Search

The little owl Athene noctua is a widespread species in Europe. This mainly sedentary owl experienced reduction in population sizes in some areas due to habitat loss and modification of the landscape. To assess the genetic structure of the populations of western and central Europe, we analysed 333 specimens from 15 geographical areas at 13 microsatellite loci. Statistical analyses and Bayesian clustering procedures detected two major genetically distinct clusters, the first distributed from Portugal to the Czech Republic and the second from the Balkans to Italy. The second cluster was further split into three groups, located in Italy, Sardinia and the Balkans. These groups match four previously-described mtDNA haplogroups, and probably originated from the isolation of little owl populations in Sardinia and in three glacial refugia (Iberia, south Italy and Balkans) during the ice ages. High genetic admixture was recorded in central and northern Europe, probably as a consequence of the expansion from the refugia during interglacial. The main colonization route originated from the Iberian Peninsula towards central and northern Europe. Contact zones with colonization events from Italy and the Balkans were detected respectively in northern Italy and central Europe. Genetic indices show the existence of moderate levels of genetic variability throughout Europe, although evidence of recent evolutionary bottlenecks was found in some populations. Estimation of migration rates and approximate Bayesian computations highlighted the most likely phylogeographical scenario for the current distribution of little owl populations. [ABSTRACT FROM AUTHOR]

When a bird population is facing extinction, ecologically artificial conservation actions such as feeding and captive breeding may be considered as temporary efforts to rescue the population remains until environmental conditions for a self-sustaining population have been restored. Population viability analysis can be used to evaluate different management options for endangered bird populations. Here we use the program VORTEX to explore different management strategies using the Danish population of Little Owl (Athene noctua) as a model species. The Little Owl is declining in several countries, including Denmark, where lack of food during the breeding season has been identified as the main reason for the decline. Four scenarios were run, simulating 25 years of population dynamics: (1) "do nothing" scenario, (2) captive breeding scenario where individuals are supplemented to the population, (3) food supplementation or habitat improvement scenario and (4) scenario combining captive breeding and food supplementation/habitat improvements. In scenarios where no management actions were taken the population went extinct within 12 years. When supplementing individuals continuously the population remained extant but the population size remained small. Food supplementation/habitat improvements can restore the population, though there must be capacity to secure food/habitat for a minimum of 100 individuals to minimize genetic losses. By combining food supplementation and the release of captive bred individuals, the population has a chance of being restored and become independent of human aid. This study exemplifies how management scenarios can be used to guide managers to make informed decisions. [ABSTRACT FROM AUTHOR]

Newcastle disease is a contagious and often fatal disease, capable of affecting all species of birds. A velogenic Newcastle disease virus ( vNDV) outbreak occurred in an Israeli zoo, in which Little owls ( Athene noctua) and African penguins ( Spheniscus demersus) were found positive for presence of NDV. Some of them have died. The diagnostic process included: post-mortem examination, histopathology, real-time RT-PCR assay, virus isolation, serology, intracerebral pathogenicity index and phylogenetic analysis. A vNDV was diagnosed and found to be closely related to isolates from vNDV outbreaks that occurred in commercial poultry flocks during 2011. All isolates were classified as lineage 5d. [ABSTRACT FROM AUTHOR]

Several studies suggest that species' mortality rates are positively related with local population abundances. Because owls have shown both high road mortality rates and road avoidance behaviours, we hypothesize that road-kill likelihood is not always directly linked to their occurrence. In this study, we examined the relationship between the likelihood of species occurrence in the vicinity of major roads and the road-kill risk for barn owls T yto alba, tawny owls S trix aluco and little owls A thene noctua. Specifically, we address: (1) the role of road-related features on spatial patterns of species' occurrence and road kills; (2) the composition of road kills and their distribution throughout the year; (3) the relationship between species' occurrence likelihood and mortality risk. Our findings show that changes in movement patterns is probably the main behavioural mechanism that threatens owls in roaded landscapes. The high mortality risk of barn owls in autumn and winter seasons, after the peak of dispersal period, provides support for the hypotheses of expanding movements because of lack of food. However, mortality because of high occurrence likelihood seems to also explain tawny owls' response towards roads. The high occurrence likelihood of little owls combined with low mortality rate also suggests avoidance of road crossings. Although, it is clear that within species there is variation according to age- and territory-holding status, closely related species have different sensitivities to roads as a function of their varying food preferences. We believe that linking species distribution with mortality risk may be more effective in focus conservation efforts. Therefore, we suggest measures should be applied to reduce prey availability close to roads and in road verges. This is particularly important for barn owls, for which foraging in the vicinity of roads during the cold season is especially risky. [ABSTRACT FROM AUTHOR]

