a unified framework, and present recommendations for the future focus of avian dietary research.

DNA metabarcoding reveals broadly overlapping diets in three sympatric North American hummingbirds

ABSTRACT Hummingbirds, a highly diverse avian family, are specialized vertebrate pollinators that feed upon carbohydrate-rich nectar to fuel their fast metabolism while consuming invertebrates to obtain protein. Previous work has found that morphologically diverse hummingbird communities exhibit higher diet specialization on floral resources than morphologically similar hummingbird communities. Due to the difficulties of studying avian diets, we have little understanding whether hummingbirds show similar patterns with their invertebrate prey. Here, we use DNA metabarcoding to analyze floral and invertebrate diets of 3 species of sympatric North American hummingbirds. We collected fecal samples from 89 Anna’s (Calypte anna), 39 Black-chinned (Archilochus alexandri), and 29 Calliope (Selasphorus calliope) hummingbirds in urban and rural localities as well as across an elevational gradient from sea level to 2,500 meters above sea level in California, USA. We found hummingbirds showed high dietary overlap in both invertebrate and plant resources, with few invertebrate and plant families common to most individuals and many families found in only a few individuals. Chironomidae was the most common invertebrate family across all species, and Rosaceae and Orobanchaceae were the most common plant families. Anna’s Hummingbirds had significantly higher invertebrate diet diversity than Black-chinned Hummingbirds when found at the same sites, but we found no difference in plant diet diversity among any of the 3 species. Hummingbirds in urban sites had higher plant diet diversity than in rural sites, but we found no effect of elevation on dietary richness. Our study shows how DNA metabarcoding can be used to non-invasively investigate previously unknown life-histories of well-studied birds, lending insight to community structure, function, and evolution.

Diet and Adaptive Evolution of Alanine-Glyoxylate Aminotransferase Mitochondrial Targeting in Birds.

Adaptations to different diets represent a hallmark of animal diversity. The diets of birds are highly variable, making them an excellent model system for studying adaptive evolution driven by dietary changes. To test whether molecular adaptations to diet have occurred during the evolution of birds, we examined a dietary enzyme alanine-glyoxylate aminotransferase (AGT), which tends to target mitochondria in carnivorous mammals, peroxisomes in herbivorous mammals, and both mitochondria and peroxisomes in omnivorous mammals. A total of 31 bird species were examined in this study, which included representatives of most major avian lineages. Of these, 29 have an intact mitochondrial targeting sequence (MTS) of AGT. This finding is in stark contrast to mammals, which showed a number of independent losses of the MTS. Our cell-based functional assays revealed that the efficiency of AGT mitochondrial targeting was greatly reduced in unrelated lineages of granivorous birds, yet it tended to be high in insectivorous and carnivorous lineages. Furthermore, we found that proportions of animal tissue in avian diets were positively correlated with mitochondrial targeting efficiencies that were experimentally determined, but not with those that were computationally predicted. Adaptive evolution of AGT mitochondrial targeting in birds was further supported by the detection of positive selection on MTS regions. Our study contributes to the understanding of how diet drives molecular adaptations in animals, and suggests that caution must be taken when computationally predicting protein subcellular targeting.

From Landfills to the Dinner Table: Red Grape Pomace Waste as a Nutraceutical for Broiler Chickens

The disposal of red grape pomace (GP) in landfills and by incineration has negative impacts on the environment. It is, therefore, imperative that alternative and sustainable ways of managing this waste product are identified. Using GP as a source of nutrients and beneficial bioactive compounds in avian diets is a potential waste-reduction and valorization strategy that promotes sustainable agriculture. However, there is limited information on the valorization of GP for this purpose. This study, therefore, investigated the effect of dietary inclusion of GP on growth performance, blood parameters, carcass characteristics, and breast meat quality traits of broilers. Four hundred, two-week old Cobb 500 broilers (279.2 ± 18.87 g) were allocated to 40 pens. Five isonitrogenous and isoenergetic diets were formulated by including GP in commercial broiler diets at 0 (GP0), 2.5 (GP25), 4.5 (GP45); 5.5% (GP55); and 7.5% (GP75). Feed intake, weight gain, feed utilization efficiency, hematology, serum biochemistry, carcass characteristics, and breast meat quality traits were measured. Chickens on GP75 had the least feed intake (p < 0.05) but there were no dietary effects on weight gain. Birds on GP0 had the highest (p < 0.05) feed conversion ratio (1.79) while those fed GP75 had the lowest (p < 0.05) ratio (1.45). Breast meat from broilers offered GP75 had the highest (p < 0.05) redness value (0.75) while the GP0 diet promoted the least (p < 0.05) redness value (0.49). Broilers fed GP55 and GP75 diets had higher (p < 0.05) feed conversion efficiency compared to GP0 birds. Inclusion of GP in broiler diets has the potential to reduce feed costs, thus making this valorization strategy a sustainable alternative to current pomace disposal methods. Adoption of this waste-reduction and valorization strategy promotes sustainable agriculture by contributing to food security and environmental stewardship.

