Feather Tips Research Articles

Dynamic Changes in Viral Loads during Co-Infection with a Recombinant Turkey Herpesvirus Vector Vaccine and Very Virulent Marek's Disease Virus In Vivo.

Marek's disease (MD), caused by the Marek's disease virus (MDV), is a common infectious tumor disease in chickens and was the first neoplastic disease preventable by vaccination. However, the vaccine cannot completely prevent virulent MDV infections, allowing both the vaccine and virulent MDV to coexist in the same chicken for extended periods. This study aims to investigate the changes in viral load of the very virulent strain Md5 and the rHVT-IBD vaccine in different chicken tissues using a real-time PCR assay. The results showed that the rHVT-IBD vaccine significantly reduced the viral load of MDV-Md5 in different organs, while the load of rHVT-IBD was significantly increased when co-infected with Md5. Additionally, co-infection with Md5 and rHVT-IBD in chickens not only changed the original viral load of both viruses but also affected the positive rate of Md5 at 14 days post-vaccination. The positive rate decreased from 100% to 14.29% (feather tips), 0% (skin), 33.33% (liver), 16.67% (spleen), 28.57% (thymus), 33.33% (bursa), and 66.67% (PBL), respectively. This study enhances our understanding of the interactions between HVT vector vaccines and very virulent MDV in chickens and provides valuable insights for the future development of MD vaccines.

Proof of concept evidence that stable isotopes of carbon, nitrogen and sulphur may identify individual kittiwakes breeding in different colonies.

Carbon, nitrogen and sulphur stable isotopes in feathers grown by seabirds while breeding reflect the local isoscape and diet in the vicinity of the colony, so may make it possible to discriminate individual birds from different colonies. Black-legged kittiwake Rissa tridactyla inner primary feathers from two colonies about 350 km apart in the North Sea were used to test whether δ13C, δ15N and δ34S differed between individuals from the two colonies. Feather tips cut from breeding birds caught at nests were compared with tips of moulted feathers (grown 1year earlier) found on the ground. Isotopic compositions showed no overlap between the two colonies in δ13C, δ15N or δ34S in tips of newly-grown feathers sampled from breeding adult kittiwakes. There was some overlap in δ13C, δ15N and δ34S from moulted feathers, but discriminant analysis allowed >90% of individuals to be assigned to their colony. In five of six comparisons, mean isotopic compositions were the same in new and moulted feathers but not for δ34S at one of the two colonies. This study has demonstrated for the first time that stable isotopes in inner primary feathers of kittiwakes can allow accurate identification of the breeding colony of individual birds from two different colonies within the North Sea. Further research is required to determine if this method can be applied with greater spatial resolution and to a larger number of colonies.

Efficacy and tolerability of an mRNA vaccine expressing gB and pp38 antigens of Marek’s disease virus in chickens

Marek's disease is a contagious proliferative disease of chickens caused by an alphaherpesvirus called Marek's disease virus. A bivalent mRNA vaccine encoding MDV's glycoprotein-B and phosphoprotein-38 antigens was synthesized and encapsulated in lipid nanoparticles. Tumor incidence, lesion score, organ weight indices, MDV genome load and cytokine expression were used to evaluate protection and immunostimulatory effects of the tested mRNA vaccine after two challenge trials. Results from the first trial showed decreased tumor incidence and a reduction in average lesion scores in chickens that received the booster dose. The second trial demonstrated that vaccination with the higher dose of the vaccine (10 μg) significantly decreased tumor incidence, average lesion scores, bursal atrophy, and MDV load in feather tips when compared to the controls. Changes in expression of type I and II interferons suggested a possible role for these cytokines in initiation and maintenance of the vaccine-originated immune responses.

