Equivocal knowledge of the phase-specific drivers of natal dispersal remains a major deficit in understanding causes and consequences of dispersal and thus, spatial dynamics within and between ...populations. We performed a field experiment combining partial cross-fostering of nestlings and nestling food supplementation in little owls (Athene noctua). This approach disentangled the effect of nestling origin from the effect of the rearing environment on dispersal behaviour, while simultaneously investigating the effect of food availability in the rearing environment. We radio-tracked fledglings to quantify the timing of pre-emigration forays and emigration, foray and transfer duration, and the dispersal distances. Dispersal characteristics of the pre-emigration phase were affected by the rearing environment rather than by the origin of nestlings. In food-poor habitats, supplemented individuals emigrated later than unsupplemented individuals. By contrast, transfer duration and distance were influenced by the birds' origin rather than by their rearing environment. We found no correlation between timing of emigration and transfer duration or distance. We conclude that food supply to the nestlings and other characteristics of the rearing environment modulate the timing of emigration, while innate traits associated with the nestling origin affect the transfer phases after emigration. The dispersal behaviours of juveniles prior and after emigration, therefore, were related to different determinants, and are suggested to form different life-history traits.
Telomeres are non-coding DNA sequences located at the end of linear chromosomes, protecting genome integrity. In numerous taxa, telomeres shorten with age and telomere length (TL) is positively ...correlated with longevity. Moreover, TL is also affected by environmental stressors and/or resource-demanding situations particularly during early-life. Thus, TL has been used as a physiological marker of individual quality and also as an indicator of population trend in conservation physiology. In this study, we investigated the effects of hatching rank, year of birth (2014 to 2017), sex and nest environment on TL of 137 Little Owls nestlings (Athene noctua). Little Owls' populations in Europe showed a marked declined in the end of the 20th century. Nowadays, in the studied Alsatian population, the population is increasing. In this study, our results indicated that telomeres are longer in females and, independently of sex, in nestlings with the highest body condition. There was also a negative effect of hatching rank but only for last-hatched nestlings in large clutches of 5 nestlings. We did not find any effect of the environmental covariates on nestlings' TL. Finally, we found that nestlings' TL were shorter the last year of the study, while nestlings' body condition stayed unchanged over the same period. This result is intriguing given the local positive population dynamics and is further discussed in the context of physiological conservation. Future studies should investigate the link between reduced TL and survival prospects in this species.
There is scanty data about the comparative morphological features between the pecten oculi of two carnivorous birds with different visual active clock hours: the diurnal common kestrel and the ...nocturnal little owl. This study illustrated the comparative gross, scanning electron microscopy, and histological characteristics between pecten oculi of kestrel and little owl. This study first attempts to describe the scanning electron microscopy-energy dispersive x-ray (SEM-EDX) elemental analysis at the parts (apex, middle, and base) of the pecten oculi of these two birds. The present study results observed the same position, origin, directions, parts, convoluted outer pleat surfaces, and SEM-EDX elemental analysis, but there were some minor variations due to the different visual active clock hours. These minor variations were summarized in the following points: pleat number (21-23 in the kestrel and 10-11 in the owl), shape (fan rhomboid in the kestrel and accordion in the owl), inter-pleat spaces (wider in the kestrel than in the owl), pigmentations (highly black pigmented in the owl than in the kestrel), hyalocyte cell aggregations (highest in the middle and dwindling at the apex and base in the kestrel, while highest in the middle and base and dwindling at the apex in the owl), and SEM-EDX elemental analysis percentage. SEM/EDX elemental analysis confirmed the presence of oxygen (the highest one), carbon, nitrogen (the second one), nitrogen (the third one), and aluminum (the lowest one) in varying percentages within the pecten oculi; these findings contribute to our understanding of its structural, adaptations with different visual active clock hours, and functional characteristics. RESEARCH HIGHLIGHTS: This study compared the pecten oculi of two carnivorous birds with different visual active clock hours: the diurnal common kestrel and the nocturnal little owl. Anatomically, the characteristic features were similar in both the birds, but some minor variations were observed adapted to their visual active clock hours. The pecten oculi of both birds were analyzed using SEM-EDX for elemental analysis, and it revealed that oxygen was the highest elemental concentration, followed by carbon and nitrogen. Aluminum concentrations were small as per SEM-EDX analysis. The study suggested that the pecten oculi of these birds are related to their active visual clocks and adaptive nutritional mechanisms.
To combat the threat of predation, prey species have developed a variety of ways to recognize and respond appropriately to novel predators. While there is evidence that predator recognition does not ...require learning in certain species, learning appears to play an important role for other species. In systems where learning is important, it is less clear whether predator identification requires prior experience with specific predators or, whether general experience with predators provides sufficient tools for identifying similar species of novel predators. Here we test whether wild-living adult birds recognize a dangerous predator that occurs in only part of their geographical range. We presented taxidermy mounts of little owls, Athene noctua, and sparrowhawks, Accipiter nisus, to blue tits, Cyanistes caeruleus, and great tits, Parus major. All populations of both tit species co-occur with sparrowhawks, but populations differ in their prior experience with little owls. We found that tits that overlap geographically with little owls responded to little owls using the same intensity of mobbing behaviour exhibited toward sparrowhawks. In populations with no historical contact with little owls, however, both blue and great tits treated little owls as a lower threat than sparrowhawks. These results suggest that blue tits and great tits do not generalize ‘predatory features’ to novel predators and instead need prior experience with specific predators before they assign the correct level of threat.
