Bird Claws Research Articles

Design and Assessment of Bird-Inspired 3D-Printed Models to Evaluate Grasp Mechanics.

Adapting grasp-specialized biomechanical structures into current research with 3D-printed prostheses may improve robotic dexterity in grasping a wider variety of objects. Claw variations across various bird species lend biomechanical advantages for grasping motions related to perching, climbing, and hunting. Designs inspired by bird claws provide improvements beyond a human-inspired structure for specific grasping applications to offer a solution for mitigating a cause of the high rejection rate for upper-limb prostheses. This research focuses on the design and manufacturing of two robotic test devices with different toe arrangements. The first, anisodactyl (three toes at the front, one at the back), is commonly found in birds of prey such as falcons and hawks. The second, zygodactyl (two toes at the front, two at the back), is commonly found in climbing birds such as woodpeckers and parrots. The evaluation methods for these models included a qualitative variable-object grasp assessment. The results highlighted design features that suggest an improved grasp: a small and central palm, curved distal digit components, and a symmetrical digit arrangement. A quantitative grip force test demonstrated that the single digit, the anisodactyl claw, and the zygodactyl claw designs support loads up to 64.3 N, 86.1 N, and 74.1 N, respectively. These loads exceed the minimum mechanical load capabilities for prosthetic devices. The developed designs offer insights into how biomimicry can be harnessed to optimize the grasping functionality of upper-limb prostheses.

A Goddess with Bird’s Claws: An Exploration of the Image of Magu

In China, Magu is a household name for a female Daoist immortal. As a symbol of longevity, people believe that she can prolong their lives and bring them good luck. This paper takes the fact that Magu has hands that look like birds’ feet as a clue to sort out the evolution of the image of Magu. In this article, it is argued that the prototype for the image of the Daoist immortal, Magu, is the bird goddess of the Neolithic goddess and that Magu’s hands, which look like bird claws, are a symbol of the goddess’s divine power. After entering the patriarchal society, the figure of Magu was eroticized and her hands, which represented divine power, became a tool for men to scratch their backs. Daoism, however, inherited the matriarchal society’s worship of women and retained the image of Magu with her hands that resembled the feet of a bird. When Daoism incorporated Magu into its system of deities, the image of Magu was remodeled to conform to the teachings of Daoism, thus making Magu a beautiful, kind-hearted immortal with high moral sentiments.

Numerical investigation of novel 3D-SPA for gripping analysis in multi-environment

The soft pneumatic actuator (SPA) has strong flexibility and good compliance, allowing its assembly into a multi-functional soft gripper that can be applied to object grasping and handling, post-disaster rescue, rehabilitation training, and in other fields. However, many actuators have limited grasping modes and can only bend in a single direction. And most of the soft grippers are studied in free space for grasping. Herein, a novel 3D-SPA with internal bellows chambers, inspired by the structure of the bird claws and the human fingers, is presented. Based on Yeoh hyperelasticity theory and virtual work principle, the mechanical theoretical model between different input air pressure Pin and the bending angle θ of the actuator is established, and the spatial conversion relationship of obstacle avoidance motion is given. The influence of the length and number of the chamber, the radius of the circular section, the shape of the cross section and the length of the joint on the bending performance and stress distribution of the actuator are studied in detail, respectively. Two soft grippers with different structures, composed of 3D-SPA, have a variety of bending configurations on different planes, which improves the inclusiveness of grasping objects with different shapes and sizes. Finally, the process of object grasping in free space and obstacle avoidance grasping and handling in obstacle space are studied respectively. The validity of the proposed mechanical model and spatial transformation relationship are verified. The investigation results reveal that the developed scheme assists the robot’s obstacle avoidance and grasping, which can be integrated into industrial robotic arms and AGVs for mobile operations and applied to rehabilitation training to help patients gradually recover hand joint function.

