Stomachs Of Birds Research Articles

Information on forage fish ages from otoliths collected in avian stomach contents

Otolith analysis allows studying multiple aspects of fish biology, including age estimation; however, otoliths collected from avian stomach content have not been used to estimate the age of ingested fish. We evaluated the potential ability to estimate the age of Pacific sardine (Sardinops sagax) from otoliths collected from blue-footed booby (Sula nebouxii) stomach contents sampled in the Galapagos Islands. Blue-footed boobies were selected because they mostly forage close to their colony (<100 m) and were, therefore, more likely to have almost intact otoliths. To estimate age, we employed three previously developed methods for otoliths. We then related these estimates to the fish's standard length and compared these relations statistically using the Akaike Information Criterion (AIC) to determine which method was most parsimonious. We collected 32 otoliths in relatively good condition, of which we aged 31 with the surface-reading method, 26 with the otolith weight method, and 29 with the posterior otolith length method. Average ages obtained with the otolith methods were 5.6 ± 1.7 yr (± standard deviation), 5.7 ± 2.0 yr, and 3.9 ± 1.5 yr, respectively. Estimates obtained with the otolith weight method had the highest correlation with standard length and the lowest AIC values of the three suggesting it was the best method for aging. Our results indicate that aging otoliths extracted from bird stomachs are possible; however, their use depends on the availability of previously developed methods and how digested the fish are when the birds return to the colony.

Co-contaminants of microplastics in two seabird species from the Canadian Arctic

Through ingestion and subsequent egestion, Arctic seabirds can bioaccumulate microplastics at and around their colony breeding sites. While microplastics in Arctic seabirds have been well documented, it is not yet understood to what extent these particles can act as transport vehicles for plastic-associated contaminants, including legacy persistent organic pollutants (POPs), trace metals, and organic additives. We investigated the occurrence and pattern of organic and inorganic co-contaminants of microplastics in two seabird species from the Canadian Arctic — northern fulmar (Fulmarus glacialis) and black-legged kittiwake (Rissa tridactyla). We found that fulmars had higher levels of plastic contamination and emerging organic compounds (known to be plastic additives) than kittiwakes, whereas higher concentrations of legacy POPs were found in kittiwakes than the fulmars. Furthermore, fulmars, the species with the much larger foraging range (∼200 km), had higher plastic pollution and overall contaminant burdens, indicating that birds may be acting as long-range transport vectors for plastic-associated pollution. Our results suggest a potential connection between plastic additive contamination and plastic pollution burdens in the bird stomachs, highlighting the importance of treating plastic particles and plastic-associated organic additives as co-contaminants rather than separate pollution issues.

Особенности осенне-зимнего питания фазана обыкновенного (Phasianus colchicus) в Центральном Предкавказье

Pheasants are game birds that feed on many insect pest species. The study of the pheasant food spectrum, especially in the autumn and winter period, is relevant and can be used to assess the food supply of birds in natural habitats and form the diet when they are bred in captivity.
 The authorities of the Stavropol Region try to preserve pheasant diversity and rationalize its use. In this respect, pheasants’ autumn-winter diet in natural environment is an important research subject that can help poultry farmers.
 The research featured the common pheasant (Phasianus colchicus) inhabiting various biotopes of the Stavropol Territory. The visual food spectrum analysis was based on the stomachs of birds killed by hunters in October–January 2011–2021.
 The morning and evening visual observation included eight observation points located on linear routes and stationary sites of the Stavropol Territory. The analysis featured 94 stomachs obtained from the Stepnoye area and 28 stomachs from other areas of the Stavropol Region. Matured seeds and grains represented more than 50% of the stomach content and included wheat, corn, narrow-leaved oleaster, etc. Some samples contained a large number of ants with a minimal content of other foods.
 In the Central Ciscaucasia, pheasants inhabit communal gardens, river valleys, agricultural fields, and forest belts. Nowadays, they can be found in urban areas, where they prefer quasi-natural habitats, e.g. green backyards overgrown with such thorny bushes as oleaster, sea buckthorn, blackberry, blackthorn, wild rose, etc. Pheasants are omnivorous; their autumn and winter diet includes cultivated and wild fruits and seeds, as well as insect larvae.

