Asio Otus Research Articles

Morphologic and Genetic Analysis of Synhimantus (Synhimantus) laticeps from a Long-Eared Owl (Asio otus).

The long-eared owl (Asio otus) is a medium-sized owl species that is well-distributed in almost all of the territories in Portugal. Nematodes were found in the oral cavity of a long-eared owl (A. otus) admitted to CRASSA (Wildlife Rehabilitation Centre of Santo André). During a physical exam and stabilization of the bird, five nematodes were collected. The worms were examined and measured under light microscopy, and photos were taken. After a morphological analysis was conducted, all the nematodes (five females) were identified as Synhimantus (Synhimantus) laticeps. Two specimens were subjected to molecular analysis, which confirmed the result. This study provides a combined morphological and genetic approach to S. laticeps. To the authors' best knowledge, this is the first report including genetic sequencing of S. laticeps in a long-eared owl (A. otus) from Portugal.

Long Eared Owls (Asio otus Linnaeus, 1758) as Field-Assistants in an Integrative Taxonomy Survey of a Peculiar Microtus savii (Rodentia, Cricetidae) Population

Voles from the Genus Microtus are rodents with a subterranean lifestyle. Central Italy is populated by two species of the Genus, the North-Western Microtus savii and the South-Eastern endemic Microtus brachycercus. Although morphometric features able to help distinguish M. savii from M. brachycercus are lacking, a peculiar morphology of the anterior end of the first lower molar is typical, but not exclusive, of M. brachycercus. Since some skulls with a compatible dental morphology were collected from Long-eared owl pellets in Umbria (Central Italy), a genetic assessment was deemed necessary to verify the possible presence of M. brachycercus outside of its known distribution range. Hemimandibles were isolated and used for both genetic and morphometric dental analyses. Despite the fact that this could suggest the presence of a M. brachycercus population, genetic analyses confirmed the species attribution to the M. savii complex, showing peculiar genetic polymorphisms that can either be due to the wide sampling area, represented by the owls’ hunting grounds, or to the recent evolutive history of the analysed population. This study, once again, underlines the importance of integrative taxonomy, suggesting the key role of predators as field-assistants to minimize the impact of sampling campaign on natural populations.

Predation of the Cuban Treefrog (Osteopilus sepentrionalis) and three nonnative lizard species by Eastern Screech-Owls (Megascops asio) in Manatee County, Florida, USA

Predation of the Cuban Treefrog (Osteopilus sepentrionalis) and three nonnative lizard species by Eastern Screech-Owls (Megascops asio) in Manatee County, Florida, USA

Muscle architecture of the hindlimb of Tyto furcata (Aves Strigiformes): Highlights in owl morphology.

The American barn owl is a nocturnal bird of prey in which hind limb movements are a key factor in obtaining food; however, the architectural properties of its hind limb muscles have not been studied. This study sought to identify functional trends in the Tyto furcata hindlimb muscles by studying muscular architecture. The architectural parameters of the selected hip, knee, ankle, and digit muscles were studied in three specimens of the Tyto furcata and joint muscular proportions with an additional dataset were calculated. Previously published information on Asio otus was used for comparison. The flexor muscles of the digits had the highest muscle mass. Regarding architectural parameters, the main flexor of the digits (flexor digitorum longus) and the muscles that extend the knee and ankle joints (femorotibialis and gastrocnemius) showed a high physiological cross-sectional area (PCSA) and short fibers, allowing powerful digit flexion and knee and ankle extension. These mentioned features are in accordance with hunting behavior, in which prey capture is not only closely linked to the flexion of the digits but also to the movements of the ankle. During hunting, the distal hind limb is flexed and then fully extended at the moment of contact with the prey, whereas the digits are close to grasping the prey. The hip muscles showed a predominance of extensors over flexors, which were more massive, with parallel fibers and without tendons or short fibers. These features lead to a higher capacity to generate velocity to the detriment of forces, as indicated by the high values of the architectural index, their relatively low PCSA, and short or intermediate fiber length, which enhance the control of the joint positions and muscle length. Compared to Asio otus, Tyto furcata showed longer fibers; however, the relationship between fiber length and PCSA was similar for both species.

