Inclusion body disease (herpesvirus infection) of falcons (IBDF).

Inclusion body disease of falcons (IBDF) is caused by a herpesvirus. The clinical course is short, 24 to 72 hours in duration, and is characterized by mild to severe depression and weakness often accompanied by anorexia. The disease is invariably fatal. The virus has a marked affinity for the reticuloendothelial system and hepatocytes,producing focal to diffuse necrosis of infected tissues accompanied by the formation of intranuclear inclusion bodies. The virus is pathogenic for American kestrels (Falco sparverius) and great horned owls (Bubo virginianus) in which typical lesions of IBDF are reproduced. The lesions of IBDF are similar to those produced by some herpesvirus infections in other avian species.     

Isolation of a herpesvirus from an American kestrel with inclusion body disease.

A herpesvirus was isolated from the liver of a captive-bred American kestrel (Falco sparverius) which had died of inclusion body disease. Initial isolation was achieved in chicken embryo fibroblasts after three blind passages. Cell-adapted virus produced a distinct rounding of CEF cells within 24 to 48 h. Biologic and serologic tests suggested that the kestrel virus is similar to falcon herpesvirus and pigeon herpesvirus and is at least partially related to owl herpesvirus. However, serologic tests indicated that the kestrel herpesvirus is neither related to infectious laryngotracheitis virus nor to a herpesvirus from a psittacine bird; (Eupsittula canicularis) with Pacheco's parrot disease. This is the first report on the recovery of a herpesvirus similar to falcon herpesvirus from an American kestrel with naturally-occurring inclusion body disease, and on the serologic comparison between falcon herpesvirus and a psittacine herpesvirus.     

Newcastle disease in falcons.

Between March and October, 1975, 37 captive lanners (Falcon biarmicus abyssinicus) destined for exportation to Europe from Kano, Nigeria were examined for Newcastle Disease (ND) by the haemagglutination-inhibition technique in our laboratory. Twenty-one or 57% of the falcons showed high titres, presumably as the result of natural exposure to ND virus.     

Inclusion body disease in a great horned owl.

The carcass of a great horned owl (Bubo virginianus), which had been found moribund in southern Ontario, was presented for necropsy. Throughout the liver and spleen were numerous white foci 1-2 mm in diameter; also noted were white plaques in the mucosae of the pharyngeal papillae and intestine. Results of light and electron microscopic studies and experimental transmission to two captive great horned owls suggested that this was a herpvirus disease similar and possibly indentical to the owl disease reported by other workers in Wiconsin and Australia.     

Postexposure immunoprophylaxis against B virus (Herpesvirus simiae) infection.

Local infiltration of antiserum into sites inoculated with B virus protected rabbits from an otherwise fatal encephalomyelitis. Treatment was effective when delayed for six hours but not after 24 hours. Homologous rabbit antisera were more effective than heterologous monkey antisera, and protection was unrelated to neutralisation titres. Protection apparently depended not on neutralisation of inoculated virus but on destruction of infected cells before they produced progeny virus. Normal human immunoglobulin able to neutralise B virus did not protect. Intravenously administered antibody was effective only if large doses were given. The findings suggest that persons bitten or scratched by monkeys latently infected with B virus may be treated successfully by immunoprophylaxis with specific antibody. Stocks of human or of more readily available simian antisera should be held in laboratories where such animals are used.     

Herpesviral inclusion body disease in owls and falcons is caused by the pigeon herpesvirus (columbid herpesvirus 1)

A herpesviral disease of Rock Pigeons (Columba livia), called "inclusion body disease" or "inclusion body hepatitis," was first described in the 1940s. The disease involves hepatic and splenic necrosis with associated intranuclear inclusion bodies and occurs primarily in young squabs. A similar herpesviral disease occurs in falcons and owls. Serologic and restriction endonuclease digestion studies indicate that herpesviruses from pigeons, falcons, and owls are very closely related and that most reported cases of disease in falcons and owls involve prior documented or possible ingestion of pigeons. These findings led to the hypothesis that an endemic herpesvirus of pigeons may be causing disease in falcons and owls. In order to test this hypothesis, we sequenced a fragment of the herpesviral DNA polymerase gene from naturally infected owls, falcons, and pigeons with inclusion body disease collected between 1991 and 2006. Sequences from all three sources were almost identical, and we therefore propose that the usual agent of inclusion body hepatitis in owls and falcons is columbid herpesvirus 1.     