Минеральный состав гастролитов в желудках утиных в Приморском крае и значение кремниевых минералов в физиологии птиц

The function of gastroliths contained in the stomachs of birds is still not fully explored. In our research we described the mass, size, and composition of gastroliths from 96 stomachs of 12 Anatidae species harvested in 2012 and 2014 in the south of Primorsky Region. The mass of gastroliths from one stomach was up to 3.80 g in ducks and 27.22 g in geese. In 65–85% of cases the gastroliths consisted of quartz. Of other minerals we found feldspars, impurities of other silicates and aluminosilicates, carbonates, ore and other minerals. The function of gastroliths is discussed on the basis of the obtained results on their composition and the review of literature data. The analysis shows that birds instinctively ingest mineral grains for adjusting the chemical composition of the digestive electrolyte. The removal of excess chemicals from the body occurs with the participation of silica gels formed in the neutral and slightly alkaline environment of the intestine from microcrumbs of siliceous minerals, which are produced in the muscular section of the stomach as a result of mechanochemical interaction of gastrolith grains. In addition, gastroliths have other functions, including the prolongation and activation of digestive enzymes, food grinding, and others.

Avian stomach anatomy – a mini review

The stomach of birds comprises three parts – glandular (proventriculus gastris), muscular (ventriculus gastris) and pyloric (pars pylorica gastris). Depending on the diet, these three parts are well differentiated in omnivorous, herbivorous, insectivorous and granivorous birds and slightly differentiated in fish- and meateaters. In fruit-eating, nectar-eating and testacivorous birds, the stomach has an intermediate structure between the two types. In some birds from the genus Tangara, the stomach is reduced to a diverticulum.

Outbreak of Type C Botulism in Birds and Mammals in the Emilia Romagna Region, Northern Italy

Over a 7-day period beginning 8 August 2011, a large number of wild birds of several species were found dead or with neurologic clinical signs along the shore of Crostolo stream, in the Emilia Romagna region, Italy. Twenty-eight Mallards (Anas platyrhynchos), two Hooded Crows (Corvus corone cornix), and three coypus (Myocastor coypus) were found moribund on the Crostolo stream bank, collected, and sent to Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna, Reggio Emilia Section. The cause of mortality was determined to be Clostridium botulinum type C toxin. The toxin was identified by a mouse bioassay for botulinum toxins and confirmed in bird sera and blowfly larvae (Lucilia caesar) collected from the stomachs of birds.

Can seed‐eating birds exert top‐down effects on grasses of the Monte desert?

Granivorous animals can exert major effects on the abundance and diversity of plants when they are selective as well as efficient consumers. However, even under such conditions granivore impact will ultimately depend on whether environmental stress obscures plant‐animal interactions. We studied diet and seed selection patterns of seed‐eating birds to corroborate whether they are selective consumers in the central Monte desert of Argentina. Overall, 83% of seeds in bird stomachs were grass seeds, whereas only 30% of available seeds were from grass species. Therefore, we conclude that avian granivory is highly selective. We developed a set of a priori expectations to test whether birds are efficient consumers (i.e. whether they reduce seed reserves significantly), through short‐term mechanism‐explicit enclosure experiments. Birds decreased the number of selected grass seeds by >50%, and also reduced the amount of non‐selected grasses and selected forbs when selected grass seeds were scarce in the habitat. Thus, consumption was context‐dependent, varying with the composition of background seed reserves. The corroboration of foraging plasticity through mechanism‐explicit trials seems to be crucial to correctly assign direct and indirect effects of seed predation in long‐term enclosure experiments. The comparison of average grass seed reduction caused by bird predation with mean declines of grass seedlings caused by senescence (ca 95%) allowed us assess top‐down (e.g. seed availability) vs bottom‐up control (e.g. rainfall) on grass recruitment. Despite moderate to high seed predation, the number of grass seeds that remains in the soil in spring would not limit seed germination and seedling recruitment. By contrast, safe‐site availability and drought may be important factors limiting grass recruitment, at least in the undisturbed habitats of the Biosphere Reserve of Ñacuñán.

Growth and Metabolic Characterization of Macrorhabdus Ornithogaster

Macrorhabdus ornithogaster (M. ornithogaster) is an anamorphic ascomycetous yeast found only in the stomach of birds. Infection is often benign but has also been associated with disease in some species of birds under some circumstances. In vitro efforts to grow M. ornithogaster have been largely unsuccessful. In this report, multiple liquid and solid media of varying pH, sugar concentration, and fetal bovine serum (FBS) concentrations, incubated at various temperatures in room air or microaerophilic conditions, were examined for their ability to support the growth of M. ornithogaster, obtained from a budgerigar (Melopsittacus undulatus). Optimum growth conditions were found to be Basal Medium Eagle's, pH 3 to 4, containing 20% FBS, and 5% glucose or sucrose under microaerophilic conditions at 42 degrees C. Using these conditions, M. ornithogaster was repeatedly passaged without loss of viability. Polyclonal isolates of M. ornithogaster consistently assimilated glucose, sucrose, and trehalose. M. ornithogaster did not grow with prolonged exposure to atmospheric oxygen, but growth in microaerophilic conditions was moderately enhanced by preincubation with atmospheric oxygen for 24 hours. An isolate of M. ornithogaster was found to be infective to day-old chickens, reduce their rate of weight gain, and induce a mild to moderate heterophilic inflammation of the isthmus. M. ornithogaster was reisolated from the chicks 7 days after infection, fulfilling Koch's postulates. A 761-bp sequence of 18S rDNA from this isolate was compared to the originally reported M. ornithogaster sequence and was found to be 97% identical.