HABITAT STRUCTURE AND HETEROGENEITY DETERMINE A SUCCESSFUL BREEDING PROBABILITY OF THE LONG-EARED OWL (<i>ASIO OTUS</i>, STRIGIDAE, STRIGIFORMES)

In 2001 to 2020, for each Long-eared owl nest in the Crane Homeland Nature Reserve territory with an area of 48 km2, the following microhabitat parameters were determined using standard field methods: the nest type built by different bird species, the presence of a nest roof, the nesting tree species, and the nest height above the ground. In most cases, for nesting the Long-eared owl reused magpie nests (Pica pica) (77%), and half of the nests were found on willow trees (family Salicaceae) (50%). The nest height above the ground varied from 1.5 to 22 m. Vegetation on the nesting area with a radius of 500 m was determined using the “Semi-Automatic Classification Plugin” automatic vegetation classifier of QGIS software. Five habitat types were so classified: forests, shrubs, meadows, arable land, and satellite image mistakes. Village areas were allocated separately. The average shares of the largest habitat types for over 20 years on the nesting sites included meadows (51.1%) and shrubs (16%). From 2001 to 2020, a habitat change in the breeding area was observed: forest and shrub areas decreased, while the meadow, village and arable land areas increased. An analysis of the effect of habitat types on the nesting success was evaluated by means of the “gbm” and “dismo” modules in the R program using the Boosted Tree classifier algorithm. The presence of such habitat types in the nesting area as villages (24.2%), shrubs (19.3%), meadows (11.8%), and habitat heterogeneity (11.6%) most strongly affected the probability of owl successful nesting. That owls tend to use anthropogenic and agricultural territories is associated with the diversity, easy foraging and more effective protection from predators during the breeding season.

Temperament traits and glucocorticoid metabolites in tropical screech owl (Megascops choliba)

Animals constantly respond to stimuli from their surroundings, showing individual behavioral and endocrine differences upon perceived challenging and/or threatening stimuli. The temperament of 13 captive tropical screech owls (Megascops choliba) was defined by performing three challenge tests (novel space, taxidermist predator and trapping) to identify inter-individual differences and their possible relationship with the production of glucocorticoid metabolites (GCM). Feces samples of each bird were taken pre-and-post predator challenge to quantify GCM concentration by means of enzymatic immunoassay (EIA). The intensity of 13 adjectives selected to describe the owls' temperament was determined by three judges during behavioral testing. Only 3 adjectives (passive, vulnerable, and attentive) that showed strong inter-test and intra-individual correlation coefficients were considered. These adjectives were later grouped in a single dimension named “shyness”, enabling establishment of individual scores. The temperament of the owls showed correlation to post-predator challenge GCM levels (ρ = 0.79; p < 0.001). However, no significant differences were found in GCM levels before and after predator challenge. Our results both confirm that nocturnal behavior raptorial birds show positive relation between shy temper and adrenal response, and offer the non-invasive herein implemented methods for establishment of new hypotheses that will assess welfare of species kept under human care.

Fragment size and isolation is associated with the presence of two forest owls in a fragmented environment in Central Argentina

In the semiarid Espinal ecoregion from central Argentina, deforestation has produced a large retraction of native forests and an accelerated process of fragmentation. Here we assess the effects of forest fragmentation within an agricultural matrix on the presence of two forest owls: the Ferruginous pygmy-owl (Glaucidium brasilianum) and the Tropical screech-owl (Megascops choliba). We searched for the species in fragments of different sizes and at different distances from large-continuous forest tracts. We detected one or both species at 43% of the 84 surveyed points. The Tropical Screech Owl was detected at 13 points, the Ferruginous Pygmy Owl was detected at 14 points, and both species were detected at 9 points. For the Ferruginous pygmy-owl, the area of the fragment where the point registration was made was the only variable associated with its presence. The model for Tropical Screech-Owl indicated that the variable that best explained its presence was the distance to the nearest forest fragment. For both species the association was negative. Our results suggest that despite being generalist and widely distributed species, both owls were negatively affected by the fragmentation process, highlighting the importance of the preservation of forest remnants and their connectivity.