Калмыцкий «каркасный» шлем из собрания Смоленского государственного музея-заповедника

Introduction. The article deals with an iron helmet stored at Smolensk State Reserve Museum (inv. no. OР-375) that has never been subject to any academic research. The goal. The paper aims to introduce the item into scientific circulation, describe its construction and design, clarify some dating and attribution properties. Results. The efforts to establish when and how the helmet had been obtained by the museum came to nothing but it can still be dated and attributed on the basis of a typological analysis. The headpiece clusters with a large group of riveted helmets characterized by a four-piece crown and a specific ‘frame’ consisting of narrow faceted overlays with a smooth edge and one (two) narrow hoops. Helmets of this type are equipped with a cylindrical (less often conical) pommel (top) with a plume tube. Another frequent design element of such helmets is a ‘box-shaped’ visor. Such headpieces come from Central Asia, South Siberia, and the Volga Region and are dated back to the Late Middle Ages and early modern period. The helmet from Smolensk State Reserve Museum is distinguished by multiple ornamental patterns on the crown, as well as the shape of the two-part top piece. It is very likely that the armorer to have authored this element of the helmet may have been inspired by images of Buddhist stupas inherent to the Kadampa tradition. The crown and other elements of the helmet bear a jagged ornament that creates rhombic and triangular patterns, as well as ones in the form of three-toed bird claws. Conclusions. The construction and design structures of the examined headpiece — including the Buddhist symbols on the pommel — suggest that the helmet was forged by armorers of Dzungaria or Volga Kalmykia for an Oirat Buddhist warrior between the 1610s and 1750s (most likely in the second half of this period). The available visual materials attest to that such helmets were long used in weaponry of nomads across the Great Steppe. So, in particular, one can see them on images of Bashkir warriors dated to the 1800s–1820s.

Numerical investigation of a bioinspired multi-segment soft pneumatic actuator for grasping applications

Soft robotic gripper is useful for grasping applications, such as pick-and-place tasks, post-disaster rescue and health monitoring of civil infrastructure. Inspired by the versatility of the human hand and bird claws, this paper designed a bioinspired actuator made of multi-segment fibre-reinforced pneumatic bending actuator and bellow-shape pneumatic rotational actuator joints. A numerical model was established to investigate the bending performance and stress distribution of the designed actuator under different input pressures. The influences of bottom layer thickness, chamber number at the actuator joints, and bending segment length on the overall bending performance of the designed soft actuator have been comprehensively investigated. In addition, the stress distribution of the actuator joints has been studied for understanding the mechanical performance of the actuator joints. Finally, a soft gripper made of two designed actuators has been demonstrated for grasping objects with different shapes and weights. The findings found in this investigation are helpful for the design and fabrication of robotic grasper, which can be further integrated on an industrial robotic arm and flying robotic platform for grasping and prosthetic hand applications.

Determination of Corticosterone Levels in Bird Claws

Determination of Corticosterone Levels in Bird Claws

Excellent Healing after Severe Lid Injury by a Bird

Eye lid lacerations secondary to penetrating trauma is quite common. Most of the injuries occur due to animal bites, falls and collision with sharp objects. They may lead to partial or full thickness lid defects. We report a case of middle aged woman who was attacked by bird claws and sustained severe upper lid laceration that was immediately thoroughly investigated and then managed surgically resulting in excellent wound healing. Ocular trauma from bird pecking injury can cause blindness in humans. The public should guard against feeding and keeping close with them. If immediate medical attention is given by the ophthalmologist and urgent primary repair is done there are high chances to save the eye from disastrous complications.
 Key Words: Lid laceration, ocular trauma, penetrating injury.

Amulets Made of Birds of Prey Claws From the Verkhnii Saltiv Burial Ground Catacombs