Influences of the invasive tamarisk leaf beetle (Diorhabda carinulata) on avian diets along the Dolores River in Southwestern Colorado USA

The tamarisk leaf beetle (Diorhabda carinulata), introduced from Eurasia in 2001 as a biological control agent for the invasive plant Tamarix ramosissima, has spread widely throughout the western USA. With D. carinulata now very abundant, scientists and restoration managers have questioned what influence this introduced arthropod might have upon the avian component of riparian ecosystems. From 2009 through 2012 we studied the consequences of biological invasions of the introduced tamarisk shrub and tamarisk leaf beetles on the diets of native birds along the Dolores River in southwestern Colorado, USA. We examined avian foraging behavior, sampled the arthropod community, documented bird diets and the use of invasive tamarisk shrubs and tamarisk leaf beetles by birds. We documented D. carinulata abundance, on what plants the beetles occurred, and to what degree they were consumed by birds as compared to other arthropods. We hypothesized that if D. carinulata is an important new avian food source, birds should consume beetles at least in proportion to their abundance. We also hypothesized that birds should forage more in tamarisk in the late summer when tamarisk leaf beetle larvae are more abundant than in early summer, and that birds should select beetle-damaged tamarisk shrubs. We found that D. carinulata composed 24.0 percent (± 19.9–27.4%) and 35.4% biomass of all collected arthropods. From the gut contents of 188 birds (25 passerine species), only four species (n = 11 birds) contained tamarisk leaf beetle parts. Although D. carinulata comprised one-quarter of total insect abundance, frequency of occurrence in bird gut contents was only 2.1% by abundance and 3.4% biomass. Birds used tamarisk shrubs for foraging in proportion to their availability, but foraging frequency did not increase during the late summer when more tamarisk leaf beetles were present and birds avoided beetle-damaged tamarisk shrubs. Despite D. carinulata being the most abundant arthropod in the environment, these invasive beetles were not frequently consumed by birds and seem not to provide a significant contribution to avian diets.

A classification scheme for avian diet types

Descriptions of avian diets currently lack consistent terminology and standardized methods. As a consequence, most available classifications, especially for tropical birds, are inconsistent and often misleading. We identified 23 food categories most commonly eaten by birds (e.g., seeds, fruits, and insects) and proposed standard names that accurately describe the diet type associated with each food category (e.g., granivore, frugivore, and insectivore). We also propose a classification scheme for avian diet types that takes into account the number of food categories consumed and the volumetric proportion (based on stomach content analysis) of each category eaten to indicate the diet type of a species, using a binomial terminology. Given that bird diets encompass a continuum between some extremes commonly treated as distinct categories, we adopted arbitrary breaking points to delimit distinct diet types. For example, species with different proportions of insects and fruits in their diets can be classified as insectivores (IN), insectivores secondarily frugivores (INFR), frugivores-insectivores (FR-IN), frugivore secondarily insectivores (FRIN), and frugivores (FR). Because many factors can influence avian diets, the diet types of species can also be classified based on age-related, sexual, seasonal, and/or geographic variation, e.g., young are insectivores and adults are frugivores, we believe that our classification scheme provides a standardized terminology that can contribute to a more consistent and effective exchange of information about avian diets.

Food sources of wintering piscivorous waterbirds in coastal waters: A triple stable isotope approach for the southeastern Baltic Sea

This study uses a triple isotope approach (δ13C, δ15N, and δ34S) to quantify the main food sources for wintering piscivorous waterbirds in the coastal zone of the southeastern Baltic Sea. Significant differences of δ15N and δ34S values among pelagic fishes, benthic fishes, and benthopelagic European smelt (Osmerus eperlanus) were detected, while δ13C was similar among these sources. Using different combinations of δ13C, δ15N, and δ34S values in mixing models, we found that common guillemot (Uria aalge) and red-throated diver (Gavia stellata) mostly foraged on pelagic prey (50–70% and 51–56%, respectively), whereas great crested grebe (Podiceps cristatus) consumed benthic prey (48–53%). European smelt comprised a substantial proportion of the diet of studied birds (19–36%). A stable isotope approach can be recommended as a non-lethal method to study avian diets in the coastal waters of the Baltic Sea.