An analysis of bones and other materials collected by Cape Vultures at the Kransberg and Blouberg colonies, Limpopo Province, South Africa

We compared bones and non-faunal items collected by Cape Vultures at the Blouberg and Kransberg colonies. Bones from the base of the nesting cliffs were on average longer than those from the crops and stomachs of birds. Bones from the Blouberg cliff base were on average shorter than those from the Kransberg. A larger proportion of bones from smaller animals was the reason for this. The smaller size of the crop material was due to a greater proportion of fragmented bone. Fragmentation made bones less identifiable to species. The proportion of fragmented material and the particular skeletal elements discovered at the two sites were very similar and did not influence this size difference. Material from these colonies was, for the most part, smaller than bones collected from other Cape and Whitebacked Vulture colonies in Zimbabwe, Botswana and South Africa. Higher proportions of bones from smaller animals and smaller skeletal elements collected were the reasons for the smaller average size. In wildlife reserves, Gyps vultures compete with large mammalian carnivores and other scavenging birds for food, including bone. Where these competitors are absent or rare (i.e.farming areas), Gyps vultures eat more bone. Small bones (i. e. carpals, tarsals, phalanges, etc.), quickly eaten by spotted hyenas in game reserves, are collected in large numbers by Gyps vultures in farming areas, where competition is reduced. As a food, bone is almost as good nutritionally and energetically as meat. Where meat is scarce (e.g.farming areas), Gyps vultures collect more bone as an alternative food source. In areas of high human density, vultures eat more human-made material. Substitution or confusion of one item for another (e.g.human-made items for bone/food) will occur more regularly as the replacement item becomes more prevalent in the environment. Most of the non-faunal pieces did not resemble bone and were probably not confused for that item. Glass was the most common human-made substance found in vulture crops and stomachs, and rocks the most common overall. Grass and sticks were collected from nestling crops and stomachs but rarely from adults. When food is scarce, vulture nestlings feed on non-food items, particularly nesting material. The increase in collection and eating of bone and non-food items is a result of the shift in Gyps vulture's diet where meat is scarce and alternative foods are sought.

DIET OF DOUBLE-CRESTED CORMORANTS (PHALACROCORAX AURITUS) WINTERING ON THE CENTRAL TEXAS COAST

Abstract Diets of double-crested cormorants (Phalacrocorax auritus) wintering on the central Texas coast were determined from the contents of 51 stomachs from Lavaca Bay and 28 stomachs from upper Laguna Madre. Diets consisted primarily of striped mullet (Mugil cephalus) and Gulf menhaden (Brevoortia patronus) in Lavaca Bay and striped mullet and Gulf toadfish (Opsanus beta) in upper Laguna Madre. Birds seemed to prefer striped mullet in both bays, and these fish were significantly larger than the other fish consumed. There were no differences between bays in the numbers of fish in bird stomachs; however, fish consumed by birds in upper Laguna Madre were larger than those taken by birds in Lavaca Bay. Based on the results of this study, there is no evidence that double-crested cormorants pose a significant threat to commercial or sport fisheries on the Texas Gulf Coast.

Topography and neurochemistry of the enteric ganglia in the proventriculus of the duck (Anas platyrhynchos).

The topographical distribution of the enteric ganglia has been investigated in the proventriculus of the duck using protein gene product 9.5 (PGP 9.5) immunohistochemistry. Myenteric ganglia were usually located between the outer longitudinal and the inner circular muscle layer. Submucous ganglia were sparsely distributed and seemed to be substituted by ganglia located in the tunica mucosa. The neurochemical profile of proventricular ganglion cells was also investigated using nicotinamide adenine dinucleotide phosphate reduced-diaphorase (NADPH-d)-histochemistry and pituitary adenylate cyclase activating peptide (PACAP)/galanin (Gal) double-labelling immunohistochemistry. The majority of mucosal ganglion cells were shown to contain the NADPH-d enzyme and both the investigated peptides. These findings provide evidence for the presence of a mucosal ganglionated plexus in the glandular stomach of birds. Moreover, the neurochemical characteristics of this plexus suggest that it plays an important role in regulating several mucosal functions and, in particular, the production and the composition of the gastric juice.