In birds, energy supply during growth is a major predictor of the fledglings' physical condition and survival prospects. Differential quantity and quality of fledglings produced under varying nestling food supplies are likely to affect the number of offspring that recruit into the breeding population. However, the underlying mechanisms and associated consequences are still poorly known. Using a partial cross-fostering and food supplementation experiment, we estimated the effect of variation in food supply during growth on nestling survival and fledgling phenotypic traits of Little Owls Athene noctua. Survival to fledging was much higher in food-supplemented nestlings (98.6%) than in control nestlings (82.4%). Furthermore, supplemented nestlings were on average 8.9 g heavier and were more likely to develop subcutaneous fat deposits (99.4 vs. 73.7% of treatment and control nestlings, respectively). Supplemented nestlings also had on average longer wings than control nestlings, but tarsi and culmen did not differ significantly. Furthermore, experimentally supplemented fledglings struggled more when handled and emerged sooner from tonic immobility than control fledglings. The irises of supplemented fledglings were less intensely coloured. The experimentally induced changes in nestling development probably affect individual performance beyond fledging. Nestlings from orchard-dominated habitats were larger than those from habitats dominated by arable land. As nestling food supply is largely determined by natural food availability, we conclude that habitat quality affects Little Owl productivity and offspring quality, and ultimately, population dynamics. [ABSTRACT FROM AUTHOR]

This study presents the concentration of mercury in feathers of 40 owls (five species) in five regions of Iran. Results showed that mercury concentration in Tawny owl's feathers (Strix aluco) were significantly higher than in the Little owl (Athena noctua), Eagle owl (Bub bubo), Long-eared owl (Asio otous) and Short-eared owl (Asio flammeus). Also, mercury concentrations in owl feathers collected from the north of Iran were significantly higher than others regions. Furthermore, mercury concentrations in owl feathers obtained in this study were higher than other regions in the world except for Sweden. This study demonstrates that mercury concentrations in Iranian owls, with the exception of the Tawny owl, are below toxic concentration (5 mg kg-1). In addition, location was a contributing factor in the mercury concentration in Iranian owl's feathers. [ABSTRACT FROM AUTHOR]

Pleistocene glaciations greatly affected the distribution of genetic diversity in animal populations. The Little Owl is widely distributed in temperate regions and could have survived the last glaciations in southern refugia. To describe the phylogeographical structure of European populations, we sequenced the mitochondrial cytochrome c oxidase I (COI) and control region (CR1) in 326 individuals sampled from 22 locations. Phylogenetic analyses of COI identified two deeply divergent clades: a western haplogroup distributed in western and northwestern Europe, and an eastern haplogroup distributed in southeastern Europe. Faster evolving CR1 sequences supported the divergence between these two main clades, and identified three subgroups within the eastern clade: Balkan, southern Italian and Sardinian. Divergence times estimated from COI with fossil calibrations indicate that the western and eastern haplogroups split 2.01–1.71 Mya. Slightly different times for splits were found using the standard 2% rate and 7.3% mtDNA neutral substitution rate. CR1 sequences dated the origin of endemic Sardinian haplotypes at 1.04–0.26 Mya and the split between southern Italian and Balkan haplogroups at 0.72–0.21 Mya, coincident with the onset of two Pleistocene glaciations. Admixture of mtDNA haplotypes was detected in northern Italy and in central Europe. These findings support a model of southern Mediterranean and Balkan refugia, with postglacial expansion and secondary contacts for Little Owl populations. Central and northern Europe was predominantly recolonized by Little Owls from Iberia, whereas expansion out of the Balkans was more limited. Northward expansion of the Italian haplogroup was probably prevented by the Alps, and the Sardinian haplotypes remained confined to the island. Results showed a clear genetic pattern differentiating putative subspecies. Genetic distances between haplogroups were comparable with those recorded between different avian species. [ABSTRACT FROM AUTHOR]