Birds Generally Carry a Small Repertoire of Bitter Taste Receptor Genes.

As they belong to the most species-rich class of tetrapod vertebrates, birds have long been believed to possess an inferior taste system. However, the bitter taste is fundamental in birds to recognize dietary toxins (which are typically bitter) in potential food sources. To characterize the evolution of avian bitter taste receptor genes (Tas2rs) and to test whether dietary toxins have shaped the repertoire size of avian Tas2rs, we examined 48 genomes representing all but 3 avian orders. The total number of Tas2r genes was found to range from 1 in the domestic pigeon to 12 in the bar-tailed trogon, with an average of 4, which suggested that a much smaller Tas2r gene repertoire exists in birds than in other vertebrates. Furthermore, we uncovered a positive correlation between the number of putatively functional Tas2rs and the abundance of potential toxins in avian diets. Because plant products contain more toxins than animal tissues and insects release poisonous defensive secretions, we hypothesized that herbivorous and insectivorous birds may demand more functional Tas2rs than carnivorous birds feeding on noninsect animals. Our analyses appear to support this hypothesis and highlight the critical role of taste perception in birds.

稳定同位素分析在鸟类食性及营养级结构中的应用

PDF HTML阅读 XML下载 导出引用 引用提醒 稳定同位素分析在鸟类食性及营养级结构中的应用 DOI: 10.5846/stxb201402120243 作者: 作者单位: 中国林业科学研究院森林生态环境与保护研究所，国家林业局森林保护学重点实验室,中国林业科学研究院森林生态环境与保护研究所，国家林业局森林保护学重点实验室,中国林业科学研究院森林生态环境与保护研究所，国家林业局森林保护学重点实验室 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然基金项目(31372226) Application of stable isotope analyses to avian diets and trophic structure Author: Affiliation: Key Laboratory of Forest Protection of State Forestry Administration,Research Institute of Forest Ecology,Environment and Protection,Chinese Academy of Forestry,Key Laboratory of Forest Protection of State Forestry Administration,Research Institute of Forest Ecology,Environment and Protection,Chinese Academy of Forestry,Key Laboratory of Forest Protection of State Forestry Administration,Research Institute of Forest Ecology,Environment and Protection,Chinese Academy of Forestry Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:稳定同位素分析(stable isotope analysis, SIA)自20世纪70年代末引入鸟类生态学领域以来,在研究鸟类食性和营养级结构方面展现了强大的发展潜力和广泛的应用前景。总结了该技术在鸟类食源组成和营养级结构方面研究的前期准备、实验流程、数据分析和研究进展等,重点阐述了其在鸟类保护与管理方面的应用。鉴于稳定同位素在生物体内存在分馏现象,从鸟类不同组织和部位对营养级富集因子、转化周期、同位素印记的差异,提出了完善该方法的建议和应用前景。 Abstract:In the past three decades, the application of the stable isotope technique to avian ecology has become increasingly widespread. The use of stable isotopes in the current studies relied on two principles. First, the isotopic composition of animal tissues reflects that of the diet in a predictable manner. Second, because tissues turn over at different rates, they integrate this information over different temporal scales and, if the animal is mobile, different spatial scales. This technique overcomes the limitations of traditional methods, especially in aspects of the different temporal-spatial diets, trophic structure of consumers, and trophic levels within the food web. In this paper, we summarize the preparation, working process, and data analysis of the application of stable isotope analyses in the avian diet and trophic structure. The paper also discusses the current progress of this technique in the origin of avian diets and trophic structure positioning. In particular, we review its main applications in terms of conservation and management: (1) to assess the impacts of habitat change on the population reproduction, (2) to detect the causes related to population dynamics, and (3) to estimate the nutrient allocation of reproduction in the breeding ground compared with that in the wintering ground. However, despite its potential, the technique is still regarded as a black box by many ornithologists. In most instances, these techniques did not fully take into account the limitations of stable isotope analysis as applied to avian ecology (for example, specific-species discrimination factor, different-tissue turn-over ratio, and isotope signatures). We also discuss the issues related to improvement and perspectives for the future application of this approach. 参考文献 相似文献 引证文献