This work introduces into scientific circulation a collection of birds of prey claws and their bronze imitations found in the catacombs of the early medieval burial ground near Verkhnii Saltiv village . Amulets made of the hawk family claws (steppe eagle — catacomb no. 30 BCM-IV, golden eagle — catacomb no. 71 BCM-IV) were found in the fourth section of the burial ground catacombs. Bronze amulets imitating the birds of prey claws are represented by 13 specimens originating from catacombs no. 15, 36, 60 BCM-I and catacombs no. 13, 37, 67, 96, 99, 119, 137 BCM-IV. Claw-shaped bronze amulets, depending on the extent they repeat their prototypes, are represented by three types: Type 1 (8 items) is represented by products that realistically reproduce the birdss claw, due to the fact that the eyelet for hanging the amulet imitates the joint at the base of the claw. Type 2 (4 items) is represented by examples that repeat the shape of the claw, but are equipped with a rounded flat eyelet, typical for most Saltiv bronze amulets. Type 3 is represented by a single item in the shape of a simple bent plate repeating the form of the claw with a punched hole in the upper part. Complexes, in which amulets made of claws of birds and their bronze imitations are found, are dated from the end of the first quarter of  IX century (catacomb no. 30) — second half of IX century (cat. no. 15 BCM-I, cat. no. 99, 119, 137 BCM-IV). In most cases the amulets were included to the teenagers’ implements. Only in the catacombs no. 96 and no. 99 they were found in the burials of young women. The amulets are often placed close to the human waist at the right pelvic bone. Only in the catacomb no. 13 the amulet was found close to the chest of a buried teenager and in the catacomb no. 60 it was at the head. The inclusion of bird claws and their imitations in the costume was supposed to provide protection for a human against the impact of  supernatural forces and to obtain certain qualities of a certain bird of prey (sharp-sightedness, speed etc.). Due to the fact that in Ossetian and wider Indo-European mythology, birds were markers of the upper world, these amulets should be considered as symbols of the sun, heavenly fire, and their wearing should be associated with the cult of the sun.

Quantifying shape and ecology in avian pedal claws: The relationship between the bony core and keratinous sheath.

Terrestrial tetrapods use their claws to interact with their environments in a plethora of ways. Birds in particular have developed a diversity of claw shapes since they are often not bound to terrestrial locomotion and have heterogeneous body masses ranging several orders of magnitude. Numerous previous studies have hypothesized a connection between pedal claw shape and ecological mode in birds, yet have generated conflicting results, spanning from clear ecological groupings based on claw shape to a complete overlap of ecological modes. The majority of these studies have relied on traditional morphometric arc measurements of keratinous sheaths and have variably accounted for likely confounding factors such as body mass and phylogenetic relatedness. To better address the hypothesized relationship between ecology and claw shape in birds, we collected 580 radiographs allowing visualization of the bony core and keratinous sheath shape in 21 avian orders. Geometric morphometrics was used to quantify bony core and keratinous sheath shape and was compared to results using traditional arc measurements. Neither approach significantly separates bird claws into coarse ecological categories after integrating body size and phylogenetic relatedness; however, some separation between ecological groups is evident and we find a gradual shift from the claw shape of ground‐dwelling birds to those of predatory birds. Further, the bony claw core and keratinous sheath are significantly correlated, and the degree of functional integration does not differ across ecological groups. Therefore, it is likely possible to compare fossil bony cores with extant keratinous sheaths after applying corrections. Finally, traditional metrics and geometric morphometric shape are significantly, yet loosely correlated. Based on these results, future workers are encouraged to use geometric morphometric approaches to study claw geometry and account for confounding factors such as body size, phylogeny, and individual variation prior to predicting ecology in fossil taxa.

Examining carry‐over effects of winter habitat on breeding phenology and reproductive success in prairie warblers Setophaga discolor

Winter habitat quality can influence breeding phenology and reproductive success of migratory birds. Using stable isotope ratios of carbon (δ13C) from bird claws and red blood cells collected in Massachusetts, USA, we assessed if winter habitat occupancy carried over to affect prairie warbler Setophaga discolor breeding arrival dates, body condition upon arrival, pairing success, first‐egg dates and reproductive success. In two of three years (in 2011 and 2012, but not in 2013), after‐second‐year (ASY) males wintering in drier habitat, as indicated by enriched δ13C values, arrived later on the breeding grounds. Based on the North Atlantic Oscillation index, there was likely less rainfall in the Caribbean wintering grounds during the winters of 2011 and 2012 compared to the winter of 2013, suggesting increased winter rainfall in 2013 may have diminished the influence of winter habitat occupancy on arrival date. We did not find any effects of winter habitat on breeding season phenomena for second‐year (SY) males or females, but our sample sizes for these age/sex classes were relatively low. Although winter habitat quality influenced arrival dates of ASY males, there was no evidence that it affected reproductive performance, perhaps because of high rates of nest depredation in our system. Our study adds to a growing body of research that shows the influence of carry‐over effects can differ among species and within populations, and also can be modulated by other environmental conditions. This information enriches our understanding of the role of carry‐over effects in population limitation for migratory birds.

