Integrity of and damage to wings, feather vanes and serrations in barn owls.

The silent flight of owls is well known. It has served as role model for the designs of new airplane wings and ventilators. One of the structural features that underlies silent flight is the serrated leading edge of the wing that is mainly formed by the tenth primary flight feather (P10). We examined here how much the wings, the P10 feather and the serrations in different populations of barn owls reflect the intact situation. First, when the P10 feather molts, no or fewer serrations are present. Furthermore, damage to feathers and serrations may occur. Damage may be due to several factors like broken feather tips, lost rami, barbules, or broken tips of serrations. The latter may cause a narrowing of the outer vane of the P10 feather. We quantitatively assessed damage by counting the number of wings with missing or broken primary feathers, the number of wings with a narrowed outer vane of the P10 feather, and the number of serrations with reduced length. Considerable damage occurred on wings and feathers on both the macroscopic and microscopic levels. The observed damage most likely influences flight performance. More damage occurred in Galapagos barn owls than in North American and European barn owls. The Galapagos population may be more vulnerable than the other populations because it may at least temporarily be in a bad nutritional state and, thus, postpone molt.

Fracture status of wild cranes (Grus monacha and G. vipio) found dead or in a weak condition at Izumi Plain in Japan.

The Izumi Plain in Kagoshima Prefecture, Japan, is a major wintering ground for wild cranes. Between October 2009 and March 2016, a total of 204 Hooded Cranes Grus monacha and White-naped Cranes G. vipio were found dead or in a weak condition in the plane. Of these, 56 cranes had bone fractures. The rate of incidence of fracture was considered to be higher in White-naped than in Hooded Cranes. Tibia fractures were the most common. The leg and wing fracture numbers were almost equal. Forty six percent of the fracture cases were believed to be caused by collisions with the power line.

Bidirectional Regulation of Sleep and Synapse Pruning after Neural Injury.

Following acute neural injury, severed axons undergo programmed Wallerian degeneration over several following days. While sleep has been linked with synaptic reorganization under other conditions, the role of sleep in responses to neural injuries remains poorly understood. To study the relationship between sleep and neural injury responses, we examined Drosophila melanogaster following the removal of antennae or other sensory tissues. Daytime sleep is elevated after antennal or wing injury, but sleep returns to baseline levels within 24 h after injury. Similar increases in sleep are not observed when olfactory receptor neurons are silenced or when other sensory organs are severed, suggesting that increased sleep after injury is not attributed to sensory deprivation, nociception, or generalized inflammatory responses. Neuroprotective disruptions of the E3 ubiquitin ligase highwire and c-Jun N-terminal kinase basket in olfactory receptor neurons weaken the sleep-promoting effects of antennal injury, suggesting that post-injury sleep may be influenced by the clearance of damaged neurons. Finally, we show that pre-synaptic active zones are preferentially removed from severed axons within hours after injury and that depriving recently injured flies of sleep slows the removal of both active zones and damaged axons. These data support a bidirectional interaction between sleep and synapse pruning after antennal injury: locally increasing the need to clear neural debris is associated with increased sleep, which is required for efficient active zone removal after injury.

Wing Abnormality in a Wild-Hatched Whooping Crane (Grus americana) Chick from the Nonmigratory Population in Louisiana, USA.

We describe a wing abnormality in a wild-hatched Whooping Crane (Grus americana) chick from the reintroduced Louisiana, US nonmigratory population. Despite its seemingly compromised flight ability, the chick fledged, reached independence, and lived until 13 mo of age. Necropsy revealed an axial malunion near the left carpus likely resulting from trauma.

Developmental regulation of regenerative potential in Drosophila by ecdysone through a bistable loop of ZBTB transcription factors.