A Kist o’ Whistles

A Kist o’ Whistles

First description of Long-eared Owl (Asio otus) migration using GPS telemetry

El uso de GPS ha revolucionado el estudio de la migración de aves al revelar detalles de rutas migratorias, tiempos de migración y conectividad que no hubieran podido ser descubiertos por otros métodos. Hasta ahora los estudios usando migraciones de rapaces habían sido limitados a especies cuyo tamaño, comportamiento y hábitat permitían el uso de transmisores GPS recargables solarmente. Probamos el uso de transmisores GPS con batería programados en plazos fijos muy conservadores para seguir la migración de búho Asio otus, un búho de bosque de tamaño medio. Varios búhos (n = 5) fueron equipados con transmisores GPS en su zona de hibernación en New Jersey y monitoreados en los meses siguientes. La mortalidad de los búhos marcado con GPS fue alta, lo que es consistente con reportes anteriores en especies relacionadas. Los búhos sobrevivientes migraron hacia el norte más allá del límite de su rango de distribución conocido en Norte América, pasando el verano en bosques de abeto/musgo y de abeto/líquenes (taiga) a los 50–55°N en regiones muy poco desarrolladas al norte de Quebec. Este estudio piloto demuestra que transmisores de batería de poco peso programados en plazos fijos muy conservadores pueden revelar movimientos a larga distancia en aves de tamaño medio (por ejemplo, <300 g). Este enfoque puede ayudar a llenar vacíos de información para aves cuyo hábitat y comportamiento están poco estudiados debido al mal desempeño de los transmisores solares, particularmente especies de las que no se tienen detalles de movimientos a larga distancia. Palabras clave: Argos, conectividad, rastreo, satélite, transmisor.

Raptors benefit from biosolids applications on rangelands

Globally, many grasslands have been lost or degraded via settlement, conversion to agriculture, or use as pasture. These losses have damaged the ability of migratory and nomadic birds of prey to find suitable breeding territories. Habitat restoration of degraded grasslands via the application of biosolids, the treated and sterilized remains from sewage treatment plants, improves soil water retention and nutrient profile, leading to substantial gains in plant growth and nutritive quality. Gains to wild and domestic herbivores have been documented, but impacts to predators are poorly known. Here, we test the hypothesis that biosolids-applied pastures are attractive to and support migratory and nomadic avian predators in central British Columbia, Canada. We obtained habitat records from sightings and prey remains from pellets for three vole-specialists, Long-eared Owls (<em>Asio otus</em>), Short-eared Owls (<em>A. flammeus</em>), and Northern Harriers (<em>Circus hudsonius</em>), as well as the generalist American Kestrels (<em>Falco sparverius</em>). During 5 years, the three diurnal species preferentially used biosolids-applied pastures, and kestrels and owls nested in biosolids-applied pastures or in forest patches adjacent to these pastures. Grasshoppers were more abundant on pastures with biosolids and were common prey for American Kestrels. The owls and harriers preferentially consumed voles, although Short-eared Owls consumed deermice (<em>Peromyscus maniculatus</em>) as a major additional food source during years when voles were scarce. Long-eared Owls were documented only in the 2 years when voles were common. Collectively, these results suggest that biosolids-amended landscapes may attract raptors, even when vole densities are low.

The diet of the White-Tailed Sea Eagle in South Moravia, Czech Republic

White-Tailed Sea Eagle (Haliaeetus albicilla) re-settled the area of South Moravia (the south-eastern region of Czech Republic) in 1984. It became a regular breeding species in 2004 and since then, the population rose up to present ca 30 breeding pairs. Its diet was studied by identification of food remains on nests, mainly during ringing of nestlings (i.e. usually late April / first half of May). 605 food items were identified during 97 nest checks within the period of 1999–2023. Fish composed 47%, birds 28% and mammals 25% of the identified items. The most numerous taxa were European Hare (Lepus europaeus) – 151 inds, Carp (Cyprinus carpio) – 87, Silver Crucian Carp (Carassius auratus) – 61, Common Pheasant (Phasianus colchicus) – 54, Northern Pike (Esox lucius) – 50, and Eurasian Coot (Fulica atra) – 33. The number of food items per nest varied between 1 and 28. The interesting findings included e.g. Common Shelduck (Tadorna tadorna), Stock Dove (Columba oenas), Tawny Owl (Strix aluco), or Long-Eared Owl (Asio otus).