Matching geographical assignment by stable isotopes with African non-breeding sites of barn swallows Hirundo rustica tracked by geolocation.

Knowledge on whereabouts within the annual cycle of migratory species is prerequisite for many aspects in ecology and biological conservation. Spatial assignments of stable isotopes archived in tissues allows for later inference on sites where the specific tissue had been grown. It has been rarely tested whether spatial assignments match directly tracked non-breeding residences, especially for migratory songbirds. We here compare assignments of stable isotopes from feathers of Palaearctic Barn swallows Hirundo rustica with their African non-breeding residence sites tracked by geolocation.Assignments based on δ2H, δ13C and δ15N isotope compositions delineate three main non-breeding regions: a main cluster in central Africa, a second in West Africa, and the third cluster in Northern Africa. Using δ13C, δ15N only, non-breeding sites ranged from clusters in West/Southwest Africa to South East Africa with a centre in Central Africa. The non-breeding areas (50% and 75% Kernel density estimates, KDE) of the birds tracked by geolocation stretched from West Africa via central Africa to southern Africa. We found little overlap of 0.3% (assuming a 1:1 odds ratio) to 1.4% (3:1 odds ratio) in the three element assignments and KDEs for only 2 and 13 individuals out of 32 birds. Assignment maps for two elements (δ13C, δ15N) and KDEs showed higher consistencies with an overlap of 3.6 and 8.5% for 12 and 18 birds. We argue that the low matching between stable isotope assignments and non-breeding sites in our study arise from insufficient baseline data for Africa (concerning both isoscapes and specific discrimination functions). However, other factors like aerial foraging habit of the species, and a potential mismatch of non-breeding site location and the spatial origin of aerial plankton might further hamper accurate assignments. Finally we call for concerted analyses of tissues i.e. feathers and claws of birds which are grown at known sites across the continent and from species with various ecological requirements (diverse habitats, foraging behaviours, and diet compositions) to establish isoscapes for general applicability.

Points on the curve: An analysis of methods for assessing the shape of vertebrate claws.

The form of amniote claws has been extensively investigated, often with inferences about ecological association being drawn from studies of their geometry. Various methods have been used to quantify differences in the geometry of claws, but rarely have the underlying assumptions of such methods been addressed. Here, we use one set of bird claws and apply six methods (five that have been previously used, and a new one) that are tasked with comparing their shape. In doing so, we compare the (1) ability of these methods to represent the shape of the claw; (2) validity of the assumptions made about underlying claw geometry; (3) their ability to be applied unambiguously; and (4) their ability to differentiate between predetermined functional clusters. We find that of the six methods considered only the geometric morphometric approach reveals differences in the shapes of bird claws. Our comparison shows that geometry-based methods can provide a general estimate of the degree of curvature of claw arcs, but are unable to differentiate between shapes. Of all of the geometry-based approaches, we conclude that the adjusted version of the Zani (2000) method is the most useful because it can be applied without ambiguity, and provides a reliable estimate of claw curvature. The three landmarks that define that method (tip and base of the claw arc, plus the intersection between said claw arc and a line drawn perpendicular from the midpoint of tip and claw base) do not all bear biological significance, but relatively clearly circumscribe the length-to-height ratio of the claw, which relates to its curvature. Overall, our comparisons reveal that the shape of avian claws does not differ significantly between climbing and perching birds, and that the utilization of preordained functional clusters in comparative data analysis can hinder the discovery of meaningful differences in claw shape. J. Morphol. 278:150-169, 2017. © 2016 Wiley Periodicals,Inc.

Emlen funnel experiments revisited: methods update for studying compass orientation in songbirds.

