Buteo Buteo Research Articles

Causes, temporal trends, and the effects of urbanization on admissions of wild raptors to rehabilitation centers in England and Wales.

Data from wildlife rehabilitation centers (WRCs) can provide on‐the‐ground records of causes of raptor morbidity and mortality, allowing threat patterns to be explored throughout time and space. We provide an overview of native raptor admissions to four WRCs in England and Wales, quantifying the main causes of morbidity and mortality, trends over time, and associations between threats and urbanization between 2001 and 2019. Throughout the study period, 14 raptor species were admitted totalling 3305 admission records. The Common Buzzard (Buteo buteo; 31%) and Tawny Owl (Strix aluco; 29%) were most numerous. Relative to the proportion of breeding individuals in Britain and Ireland, Peregrine Falcons (Falco peregrinus), Little Owls (Athene noctua), and Western Barn Owls (Tyto alba) were over‐represented in the admissions data by 103%, 73%, and 69%, respectively. Contrastingly Northern Long‐eared Owls (Asio otus), Western Marsh Harriers (Circus aeruginosus), and Merlin (Falco columbarius) were under‐represented by 187%, 163%, and 126%, respectively. Across all species, vehicle collisions were the most frequent anthropogenic admission cause (22%), and orphaned young birds (10%) were most frequent natural cause. Mortality rate was highest for infection/parasite admissions (90%), whereas orphaned birds experienced lowest mortality rates (16%). For one WRC, there was a decline in admissions over the study period. Red Kite (Milvus milvus) admissions increased over time, whereas Common Buzzard and Common Kestrel admissions declined. There were significant declines in the relative proportion of persecution and metabolic admissions and an increase in orphaned birds. Urban areas were positively associated with persecution, building collisions, and unknown trauma admissions, whereas vehicle collisions were associated with more rural areas. Many threats persist for raptors in England and Wales, however, have not changed substantially over the past two decades. Threats associated with urban areas, such as building collisions, may increase over time in line with human population growth and subsequent urban expansion.

Mercury speciation in Scottish raptors reveals high proportions of inorganic mercury in Scottish golden eagles (Aquila chrysaetos): Potential occurrence of mercury selenide nanoparticles

Knowledge of the uptake and fate of mercury (Hg) compounds in biota is important in understanding the global cycling of Hg and its transfer pathways through food chains. In this study, we analysed total mercury (T-Hg) and methylmercury (MeHg) concentrations in 117 livers of Scottish birds of prey that were found across Scotland and submitted for post-mortem examination through the Raptor Health Scotland project between 2009 and 2019. Statistical comparisons focussed on six species (barn owl, Tyto alba; Eurasian common buzzard, Buteo buteo; golden eagle, Aquila chrysaetos; hen harrier, Circus cyaneus; Eurasian sparrowhawk, Accipiter nisus; and tawny owl, Strix aluco) and showed that golden eagles had a statistically lower fraction of MeHg compared to other raptor species. Further investigation using stable carbon and stable nitrogen isotope ratio measurements carried out for the golden eagles (n = 15) indicated that the increased presence of inorganic mercury (iHg) correlated with a marine influence on the primarily terrestrial diet. Additional bioimaging (n = 1) with laser ablation – inductively coupled plasma – mass spectrometry indicated the co-location of Hg and selenium (Se) within the liver tissue and transmission electron microscopy showed evidence of nanoparticles within the range of 10–20 nm. Further analysis using single particle – inductively coupled plasma – mass spectrometry (n = 4) confirmed the presence of Hg nanoparticles. Together, the evidence suggests the presence of mercury selenide (HgSe) nanoparticles in the liver of some golden eagles that, to our knowledge, has never been directly observed in terrestrial birds of prey. This study points to two alternative hypotheses: these golden eagles may be efficient at breaking down MeHg and form HgSe nanoparticles as a detoxification mechanism (as previously observed in cetaceans), or some golden eagles with elevated iHg may have accumulated these nanoparticles by foraging on stranded cetaceans or seabirds.

Detection of Toxocara cati Larvae in a Common Buzzard (Buteo buteo) and in a Red Kite (Milvus milvus) in Basilicata Region, Italy.