Мониторинг солнечного орла в национальном парке «Хвалынский» (Саратовская область, Россия)

Мониторинг солнечного орла в национальном парке «Хвалынский» (Саратовская область, Россия)

Vércse költőláda kihelyezések tapasztalatai a Mosoni-Síkon

The Mosoni Plain Natura 2000 site is one of the most western nesting sites of the strictly protected Red-footed Falcon (Falco vespertinus) in Hungary, and the Common Kestrel (Falco tinnunculus) is the most common nesting bird of prey in the area. The breeding success of these two species, which do not build nests, can be greatly enhanced by the installation of good quality and properly placed artificial nests boxes. Monitoring of the artificial nest-boxes was previously not regularly and entirely conducted. However, from 2019 onwards, the now nearly 100 active nest-boxes are being regularly monitored, recording nest occupancy, clutch size and fledging data for Red-footed falcon, Common Kestrel, as well as for the Long-eared owl. The presenent paper summarises the nesting records of these three species on artificial breeding sites on the Moson Plain. During the period 2019–2023, we observed a total of 12 Red-footed Falcon breedings, 7 of which were in artificial nestboxes. On average, 3.0 chicks were successfully fledged from the boxes. Regarding Common Kestrel, a total of 121 breedings were recorded in nesting boxes, of which more than 80% were successful. On average 3.84 chicks fledged per nest box. During the 5 years of the study, a total of 14 pairs of Long-eared Owl breeding were associated with artificial nest-boxes, of which 10 proved successful. A total of 35 chicks fledged successfully.

The Witch in Flight

The Witch in Flight

Glucocorticoid metabolites in an ex situ nocturnal bird, the tropical screech owl Megascops choliba: effects of sex, activity period and inter-individual variation

Glucocorticoids mediate physiological processes to obtain energy, presenting daily variation in basal levels that may be related to behavioural activity pattern. Identification of plasticity in the secretion of these hormones is essential to understand their effects on physiology and behaviour of wild birds and, therefore, their success in their natural or artificial environment. Serial endocrine evaluations are facilitated by implementing non-invasive methodologies that minimize possible effects of manipulation on the animal's physiological variables. However, non-invasive endocrine-behavioural studies in nocturnal birds, such as owls, are immature. The present work aimed to validate an enzyme immunoassay (EIA) to quantify glucocorticoid metabolites (MGC) in Megascops choliba as well as to evaluate differences in their production at the individual, sexual or daily level. We recorded the behaviour of nine owls during three continuous days to establish activity budget under captive conditions and aiming to correlate with daily MGC variation. The EIA proved to be effective in analytical assays and in pharmacological testing with synthetic ACTH, validating this immunoassay for the species. Additionally, individual differences in MGC production were confirmed in relation to the time of day, especially at 1700 and 2100, but not in relation to sex. During night hours, the owls showed greater behavioural activity, positively related to MGC values. Higher MGC concentrations were significantly related to greater expressions of active behaviours, such as maintenance, while lower MGC concentrations were recorded during moments of higher alertness and resting. The results presented show daily MGC variation to be inversed in this nocturnal species. Our findings can aid future theoretical studies of daily rhythm and evaluations of challenging and/or disturbing situations that result in changes in behaviour or hormonal cascades of these changes in ex situ populations of owls.

Optimization of the Bionic Wing Shape of Tidal Turbines Using Multi-Island Genetic Algorithm

In this study, we improved the energy acquisition efficiency of tidal turbines with bionic airfoils by optimizing the seagull, long-eared owl, sparrowhawk, and two-dimensional airfoils, thereby obtaining a better lift–drag ratio. We used Isight software to integrate the Integrated Computer Engineering and Manufacturing (ICEM) software and used Fluent simulation software, batch operation file, and multi-island genetic algorithm to maximize the lift–drag ratio as the objective function for optimizing the original airfoil. The optimized upper airfoil profile was distributed upward from the starter wing, and the thickness of the upper wing was the greatest. Meanwhile, the lower airfoil profile was thinner and more curved. The thickness of the three airfoils was distributed backward from the front of the wing, with the maximum thickness at the front, and the maximum camber was distributed backward from the front. The three optimized wings exhibited a maximum lift–drag ratio at an angle of attack of approximately 5°, with the sparrowhawk wing having a maximum lift–drag ratio of 80.87 at an angle of attack of 6°, the seagull wing having a maximum lift–drag ratio of 76.82 at an angle of attack of 4°, and the long-eared owl wing having a maximum lift–drag ratio of 68.43 at an angle of attack of 5°.