Chromatic signals of offspring quality have been shown to play a role in parent-offspring communication in diurnal birds, but are assumed to be useless in dim light conditions because colour-based discrimination probably requires more light. A major ecological and evolutionary conundrum in this scenario is why the nestlings of some nocturnal owls display colourful beaks. Here, we test the hypothesis that yellow bill coloration of owlets of the nocturnal little owl Athene noctua may function as a chromatic signal revealing to parents aspects of quality of their offspring. In a first step, we examined physical variation in bill coloration and its covariation with owlet quality. Secondly, we studied parental provisioning in relation to an experimental manipulation of bill coloration of owlets. Bills of owlets showed higher within-nest variation in yellow-red chroma than in brightness. Plasma carotenoid concentration and nestling immunological status were not associated with chromatic or achromatic features of the bill. Interestingly, however, heavier owlets displayed more yellow bills than lighter ones. The effect of bill coloration on parental favouritism changed with brood size. Parents holding large broods preferentially fed owlets with enhanced over reduced yellow bill coloration, whereas those with small broods did not significantly bias feeding in relation to owlet bill coloration. Our results, based on integration of objective spectrophotometric assessment of colour and experimental procedures, confirm that parent little owls use bill coloration to reveal information on owlet body mass to adjust their feeding strategies, thus highlighting the importance of considering potential chromatic signals for a full comprehension of parent-offspring communication processes in nocturnal bird species. [ABSTRACT FROM AUTHOR]

Roost site selection is a state-dependent process, affected by the individual's costs and benefits of roosting at a specific site in the available environment. Costs and benefits of different roost sites vary in relation to intrinsic factors and environmental conditions. Thus, the cost-benefit functions of roost sites are expected to differ between seasons and life-history stages, resulting in adjustments in roost site selection. Studying roost site selection throughout the year therefore provides information about year-round habitat requirements at different life-history stages. However, little is known about the roosting behaviour of birds. Here, the roost site selection of Little Owls Athene noctua was studied by repeated daytime location of 24 adult and 75 juvenile radiotagged individuals from July to November. Little Owls preferred sheltered roost sites such as tree cavities with multiple entrances. They increasingly used sheltered sites from summer to winter and preferentially used sheltered roost sites with low ambient temperatures. Juveniles used significantly less sheltered sites during dispersal than before and afterwards, and used less sheltered sites than adults within their home-range. The survival probability of birds roosting frequently at exposed sites was reduced. Roost site selection is probably driven by the two mechanisms of predator avoidance and thermoregulation, and the costs of natal dispersal may include increased predation threat and higher energy expenditure for thermoregulation. We suggest that adequate roost sites, such as multi-entrance tree cavities, are an important habitat requirement for Little Owls and that habitat quality can be affected by manipulating their availability. [ABSTRACT FROM AUTHOR]

The article provides information on a study investigation the factors affecting social interaction with mates and neighbors of the Little Owl birds in Northern Jutland, Denmark. It is stated that vocal signals is the owl's way of ensuring food supply, defending its territory and attracting mates. Factors considered in projecting the probability of an owl to call include the male's distance his mate and nest, the distance from the male's nest to the nearest neighboring nest with a territory-holding male.