Simple SummaryIn this study we report the detection of Toxocara cati larvae in the muscle tissue of two birds of prey, a red kite (Milvus milvus) and a common buzzard (Buteo buteo), received in our laboratory as part of the Wildlife Monitoring and Control Plan of the Basilicata Region (Italy). To the authors’ knowledge, this is the first report of identification of T. cati larvae in these two species.Toxocara cati is a common parasite of wild and domestic felines, and presents a cosmopolitan distribution. Adult parasites localize in the gut of the definitive host giving rise to the infection, which usually runs asymptomatic. These worms produce eggs that are excreted with feces into the environment, where they become a source of infection for paratenic hosts, such as mammals, birds, and invertebrates. In this brief communication, we report the detection of T. cati larvae in a common buzzard (Buteo buteo) and a red kite (Milvus milvus), in the Basilicata Region of Italy. This result may be important to define new pathways of spread and survival of T. cati in the wild.

Pathology and virology of natural highly pathogenic avian influenza H5N8 infection in wild Common buzzards (Buteo buteo)

Highly pathogenic avian influenza (HPAI) in wild birds is a major emerging disease, and a cause of increased mortality during outbreaks. The Common buzzard (Buteo buteo) has a considerable chance of acquiring the infection and therefore may function as bio-sentinel for the presence of virus in wildlife. This study aimed to determine the virus distribution and associated pathological changes in the tissues of Common buzzards that died with HPAI H5 virus infection during the 2020–2021 epizootic. Eleven freshly dead, HPAI H5 virus-positive Common buzzards were necropsied. Based on RT-PCR, all birds were systemically infected with HPAI H5N8 virus, as viral RNA was detected in cloacal and pharyngeal swabs and in all 10 selected tissues of the birds, with mean Ct values per tissue ranging from 22 for heart to 32 for jejunum. Based on histology and immunohistochemistry, the most common virus-associated pathological changes were necrotizing encephalitis (9/11 birds) and necrotizing myocarditis (7/11 birds). The proventriculus of two birds showed virus-associated necrosis, indicating tropism of this virus for the digestive tract. Our advice is to collect at least a miniset of samples including brain, heart, liver, and spleen, as these tissues were positive both by RT-PCR and for virus-antigen-associated lesions.

Clinical evaluation of the intranasal administration of midazolam and reverse effects of flumazenil in Eurasian Buzzards (Buteo buteo)

Midazolam, the most commonly used drug in birds, has sedative, muscle relaxant, anxiolytic, amnestic, and appetite-enhancing effects. In this study, we aimed to reach the proper sedation level with intranasal (IN) administration of midazolam, and quick and safe recovery with intranasal flumazenil application after a certain period of time. The buzzards in the experiment reached the desired and controllable sedation at 6.7 ± 1.6 min after administration of IN midazolam at a dose of 2 mg / kg of body weight. In the saline group (%0.9 NaCl), the doses of midazolam and flumazenil calculated according to their weight were administered intranasally as 0.9% NaCl. The heart rate was 290.4 ± 17.81 and 294.8 ± 18.19 beats/min in the midazolam group, and 300.8 ± 17.76 beats/min in the saline group. Cloacal temperature was 41.42 ± 07, 41.39 ± 0.85 °C in the midazolam group and 41.6 ± 0.45 °C in the saline group. The respiratory rate was 48.8 ± 4.5, 47.1 ± 4.3 breaths/min in the midazolam group and 54.6 ± 2.7 breaths/min in the saline group. Flumazenil was used as an antagonist at 0.05 mg/kg intranasally, and after 14.1 ± 1.8 minutes the sedation effect disappeared. Then the buzzards returned to their standard behavior. In conclusion, we suggest IN use of midazolam and use of flumazenil for faster recovery in buzzards as a simple, fast, practical, and economical mode of sedation for minimally invasive procedures.