Burden of rare earth elements and trace elements in feathers of magellanic penguins (Spheniscus magellanicus) from the southern Chilean Patagonia

Patagonia is one of the last pristine regions on the southern hemisphere. The impact of rare earth element (REEs) and trace elements (TEs) in this region have received little attention. The main goal was to assess REEs burden in feathers of adult magellanic penguins (Spheniscus magellanicus). Sampling was performed at Magdalena Island of the Chilean Patagonia during the austral summer of 2011. Multi-elemental determination of 16 REEs and 24 TEs was performed with ICP-MS. The levels of REEs, TEs, and stable isotopes (δ15N, δ13C, and δ34S) were measured to assess the factors that condition the avian exposure to environmental contaminants. The results showed an increase of the levels of REEs and TEs from the calamus to the feather's tip. In the whole feather, the highest levels corresponded to Ce, which exhibited more than two order of magnitude than Lu and Tm levels. Similar to other penguin species, magellanic penguins can be vectors of REEs and metals in remote regions. Stable isotopes revealed that trophic ecology may influence some of the element concentrations in feathers of magellanic penguins, an issue that requires deeper attention.

How woodcocks produce the most brilliant white plumage patches among the birds.

Until recently, and when compared with diurnal birds that use contrasting plumage patches and complex feather structures to convey visual information, communication in nocturnal and crepuscular species was considered to follow acoustic and chemical channels. However, many birds that are active in low-light environments have evolved intensely white plumage patches within otherwise inconspicuous plumages. We used spectrophotometry, electron microscopy, and optical modelling to explain the mechanisms producing bright white tail feather tips of the Eurasian woodcock Scolopax rusticola. Their diffuse reflectance was approximately 30% higher than any previously measured feather. This intense reflectance is the result of incoherent light scattering from a disordered nanostructure composed of keratin and air within the barb rami. In addition, the flattening, thickening and arrangement of those barbs create a Venetian-blind-like macrostructure that enhances the surface area for light reflection. We suggest that the woodcocks have evolved these bright white feather patches for long-range visual communication in dimly lit environments.

Evaluation of Recombinant Herpesvirus of Turkey Laryngotracheitis (rHVT-LT) Vaccine against Genotype VI Canadian Wild-Type Infectious Laryngotracheitis Virus (ILTV) Infection.

In Alberta, infectious laryngotracheitis virus (ILTV) infection is endemic in backyard poultry flocks; however, outbreaks are only sporadically observed in commercial flocks. In addition to ILTV vaccine revertant strains, wild-type strains are among the most common causes of infectious laryngotracheitis (ILT). Given the surge in live attenuated vaccine-related outbreaks, the goal of this study was to assess the efficacy of a recombinant herpesvirus of turkey (rHVT-LT) vaccine against a genotype VI Canadian wild-type ILTV infection. One-day-old specific pathogen-free (SPF) White Leghorn chickens were vaccinated with the rHVT-LT vaccine or mock vaccinated. At three weeks of age, half of the vaccinated and the mock-vaccinated animals were challenged. Throughout the experiment, weights were recorded, and feather tips, cloacal and oropharyngeal swabs were collected for ILTV genome quantification. Blood was collected to isolate peripheral blood mononuclear cells (PBMC) and quantify CD4+ and CD8+ T cells. At 14 dpi, the chickens were euthanized, and respiratory tissues were collected to quantify genome loads and histological examination. Results showed that the vaccine failed to decrease the clinical signs at 6 days post-infection. However, it was able to significantly reduce ILTV shedding through the oropharyngeal route. Overall, rHVT-LT produced a partial protection against genotype VI ILTV infection.

Mercury contamination in terrestrial predatory birds from Northeast China: Implications for species and feather type selection for biomonitoring

Mercury (Hg), a persistent potent neurotoxin, poses a serious hazard to human and wildlife health. Although highly elevated concentrations were documented in the environmental compartments of China, very few investigations were conducted regarding Hg bioaccumulation in terrestrial vertebrates, particularly avian species at the top trophic position. To assess to what degree the predatory raptors are subject to Hg contamination, we measured feather Hg concentrations from two diurnal raptors, two nocturnal owls, and one predatory passerine, collected from Northeast China. Results showed that the feather Hg concentrations were not greater than 3.67 mg/kg. Notably, there is a significant difference in feather Hg among species: Brown Shrike > Amur Falcon = Common Kestrel > Long-eared Owl > Little Owl. Brown Shrike had the highest feather Hg (1.27 ± 0.91 mg/kg), approximately three times higher compared to the diurnal predators (0.41 ± 0.33 mg/kg), and about seven-folds higher than the owls (0.18 ± 0.19 mg/kg). There were no differences in Hg concentrations between the tips of primary and tail feathers, but their correlations were significantly positive (between 0.45 and 0.96). Overall, the primary Hg = 0.15 + 0.74 × tail Hg (R2 = 0.61). Specifically, a great correlation between the primaries and tails in owls, while a weaker but significant correlation found in falcons/shrikes, provides insight into Hg content in feather tracts for biomonitoring. Our research is among the few studies regarding Hg contamination in the terrestrial predatory avian population in China. We discussed the influencing factors, the ecotoxicological risks to the terrestrial/marine avian population, and the limitations of this research.