Survival rate is an essential component of population dynamics; therefore, identification of variation in mortality rates and the factors that influence them might be of key importance in understanding why populations increase or decrease. In Denmark, the Little Owl Athene noctua, a species strongly associated with anthropogenically modified landscapes, is declining fast and may soon face extinction. The population decline is ultimately associated with reduced survival of independent offspring, but reduced survival rates of adults may possibly contribute to the observed decline. To explore the causes of current survival rates, we estimated age- and season-specific survival rates and causes of mortality in Danish Little Owls on the basis of ringed birds 1920-2002, radio tagged adult and juveniles 2005-2008 and nest surveys 2006-2008. We estimate that 32 % of all eggs fledge and survive to 2 weeks post hatching (age of ringing) and 47 % of the nestlings from ringing to fledging. Fifty-five percentage of the radio-tracked fledged young survived to dispersal, i.e. a total survival rate from egg to dispersal of 8 %. Analyses of combined ringing and radio tracking data showed a lower survival rate in the 1st year of life and a much lower rate in the first 3 months of life. Furthermore, the analyses indicated that survival was lower in the winter months for ringing data during 1920-2002 but not for radio-tagged owls during 2005-2008 that experienced the highest mortality rates during the breeding season. In radio-tagged adults and fledged juveniles, accidents in buildings and other human infrastructures were responsible for two-thirds of all fatalities. Anthropogenic habitats currently comprise the nesting and roosting habitats for the last Danish Little Owls. The accidental deaths associated with these might to some extent be considered as a contributing factor to the present negative population growth rate of this population. [ABSTRACT FROM AUTHOR]

Objective To determine the type, prevalence, and prognosis of ocular and periocular lesions in free-living little owls (LO) and scops owls (SO), injured by blunt trauma. Procedures Medical records from LO and SO with ocular or periocular lesions secondary to blunt trauma were reviewed. A complete ophthalmic examination was performed in all birds. Short protocol electroretinography (ERG) and ocular ultrasound were performed as dictated by the case. Results During the study period, a total of 158 LO and 99 SO with blunt trauma were admitted. Among these, 43 LO (27.8%) and 27 SO (27.3%) had ocular or periocular lesions. Bilateral injuries (72.1% LO and 81.5% SO) were more common than unilateral. Common findings in both species were: corneal erosions/superficial ulcers, anterior and posterior uveitis, cataracts, hyphema, posterior synechia, vitreal hemorrhage, and retinal detachment. Electroretinography was performed in 32 LO and eight SO, which had posterior segment lesions or opacity of the transparent media. Normal to nonrecordable b-wave amplitudes were observed. Follow-up was available in 13 LO and 11 SO. Among these, nine LO (14 eyes) and 10 SO (17 eyes) had resolution of the clinical signs following medical treatment. Conclusions Ocular lesions are common in LO and SO injured by blunt trauma. Electroretinography is a valuable diagnostic tool to assess the severity of retinal dysfunction secondary to blunt trauma and to determine the response to medical treatment. A complete ophthalmic examination is a determining factor in the early management of trauma in these species. [ABSTRACT FROM AUTHOR]

Athene vallgornerensis nov.sp. (Aves: Strigiformes: Strigidae) from the Early Pleistocene of the island of Mallorca (Balearic Islands, Western Mediterranean) is described. The material came from a fossil assemblage obtained in a collapsed gallery from Cova des Pas de Vallgornera (Llucmajor, south of Mallorca), the longest karstic system currently known in the Balearics. Associated remains include primitive representatives of the insular endemic fauna of Mallorca ( Myotragus, Hypnomys, Nesiotites), as well as fossils of bats, birds (among them, Tyto balearica), lizards and toads. Although only two bones of Athene have been obtained, its highly distinctive tarsometatarsus-short, highly robust and significantly small-differentiates it from the remaining extant and extinct Athene species from the Palaearctic, justifying its description as a new species. At least four insular species of Athene are now known from the Mediterranean area, and two groups can be identified according to the shape of their tarsometatarsi. [ABSTRACT FROM AUTHOR]

We assessed dietary exposure of the little owl Athene noctua to trace metal contamination in a Dutch Rhine River floodplain area. Diet composition was calculated per month for three habitat types, based on the population densities of six prey types (earthworms, ground beetles and four small mammal species) combined with the little owl’s functional response to these prey types. Exposure levels showed a strong positive relationship with the dietary fraction of earthworms, but also depended on the dietary fraction of common voles, with higher common vole fractions resulting in decreasing exposure levels. Spatio-temporal changes in the availability of earthworms and common voles in particular resulted in considerable variation in exposure, with peaks in exposure exceeding a tentative toxicity threshold. These findings imply that wildlife exposure assessments based on a predefined, average diet composition may considerably underestimate local or intermittent peaks in exposure. [Copyright &y& Elsevier]

The article focuses on a study about the niche separation of two sympatric owls in the desert of Northwestern China. In this study, the researchers compared the diets of Little Owls (Athene noctua) and Long-eared Owls (Asio otus) near the Minqin Desert Experimental Research Station. The study revealed the significant difference in their diets by frequency as well the difference in four dimensions. Based from the result of the study, it is concluded that the owls coexisted mainly by consuming prey of different size even if the roost sites of the two species were in close proximity.

