Diurnal birds of prey (Accipitriformes and Falconiformes) has traditionally been known as comprising a single order. Recently, this classification has been used in the non-taxonomic sense as referring to a convergent group of birds that are largely classified as predatory birds. Although these birds are similar in their morphology, the species differ in their foraging methods and prey preference. The cranial shape and the physical attributes determine the efficiency of the resource use. The aim of this study is to increase our knowledge of the relationship between skull shape, prey preference, and foraging habits. A geometric morphometric approach was used to analyse two-dimensional cranial landmarks. We used principal component (PC) analyses on measurements that may be related to prey preference and foraging habits. The PCs are resulted described the relative height of the skull and beak, the variation in the relative size, the orientation and robustness of the lacrimal bone, the variation in the relative size of the neurocranium compared to the viscerocranium, and the orientation of the palatine bone. The dietary categories significantly overlap. The skull morphology reflects more on foraging habits than diet or prey preference.
Wildfowl (Anatidae) are a diverse group of birds and globally distributed. These birds feed by widely varying methods, there are generalist and specialist species. In a number of vertebrate taxa trophic specializations have led to distinct differences in the morphology of the skull, like in birds. Our knowledge and understanding of the relationship between cranial morphology and feeding mechanism of wildfowl are limited. The aim of this article is to increase our knowledge of the relationship between skull shape and foraging habits and find the identifiable attributes of the differently adapted groups. We used morphometric methods with 7 linear measurements of the skull. We used principal component (PC) analysis to identify the groups with different foraging habits. The PCs were related to measurements which represent the demanded muscle mass for feeding and the amount of capable food items. The grazers have a narrower bill and bigger bone surface which requires more muscle tissue than the broad billed filter-feeders. We observed the structural and functional differences between grazers and filter-feeders. There are no important differences in the bill measurements between omnivore dabbling and diving ducks. Only the bill is not enough to deduce the foraging habits.
Owls (Strigiformes) are small to large birds, mostly solitary and nocturnal predators. They can be found all around the Earth except Antarctica and some remote islands. The species differ in size, diet and habitat, which led to different morphological adaptations of the skull. The main differences are in the orbital and the otical region, which are connected to the visual and hearing capabilities. The aim of the recent study is to increase our knowledge of the relationship between skull shape and foraging habits and tried to find those characters that are related to diet. A geometric morphometric approach was used to analyse two-dimensional cranial landmarks. We used principal component (PC) analyses on measurements that may be related to visual and hearing abilities. The PCs are resulted in the robusticity of the skull and the asymmetry of the otical region. There are differences in position and shape of postorbital processes (POP) and tympanic wings (TW). Species with symmetrical skull shape are basically crepuscular or diurnal predators and species with more asymmetrical skulls are mostly nocturnal hunters and have better hearing capabilities.
Parrots (Psittaciformes) are a unique and diverse avian group and vary tremendously in size, shape, and colour. Mainly distributed throughout the tropics and subtropics, most species of parrots are largely or exclusively arboreal with several exceptions. The species also differ in diet and habitat, which led to different musculoskeletal adaptations of the skull. However, parrots have conspicuous generalized external features; in this recent study, we tried to increase our knowledge of the cranial shape and foraging habits. A geometric morphometric approach was used to analyse two-dimensional cranial landmarks. We used principal component (PC) analyses on measurements that may be related to diet. The PCs described the relative height of the cranium, the relative length and curvature of the beak, differences in the orientation and curvature of the lacrimal bone and the upper margin of orbits, variation in the size and position of the palatine bone and the relative width of the cranium, and variation in the relative size of the neurocranium compared to the viscerocranium. The dietary categories overlap in the morphospace but the analysis in lateral and ventral view resulted in significant differences.