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.

COMPARISON OF CVI AND HVT VACCINE STRAINS REPLICATION IN FEATHER TIPS IN DIFFERENT MAREK´S DISEASE VACCINATION PROGRAMS

Marek's disease is an important neoplastic disease in birds caused by a serotype 1 specific herpesvirus; it is controlled by vaccination. In commercial breeders and layers in Brazil, current vaccination programs use the combination of attenuated or non-pathogenic strains of the HVT virus (turkey herpesvirus - serotype 3) and CVI 988 (Rispens - serotype 1). The combination of serotype 3 and 1 it has been an important and effective control strategy through the vaccination of long-lived birds. In addition, more recently the recombinant rHVT strain (vectorized vaccines) has been used in some vaccine programs. This study’s main objective was to compare CVI and HVT components’ replication in feather tips in three different Marek's disease (MD) immunoprophylactic programs (T01 – program A, T02 – program B and T03 – program C). Quantification of these two vaccine strains was performed by real-time PCR in samples collected at the ages of 14, 21, and 28 days. At 14 days, mean of log[cvi] in program B was significantly higher than C (p<0.05). At 21 and 28 days, mean of log[cvi] of program C was significantly lower than A and B (p<0.05). For mean of log[hvt], at 28 days, program B was significantly higher than A (p<0.05). For proportion of positives, at 14 days, program B had 2.7 times more risk to be positive in CVI than program C (p<0.001). At 21 days, program B had 1.7 times more risk to be positive in CVI than program C (p=0.005). For HVT, at 28 days, program B had 3.2 times more risk to be positive than program A (p=0,009). Results showed significant differences between the treatments evaluated. In general the conventional combination Marek’s vaccine containing CVI+HVT (program B) showed higher replication rate and percentage of vaccine coverage than the programs with rHVT vector vaccines (program A and C).

Phenotypic divergence in two sibling species of shorebird: Common Snipe and Wilson’s Snipe (Charadriiformes: Scolopacidae)

Natural and social selection are among the main shapers of biological diversity but their relative importance in divergence remains understudied. Additionally, although neutral evolutionary processes may promote phenotypic divergence, their potential contribution in speciation is often overlooked in studies of comparative morphology. In this study, we investigated phenotypic differentiation in two allopatric shorebirds: the Palaearctic Common Snipe Gallinago gallinago and the Nearctic Wilson's Snipe Gallinago delicata. Specimens of Common Snipe (n = 355 skins, n = 163 skeletons) and Wilson's Snipe (n = 403 skins, n = 141 skeletons) in natural history collections were examined to quantify differences in skeletal and external measurements, and measures of wing and tail plumage variables. The species do not differ in skeletal variables except for the relatively larger sternum of the Common Snipe. The two species do not differ in multivariate wing size or shape (pointedness). Previously known plumage differences between these species were confirmed: the Common Snipe has fewer rectrices, longer and wider outermost rectrices, more extensive white on tips of the secondary feathers, and more white in the axillaries. Between‐species variance in skeleton, primary length and plumage variables was greater than expected if drift was mainly responsible for phenotypic divergence, suggesting a role of selective processes. However, drift could not be rejected after adjusting for multiple comparisons. Differences in plumage traits were greater than in skeletal or external measurements. Because snipe use plumage traits in signalling, the results suggest a more rapid divergence in socially selected traits between these species than in traits related to resource use.