Migratory songbirds carry an inherited capacity to migrate several thousand kilometers each year crossing continental landmasses and barriers between distant breeding sites and wintering areas. How individual songbirds manage with extreme precision to find their way is still largely unknown. The functional characteristics of biological compasses used by songbird migrants has mainly been investigated by recording the birds directed migratory activity in circular cages, so‐called Emlen funnels. This method is 50 years old and has not received major updates over the past decades. The aim of this work was to compare the results from newly developed digital methods with the established manual methods to evaluate songbird migratory activity and orientation in circular cages.We performed orientation experiments using the European robin (Erithacus rubecula) using modified Emlen funnels equipped with thermal paper and simultaneously recorded the songbird movements from above. We evaluated and compared the results obtained with five different methods. Two methods have been commonly used in songbirds’ orientation experiments; the other three methods were developed for this study and were based either on evaluation of the thermal paper using automated image analysis, or on the analysis of videos recorded during the experiment.The methods used to evaluate scratches produced by the claws of birds on the thermal papers presented some differences compared with the video analyses. These differences were caused mainly by differences in scatter, as any movement of the bird along the sloping walls of the funnel was recorded on the thermal paper, whereas video evaluations allowed us to detect single takeoff attempts by the birds and to consider only this behavior in the orientation analyses. Using computer vision, we were also able to identify and separately evaluate different behaviors that were impossible to record by the thermal paper.The traditional Emlen funnel is still the most used method to investigate compass orientation in songbirds under controlled conditions. However, new numerical image analysis techniques provide a much higher level of detail of songbirds’ migratory behavior and will provide an increasing number of possibilities to evaluate and quantify specific behaviors as new algorithms will be developed.

Detecting Densely Distributed Graph Patterns for Fine-Grained Image Categorization.

Fine-grained image categorization is a challenging task aiming at distinguishing objects belonging to the same basic-level category, e.g., leaf or mushroom. It is a useful technique that can be applied for species recognition, face verification, and so on. Most of the existing methods either have difficulties to detect discriminative object components automatically, or suffer from the limited amount of training data in each sub-category. To solve these problems, this paper proposes a new fine-grained image categorization model. The key is a dense graph mining algorithm that hierarchically localizes discriminative object parts in each image. More specifically, to mimic the human hierarchical perception mechanism, a superpixel pyramid is generated for each image. Thereby, graphlets from each layer are constructed to seamlessly capture object components. Intuitively, graphlets representative to each super-/sub-category is densely distributed in their feature space. Thus, a dense graph mining algorithm is developed to discover graphlets representative to each super-/sub-category. Finally, the discovered graphlets from pairwise images are integrated into an image kernel for fine-grained recognition. Theoretically, the learned kernel can generalize several state-of-the-art image kernels. Experiments on nine image sets demonstrate the advantage of our method. Moreover, the discovered graphlets from each sub-category accurately capture those tiny discriminative object components, e.g., bird claws, heads, and bodies.

Use of Stable Isotopes to Investigate Keratin Deposition in the Claw Tips of Ducks

Stable isotopes derived from the claws of birds could be used to determine the migratory origins of birds if the time periods represented in excised sections of claws were known. We investigated new keratin growth in the claws of adult female Lesser Scaup (Aythya affinis) by estimating the equilibration rates of stable isotopes (δ 13C, δ 15N, and δ 2H) from the breeding grounds into 1 mm claw tips. We sampled birds on their breeding ground through time and found that it took approximately 3–3.5 months for isotope values in most claw tips to equilibrate to isotope values that reflected those present in the environment on their breeding grounds. Results from this study suggest that isotopes equilibrate slowly into claw tips of Lesser Scaup, suggesting isotopes could potentially be used to determine the wintering grounds of birds. We suggest using controlled feeding experiments or longitudinal field investigations to understand claw growth and isotopic equilibration in claw tips. Such information would be valuable in ascertaining whether claw tips can be used in future studies to identify the migratory origins of birds.