Comparative analysis of the digestive system’s anatomical parts in two zoophagous bird species: White Stork (Ciconia ciconia) and Common Buzzard (Buteo buteo)

Aristotle in his anatomical observations is marking the beginning of functional anatomy followed by Georges Cuvier that formulate the low of the correlation of parts. According with this we can expect that the digestive system structures tend to be similar between species that consume approximately the same type of food. In this study we chose to evaluate macroscopic the digestive system of two different zoophytophagous species, with similar body size but different life behavior and feeding strategies: White Stork (Ciconia ciconia) and Common Buzzard (Buteo buteo). Data were collected after the dissection of 10 carcass (5 White Stork and 5 Common Buzzard). The digestive tract and its structures were measured and weighed. In common buzzard the beak is strong and short adapted for the laceration of the prey. In white stork the beak is long, strong, straight adapted to capture prey like a harpoon. In both species, the esophagus is located on the right side of the neck, the length is different, proportional to the neck. In common buzzard the crop is present and absent in white storks. The cuticle or koilin layer is highlighted in white stork compared to common buzzard. In common buzzard, the small intestine is reduced in size, without marked transition between the duodenum and the ileum. The white storks have a long small intestine with many loops, with no transition between the segments. In both species, the cecum is reduced in size and has a vestigial appearance; the colon is reduced in size, and extends from the level of the ileo-colic junction to the cloaca. The digestive system is adapted to a strictly carnivorous diet and the differences identified between the anatomical structures of the digestive tract of the two species are correlated with the differences of their feeding behavior.

Conservation Letter: Raptors and Anticoagulant Rodenticides

Conservation Letter: Raptors and Anticoagulant Rodenticides

Novelty at dawn: Exploration, low neophobia and crepuscular activity in a wild Common Buzzard (Buteo buteo)

Raptor cognition has received limited research attention, despite the importance of comparative investigations for reconstructing the evolution of complex cognition. Field studies provide essential ecological context for cognition in the natural habitat, although this approach is often challenging due to extensive procedures involved in cognitive testing. One predisposition suggested to contribute to problem-solving behaviour is the response to novel stimuli. In this pilot study, a novel object test was conducted on an outdoor feeding platform to assess the neotic responses of a single wild free-ranging Common Buzzard ( Buteo buteo), a generalist/opportunist diurnal predator species. Additionally, data on its daily activity were collected. As predicted, the subject expressed low neophobia and some exploratory behaviours. Interestingly, it repeatedly arrived on the platform in low light conditions. This study highlights the influence of foraging ecology on cognitive predispositions and offers a field method for research on raptor cognition.

The prevalence of Leucocytozoon spp. in nestlings of three wild raptor species including implications on haematological and blood chemistry values.

Leucocytozoonosis is a vector-borne infection of birds, caused by members of the haemosporidian genus Leucocytozoon. The clinical presentation may range from asymptomatic to severe disease. Consequences of Leucocytozoon infection on blood profiles remain to be described, especially for different host species in the wild. In the current study, the prevalence of Leucocytozoon infection was determined in wild nestlings of three European raptor species, the common buzzard (Buteo buteo, n = 464), red kite (Milvus milvus, n = 46) and northern goshawk (Accipiter gentilis, n = 18). Among 528 nestlings, 51.9% (n = 274) were infected with Leucocytozoon spp., whereby the highest prevalence was found in common buzzards (54.9%), followed by red kites (32.6%) and northern goshawks (22.2%). For a subset of 87 individuals (50 common buzzards, 29 red kites, 8 northern goshawks), a detailed analysis of differential leukocyte counts and several blood chemistry parameters in response to infection was conducted: AP (alkaline phosphatase), AST (aspartate aminotransferase), GLDH (glutamate dehydrogenase), LDH (lactate dehydrogenase), GGT (gamma glutamyl transferase), CK (creatine kinase), BuChE (butyrylcholinesterase), BA (bile acids), ALB (albumin) and TP (total protein). Even though in the physiological range, infected nestlings displayed significantly increased levels of heterophils, aspartate aminotransferase, lactate dehydrogenase, bile acids and butyrylcholinesterase, but decreased lymphocyte and monocyte values compared to uninfected ones. Furthermore, significant species differences with regard to blood parameters, but no sex differences were found. Overall, obtained results show a high prevalence, but a low pathogenicity of Leucocytozoon spp. in wild raptor chicks, presumably resulting from coevolutionary adaptation, but show signatures of infection in the haematological and blood chemistry profiles.