Too salty for you? Changes of diet in the laughing gull nestlings during the growing period

In many seabird and waterbird species, salinity can impose physiological stress on recently hatched chicks because they have a limited capacity to excrete salt loads. In response, parents can select low‐salt food for their nestlings in the first stage of their growth. We determined the growth‐related variation in the diet of laughing gull Leucophaeus atricilla nestlings by using stable isotope analysis of feathers. Isotopic measurement of hatchling down reflects the mother's diet before laying eggs. At the same time, the primary feather tip indicates the food intake during the initiation of feather growth (one week of age), and the primary feather base indicates the food provided by parents during the period immediately before fledging. δ15N and δ13C values among the feather types showed a spatiotemporal shift in the nestlings’ diet. Younger chicks consumed more terrestrial prey sources (weevil beetles Sphenophorus sp.; ~51%) than chicks at fledging (~2%). However, fledging chicks and females before egg‐laying consumed mostly marine prey sources (Pacific white shrimp Litopenaeus vannamei and anchovy Anchoa sp.; > 90%). The base and primary tip portions had similar δ15N values, but both sections were less enriched than the hatchling down. This change was diet‐related, as the nestlings showed a lower percentage of anchovy consumption (13.3–14.7%) compared to females before egg‐laying (30.4%). Younger chicks had a different spatial niche than fledglings and females before egg‐laying, indicating a diet shift through the chick growth period. Assuming that the availability of food in the terrestrial or marine foraging areas did not vary through the nestlings’ growth period (five weeks), our findings support food resource selectivity by parents for their offspring during the first days of life, to reduce the physiological stress caused by high salt loads.

Morphological characterization of flight feather shafts in four bird species with different flight styles

AbstractVariation in rachis (central shaft) morphology in individual remiges (flight feathers) within and among species reflects adaptations to requirements imposed by aerodynamic forces, but the fine-scale variation of feather morphology across remiges is not well known. Here we describe how the shape of the rachis, expressed by the height/width ratio, changes along the longitudinal and lateral axis of the wing in four bird species with different flight styles: flapping-soaring (white storks), flapping-gliding (common buzzards), passerine-type (house sparrows) and continuous flapping (pygmy cormorants). Overall, in each wing feather, irrespective of species identity, rachis shape changed from circular to rectangular, from the base towards the feather tip. The ratio between the height and width of the calamus was similar across remiges in all species, whereas the ratio at the base, middle and tip of the rachis changed among flight feathers and species. In distal primaries of white storks and common buzzards, the ratio decreased along the feather shaft, indicating a depressed (wider than high) rachis cross section towards the feather tip, whereas the inner primaries and secondaries became compressed (higher than wide). In house sparrows, the rachis was compressed in each of the measurement points, except at the distal segment of the two outermost primary feathers. Finally, in pygmy cormorants, the width exceeds the height at each measurement point, except at the calamus. Our results may reflect the resistance of the rachis to in-plane and out-of-plane aerodynamic forces that vary across remiges and across study species. A link between rachis shape and resistance to bending from aerodynamic forces is further indicated by the change of the second moment of areas along the wing axes.

Passive aeroelastic deflection of avian primary feathers

Bird feathers are complex structures that passively deflect as they interact with air to produce aerodynamic force. Newtonian theory suggests that feathers should be stiff to effectively utilize this force. Observations of flying birds indicate that feathers respond to aerodynamic loading via spanwise bending, twisting, and sweeping. These deflections are hypothesized to optimize flight performance, but this has not yet been tested. We measured deflection of isolated feathers in a wind tunnel to explore how flexibility altered aerodynamic forces in emulated gliding flight. Using primary feathers from seven raptors and a rigid airfoil, we quantified bending, sweep, and twisting, as well as α (attack angle) and slip angle. We predicted that (1) feathers would deflect under aerodynamic load, (2) bending would result in lateral redirection of force, (3) twisting would alter spanwise α ‘washout’ and delay the onset of stall, and (4) flexural stiffness of feathers would exhibit positive allometry. The first three predictions were supported by our results, but not the fourth. We found that bending resulted in the redirection of lateral forces more toward the base of the feather on the order of ∼10% of total lift. In comparison to the airfoil which stalled at α = 13.5°, all feathers continued to increase lift production with increasing angle of attack to the limit of our range of measurements (α = 27.5°). We observed that feather stiffness exhibited positive allometry (∝ mass1.1±0.3), however this finding is not statistically different from other hypothesized scaling relationships such as geometric similarity (∝ mass1.67). These results demonstrate that feather flexibility may provide passive roll stability and delay stall by twisting to reduce local α at the feather tip. Our findings are the first to measure forces due to feather deflection under aerodynamic loading and can inform future models of avian flight as well as biomimetic morphing-wing technology.