The little owl ( Athene noctua) has declined significantly in many parts of Europe, including the Netherlands. To understand the demographic mechanisms underlying their decline, we analysed all available Dutch little owl ringing data. The data set spanned 35 years, and included more than 24,000 ringed owls, allowing detailed estimation of survival rates through multi-state capture-recapture modelling taking dispersal into account. We investigated geographical and temporal variation in age-specific survival rates and linked annual survival estimates to population growth rate in corresponding years, as well as to environmental covariates. The best model for estimating survival assumed time effects on both juvenile and adult survival rates, with average annual survival estimated at 0.258 (SE = 0.047) and 0.753 (SE = 0.019), respectively. Juvenile survival rates decreased with time whereas adult survival rates fluctuated regularly among years, low survival occurring about every 4 years. Years when the population declined were associated with low juvenile survival. More than 60% of the variation in juvenile survival was explained by the increase in road traffic intensity or in average temperature in spring, but these correlations rather reflect a gradual decrease in juvenile survival coinciding with long-term global change than direct causal effects. Surprisingly, vole dynamics did not explain the cyclic dynamics of adult survival rate. Instead, dry and cold years led to low adult survival rates. Low juvenile survival rates, that limit recruitment of first-year breeders, and the regular occurrence of years with poor adult survival, were the most important determinants of the population decline of the little owl. [ABSTRACT FROM AUTHOR]

The article describes a case that analyzes the dependence of occupancy rate and breeding success on the surrounding habitat involving 798 Little Owl (Athene noctua) nest boxes in central Germany. Focus was given on whether nest boxes were occupied for breeding or were unoccupied, and whether the location of nest boxes had an effect on the Little Owls' reproductive rates. It was suggested that nest boxes became more efficient if located in areas where occupancy is more likely to occur and in locations that could enhance successful breeding.

The article presents the ninth report by the Rare Breeding Birds Panel (RBBP) in Great Britain which summarizes the non-native bird species in the region from 2006 to 2008. It offers details of observations involving the 24 rare species including the Black Swan Cygnus atratus, the Barnacle Goose Branta leucopsis, and the Little Owl Athene noctua. It provides estimates of the breeding population of other species such as the Red-legged Partridge Alectoris rufa, Common Pheasant Phasianus colchicus, and the Mandarin Duck Aix galericulata.

Many farmland bird species have declined markedly in Europe in recent decades because of changes in agricultural practice. The specific causes vary and are poorly known for many species. The Little Owl, which feeds extensively on large invertebrates and is strongly associated with the agricultural landscape, has declined over most of northwestern Europe, including Denmark. We investigated the likely reasons for the population decline in Denmark by identifying patterns of local extinction (scale, 5 × 5 km2) and estimating demographic parameters affecting local survival, focusing on changes over time and their relationship to habitat characteristics. The distribution of the Little Owl in Denmark contracted considerably between 1972-74 and 1993-96. The extent of contraction varied across the country, and the only habitat correlate was that local disappearance was associated with smaller amounts of agricultural land. Analyses of ring recovery data suggested a constant annual adult survival rate of 61% from 1920 to 2002, which is similar to estimates from countries with stable populations. First-year annual survival rates were much lower than values previously reported. From the 1970s into the 21st century, the mean number of fledglings declined from around 3 to < 2 young per territory, but the decline in clutch size was considerably less. Reproductive parameters were higher closer to habitat types known to be important foraging habitats for Little Owls, and were also positively correlated with the amount of seasonally changing land cover (mostly farmland) within a 1-km radius around nests as well as temperatures before and during the breeding season. Experimental food supplementation to breeding pairs increased the proportion of eggs that resulted in fledged young from 27 to 79%, supporting the hypothesis that the main proximate reason underlying the ongoing population decline is reduced productivity induced by energetic constraints after egg-laying. Conservation efforts should target enhancement of food availability during the breeding season. Other farmland species dependent on large invertebrates are likely to share the problems that Little Owls face in modern agricultural landscapes. [ABSTRACT FROM AUTHOR]