Persecution of Birds of Prey in Flanders: A Retrospective Study 2011-19.

For decades birds of prey have been under the protection of European law, but deliberate or unintentional killing is still a large-scale problem in Europe. In an effort to monitor illegal practices, the Flemish government established several bird of prey hotlines in 2006. Since then, every suspicious death of a bird of prey has been investigated. This retrospective study reviews the necropsy results of every bird of prey submitted for investigation from January 2011 to December 2019, with a focus on illegal practices. In 36.7% (83/226) of all necropsy cases, an illegal cause of death was found, with poisoning being demonstrated in 88% (73/83) of these cases. Cholinesterase inhibitors were the most commonly used toxins, despite being prohibited in Europe. With a prevalence of 82.5% (260/315) of all cases, the Common Buzzard (Buteo buteo) was the species most submitted for necropsy.

Use of DNA metabarcoding of bird pellets in understanding raptor diet on the Qinghai-Tibetan Plateau of China

BackgroundDiet analysis is essential to understanding the functional role of large bird species in food webs. Morphological analysis of regurgitated bird pellet contents is time intensive and may underestimate biodiversity. DNA metabarcoding has the ability to circumvent these issues, but has yet to be done.MethodsWe present a pilot study using DNA metabarcoding of MT-RNR1 and MT-CO1 markers to determine the species of origin and prey of 45 pellets collected in Qinghai and Gansu Provinces, China.ResultsWe detected four raptor species [Eurasian Eagle Owl (Bubo bubo), Saker Falcon (Falco cherrug), Steppe Eagle (Aquila nipalensis), and Upland Buzzard (Buteo hemilasius)] and 11 unique prey species across 10 families and 4 classes. Mammals were the greatest detected prey class with Plateau Pika (Ochotona curzoniae) being the most frequent. Observed Shannon’s and Simpson’s diversity for Upland Buzzard were 1.089 and 0.479, respectively, while expected values were 1.312 ± 0.266 and 0.485 ± 0.086. For Eurasian Eagle Owl, observed values were 1.202 and 0.565, while expected values were 1.502 ± 0.340 and 0.580 ± 0.114. Interspecific dietary niche partitioning between the two species was not detected.ConclusionsOur results demonstrate successful use of DNA metabarcoding for understanding diet via a novel noninvasive sample type to identify common and uncommon species. More work is needed to understand how raptor diets vary locally, and the mechanisms that enable exploitation of similar dietary resources. This approach has wide ranging applicability to other birds of prey, and demonstrates the power of using DNA metabarcoding to study species noninvasively.

Determination of 56 per- and polyfluoroalkyl substances in top predators and their prey from Northern Europe by LC-MS/MS