Influence of Bill and Foot Morphology on the Ectoparasites of Barn Owls

Preening is the principle behavioral defense used by birds to combat ectoparasites. Most birds have a small overhang at the tip of their bills that is used to shear through the tough cuticle of ectoparasitic arthropods, making preening much more efficient. Birds may also scratch with their feet to defend against ectoparasites. This is particularly important for removing ectoparasites on the head, which birds cannot preen. Scratching may be enhanced by the comb-like serrations that are found on the claws of birds in many avian families. We examined the prevalence and intensity of ectoparasites of barn owls (Tyto alba pratincola) in southern Idaho in relation to bill hook length and morphological characteristics of the pectinate claw. The barn owls in our study were infested with 3 species of lice (Phthiraptera: Ischnocera): Colpocephalum turbinatum , Kurodaia subpachygaster, and Strigiphilus aitkeni . Bill hook length was associated with the prevalence of these lice. Owls with longer hooks were more likely to be infested with lice. Conventional wisdom suggests that the bill morphology of raptors has been shaped by selection for efficient foraging; our data suggest that hook morphology may also play a role in ectoparasite defense. The number of teeth on the pectinate claw was also associated with the prevalence of lice. Owls that had claws with more teeth were less likely to be infested with lice, which suggests that larger pectinate claws may offer relatively more protection against ectoparasitic lice. Experiments that manipulate the bill hook and pectinate claw are needed to confirm whether these host characters are involved in ectoparasite defense. Finally, we recovered mammalian ectoparasites from 4 barn owls. We recovered species of mammalian lice (Phthiraptera:Anoplura) and fleas (Siphonaptera) that are commonly found on microtine rodents. The owls probably acquired these parasites from recently eaten prey. This represents 1 of the few documented cases of parasites "straggling" from prey to predator.

The influence of microhabitat, moisture and diet on stable-hydrogen isotope variation in a Neotropical avian food web

Abstract:The application of stable-hydrogen isotope (δD) measurements to the study of animal movement, resource use and physiology depends on understanding factors driving variation in δD in animal tissues. The source of micro-scale variation in δD is poorly known, yet understanding micro-scale patterns of δD could shed light on important ecological processes and improve our abilities to track animal movements. Using linear and additive models, we explored the influence of micro-scale habitat use, moisture and diet on tissue δD values of Nicaraguan cloud-forest birds. Using mist nets, we captured 211 individuals of 22 resident Neotropical species at 500–1390 m asl and collected feather and claw samples. Based on three years of data from year-round sampling, our results suggest that microhabitat, seasonal shifts in moisture δD, and diet all influence bird tissue δD values. Our model results reveal a previously undescribed microgeographical effect on δD, where foraging level (understorey versus overstorey) and foraging location (forest interior versus adjacent coffee plantation) were significant predictors of δD values in bird claws and feathers. Mean claw and feather δD values among species varied from −83‰ to −19‰. Top models for claws and feathers explained 57% and 52% of variation in δD respectively. Direct comparisons of understorey (mean ± SD of −30‰ ± 15‰) versus overstorey (−50‰ ± 15‰) claw values suggest that δD may be useful in tracking vertical, micro-scale movement. Higher δD values in forest understorey birds reveal a heavy reliance upon recycled, fog moisture. Fragmentation and climate change may result in increasingly desiccated cloud forest that may exert a more negative influence on the food webs of understorey species that seem to be supported by recycled sources of moisture in the dry season.