In many organisms, the regenerative capacity of tissues progressively decreases as development progresses. However, the developmental mechanisms that restrict regenerative potential remain unclear. In Drosophila, wing imaginal discs become unable to regenerate upon damage during the third larval stage (L3). Here, we show that production of ecdysone after larvae reach their critical weight (CW) terminates the window of regenerative potential by acting on a bistable loop composed of two antagonistic Broad-complex/Tramtrack/Bric-à-brac Zinc-finger (ZBTB) genes: chinmo and broad (br). Around mid L3, ecdysone signaling silences chinmo and activates br to switch wing epithelial progenitors from a default self-renewing to a differentiation-prone state. Before mid L3, Chinmo promotes a strong regenerative response upon tissue damage. After mid L3, Br installs a nonpermissive state that represses regeneration. Transient down-regulation of ecdysone signaling or Br in late L3 larvae enhances chinmo expression in damaged cells that regain the capacity to regenerate. This work unveils a mechanism that ties the self-renewing and regenerative potential of epithelial progenitors to developmental progression.

Successful Management of Open, Contaminated Metacarpal Fractures in an Adult Snowy Owl ( Bubo scandiacus) With a Minimal Type II External Skeletal Fixator.

An adult, male snowy owl ( Bubo scandiacus) was found down and unable to fly in western New York State. Physical examination and radiographs revealed a subacute, open wound and fractured major and minor metacarpals of the right wing. A minimal type II external skeletal fixator (ESF) device was placed on the right major metacarpal bone and the open wound was allowed to granulate and close. After evidence of bone union, the ESF device was removed. The owl performed auto-physiotherapy throughout the process and was released with sustained flight 2 months postoperatively. It was recaptured 7 weeks later and underwent further rehabilitation to allow successful release 11 months after surgical stabilization. To our knowledge, this is the first case report describing use of a type II ESF device on the metacarpus of a bird.

Axon Death Pathways Converge on Axundead to Promote Functional and Structural Axon Disassembly.

Axon degeneration is a hallmark of neurodegenerative disease and neural injury. Axotomy activates an intrinsic pro-degenerative axon death signaling cascade involving loss of the NAD+ biosynthetic enzyme Nmnat/Nmnat2 in axons, activation of dSarm/Sarm1, and subsequent Sarm-dependent depletion of NAD+. Here we identify Axundead (Axed) as a mediator of axon death. axed mutants suppress axon death in several types of axons for the lifespan of the fly and block the pro-degenerative effects of activated dSarm in vivo. Neurodegeneration induced by loss of the sole fly Nmnat ortholog is also fully blocked by axed, but not dsarm, mutants. Thus, pro-degenerative pathways activated by dSarm signaling or Nmnat elimination ultimately converge on Axed. Remarkably, severed axons morphologically preserved by axon death pathway mutations remain integrated in circuits and able to elicit complex behaviors after stimulation, indicating that blockade of axon death signaling results in long-term functional preservation of axons.

Drosophila wing imaginal discs respond to mechanical injury via slow InsP3R-mediated intercellular calcium waves.

Calcium signalling is a highly versatile cellular communication system that modulates basic functions such as cell contractility, essential steps of animal development such as fertilization and higher-order processes such as memory. We probed the function of calcium signalling in Drosophila wing imaginal discs through a combination of ex vivo and in vivo imaging and genetic analysis. Here we discover that wing discs display slow, long-range intercellular calcium waves (ICWs) when mechanically stressed in vivo or cultured ex vivo. These slow imaginal disc intercellular calcium waves (SIDICs) are mediated by the inositol-3-phosphate receptor, the endoplasmic reticulum (ER) calcium pump SERCA and the key gap junction component Inx2. The knockdown of genes required for SIDIC formation and propagation negatively affects wing disc recovery after mechanical injury. Our results reveal a role for ICWs in wing disc homoeostasis and highlight the utility of the wing disc as a model for calcium signalling studies.

Wing wear reduces bumblebee flight performance in a dynamic obstacle course.

Previous work has shown that wing wear increases mortality in bumblebees. Although a proximate mechanism for this phenomenon has remained elusive, a leading hypothesis is that wing wear increases predation risk by reducing flight manoeuvrability. We tested the effects of simulated wing wear on flight manoeuvrability in Bombus impatiens bumblebees using a dynamic obstacle course designed to push bees towards their performance limits. We found that removing 22% wing area from the tips of both forewings (symmetric wear) caused a 9% reduction in peak acceleration during manoeuvring flight, while performing the same manipulation on only one wing (asymmetric wear) did not significantly reduce maximum acceleration. The rate at which bees collided with obstacles was correlated with body length across all treatments, but wing wear did not increase collision rate, possibly because shorter wingspans allow more room for bees to manoeuvre. This study presents a novel method for exploring extreme flight manoeuvres in flying insects, eliciting peak accelerations that exceed those measured during flight through a stationary obstacle course. If escape from aerial predation is constrained by acceleration capacity, then our results offer a potential explanation for the observed increase in bumblebee mortality with wing wear.