Per- and polyfluoroalkyl substances (PFAS) are a group of emerging substances that have proved to be persistent and highly bioaccumulative. They are broadly used in various applications and are known for their long-distance migration and toxicity. In this study, 65 recent specimens of a terrestrial apex predator (Common buzzard), freshwater and marine apex predators (Eurasian otter, harbour porpoise, grey seal, harbour seal) and their potential prey (bream, roach, herring, eelpout) from northern Europe (United Kingdom, Germany, the Netherlands and Sweden) were analyzed for the presence of legacy and emerging PFAS, employing a highly sensitive liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) method. 56 compounds from 14 classes were measured; 13 perfluoroalkyl carboxylic acids (PFCAs), 7 perfluoroalkyl sulphonic acids (PFSAs), 3 perfluorooctane sulfonamides (FOSAs), 4 perfluoroalkylphosphonic acids (PFAPAs), 3 perfluoroalkylphosphinic acids (PFPi's), 5 telomer alcohols (FTOHs), 2 mono-substituted polyfluorinated phosphate esters (PAPs), 2 di-substituted polyfluorinated phosphate esters (diPAPs), 6 saturated fluorotelomer acids (FTAS), 3 unsaturated fluorotelomer acids (FTUAs), 2 N-Alkyl perfluorooctane sulfonamidoethanols (FOSEs), 3 fluorotelomer sulphonic acids (FTSAs), 2 perfluoroether carboxylic acids (PFECAs) and 1 chlorinated perfluoroether sulphonic acid (Cl-PFESA). All samples were lyophilized before analysis, in order to enhance extraction efficiency, improve the precision and achieve lower detection limits. The analytes were extracted from the dry matrices through generic methods of extraction, using an accelerated solvent extraction (ASE), followed by clean-up through solid phase extraction (SPE). Method detection limits and method quantification limits ranged from 0.02 to 1.25 ng/g wet weight (ww) and from 0.05 to 3.79 ng/g (ww), respectively. Recovery ranged from 40 to 137%. Method precision ranged from 3 to 20 %RSD. The sum of PFAS concentration in apex predators livers ranged from 0.2 to 20.2 μg/g (ww), whereas in the fish species muscle tissues it ranged from 16 to 325 ng/g (ww). All analyzed specimens were primarily contaminated with PFOS, while the three PFPi's included in this study exhibited frequency of appearance (FoA) 100 %. C9 to C13 PFCAs were found at high concentrations in apex predator livers, while the overall PFAS levels in fish fillets also exceeded ecotoxicological thresholds. The findings of our study show a clear association between the PFAS concentrations in apex predators and the geographical origin of the specimens, with samples that were collected in urban and agricultural zones being highly contaminated compared to samples from pristine or semi-pristine areas. The high variety of PFAS and the different PFAS composition in the apex predators and their prey (AP&P) samples is alarming and strengthens the importance of PFAS monitoring across the food chain.

Exo-erythrocytic stages of Haemoproteus sp. in common buzzard (Buteo buteo): A histopathological and molecular study.

Haemosporidian parasites are responsible for anemia, acute tissue degeneration, and depopulation in wild birds. This study aimed to investigate the prevalence of haemosporidians and also morphologic and molecular evaluation of tissue stages of Haemoproteus sp. in common buzzards (Buteo buteo). Eleven free-living common buzzards were referred to the Avian Clinic of Veterinary School of Lorestan University with lethargy, weight loss, and ataxia. Gametocytes of Leucocytozoon buteonis were found in blood smears of six (54.5 %) birds, while one had simultaneous infection with blood stages of Haemoproteus and Leucocytozoon. During histopathological examinations, exo-erythrocytic stages of the genus Haemoproteus were seen in the lung and kidney of a dead bird. This study is the first report of exo-erythrocytic infection of Haemoproteus in common buzzards. Molecular assays confirmed the infection of Haemoproteus sp. (lineage BUTBUT15) in tissue samples. Phylogenetic analysis using cytochrome b gene suggested that BUTBUT15 was more closely related to the lineages isolated from the family Falconidae in contrast to the Accipitridae.

Predisposing Anatomical Factors of Humeral Fractures in Birds of Prey: A Preliminary Tomographic Comparative Study.

The aim of this study was to identify possible predisposing anatomical factors associated with humeral fractures in birds of prey through comparison of specific anatomical features in different raptor species. An anatomical study of bone features in birds of prey was performed on 3 male subjects from 5 different species. The selected species included in this investigation were 3 diurnal species (the common buzzard [Buteo buteo], the peregrine falcon [Falco peregrinus], and the European honey-buzzard [Pernis apivorus]) and 2 nocturnal species (the barn owl [Tyto alba] and the tawny owl [Strix aluco]). Humeral bone samples were tomographically analyzed with a micro-macro-focus computed tomographic machine. Specific humeral anatomical points were selected (foramen pneumaticum and tuberculum dorsale for the proximal humerus; corpus humeri for the diaphyseal humerus; and above the condylus dorsalis for the distal humerus) to measure foramen pneumaticum diameter (in millimeters), cortical thickness (in millimeters), and trabeculae number and sizes (in millimeters). Apparent density, measured with the Hounsfield unit, was used to assess the degree of bone resistance. Statistical analysis was performed with a Spearman's correlation, and significance was set at P < .05. The differences among the observed bone volumes were highly significant (P = .00). Trabeculae number and the humeral anatomical point measurements showed differences in all 5 avian species investigated. However, those differences were not significant, except at the condylus dorsalis; in which, a significant interspecies difference (P = .002) was recorded. Trabecular size, cortical thickness, bone density, and diameter of the foramen pneumaticum were all different in all raptor species; however, these variations were not significant. The study confirms the existence of humeral bone volume differences between diurnal and nocturnal species. Furthermore, the data suggest that the humeri of peregrine falcons and European honey-buzzards may be stronger than the humeri of common buzzards, tawny owls, and barn owls.