Speciation Associated with Shifts in Migratory Behavior in an Avian Radiation.

Migratory animals move up to thousands of kilometers every year [1]. Losses of migration (i.e., migratory drop-offs) occur when individuals of a migratory species stop migrating and establish founder sedentary populations, a phenomenon documented in birds [2-5] and butterflies [6]. In theory, losses-and also gains-of migration might promote speciation if sedentary and migratory populations become reproductively isolated [7-9]. Because migratory and sedentary strategies involve alternative physiological, behavioral, and morphological traits [10-13], divergence along multiple axes of organismal function is expected to accompany switches in migratory behavior, potentially accelerating speciation. We present evidence of speciation driven by a migratory drop-off in the fork-tailed flycatcher (Tyrannus savana) resulting in reproductive isolation likely driven by changes in breeding schedules (allochronic speciation [13-15]) and geographic isolation of breeding grounds (allopatric speciation [16]). Phylogenetic analyses across New World flycatchers (Tyrannidae) showed that an association between speciation and drop-offs is also observable at a macroevolutionary scale. Loss of migration was significantly more frequent than its gain, and speciation rates of migratory and partially migratory lineages (i.e., species having both migratory and sedentary populations) exceeded those of sedentary lineages. Models of trait evolution indicated that partial migration is an intermediate step between migratory and sedentary states in this family. Given that partial migration is widespread across migratory animals (e.g., of all migratory birds, ca. 51% are partially migratory [5]), speciation via switches in migratory behavior might be an important yet overlooked mechanism of animal diversification.

Evaluation of Viral-Induced Stress by Quantitating Corticosterone in Feathers of Virus-Infected Specific Pathogen-Free Chicks

Physiological stress is known to promote economic losses by causing immunosuppression. Various factors induce stress, including non-optimal management and infection with various pathogens. The concentration of the stress hormone, corticosterone, is indicative of stress in birds. However, its measurement is difficult due to its elevation caused by catching, handling, bleeding, short half-life in the blood, and short secretion period in feces. We describe a novel method to assess corticosterone concentration by sampling feathers. The viruses studied were 2 immunosuppressive viruses, Marek's disease virus and chicken anemia virus, the respiratory viruses, influenza virus H9N2, Newcastle disease virus, and Infectious bronchitis virus. The study contributes novelty as virus-induced stress by feather examination was described sporadically in chickens previously, and feathers were used to detect corticosterone mainly in dead wild and captive birds. Also, the development of extraction method from feathers is novel by using PBS instead of methanol, and by preparing the feather homogenate with steroid displacement reagent. The study findings revealed that virus infections increased the corticosterone concentrations in feather tips to various extents, from 2× to 10× fold, demonstrating that birds endure stress in addition to the clinical and pathological effects induced by the virus infections.

Transcripts of antibacterial peptides in chicken erythrocytes infected with Marek\u2019s disease virus

BackgroundChicken erythrocytes are involved in immunity through binding of toll-like receptors (TLRs) with their ligands to activate downstream signaling and lead to cytokine production in erythrocytes. Some avian β-defensins (AvBDs) are constitutively expressed in tissues and some others can be induced by various bacteria and viruses. However, the expression of AvBDs in erythrocytes has not yet been studied extensively.ResultsThe transcripts of eight AvBDs (AvBD1 to AvBD7, and AvBD9) and liver-expressed antimicrobial peptide-2 (LEAP-2) were found in normal chicken erythrocytes. The expression levels of AvBD2, 4 and 7 were significantly increased (P < 0.01), whereas the levels of AvBD1, 6 and 9 were significantly decreased (P < 0.01) after Marek’s disease virus (MDV) infection. The mRNA expression level of LEAP-2 was not significantly changed after MDV infection. Highest viral nucleic acid (VNA) of MDV in the feather tips among the tested time points was found at 14 days post-infection (d.p.i.). In addition, 35 MD5-related gene segments were detected in the erythrocytes at 14 d.p.i. by transcriptome sequencing.ConclusionsThese results suggest that the AvBDs in chicken erythrocytes may participate in MDV-induced host immune responses.

