Raptor gastroenterology

DIGESTIVE AND FEEDING BEHAVIOR DIFFERENCES BETWEEN LAPPET-FACED VULTURES (TORGOS TRACHELIOTOS) AND GRIFFON VULTURES (GYPS FULVUS) EX SITU

Appropriate diets for ex situ wildlife are essential for animal health and welfare and yet ex situ facilities are often constrained by feed ingredient availability when attempting to replicate natural diets. In obligate carnivores such as vultures, digestive strategies are likely to have evolved alongside feeding behaviors, which may differ between even sympatric species. To begin to understand the digestive strategies of two Old World vulture species (lappet-faced vulture Torgos tracheliotos, n = 3, and griffon vulture Gyps fulvus, n = 4) of similar body size but divergent feeding habits, their feeding and digestion strategies on a diet of whole rats were compared. The food intake, color of excreta, excreta consistency, and carbon and nitrogen excretion were measured. Mean retention time of the digesta was analyzed using titanium dioxide as an inert marker in a diet of chicken carcass. Lappet-faced vultures consumed significantly greater quantities of food than griffon vultures and were less selective. Lappet-faced vultures primarily produced brown excreta while griffon vultures primarily produced green excreta, with much higher carbon and nitrogen concentrations. The consistency of excreta and the mean retention time did not differ between the species but may have been too variable to detect differences. A strong positive correlation was found between food intake per metabolic weight and the proportion of brown excreta, and both were negatively correlated with green excreta, as well as excreta concentrations of nitrogen and carbon. These findings align with their reported feeding ecology, with lappet-faced vultures showing adaptations to less-digestible carcass material compared with griffon vultures. Despite their similar size and overlapping natural habitat, these results suggest a need for differentiated feed provisioning for these species when under human care.

Seasonal Variations in the Digestive Tract of the Little Owl, Athene noctua: Anatomical, Histological, and Scanning Electron Microscopical Studies

The digestive tract of the little owl, Athene noctua (Strigiformes: Strigidae), is described in two different seasons. The digestive tract of this bird follows the basic model for that of a predatory bird. The cervical esophagus is not expanded to form a crop. The internal surface of the esophagus forms numerous longitudinal folds provided with numerous mucous glands. These longitudinal folds increase in number and vary in depth posteriorly. The folds of the proventriculus are composed of simple branched tubular glands. The ventriculus is lined by a thin layer of koilin. The number of goblet cells gradually increases from the duodenum to the rectum, and the lymphatic tissue diffuses within the lamina propria. The esophageal glands secrete acid mucopolysaccharides, while the gastric glands of the stomach, the goblet cells, and crypts of Lieberkühn secrete acid mucopolysaccharides. Proteins were observed in the different histological structures of the digestive tract. Morphometric and histometric studies showed differences between summer and winter in the esophagus and glandular stomach (especially in winter), but no seasonal differences were seen in the muscular stomach, or small and large intestines.

The emergence of Caryospora neofalconis in falcons in Central Saudi Arabia

Objective:

This study aimed to examine the occurrence of Caryospora (C.) neofalconis in falcons from the central region of the Kingdom of Saudi Arabia (KSA).

Materials and methods:

Fecal samples (n = 149) from 149 healthy falcons including 56 saker falcons (Falco cherrug), 13 lanner falcons (F. biarmicus), 18 peregrine falcons (F. peregrinus), 40 Barbary falcons (F. pelegrinoides), and 22 gyrfalcons (F. rusticolus) were collected between October 2018 and May 2019. The fecal samples were examined for the presence of C. neofalconis by microscopic examination followed by confirmation by polymerase chain reaction targeting 18S rRNA genes and their phylogenetic analyses.

Results:

The overall prevalence of C. neofalconis in the falcons was recorded as 10.7% (16/149) by microscopic examination. The highest prevalence was found in F. peregrinus (6/18, 33.3%), followed by F. rusticolus (3/22, 13.6%), F. cherrug (5/56, 8.9 %) and F. pelegrinoides (2/40, 5.0%). There was no C. neofalconis infection observed in F. biamicus. The 18S rRNA gene could be amplified in eight samples. The phylogenetic analysis of two C. neofalconis isolates exhibited a close relationship with the Mexican isolate (KT03081) with a 99.7% identity.

Conclusion:

To our knowledge, based on the microscopic and molecular analysis, this is the first report of C. neofalconis in F. cherrug, F. rusticolus, F. pelegrinoides, and F. peregrinus from the central region of the KSA and it emphasize the value of adopting preventive measures to limit the spread of C. neofalconis.