Common Buzzards wintering strategies as an effect of weather conditions and geographic barriers.

AimMigration is a constantly changing adaptation due to the climate condition evolution. The struggle for surviving during harsh winter season is different across Europe, being more complex toward the inner parts of the continent. The current approach explores the Common Buzzard number variation during the cold season and the climatic predictors of birds of prey wintering movements in relation to the possible influences of the Carpathian Mountains, which may act as a geographical barrier providing shelter from cold air outbreak from north and northeast of the continent.LocationRomania (45°N25°E).TaxonBirds of Prey.MethodsWe applied a GLMM to investigate the relation between continental and local climatic factors with the number of Common Buzzard observations in two regions. The first region is located inside the Carpathian Arch and the other one outside, east of this large mountains chain.ResultsThe Common Buzzard numbers wintering Eastern from the Carpathian Mountains are highly influenced by AO (Z = 2.87, p < .05%), while those wintering western are influenced by NAO (Z = 2.17, p < .05%). This is the first proof of separating influences for biodiversity of AO and NAO at continental scale, outlining the influence limit placed over the Eastern Carpathian Mountains.Main conclusionsThe Carpathian Mountains act like a geographic barrier, separating the wintering Common Buzzard populations from both sides of the mountain range. While the high number of individuals in Moldova is related to their eastern and northeastern Europe origins, in Transylvania the large number of individuals observed is related to the more sheltered characteristics of the region attracting individuals from central Europe. Also, since Transylvania region is well sheltered during cold air outbreak, it represents a more favorable region for wintering. From this point of view, we can consider that the Carpathian Mountains are a geographic barrier for wintering birds of prey.

The Common Buzzard

The Common Buzzard

Treatment of extremity fractures in 20 wild birds with a modified Meynard external fixator and clinical assessment of the results

The aim of this study is to evaluate the outcome of the treatment on twenty wild birds presenting with fractures that were stabilised with modified Meynard external fixators. The study material consisted of a total of twenty birds of eight different species, six white storks (Ciconia ciconia), one eastern imperial eagle (Aquila heliaca), one European honey buzzard (Pernis apivorus), one long-legged buzzard (Buteo rufinus), three common buzzard (Buteo buteo), one northern goshawk (Accipiter gentilis), one Armenian gull (Larus armenicus), and six yellow-legged gulls (Larus michahellis), which were diagnosed with fractures in their extremity bones following clinical and radiological examinations. The lesions of the twenty cases evaluated in the study were diagnosed as humerus fractures in nine cases, ulna fractures in three cases, tibiotarsus fractures in seven cases and a femur fracture in one case. The external fixators were removed between weeks five and nine postoperatively. While healing was seen in twelve of the twenty evaluated cases, the complete functional recovery occurred in six of these and they were released into nature. It was concluded that modified Meynard external fixator, which was made applicable for fractures in birds, could be an alternative method for fracture treatments in wild birds.

Increasing incidence of barbiturate intoxication in avian scavengers and mammals in Spain