Isolation and characterization of chicken bile matrix metalloproteinase

Avian bile is rich in matrix metalloproteinases (MMP), the enzymes that cleave extracellular matrix proteins such as collagens and proteoglycans. Changes in bile MMP expression have been correlated with hepatic and gall bladder pathologies, but the significance of their expression in normal, healthy bile is not understood. We hypothesized that the MMP in bile may aid the digestion of native collagens that are resistant to conventional gastric proteases. Hence, the objective of this study was to characterize the bile MMP and check its regulation in association with dietary factors. We used substrate zymography, azocoll protease assay, and gelatin affinity chromatography to identify and purify the MMP from chicken bile. Using zymography and SDS PAGE, 5 bands at 70, 64, 58, 50, and 42 kDa were detected. The bands corresponding to 64, 50, and 42 kDa were identified as MMP2 using trypsin in-gel digestion and matrix-assisted laser desorption time-of-flight mass spectrometry and peptide mass fingerprinting. Chickens fed diets containing gelatin supplements showed higher levels of MMP expression in the bile by both azocoll assay and zymography. We conclude that the bile MMP may be associated with the digestion of collagens and other extracellular matrix proteins in avian diets.

Advancing avian nutrition through best feeding practice

At a time when zoo populations are being relied upon for future progeny and long‐term sustainability of our avian populations, nutrition is vitally important. However, diet review, evaluation and change are often met with disinterest and complacency. Link nutrition to poor health, associated veterinary costs, poor egg production and low chick viability and suddenly the subject becomes more important. High standards are expected in other aspects of avian husbandry yet the nutritional composition of the diets often remains unknown. This article highlights advances in nutrition, useful resources, means of keeping feeding records, and tools available to evaluate and review avian diets in nutritional terms. Regularly reviewing diets ensures the nutritional care of birds keeps pace with other areas of husbandry.

Metabarcoding avian diets at airports: implications for birdstrike hazard management planning.

BackgroundWildlife collisions with aircraft cost the airline industry billions of dollars per annum and represent a public safety risk. Clearly, adapting aerodrome habitats to become less attractive to hazardous wildlife will reduce the incidence of collisions. Formulating effective habitat management strategies relies on accurate species identification of high-risk species. This can be successfully achieved for all strikes either through morphology and/or DNA-based identifications. Beyond species identification, dietary analysis of birdstrike gut contents can provide valuable intelligence for airport hazard management practices in regards to what food is attracting which species to aerodromes. Here, we present birdstrike identification and dietary data from Perth Airport, Western Australia, an aerodrome that saw approximately 140,000 aircraft movements in 2012. Next-generation high throughput DNA sequencing was employed to investigate 77 carcasses from 16 bird species collected over a 12-month period. Five DNA markers, which broadly characterize vertebrates, invertebrates and plants, were used to target three animal mitochondrial genes (12S rRNA, 16S rRNA, and COI) and a plastid gene (trnL) from DNA extracted from birdstrike carcass gastrointestinal tracts.ResultsOver 151,000 DNA sequences were generated, filtered and analyzed by a fusion-tag amplicon sequencing approach. Across the 77 carcasses, the most commonly identified vertebrate was Mus musculus (house mouse). Acrididae (grasshoppers) was the most common invertebrate family identified, and Poaceae (grasses) the most commonly identified plant family. The DNA-based dietary data has the potential to provide some key insights into feeding ecologies within and around the aerodrome.ConclusionsThe data generated here, together with the methodological approach, will greatly assist in the development of hazard management plans and, in combination with existing observational studies, provide an improved way to monitor the effectiveness of mitigation strategies (for example, netting of water, grass type, insecticides and so on) at aerodromes. It is hoped that with the insights provided by dietary data, airports will be able to allocate financial resources to the areas that will achieve the best outcomes for birdstrike reduction.

Dietary Considerations for Atherosclerosis in Common Companion Avian Species

Atherosclerosis is a disease that occurs in many avian species commonly presented to veterinarians. Many risk factors for atherosclerosis are well defined in mammals but not in avian species. Dietary nutrients can play a large role in reducing the severity and prevalence of atherosclerosis in both avian and mammalian species. Information on the effect of dietary nutrients on atherosclerosis in Falconiformes and other birds of prey is extremely limited as no studies were identified by the authors. Dietary cholesterol can be fed to induce the development of atherosclerosis in avian species that consume nonanimal protein. Diets containing high levels of omega-3 fatty acids reduce the prevalence and severity of atherosclerosis, with fish oil being more effective than α-linolenic acid. The presence of dietary cholesterol results in higher levels of dietary protein, increasing the prevalence and severity of atherosclerosis, but if dietary cholesterol is absent, there is a subsequent decrease in atherosclerosis. Pectin in the diet decreased the occurrence of atherosclerosis but also decreased the availability of nutrients owing to faster ingesta passage rates. Feed restriction has also been found to decrease the prevalence of atherosclerosis in birds. It should be noted that many studies have found nutrient interaction effects on the development of atherosclerosis, with some being “neutralizing” or negative, so caution should be observed when manipulating avian diets. The objective of this article is to review the effects of dietary nutrients on atherosclerosis.