[Non-infectious unilateral wing lameness of pigeons, so called "Schieffliegersyndrom". First clinical and pathological results]. / Belastungsbedingte, nichtinfektiöse unilaterale Buggelenksarthropathie der Brieftauben ("Schieffliegersyndrom"). Erste Resultate zu klinischen Symptomen und pathologischen Veränderungen.

OBJECTIVE: After medium- and long-distance flights and following the first training units of the year, a unilateral injuring of the shoulder joint is observed in racing pigeons. The objective of the study was to discuss the pathogenesis and aetiology of the damage. MATERIAL AND METHODS: In 35 pigeons suffering from unilateral wing lameness, the affected shoulder joints were examined microbiologically and histopathologically. Additionally, both shoulder joints of 12 affected pigeons were examined pathologically and histopathologically. RESULTS: Joint capsule, articular cartilage, tendons and bone structures displayed pathological changes. CONCLUSION: The non-infectious unilateral wing lameness of pigeons appears to be a stress-induced mechanical damage of the shoulder joint. The different structures of the joint are over-extended by the physical/mechanical influences during longer flights.

Use of a caudoventral-craniodorsal oblique radiographic view made at 45° to the frontal plane to evaluate the pectoral girdle in raptors.

OBJECTIVE: To evaluate use of a caudoventral-craniodorsal oblique radiographic view made at 45° to the frontal plane (H view) for assessment of the pectoral (thoracic) girdle in raptors. DESIGN: Retrospective cross-sectional analysis. ANIMALS: 24 raptors suspected to have a fracture of the thoracic girdle. PROCEDURES: Standard ventrodorsal and H views were obtained for all birds. Radiographs were evaluated twice by a radiologist blinded to the final diagnosis, with each view first evaluated independently and views then evaluated in combination. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated, with results of surgery or necropsy used as the gold standard. RESULTS: 9 birds had thoracic girdle fractures; fractures were correctly identified in 8 of these 9 birds on the ventrodorsal view alone, 7 of these 9 birds on the H view alone, and all 9 birds on the 2 views in combination. Fifteen birds did not have thoracic girdle fractures; radiographs were correctly classified in 12 of these 15 birds when the ventrodorsal view was evaluated alone, all 15 birds when the H view was evaluated alone, and 14 of these 15 birds when the 2 views were evaluated in combination. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that the H view or the addition of the H view to the VD view could be useful in raptors suspected to have fractures of the thoracic girdle. Agreement with the gold standard (ie, fracture present or absent) was higher with the H view and combination of views than with the ventrodorsal view alone.

Histologic Evaluation of Critical Size Defect Healing With Natural and Synthetic Bone Grafts in the Pigeon ( Columba livia ) Ulna.

Fracture and bone segment loss are major clinical problems in birds. Achieving bone formation and clinical union in a fracture case is important for the survival of the bird. To evaluate the efficacy of bone grafts for defect healing in birds, 2 different bone grafts were investigated in the healing of a bone defect in 24 healthy pigeons ( Columba livia ). In each bird, a 1-cm critical size defect (CSD) was created in the left ulna, and the fracture was stabilized with external skeletal fixation (ESF). A graft of hydroxyapatite (HA) alone (n = 12 birds) or demineralized bone matrix (DBM) combined with HA (n = 12 birds) was implanted in the CSD. The CSD healing was evaluated at 3 endpoints: 3, 6, and 12 weeks after surgery. Four birds were euthanatized at each endpoint from each treatment group, and bone graft healing in the ulna CSD was evaluated by histologic examination. The CSD and graft implants were evaluated for quality of union, cortex development, and bone graft incorporation. Results showed no graft rejection in any bird, and all birds had connective tissue formation in the defect because of the bone graft application. These results suggest that bone defect healing can be achieved by a combination of osteoinductive and osteoconductive bone graft materials for clinical union and new bone regeneration in birds. The combination of DBM and HA resulted in a better quality bone graft (P < .05) than did HA alone, but there was no significant differences in cortex development or bone graft incorporation at 3, 6, or 12 weeks. From the results of this study, we conclude that HA bone grafts, alone or in combination with DBM, with external skeletal fixation is suitable and safe for bone defect and fracture treatment in pigeons.