Pharmaceuticals are considered emerging contaminants in terms of impacts on wildlife. One chemical group of concern is euthanasia agents used in veterinary medicine. Here we present data on the occurrence of barbiturate intoxication using samples collected from 2004 to 2020 of suspected wildlife and domestic animal poisoning cases in Spain (n = 3210). Barbiturate intoxication was seen in 3.4% (45/1334) of the total number of confirmed intoxicated animals. Barbiturates were detected in 0.2% (1/448) of baits containing detectable poisons. The most frequently detected barbiturate was pentobarbital (42/45, 93.3%), but we also detected phenobarbital, barbital, and thiopental (2.2% prevalence for each). Avian scavengers were most frequently affected by barbiturate intoxication (n = 36), especially Eurasian griffon vultures (Gyps fulvus) (n = 28). Median pentobarbital concentrations detected in intoxicated griffon vultures was 27.3 mg kg−1 in gastric content and 38.1 mg kg−1 in liver, which highlights the acute effect of the chemical soon after ingestion. At least two large intoxication events affecting griffon vultures were related to the consumption of carcasses from euthanized livestock. We also found phenobarbital in a prepared bait linked to the intoxication of one Eurasian buzzard (Buteo buteo). This study highlights the need for stronger regulation of barbiturates to avoid secondary intoxications due to improper disposal of euthanized livestock.

Expression of cell markers and transcription factors in the avian retina compared with that in the marmoset retina

In the vertebrate retina, amacrine and ganglion cells represent the most diverse cell classes. They can be classified into different cell types by several features, such as morphology, light responses, and gene expression profile. Although birds possess high visual acuity (similar to primates that we used here for comparison) and tetrachromatic color vision, data on the expression of transcription factors in retinal ganglion cells of birds are largely missing. In this study, we tested various transcription factors, known to label subpopulations of cells in mammalian retinae, in two avian species: the common buzzard (Buteo buteo), a raptor with exceptional acuity, and the domestic pigeon (Columba livia domestica), a good navigator and widely used model for visual cognition. Staining for the transcription factors Foxp2, Satb1 and Satb2 labeled most ganglion cells in the avian ganglion cell layer. CtBP2 was established as marker for displaced amacrine cells, which allowed us to reliably distinguish ganglion cells from displaced amacrine cells and assess their densities in buzzard and pigeon. When we additionally compared the temporal and central fovea of the buzzard with the fovea of primates, we found that the cellular organization in the pits was different in primates and raptors. In summary, we demonstrate that the expression of transcription factors is a defining feature of cell types not only in the retina of mammals but also in the retina of birds. The markers, which we have established, may provide useful tools for more detailed studies on the retinal circuitry of these highly visual animals.

Clinical Evaluation of Alfaxalone in Cyclodextrin as an Intravenous Anesthetic in the Common Buzzards (Buteo buteo)

There has not been any report about the use of the Alfaxan-CD(R) in common buzzard. The objective of this study was to evaluate the effects of Alfaxan-CD(R) as an intravenous anesthetic agent for inducing anesthesia in the common buzzard and describe some of its clinical pharmacological effects. Eight healthy adult common buzzards (Buteo buteo) of unknown sex, weighing 750–1000 grams, kept in captivity at the Dilek Peninsula National Park located in Aydin, Turkey, and appropriately fed (i.e.: rats, mice, rabbits, and day-old chicks) were included in this study. Birds were given alfaxalone (10 mg/kg, by 2-4 mg/kg boluses) intravenously. Variables measured before, and 5, 10, 15, 20, 30, and 90 minutes after induction were the followings: heart rate (HR, beats/min), respiratory rate (RR, breaths/min), cloacal temperature (CT), hemoglobin concentration (Hb), sodium (Na+), potassium (K+), ionized calcium (iCa++), arterial pH (pHa), arterial oxygen tension (PaO2), arterial carbon dioxide tension (PaCO2), bicarbonate concentration (HCO3) and base excess (BE). All buzzards survived the alfaxalone anesthesia. In this study, alfaxalone provided excellent muscle relaxation and a moderate level of anesthesia. Buzzards given alfaxalone developed primary respiratory acidosis. Base excess and HCO3 were within the reference range and did not significantly change, indicating a primary respiratory acidosis without metabolic component. All physiologic parameters, except cloacal temperature, returned to approximate baseline values at recovery after anesthesia with alfaxalone. This study indicated that alfaxalone produced good to excellent anesthesia in buzzards, characterized by rapid induction of anesthesia, excellent muscle relaxation, unresponsiveness to noxious stimuli, and smooth, uneventful recovery from anesthesia. Hypoventilation and apnea were uncommon at clinically relevant doses but became the most important adverse effects when larger doses were administered rapidly IV.