Thermal paper can replace typewriter correction paper in Emlen funnels

Emlen funnels are small funnel-shaped orientation cagesused to record the spontaneously directed migratory rest-lessness (Zugunruhe) of night-migratory songbirds (Emlenand Emlen 1966). Today, almost every group studying thecompass orientation capabilities of migratory songbirdsuses the Emlen funnel method (e.g., Sandberg et al. 2002;Wiltschko and Wiltschko 2003; Ritz et al. 2004; Muheimet al. 2006; Chernetsov et al. 2008). This method providesthe most reliable and cost effective tool to analyze thespontaneous directional preference of many migratorysongbirds during the migratory season. Results from Emlenfunnel experiments also play a key role in the current rushtowards understanding how the magnetic compass sense inmigratory songbirds works (e.g., Ritz et al. 2004; Mouritsenand Ritz 2005).When Emlen first invented the method (Emlen andEmlen 1966), he used an inkpad at the bottom of the cageand lined the walls of the funnel with blotting paper toscore the ink marks as a measure of the bird’s directionalchoice. Later, Rabol (1979) got the idea to use typewritercorrection paper on the walls instead of ink and blottingpaper to record the birds’ directional preferences. This wasa significant improvement for the birds, since ‘‘Rotkehl-chen’’ (Robin Erithacus rubecula) would no longer become‘‘Blaukehlchen’’ (Bluethroat Luscinia svecica) after severalnights hopping on the inkpad. The refined typewriter cor-rection paper version of the Emlen funnel was adopted byvirtually every study using Emlen funnels after 1980 (e.g.,Mouritsen and Larsen 1998; Sandberg et al. 2002;Wiltschko and Wiltschko 2003; Ritz et al. 2004; Muheimet al. 2006). However, over the last 10 years, researchersusing the Emlen funnel method have been challengedby the disappearance of typewriters, which has made itexceedingly difficult to find a reliable supplier of appro-priately sized rolls of typewriter correction paper needed todo Emlen funnel experiments.The Wiltschko-lab in Frankfurt (e.g., Wiltschko andWiltschko 2003; Ritz et al. 2004) were instrumental inconvincing one of the producers of typewriter correctionpaper to make a final production run, which helped manycolleagues stock up on paper for several years. Unfortu-nately, the chalk-like coating on typewriter correctionpaper tends to harden with time, which means that itbecomes more and more difficult to accurately scorescratches on the paper. In addition to this problem, ourstock ran out several years ago, which made us initiate asearch for an alternative solution, as going back to the inkmethod would not be acceptable for animal welfarereasons.First, we visited the local crime unit to see if fingerprintdetection dust could help us. It did not work because itsfunction is based on the fat on the fingers which the duststicks to. But the claws of birds are normally fat free andthus claw marks cannot be visualized with fingerprintdetection dust. Second, we got the idea that maybe thepaper used in trucks to record their speed (tachopgraphcharts, ‘‘Fahrtenschreiberpapier’’ in German) could also beused to record the scratches left in Emlen funnels bymigratory birds. As a result, we tested various such papersfrom several different producers with variable success untilwe received a sample of ‘‘Thermal paper’’ product number‘‘SC55’’ from the company ‘‘Blumberg Systempapiere’’,Kalkumerstrasse 46, 40885 Ratingen-Lintorf, Germany;

Bird claws and bird of prey talons: Where is the difference?

The questions asked were (1) whether claws and toes of birds of prey are actually different from those of other perching birds, and, if so, (2) what parameter can describe such a difference. The structure of toes and claws of the first and third toe was then evaluated in three groups of birds: Falconiformes, Strigiformes and non‐raptorial species. One adult male per species was considered, and, among non‐raptorial birds, only species belonging to typically or partially perching families. Only one specimen per species was chosen, from museum skin bird collections. All species examined occur in the western Palearctic, according to Cramp & Simmons (1977–1994). Discriminant Function Analysis showed clear separation of the groups. In particular, the first canonical function segregated Falconiformes from Strigiformes, whereas the second separated Strigiformes from non‐raptorials. However, Falconiformes and non‐raptorials partially overlapped and were not separated. The characteristics segregating Falconiformes from Strigiformes mainly concerned claw curvature, claw length in relation to toe length, and the last phalanx shape, thin or rounded. Characters contributing to segregate Strigiformes from non‐raptorials were claw curvature in relation to their radius and the shape, thin or rounded, of both claws and last phalanxes. Results indicate that Strigiformes toes and claws only superficially resemble those of Falconiformes and the shape of claws and toes of Falconiformes are much more similar to those of non‐raptorial species than they are to those of Strigiformes.

Scaling of bird claws

AbstractThe claw geometry of birds can be used to predict their mode of life. Previous studies, however, have not considered how bird size might affect these predictions. Thus, in the present study, the geometric scaling relationships of bird claws are examined for a variety of extant birds with different modes of life: predatory, climbing, perching or ground‐dwelling. Measurements of hind‐limb claw radius (i.e. claw size) and claw angle (i.e. claw ‘hookedness’) of the third digit claw were made on 120 species of bird ranging from 0.0057 kg to 44 kg in body mass. Claw radius was found to be proportional to (body mass)0.34 across all species. Claw angle was found to increase with body mass for predatory and climbing birds (i.e. bigger birds have relatively more hooked claws), and decrease with body mass for ground‐dwelling birds (i.e. bigger birds have relatively less hooked or flatter claws). No significant relationship was found between claw angle and body mass for perching birds. Mode of life could not be predicted with any certainty using measurements of either claw radius or claw angle, suggesting difficulty in assigning fossil species such as Archaeopteryx to a specific locomotor category. As claw design should enable the claw to withstand the forces placed upon it, further work is needed to establish the stresses experienced by the claws of different types of bird.