Granivore impact on soil‐seed reserves in the central Monte desert, Argentina

1. Mechanisms of grass‐ and forb‐seed input and output in the central Monte desert of Argentina were studied in 1995 to test the hypothesis that seed consumption by autumn–winter granivores, especially birds, has qualitative as well as quantitative effects on soil‐seed reserves. 2. The abundance of perennial grass seeds in late summer soils (≈ 2400 seeds m–2 or 0·36 g m–2) remained unchanged the following early spring (≈ 2700 seeds m–2 or 0·39 g m–2), despite the incorporation of about 3000 seeds m–2 or 0·71 g m–2 newly produced grass seeds during autumn–winter. Grass seeds appeared to be heavily consumed, especially the medium‐sized ones. 3. The annual forb‐seed bank was about the same size in late summer (≈ 5500 seeds m–2 or 1·34 g m–2) as in early spring (≈ 6500 seeds m–2 or 1·53 g m–2). Since forb‐seed production had been relatively low (≈ 400 seeds m–2 or 0·12 g m–2), these seeds apparently suffered negligible postdispersal losses. 4. This pattern of grass‐ and forb‐seed loss coincides with the pattern of seed consumption by granivorous birds – on average, 93% of seed mass in bird stomachs was from grass seeds, while only 7% was from forb seeds. 5. Further evidence of a major impact of bird foraging on seed reserves is that the mass of particular grass seeds that was lost from soils was positively correlated with the mass of such seeds in bird diets, and that the main target of bird consumption, i.e. medium‐sized grass seeds, suffered the highest postdispersal loss. 6. It is concluded that autumn–winter granivores in the central Monte desert, particularly birds, mainly consume newly produced grass seeds and that they might have major qualitative as well as quantitative impacts on soil‐seed reserves.

Beyond Alexis St Martin: contemporary techniques for studying the functioning of the gastrointestinal tract

A range of developments in methodology for studying digestive physiology including comparative anatomy, fistulas and cannulas, imaging, electromyography, and tracers are reviewed. This gives a methodological background to the teaching of digestive physiology, with the opportunity for critical appraisal of the collection and analysis of second-hand data. Exercises for gathering first-hand data on the use of tracers, analysing secondhand data on tracers, and interpretation of comparative anatomy of bird stomachs are given as possible curriculum extensions in this field.

Aggregation of avian predators and zooplankton prey in Otago shelf waters, New Zealand

In Otago shelf waters surface swarms of krill (Nyctiphanes australis), hyperiid amphipods (Parathemisto spp.) and galatheid crab larvae (Munida gregaria) provide an abundant summer food source for planktivores. We tested the hypothesis that aggregation of avian planktivores depends upon the spatial distribution of their prey. Gulls (Larus scopulinus, L.bulleri, L.dominicanus), sooty shearwaters (Puffinus griseus) and white-fronted terns (Sterna striaXa) showed significantly aggregated distributions. The distribution of birds sitting on the sea surface was correlated with the abundance pattern of krill but was not correlated with the distribution of smaller hyperiid amphipods. The distribution of flying red-billed gulls (L.scopulinus), black-billed gulls (L.bulleri) and sooty shearwaters was correlated with the krill distribution but black-backed gulls (L.domini- canus) were not. Stomach contents of black-billed gulls were dominated by krill, in contrast to sooty shearwaters, which ate a higher proportion of Minida, and black-backed gulls, which contained Munida and fish. No amphipods were found in bird stomachs. There was no significant correlation between bird distributions and the hydrographic regime, water depth or distance offshore. The distribution of prey rather than hydrographic regime was a more important determinant of bird distributions at this spatial scale (2.6-12 km) and location.