Damage mechanism and residual strength at different impact locations for composite bonding scarf repairs

Composite scarf repair has been widely applied as a high efficiency choice for force transferring in aircraft structure repair. The damage tolerance and resistance to low velocity impact are significant for structure design especially for primary load-bearing structures. Some literature studied impact damage and resistance for scarf topology repairs or joints. However, it is not clear that which location in bonded area is the most sensitive to the impact load. The impact location effect on impact damage mechanisms and capacity of tension after impact (TAI) are studied in this paper. Central point in bonded zone has the strongest influence on impact damage. The scarf adhesive film fractured from the feather tip of the back side and oriented to the weakest material. The load capacities of tension after impact at different locations coincide with the adhesive damage area ratio. The finite element model based on CZM (Cohesive Zone Model) is built. And the simulation results validate that central location has the most sensitive characteristic to impact damage and TAI capacity.

Hidden carotenoids in the powder down of herons

Vivid plumage colors are some of the best examples of elaborate trait evolution resulting from sexual selection. Bird feathers often contain high concentrations of pigment or intricate microstructures for reflecting light at distal feather tips, in order to maximize color presentation to intended viewers (e.g., prospective mates, rivals). However, here we describe a rare form of “hidden” plumage coloration, whereby several species of heron (Pelecaniformes: Ardeidae) have powder down tracts liberally coated in yellow pigments that are hidden from view underneath contour feathers. We show using Raman spectroscopy and high-performance liquid chromatography that the yellow coloration is due to carotenoid pigmentation. We also show that fatty acids and carotenoids co-occur in samples and discuss the possible evidence and implications for the presence of esterified carotenoids in powder down. Our study of hidden feather coloration is in apparent contrast with the traditional view of carotenoid pigmentation in plumage, which holds that carotenoids are costly pigments that are displayed to advertise individual quality. We hypothesize that carotenoid pigments are transferred onto powder down as a consequence of the chemical affinity that these pigments have to lipoid secretions associated with subcutaneous fat. Further investigation may identify functions for carotenoid pigmentation in powder down (e.g., signaling, microbiological protection), but we cannot rule out the possibility that the powder down of herons may provide the first evidence for carotenoid coloration in feathers being a non-adaptive by-product of other processes.

Experimental investigation of a new spiral wingtip

Experiments on the relative merits and demerits of slotted wingtips mimicking a bird’s primary feathers have been performed. The real emargination length of feather tips, their flexibility and curved shapes during cruise are considered in the present study. The experiments were performed at a Reynolds number of 3.7 x 105 on a symmetric flat plate half wing of aspect ratio 3. Lift, drag and pitching moments were measured using a six component aerodynamic balance. Four different shapes inspired by bird primary feathers have been analysed. The rigid curved tip performed the best increasing the L/D ratio by 20%. This improvement has been compared with forty different wingtips model available in the literature which shows that rigid curved tip provide better L/D performance. Based on this improvement the key performance indicator of Jet and propeller airplane has been calculated that shows a 7.8% and 9% increase in range for propeller and Jet airplane, respectively.

Feathers for escape: the transition from juvenile to adult in red-legged partridges (Alectoris rufa)

Almost all birds use their fight feathers as a means of escaping predators, and their specific design is adapted to their individual circumstances. For example, Galliform birds use a fast, explosive, noisy take-off to startle a predator. Their legs, wings and feathers must work together to create a strong propulsive force and loud, rhythmic sound. Partridges in a group initiate escape simultaneously, even though individuals in the flock differ in size and experience, as well as in age and sex resulting in feathers that differ in length and shape. In a long-term study, we measured 13814 wild red-legged partridges (Alectoris rufa) to understand how variation in feather proportions and morphometrics between the age–sex classes relate to their escape abilities. We devised two new indexes to quantify the aerodynamic differences between age–sex classes. Our approach synthesizes the understanding of bird take-flight mechanics, feather proportions and the aerodynamic properties of wing tips to show how differences in feather length and tip shape characterize age–sex classes. Our findings suggest that the density, stiffness, permeability, size and shape of the distal primary feathers and wing tips can explain aerodynamic differences between individuals and the efficiency of groups in escape situations.