•We tested if tits generalize predator features to identify novel predators as threats.•We presented two predators: one known to all tits and one unknown to some populations.•Experienced tits mobbed both predators (little owl and sparrowhawk) equally.•Naïve tits responded less to novel (little owl) than known (sparrowhawk) predators.•Tits appear to need prior experience to ‘recognize’ a novel species as a predator.
The Little owl Athene noctua (Scopoli 1769) is believed to be widespread in Bulgaria but its actual distribution and ecology are insufficiently studied. Historical records and unpublished information ...on its abiotic requirements, habitat preferences, breeding biology and distribution were analyzed to generate an Ecological Niche Model and documented that A. noctua is found across 90.8% of Bulgaria. We also estimated its potential distribution and ecological requirements within part of its range using Maxent. The Environmental Niche Model has a high degree of predictability. The climate changes are affecting the distribution. Our results revealed that the vertical distribution of the species expands by 100 m a.s.l. In Bulgaria, the main factors which determine the status of the population are elevation, type of land use, human population density and demographic structure which seem to account for most of the variation in suitable climatic conditions, and climatic factors – Annual Mean Temperature and Mean, Driest Quarter. Threats to the Little owl in Bulgaria include habitat loss, destruction of breeding sites, vehicle collisions, poisoning, predation, and persecution due to negative stereotypes or beliefs. Bulgaria, with a high number of breeding pairs as compared to elsewhere in Europe has an opportunity and obligation to preserve the species. The results of this study will help inform conservation decisions and efforts to maintain Little owl populations in Bulgaria.
The digestive tract of the little owl, Athene noctua (Strigiformes: Strigidae), is described in two different seasons. The digestive tract of this bird follows the basic model for that of a predatory ...bird. The cervical esophagus is not expanded to form a crop. The internal surface of the esophagus forms numerous longitudinal folds provided with numerous mucous glands. These longitudinal folds increase in number and vary in depth posteriorly. The folds of the proventriculus are composed of simple branched tubular glands. The ventriculus is lined by a thin layer of koilin. The number of goblet cells gradually increases from the duodenum to the rectum, and the lymphatic tissue diffuses within the lamina propria. The esophageal glands secrete acid mucopolysaccharides, while the gastric glands of the stomach, the goblet cells, and crypts of Lieberkühn secrete acid mucopolysaccharides. Proteins were observed in the different histological structures of the digestive tract. Morphometric and histometric studies showed differences between summer and winter in the esophagus and glandular stomach (especially in winter), but no seasonal differences were seen in the muscular stomach, or small and large intestines.
Knowing people are willing to protect wildlife when they feel connected with nature, we used owls as a case study to review owl symbolism in Greek history (2900 BC − 2000 AD). For five millennia, ...Greek civilization thrived and used owls as a dominant symbol in major cultural expressions. Consequently, a broad spectrum of social beliefs evolved towards owls. Until 1500 BC, they were mainly used as decorative attributes. During the Mycenaean era, though, owls began to be worshipped as eerie creatures in funeral rituals, inducing fear and respect. When Greek civilization peaked during the Archaic, Classical and Hellenistic periods, an important shift is noticed in social perceptions. Owls are transformed into major symbols of wisdom, power, justice and divinity, connected to the goddess Athena and the city of Athens. Their significance faded in the subsequent Roman period and was absent throughout the Byzantine era, for 1500 years. When owls reappeared after 1800 AD in cultural aspects of modern Greece, society again considered them fearsome creatures. We finalize our historical review with a recent survey in Greece, capturing up-to-date trends. Our survey indicates that today: (i) owls are mostly considered beneficial and deserving of protection, but part of the population still perceives owls as bad omens, powerful and scary; (ii) elementary concepts of raptors’ importance in ecosystems are still unknown to many; (iii) a small but impactful percentage still deliberately kill house-nesting owls, outlining the need to educate and provide nest-boxes as a relocation solution. By performing a thorough review of historical perceptions toward owls, important insights are offered on how to positively connect people with their wildlife and cultural heritage. We claim that people who understand how nature was related to their country in the past are inspired and more inclined to protect it.
Birds show huge variation in color displays evolved for communication. However, among colored phenotypic traits, eyes remain largely overlooked, with only a few studies suggesting a potential ...signaling function or a role in mate recognition and crypsis. Iris color is a remarkably striking feature in the wholly cryptic pattern of many owls, and may potentially play a signaling function, a possibility so far neglected. Here, we studied variation and potential signaling of iris yellowness as an indicator of quality in parent-offspring communication and other social contexts in the Little Owl (Athene noctua) and Eurasian Scops-Owl (Otus scops). Yellowness did not differ between the sexes; however, adults of the two species had more intensely yellow irises than owlets. Most of variation in iris yellowness of owlets occurred between rather than within nests and seemed to be linked to parental qualities of Little Owls, but was unrelated to condition among Eurasian Scops-Owl owlets. In adults, however, we found that iris yellowness of females was positively associated with nest success (an index of female fitness) in Little Owls, but not in Eurasian Scops-Owls. This study suggests that iris color variation is unlikely to play a role in parent-offspring communication for these two owl species, but that iris yellowness of female Little Owls may potentially play a signaling role in social contexts, a possibility that should be studied in the future.
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