Influence of two catching methods on the occurrence of lesions in broilers.

During the catching of broilers for slaughter, 2 to 3 birds are grabbed per hand at one leg at the same time. From an animal welfare point of view, this procedure is under critical observation from animal welfare administration and the general public.In this paper 2 catching methods were compared: the routinely used 1-leg catching method, and a second tech-nique whereby birds were grabbed by both legs with a maximum of 2 birds per hand (2-leg catching method). Lesions on the body, legs, and wings (hemorrhages and fractures) were recorded by a camera system located after the plucking position. Two weight classes, 2 catching teams, and 2 flocks were included in the study.Heavy animals showed more lesions than birds of the light weight class. In all investigations, lesions on the body and legs were rare, whereas wing lesions occurred at a rate of up to 15.32%. Statistical analysis showed no significant difference between the 2 methods or between the catching teams for both weight classes. A correlation between lesions and weight was observed, with a significant odds ratio ( OR: ) of 3.6 (95% CI: 3.299-3.957).During 2-leg catching, the animals appeared to be more restless. Workers stated that the grabbing of both legs of a bird was more difficult and that working in a crouching position for a longer time was harder.We conclude that the cautious handling of animals to reduce stress is more important than "holding animals by both legs", as has been proposed.

Effects of environmental factors and appendage injury on the wing variation in the cricket Velarifictorus ornatus.

The effects of environmental factors and appendage injury on the wing variation in Velarifictorus ornatus (Shiraki) (Orthoptera: Gryllidae) were investigated. The percentage of micropters was more than 95% when the nymphs were reared at constant photoperiods, and changing photoperiod did not affect wing variation in V. ornatus at 25 or 30°C. In the crowding experiment, the percentage of macropters was only 11.2% when the nymphs were reared separately at 25°C. In contrast, the percentage of macropters was significantly higher when the rearing density was increased to two nymphs per container and lower when the rearing density was increased to five or 10 nymphs per container. These results indicate that low and high rearing densities induce micropters, but intermediate rearing density stimulates the formation of macropters. Meanwhile, severance of appendages, such as antennae, femora, and tibiae, in the nymph stage exerted a micropterizing effect. The period sensitive to such stresses ranged from 35 to 60 days of nymph development.

The effects of artificial wing wear on the flight capacity of the honey bee Apis mellifera.

The wings of bees and other insects accumulate permanent wear, which increases the rate of mortality and impacts foraging behavior, presumably due to effects on flight performance. In this study, we investigated how experimental wing wear affects flight performance in honey bees. Variable density gases and high-speed videography were used to determine the maximum hovering flight capacity and wing kinematics of bees from three treatment groups: no wing wear, symmetric and asymmetric wing wear. Wing wear was simulated by clipping the distal-trailing edge of one or both of the wings. Across all bees from treatment groups combined, wingbeat frequency was inversely related to wing area. During hovering in air, bees with symmetric and asymmetric wing wear responded kinematically so as to produce wingtip velocities similar to those bees with no wing wear. However, maximal hovering flight capacity (revealed during flight in hypodense gases) decreased in direct proportion to wing area and inversely to wing asymmetry. Bees with reduced wing area and high asymmetry produced lower maximum wingtip velocity than bees with intact or symmetric wings, which caused a greater impairment in maximal flight capacity. These results demonstrate that the magnitude and type of wing wear affects maximal aerodynamic power production and, likely, the control of hovering flight. Wing wear reduces aerodynamic reserve capacity and, subsequently, the capacity for flight behaviors such as load carriage, maneuverability, and evading predators.

Biomechanical strategies for mitigating collision damage in insect wings: structural design versus embedded elastic materials.