The habitat selection of Scops Owl Otus scops has not been studied in Hungary so far. The population in the Carpathian Basin can be considered as a range edge population. Yet, studying and conserving breeding population at the edge of the species’ range is important for the evolutionary potential of the species. In the present study, we examined Scops Owl populations situated on both sides of the Hungarian-Slovenian border. Although breeding density is significantly higher in Slovenia than in Hungary, we found no difference in the ecological diversity of the Goričko Nature Park (GNP), Slovenia and Vas County, Hungary. We found that both the proportion and total edge length of dry grasslands and intensively managed mesic grasslands were lower in Hungary. Similarly, market gardens were present in a larger proportion in GNP. These landscape features all indicate that the complex cultivation is still pronounced in GNP, favouring the Sops Owl as less intensive cultivation modes, like rural market gardens and grasslands play a key role in its habitat selection. Points with Scops Owl observations appeared to be closer to settlements than randomly generated points. They also were observed farther from primary roads than from secondary roads. This is in accordance with other studies revealing that these nocturnal birds avoid noisy roads. We briefly discuss why conserving range edge populations is important, and how time and effort optimised species conservation measures should accompany landscape protection at the political level.
The bioacoustic analyses of animal sounds result in an enormous amount of digitized acoustic data, and we need effective automatic processing to extract the information content of the recordings. Our research focuses on the song of Collared Flycatcher (Ficedula albicollis) and we are interested in the evolution of acoustic signals. During the last 20 years, we obtained hundreds of hours of recordings of bird songs collected in natural environment, and there is a permanent need for the automatic process of recordings. In this study, we chose an open-source, deep-learning image detection system to (1) find the species-specific songs of the Collared Flycatcher on the recordings and (2) to detect the small, discrete elements so-called syllables within the song. For these tasks, we first transformed the acoustic data into spectrogram images, then we trained two deep-learning models separately on our manually segmented database. The resulted models detect the songs with an intersection of union higher than 0.8 and the syllables higher than 0.7. This technique anticipates an order of magnitude less human effort in the acoustic processing than the manual method used before. Thanks to the new technique, we are able to address new biological questions that need large amount of acoustic data.
The haematocrit rate of the blood shows the individual physiological state. As the haematocrit grows, the higher erythrocyte number results in more efficient oxygen uptake capacity which can lead to better performance and probably a better survival rate of an individual. Hence we assume that the high value of haematocrit reflects good health state. Altogether 308 blood samples were collected from a wild population of Collared Flycatchers (Ficedula albicollis) in two breeding stages during a period of 2008-2010. We tried to elucidate the relationship between condition and haematocrit level of an individual and studied the haematocrit changes of an individual between years. The haematocrit values differed between years. Females had higher haematocrit values than males in 2010 but not in 2009. At courtship the haematocrit level of males was higher, than during nestling care. The different environmental effects and energy demands of the individuals may be the driving force behind the observed changes in haematocrit level. Analysing the changes between two years, there was a positive correlation between changes in condition index and haematocrit of individuals. The haematocrit values of an individual were repeatable between years. This finding suggests that haematocrit can be informative about the individual’s general health state.
In birds, individuals may show different behavioural and physiological responses when handling, and such variation may be related to individual differences in antipredator strategies. We performed a pilot study in both breeding and wintering populations of the Great Tit (Parus major), and we characterised three typical behavioural traits during a standard ringing procedure in captured birds. We assessed between- individual variations in breath rate, pecking rate and the number of distress calls displayed in response to handling, and also calculated the within-individual variation of these traits by repeated behavioural measurements. We found that these behaviours were consistently displayed within individuals (with repeatability varying between 0.44 and 0.82), and there was also some modest correlation between them (e.g. breath rate covaried with the number of distress calls). Furthermore, using multivariate linear models assessing a role of some potential predictors we found that a considerable amount of between-individual variation can be explained by sex and age differences and also by variation in body condition. However, the magnitude and direction of these relationships was inconsistent across seasons. Our results are in line with previous findings that several consistent behavioural traits measured during human handling could reflect individual specific antipredator strategy, but some confounding effects cannot be ruled out. Hence, our preliminary results require careful interpretation, and further studies are needed to assess the exact magnitude by which different behavioural traits are inter-related