The Body Size-Dependent Diet Composition of North American Sea Ducks in Winter

Daily food requirements scale with body mass and activity in animals. While small species of birds have higher mass-specific field metabolic rates than larger species, larger species have higher absolute energy costs. Under energy balance, we thus expect the small species to have a higher energy value diet. Also the weight and time constraints for flighted and diurnal foragers should set a maximum to the amount of prey items taken in one meal and to the daily number of meals, respectively. Further, avoidance of competition causes the species to reduce the amount of shared prey in their diet. Some diet segregation is therefore to be expected between species. We tested these hypotheses and investigated the role of body mass in the diet composition of 12 sea duck species (Somateria mollissima, Somateria spectabilis, Somateria fischeri, Polysticta stelleri, Bucephala clangula, Bucephala islandica, Bucephala albeola, Melanitta nigra, Melanitta perspicillata, Melanitta deglandi, Histrionicus histrionicus and Clangula hyemalis) wintering in North America. This study was based on a literature survey with special emphasis given to the diet data from the former US Bureau of Biological Survey. The data supported our hypothesis that the energy value of winter diet of sea ducks scales negatively with body mass. Diet diversity also scaled negatively with body mass. Our results suggest the existence of a minimum for the energy value of avian diets.

Historical pesticide applications coincided with an altered diet of aerially foraging insectivorous chimney swifts

Numerous environmental pressures have precipitated long-term population reductions of many insect species. Population declines in aerially foraging insectivorous birds have also been detected, but the cause remains unknown partly because of a dearth of long-term monitoring data on avian diets. Chimney swifts (Chaetura pelagica) are a model aerial insectivore to fill such information gaps because their roosting behaviour makes them easy to sample in large numbers over long time periods. We report a 48-year-long (1944-1992) dietary record for the chimney swift, determined from a well-preserved deposit of guano and egested insect remains in Ontario (Canada). This unique archive of palaeo-environmental data reflecting past chimney swift diets revealed a steep rise in dichlorodiphenyltrichloroethane (DDT) and metabolites, which were correlated with a decrease in Coleoptera remains and an increase in Hemiptera remains, indicating a significant change in chimney swift prey. We argue that DDT applications decimated Coleoptera populations and dramatically altered insect community structure by the 1960s, triggering nutritional consequences for swifts and other aerial insectivores.

Variation in carbon and nitrogen stable isotope ratios in flight feathers of a moulting White-bellied Sunbird Cinnyris talatala

We measured δ13C and δ15N isotope signatures in flight feathers of a White-bellied Sunbird to assess the value of using stable isotopes of feathers in avian dietary studies. Significant variation in δ13C and δ15N isotope values of flight feathers (range = 3.1%o and 2.7%o, respectively) indicated that the source of carbon (i.e. C3 or CAM) and trophic level position shifted significantly during the flight feather moult period. Temporal dietary changes in an individual sunbird highlight the implications for interpreting avian diets using stable isotopes. However, by analysing feathers, dietary input may be interpreted at different levels if the moult process is well understood.

Diagnostic Challenge

Atherosclerosis is a disease that occurs in many avian species commonly presented to veterinarians. Many risk factors for atherosclerosis are well defined in mammals but not in avian species. Dietary nutrients can play a large role in reducing the severity and prevalence of atherosclerosis in both avian and mammalian species. Information on the effect of dietary nutrients on atherosclerosis in Falconiformes and other birds of prey is extremely limited as no studies were identified by the authors. Dietary cholesterol can be fed to induce the development of atherosclerosis in avian species that consume nonanimal protein. Diets containing high levels of omega-3 fatty acids reduce the prevalence and severity of atherosclerosis, with fish oil being more effective than α-linolenic acid. The presence of dietary cholesterol results in higher levels of dietary protein, increasing the prevalence and severity of atherosclerosis, but if dietary cholesterol is absent, there is a subsequent decrease in atherosclerosis. Pectin in the diet decreased the occurrence of atherosclerosis but also decreased the availability of nutrients owing to faster ingesta passage rates. Feed restriction has also been found to decrease the prevalence of atherosclerosis in birds. It should be noted that many studies have found nutrient interaction effects on the development of atherosclerosis, with some being “neutralizing” or negative, so caution should be observed when manipulating avian diets. The objective of this article is to review the effects of dietary nutrients on atherosclerosis.