The wings of many insects accumulate considerable wear and tear during their lifespan, and this irreversible structural damage can impose significant costs on insect flight performance and survivability. Wing wear in foraging bumblebees (and likely many other species) is caused by inadvertent, repeated collisions with vegetation during flight, suggesting the possibility that insect wings may display biomechanical adaptations to mitigate the damage associated with collisions. We used a novel experimental technique to artificially induce wing wear in bumblebees and yellowjacket wasps, closely related species with similar life histories but distinct wing morphologies. Wasps have a flexible resilin joint (the costal break) positioned distally along the leading edge of the wing, which allows the wing tip to crumple reversibly when it hits an obstacle, whereas bumblebees lack an analogous joint. Through experimental manipulation of its stiffness, we found that the costal break plays a critical role in mitigating collision damage in yellowjacket wings. However, bumblebee wings do not experience as much damage as would be expected based on their lack of a costal break, possibly due to differences in the spatial arrangement of supporting wing veins. Our results indicate that these two species utilize different wing design strategies for mitigating damage resulting from collisions. A simple inertial model of a flapping wing reveals the biomechanical constraints acting on the costal break, which may help explain its absence in bumblebee wings.

Pattern reorganization occurs independently of cell division during Drosophila wing disc regeneration in situ.

One of the most intriguing problems in developmental biology is how an organism can replace missing organs or portions of its body after injury. This capacity, known as regeneration, is conserved across different phyla. The imaginal discs of Drosophila melanogaster provide a particularly well-characterized model for analyzing regeneration. We have developed a unique method to study organ regeneration under physiological conditions using the imaginal discs of Drosophila. Using this method, we revisited different aspects of organ regeneration. The results presented in this report suggest that during the initial stages of regeneration, different processes occur, including wound healing, a temporary loss of markers of cell-fate commitment, and pattern reorganization. We present evidence indicating that all of these processes occur even when cell division has been arrested. Our data also suggested that Wingless is not required during the early stages of disc regeneration.

Humeral remodeling and soft tissue injury of the wings caused by backpack harnesses for radio transmitters in New Zealand Takahe (Porphyrio hochstetteri).

Backpack harnesses are commonly used to attach radio and satellite transmitters to a wide range of bird species for research and conservation management. They are an integral part of the conservation management of the New Zealand Takahe (Porphyrio hochstetteri), an endangered flightless rail. Radio transmitters mounted on backpack harnesses enable the birds to be tracked in their remaining native range of remote, mountainous Fiordland, New Zealand. We evaluated 26 Takahe retrospectively at necropsy by gross examination, radiography, and computed tomography to assess damage from the backpack harness. Ten birds that had never worn a harness had no evidence of wing injury. Of the 16 birds that had worn a harness, 10 (63%) had superficial soft tissue injury to skin or patagium or more severe injury, such as remodeling of the distal humerus at the harness cord-wing interface, or pathologic fractures. Such injuries are hypothesized to be associated with discomfort, increased risk of infection or fracture, and therefore reduced fitness. These findings have implications for all avian species deployed with backpack harnesses.

Bat flight with bad wings: is flight metabolism affected by damaged wings?

Infection of North American bats with the keratin-digesting fungus Geomyces destructans often results in holes and ruptures of wing membranes, yet it is unknown whether flight performance and metabolism of bats are altered by such injuries. I conducted flight experiments in a circular flight arena with Myotis albescens and M. nigricans individuals with an intact or ruptured trailing edge of one of the plagiopatagial membranes. In both species, individuals with damaged wings were lighter, had a higher aspect ratio (squared wing span divided by wing area) and an increased wing loading (weight divided by wing area) than conspecifics with intact wings. Bats with an asymmetric reduction of the wing area flew at similar speeds to conspecifics with intact wings but performed fewer flight manoeuvres. Individuals with damaged wings showed lower metabolic rates during flight than conspecifics with intact wings, even when controlling for body mass differences; the difference in mass-specific metabolic rate may be attributable to the lower number of flight manoeuvres (U-turns) by bats with damaged wings compared with conspecifics with intact wings. Possibly, bats compensated for an asymmetric reduction in wing area by lowering their body mass and avoiding flight manoeuvres. In conclusion, it may be that bats suffer from moderate wing damage not directly, by experiencing increased metabolic rate, but indirectly, by a reduced manoeuvrability and foraging success. This could impede a bat's ability to gain sufficient body mass before hibernation.