Inclusion Body Herpesvirus Hepatitis in Captive Falcons in the Middle East: A Review of Clinical and Pathologic Findings

Inclusion body hepatitis in falcons is caused by a herpesvirus designated Falconid HV-1. This herpesvirus and other herpesviruses affecting birds of prey have not been assigned to a genus and include inclusion body herpesvirus hepatitis in eagles (Accipitrid HV-1) and inclusion body herpesvirus hepatitis in owls (Strigid HV-1). Herpesvirus infections have been diagnosed in both captive and free-living raptors across Europe, North America, and Asia in different species of the family Falconidae. Herpesviruses affecting owls and falcons have been found to be antigenically similar to pigeon herpesvirus (Columbid HV-1) and distinct from other avian herpesviruses. When the herpesvirus isolates from owls, falcons, and pigeons were compared by sequencing a fragment of the herpes viral DNA polymerase gene from those birds naturally infected with the virus, the sequences from these 3 sources were found to be nearly identical. The authors of this study concluded that the Falconid HV-1, Strigid HV-1, and Columbid HV-1 were the same virus. Furthermore, the authors also proposed that the virus therefore be referred to as Columbid HV-1 (CoHV-1), because pigeons may be responsible for the transmission of the virus to birds of prey. Pigeons are often carriers of the virus without showing any clinical signs. It has long been suspected that raptors may contract the infection by the ingestion of infected pigeons. Some studies have suggested that falcons may not contract the infection through the oral route by ingesting carrier pigeons, but through the ocular or nasal route. Inclusion body herpesvirus hepatitis is a frequently diagnosed disease in the captive falcon population used for falconry, racing, and breeding in the Middle East, and it seems to be associated with the extensive use of pigeons for training and as a food item. This paper reviews the clinical and pathological findings in falcons affected by inclusion body herpesvirus hepatitis in the Middle East.

Supplementary feeding and endoparasites in threatened avian scavengers: Coprologic evidence from red kites in their wintering stronghold

Many obligate and facultative avian scavengers are increasingly dependent on food provided in supplementary feeding stations (SFS), which are managed for the conservation of these species. Deliberate feeding can influence disease-related host demography and population dynamics through physiological changes and density-dependent parasite acquisition and transmission, but information on this threat to avian scavengers is scarce. Due to their effects on host aggregation and density, we hypothesised that the predictability and concentration of food in SFS can exacerbate parasite infection. This hypothesis was tested by comparing the prevalence, richness, abundance and mixed infection of endoparasites (coccidia and helminths) in red kites Milvus milvus foraging on livestock carcasses (mostly of pigs and poultry) in overcrowded and confined conditions at SFS, relative to those foraging alone or in small groups on wild prey unevenly randomly distributed within large areas during winter, mostly wild rabbits (Oryctolagus cuniculus). No clear differences were found between areas with and without SFS in the prevalence and abundance of oocyst of Eimeria. This coccidian genus appears to include parasites of the prey rather than the raptors, thus representing parasite transport or pseudo-parasitism rather than actual parasitism in the kites. A higher prevalence and richness of helminths, as well as mixed infections with several phyla, was found in kites exploiting SFS than in those feeding on wild prey in the area without SFS. The unsanitary conditions derived from the stack of livestock carcasses and the contamination of carrion with the faeces of multiple scavenger hosts can increase the accumulation and persistence of helminths eggs and intermediate hosts. The regular use and frequent confinement of large numbers of red kites at SFS can promote the spread of parasites to a large proportion of the European breeding population distributed across Spain during the winter. We encourage that carcasses of free roaming livestock can be left in the countryside, as well as the conservation management of wildlife exploited as food by red kites (especially wild rabbits), to attempt avoiding overcrowded and confined conditions at SFS. Further research is required to assess the impact of deliberate feeding on the spread of parasites and other disease agents in the threatened species SFS are intended to favour.

Caryospora neofalconis and other enteroparasites in raptors from Mexico

A coprological survey of enteroparasites in raptors (60 Falconiformes) from Central Mexico is reported. Three samples contained coccidian unsporulated oocysts, one contained Eimeria sp., one contained trematode eggs and one contained capillarid and trematode eggs and Eimeria sp. After sporulation at the laboratory, oocysts from a Falco peregrinus were identified as Caryospora neofalconis. The phylogenetic analysis of the C. neofalconis (GenBank accession number KT037081) showed a close relationship to the Australian strain RY 2014 isolate 16710 (GenBank accession number KJ634019) of Caryosporadaceloe, with 99.2% similarity. As far as we are aware, this is the first report of C. neofalconis in raptors from Mexico and the Americas.

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Coprological survey of enteroparasites present in 60 Falconiformes from Central Mexico.

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Caryospora neofalconis identified in one Falco peregrinus.

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First record of C. neofalconis from raptors from Mexico and the Americas.