Pliocene diversification within the South American Forest falcons (Falconidae: Micrastur)

The Neotropics are one of the most species rich regions on Earth, with over 3150 species of birds. This unrivaled biodiversity has been attributed to higher proportions of mountain ranges, tropical rain forest or rain fall in the forest than in any other major biogeographic regions. Five primary hypotheses aim to explain processes of diversification within the Neotropics; (1) the Pleistocene refuge hypothesis, (2) the riverine barrier hypothesis, (3) the Miocene marine incursions hypothesis, (4) the ecological gradient hypothesis, and (5) the impact of the last Andean uplift serving as a barrier between eastern and western population Andean populations. We assessed these hypotheses to see which best explained the species richness of the forest-falcons (Micrastur), a poorly known lineage of birds that inhabit lowland and mid-elevation humid forest. Our analyses suggest all speciation events within the genus Micrastur probably occurred in the last 2.5-3.6 myrs, at or before the Pliocene/Pleistocene boundary, with the basal split within the genus being 7 myrs old. Hence our data allow us to formerly reject the classical Pleistocene refuge for Micrastur, Our divergence time estimates are younger that dates for the Miocene marine incursions, the riverine barrier and the Andean uplift hypotheses.     

Successful treatment of experimental B virus (Herpesvirus simiae) infection with acyclovir.

The efficacy of the new nucleoside analogue acyclovir against B virus (Herpesvirus simiae) was investigated in rabbits and Vero cells infected with 2-136 and 0.3-1.0 TCD50 of the virus respectively. In the Vero cells 1 mg of acyclovir/1 reduced the yield of virus by 90%, which was slightly less than the effect on herpes simplex virus. Results in the rabbits varied with the interval between doses, duration of treatment, and delay before starting treatment. Acyclovir controlled an otherwise lethal infection when given not less than eight-hourly for 14 days. Withdrawing treatment after 9-10 days resulted in late-onset fatal disease in some rabbits. Treatment begun within 24 hours after infection gave complete protection, and rabbits first treated up to five days after infection showed a significant reduction in mortality (p less than 0.001). The plasma half life of acyclovir is twice as long in man as in rabbits and progression of the disease is much slower. Hence acyclovir may be useful for post-exposure prophylaxis against B virus infection in man and possibly also for treatment of the disease.     

Cannibalism in common kestrel (Falco tinnunculus)

acta ethologica - We report two separate observations of adult male common kestrel (Falco tinnunculus) killing and feeding upon second-year (SY) conspecifics in Israel. On 22 January 2022, while...     

Avian pox infection in an American green-winged teal (Anas crecca carolinensis) in Alaska.

Poxvirus infection was diagnosed on the basis of gross and microscopic appearance plus the presence of typical inclusion bodies in a juvenile American green-winged teal (Anas crecca carolinensis) in Alaska. This constitutes the first known report of avian pox in migratory ducks and the first report of poxvirus infection in wild birds in Alaska.     

Isolation and characterization of polymorphic microsatellite markers in lesser kestrel (Falco naumanni) and cross-amplification in common kestrel (Falco tinnunculus)

Lesser kestrel, Falco naumanni, is a colonial and migratory species breeding in part of the Mediterranean Basin and part of central Asia and north-east of China and Mongolia. This species is catalogued in IUCN red list category as vulnerable. Twenty microsatellite loci were selected from libraries enriched in AC or AG tandem repeats and specific PCR were devised from their flanking sequences. Most microsatellites (14) were found polymorphic among 30 individuals of F. naumanni representing 20 reproduction areas of the species in the region of Extremadura, Spain. Polymorphisms were detected by size variation of the amplified loci, which allele number and observed heterozygosity ranged from 3 to 20 and from 0.300 to 0.933, respectively. Cross-species amplification showed that 13 of selected loci were also found polymorphic in common kestrel species (Falco tinnunculus). Novel polymorphic microsatellites will serve to conservation studies in lesser kestrel.     