Bird Predation on Cutworms (Lepidoptera: Noctuidae) in Wheat Fields and Chlorpyrifos Effects on Brain Cholinesterase Activity

Horned larks, Eremophila alpestris (L.), and McCown's longspurs, Calcarius mccownii (Lawrence), were collected at intervals from two winter wheat fields in Montana after aerial application of chlorpyrifos to control cutworms. Both bird species had a high (95–100%) incidence of Lepidoptera, mostly pale western cutworms, Agrotis orthogonia Morrison, in their stomachs at 3 days postspray. Incidence of cutworms and other insects in stomachs of birds from sprayed fields was lower at 9 and 16 days postspray than in control birds, presumably due to insecticide-caused reduction of insects. Effects of birds on population dynamics of insect pests in wheat are unknown, but birds do contribute to cutworm mortality. Predation is one of the limiting factors to cutworm increase and can supplement insecticidal control. Brain cholinesterase activity in horned larks collected from the sprayed fields at 3 and 9 days postspray was significantly lower than in unexposed larks, but at 16 days the difference was not significant. Although nontarget birds clearly were exposed to chlorpyrifos and manifested a sublethal physiological response, toxic effects were lesssevere than those resulting from endrin application for cutworm control in wheat. More study is needed of larger chlorpyrifos-treated fields under a variety of conditions to fully assess effects on nontarget life.

Studies on the excystment of trematode metacercariae in vivo.

AbstractMetacercariae of two species of trematode (Clinostomum tilapiae, Postodiplostomum nanum) excysted in the stomach of birds, while those of three species (Parorchis acanthus, Posthodiplostomum sp., Postliodiplostomoides leonensis) excysted in the duodenum. Differences were related to the structure of the cyst wall. All could excyst in birds which were not the definitive host and the speed of excystment depended on the speed of movement of food in the gut. All, except P. acanthus, also excysted in the body cavity of the mouse.There have been few previous reports on the site of excystment of metacercarial cysts in vivo and most indicate that the duodenum is the site for most species studied, e.g. Clonorchis sinensis (Faust and Khaw, 1927), Parorchis avitus (Stunkard and Cable, 1932), Cryptocotyle lingua (Smyth, 1962) and Fasciola hepatica (Smyth, 1966). In their study of the migratory route of Paragonimus westermani in rats, cats and guinea-pigs Yokogawa et al. (1962) found that excystment occurred in the small intestine where the pH range was 5.0–6.0. Also, although the site of excystment has been established for some species, very little quantitative work has been reported about the percentage excystment in vivo and results of work on these lines is reported in this paper.

A contribution to the knowledge of receptors of the glandular stomach of birds.

A contribution to the knowledge of receptors of the glandular stomach of birds.

Food Habits of the California Gull in Utah

The California Gull (Lurus califurnicus) is generally revered in Utah for its well known role during pioneer times in helping to save the crops of the first settlers of Great Salt Lake Valley from crickets. Subsequently an interesting social taboo developed whereby the bird was rarely killed (Young, 1928). The famous Seagull Monument, erected on the Temple grounds at Salt Lake City to commemorate the role of the gull, has helped to keep the taboo alive. The first change in local feelings toward the gulls came with complaints against them because of their depredations on cherry crops in Davis County (Cottam, 193 5 ; Sugden, 193 7 ) . Similar charges have come from Boxelder and Utah counties. These birds have long been known to nest on several islands in Great Salt Lake (Behle, 1935,1949). New colonies of gulls have of recent years been established at three waterfowl refuges on the east side of Great Salt Lake, namely Farmington Bay, Ogden Bay, and the Bear River Refuge. This has brought them in close contact with nesting waterfowl and the gulls are being accused of predations on ducks. With attention being focused on these new problems, it seemed desirable to make a general study of the food habits of the California Gull. Little specific information was on record. Kalmbach (1914: 6) reported on the contents of five stomachs and Cottam and-Williams ( 1939: 153 ) listed the contents of six stomachs of birds taken in the Great Salt Lake region but these were small samples. Accordingly a study was started by the writer in 1940. This was interrupted by the war but was resumed in June of 1946 when arrangements were made with the personnel at Bear River Migratory Bird Refuge to spend the summer working on the refuge and at the laboratory of the research division at the refuge headquarters. In addition to field observations, food items in the stomachs of California Gulls previously collected on the refuge were identified and further samples were taken. The results are presented here supplemented with occasional notes from the literature and interviews with farmers. Thanks are due William H. Behle of the University of Utah for guidance in this study. I am indebted to several men at the Bear River Migratory Bird Refuge: Cecil Williams and Vanez Wilson were generous in providing facilities for me in 1946; Cecil Williams, Charles Sperry, Hortin Jensen, and Ralph Hervey were helpful in giving advice, collecting, and identifying food items. In my initial collecting around Salt Lake City I was helped by Jack Berryman, Rex Edward, Dan Gardiner, and Nathan Riser to whom I also express my thanks.

Duration of Insect Remains in the Stomachs of Birds

Duration of Insect Remains in the Stomachs of Birds

A Study of Bird Stomachs and Their Contents. Part III

A Study of Bird Stomachs and Their Contents. Part III