Structure and heterogeneity of habitat determine diet of predators despite prey abundance: Similar response in Long-eared, Short-eared Owls and Common Kestrels

According to one of the theses of optimal foraging theory, main prey species abundance in the hunting area is the main factor determining the diet and habitat choices of birds of prey. However other factors can also be important. The habitat structure influences the predators' diets as well. In this study we examined the influence of habitat structure on diet compositions of three species of birds: Long-eared Owl (Asio otus), Short-eared Owl (A. flammeus) and Common Kestrel (Falco tinnunculus). The study was carried out from 2007 to 2019 in a 48 ​km2 area of the Crane's Homeland Reserve, Moscow Region, Russia. The habitat structures of model species' hunting territories (ratio of different types of landscape elements) were classified in module “Semi-Automatic Classification Plugin” based on the QGIS. A boosted regression tree analysis identified that the share of the main prey species in the diet is primarily determined by the landscape structure of hunting territories. The largest share of Common Vole (Microtus arvalis) in birds' diet was determined by the shrubs area (15% of hunting area), the meadow area (75%), the habitat heterogeneity (70%) and the arable land area (5%). The same predictors determined the largest share of Root Vole (Microtus oeconomus): the shrubs area 25%, the meadow area 70%, and the arable land area 3%. The annual mean abundance of prey species did not determine their importance in the diet of birds of prey. Thus, the main prey abundance in the hunting area is not a determining factor for the formation of diet composition of birds of prey.

Owl-like plaques of the Copper Age and the involvement of children

In the Copper Age, slate engraved plaques were produced massively in the southwestern corner of the Iberian Peninsula. Researchers have speculated about the function of these palm-sized stone objects for more than a century, although most have favored the idea that they represented goddesses, and served ritual purposes. The plaques are engraved with different designs of varying complexity. In some of them, the ones sporting two large frontal eyes, we clearly see owls modelled after two species present in the area: the little owl (Athene noctua), and the long-eared owl (Asio otus). These two species, living in semi-open habitats, were possibly the most abundant owls around the human settlements and surrounding cultivated fields of the Chalcolithic period. People must have been aware of the owl presence and possibly interacted with them. Why owls but no other animals have been the models may relate to the fact they are the most anthropomorphic of all animals, with large frontally-placed eyes in their enormous heads. In the iconography, owls are systematically represented, even today, with their two eyes staring at the observer, as opposed to the lateral view used for any other animal. Additionally, slate is one of the commonest surface rocks in southwestern Iberia, and it provides a blank canvas for engraving lines using pointed tools made of flint, quartz or copper. The way slates exfoliate makes easy to craft owl-looking plaques. To silhouette animals other than owls in a recognizable way would request extra carving abilities and specific tools. Plaque manufacture and design were simple and did not demand high skills nor intensive labor as demonstrated in replication experiments. Owl engravings could have been executed by youngsters, as they resemble owls painted today by elementary school students. This also suggests that schematic drawings are universal and timeless. We propose that the owl-like slate plaques are the remains of a set of objects used in both playful activities and in ritual ceremonies. The actual engraving of the plaques may have been part of the game. Owlish slate plaques were often perforated twice at the top. We interpret this as insertion points for actual bird feathers added to the plaques, right at the place where tufts emerge in live owls. The frontier among play and ritual is diffuse in liminal societies and there is no contradiction in playing with animal-like toys and, at some point, using them as offerings as part of community rituals related, for instance, to the colossal megalithic tombs so characteristic of the Copper Age.

Seasonal Migrations and Population Dynamics of the Long-Eared Owl (Asio otus, Strigiformes, Strigidae) Based on 60-Year-Long Trapping and Ringing in the Eastern Baltic

Seasonal Migrations and Population Dynamics of the Long-Eared Owl (Asio otus, Strigiformes, Strigidae) Based on 60-Year-Long Trapping and Ringing in the Eastern Baltic

Small mammal community in a Mediterranean target area of Sicily by the data from the long-eared owl pellets

Small mammal community in a Mediterranean target area of Sicily by the data from the long-eared owl pellets