Musculoskeletal underpinnings to differences in killing behavior between North American accipiters (Falconiformes: Accipitridae) and falcons (Falconidae)

Accipiters (Accipiter spp.) and falcons (Falco spp.) both use their feet to seize prey, but falcons kill primarily with their beaks, whereas accipiters kill with their feet. This study examines the mechanistic basis to differences in their modes of dispatching prey, by focusing on the myology and biomechanics of the jaws, digits, and distal hindlimb. Bite, grip, and distal hindlimb flexion forces were estimated from measurements of physiological cross-sectional area (PCSA) and indices of mechanical advantage (MA) for the major jaw adductors, and digit and tarsometatarsal flexors. Estimated bite force, total jaw adductor PCSA, and jaw MA (averaged over adductors) tended to be relatively and absolutely greater in falcons, reflecting their emphasis on biting for dispatching their prey. Differences between genera in estimated grip force, total digit flexor PCSA, and digit MA (averaged over inter-phalangeal joints and digits) were not as clear-cut; each of these parameters scaled positively allometric in accipiters, which may reflect the scaling of both prey size, and the proportion of mammalian prey consumed by this lineage with increasing body size. Estimated tarsometatarsal force was greater in falcons than in accipiters, due to their greater MA, which may reflect selection for incurring greater forces during prey strikes. Conversely, the comparatively lower tarsometatarsal MA in accipiters reflects their capacity for greater foot speed potentially necessary for grasping elusive prey. Thus, this study elucidates how differences in jaw and hindlimb musculoskeletal morphology of accipiters and falcons are reflected in differences in their killing modes, and through differences in their force-generating capacities.     

Efficacy of ivermectin (Ivomec) against intestinal capulariosis in falcons

52 captive falcons out of 3,988 (1.3 %) raptors microscopically examined for intestinal parasites in the Middle East proved infested with hairworms (capillariid parasites). 26 of these (50 %) showed concurrent parasitoses. In the group of 26 falcons diagnosed with capillariosis as sole infestation (50 %) compatible clinical signs such as anorexia, weight loss, weakness, dyspnoea, regurgitation of food and blood, diarrhoea and dark tarry faeces, were recorded. These birds were treated intramuscularly with ivermectin at doses of 2 mg/kg. In fecal samples examined 10-15 days later, the eggs of capillariid parasites had disappeared, in association with complete clinical recovery.     

The refractive development of the eye of the American kestrel (Falco sparverius): a new avian model

Summary Most measures of avian visual performance are carried out on commonly available domestic species such as the chicken, and most of the data on avian induced refractive error deals with chickens. Raptors are predatory birds in which good visual resolving ability is particularly important. Behavioral studies indicate that the eyes of raptors have two to three times the resolving ability of the human eye. The domestic chicken is precocial at hatching whereas most raptors are semi-altricial. This study was an effort to determine if the effect of early visual deprivation on the refractive development of the chicken eye can be reproduced in the American kestrel, a species which is not domesticated and in which the need for acute vision is particularly important.Visual deprivation was achieved by unilaterally applying translucent plastic goggles over the eyes of kestrels two days after hatching. Refractive error was measured using a retinoscope and trial lenses. Ocular growth was monitored by A-scan ultrasonography, and frozen ocular sections of sacrificed birds. The effect of the experimental manipulation on the contralateral control eye and body weight was evaluated each day over a 42-day period. The goggles did not significantly affect the normal changes in body weight or the normal pattern of ocular growth and refractive development in the untreated eyes. An analysis of the refractive state changes as a result of form deprivation was made each week for 6 weeks after hatching on both the treated and untreated eyes in a separate group of experimental birds. Visual form deprivation caused a significant myopic shift in refractive error and a significant increase in the vitreous chamber depth in the treated eyes at 3 and 6 weeks of age. However, the amount of myopia produced is much less than that induced in chicks, and in certain cases hyperopia is produced. The kestrels recover from myopia and hyperopia within 10 days of goggle removal, after 3 to 4 weeks of deprivation.This study is the first indication that chickens may not be a representative bird model for studying form deprivation myopia. First, myopia is not always produced in kestrels in response to form deprivation. Second, kestrels are severely myopic at hatching and therefore, the direction of emmetropization is opposite to that found in hatchling chicks.