Objective To evaluate the achievement of a bilateral mydriasis in raptors induced by a concurrent topical application of rocuronium bromide and to assess any side effects that might result from its use. Animals studied Ten healthy adult common buzzards ( Buteo buteo) and 10 healthy adult little owls ( Athene noctua). Procedures Common buzzards (Group 1) received a single dose of 0.40 mg of rocuronium bromide in each eye (total dose 0.80 mg/bird), whereas the little owls (Group 2) received a single dose of 0.20 mg in each eye (total dose 0.40 mg/bird). The drug was topically instilled in all the birds of both groups. The pupil diameter was measured with a pupillary gauge and the assessment of the pupillary light reflexes was performed using a standard light source. Results Maximal pupillary diameter was 8.10 ± 0.56 mm in the right eye and 8.05 ± 0.59 mm in the left eye for Group 1 and 10.0 ± 0.75 mm in both eyes for Group 2. No statistical differences were evidenced between the achieved pupillary diameters of both eyes in each group. The maximal pupillary diameter was achieved at T110 min and T40 min for Groups 1 and 2, respectively. The drug did not cause noticeable adverse effects in the examined birds. Conclusions A single concurrent topical administration of rocuronium bromide to the eyes of the examined birds induced a complete bilateral mydriasis in both eyes without causing any adverse effect. [ABSTRACT FROM AUTHOR]

The feeding ecology of the Little Owl (Athene noctua) was studied in farmlands of southeast Poland, which is dominated by monocultural farms. 3065 prey dissected from pellets were collected at 13 pellet stations between 1999 and 2001 through 7 seasons in total. Mammals were found to dominate both in total number (54.3% of caught prey) and total biomass (93.0% of caught prey) while insects comprised 43.0% of the number, but only 1.1% of the prey biomass. However, the proportion of insects reached up to 62% in certain seasons. Coleopteran beetles dominated the insect fraction representing 98.3% of the number and 87.9% of the insect biomass. Our study also illustrated that in some seasons, the prey composition included taxa related to intensive agricultural management. The food composition of the Little Owls from the examined Polish sites is more similar to Eastern and Southern populations than to Northern and Western populations of Little Owls in Europe. [ABSTRACT FROM AUTHOR]

1. The dynamics of many populations is strongly affected by immigrants. However, estimating and modelling immigration is a real challenge. In the past, several methods have been developed to estimate immigration rate but they either require strong assumptions or combine in a piecewise manner the results from separate analyses. In most methods the effects of covariates cannot be modelled formally. 2. We developed a Bayesian integrated population model which combines capture–recapture data, population counts and information on reproductive success into a single model that estimates and models immigration rate, while directly assessing the impact of environmental covariates. 3. We assessed parameter identifiability by comparing posterior distributions of immigration rates under varying priors, and illustrated the application of the model with long term demographic data of a little owl Athene noctua population from Southern Germany. We further assessed the impact of environmental covariates on immigration. 4. The resulting posterior distributions were insensitive to different prior distributions and dominated by the observed data, indicating that the immigration rate was identifiable. Average yearly immigration into the little owl population was 0·293 (95% credible interval 0·183–0·418), which means that ca 0·3 female per resident female entered the population every year. Immigration rate tended to increase with increasing abundance of voles, the main prey of little owls. 5. Synthesis and applications. The means to estimate and model immigration is an important step towards a better understanding of the dynamics of geographically open populations. The demographic estimates obtained from the developed integrated population model facilitate population diagnoses and can be used to assess population viability. The structural flexibility of the model should constitute a useful tool for wildlife managers and conservation ecologists. [ABSTRACT FROM AUTHOR]

The article discusses research on the effects of food quality on owl reproduction. It references a study by Arnold B. van den Burg, published in the 2009 issue of "Ardea." It mentions that the breast muscle condition of owls were identified by folding a copper wire across their sternum, yielding their cross-sectional shape. The author states that to determine their body mass, he used a 1-kilogram Pesola scale. He adds that replacement feeding is initiated, as soon as possible after the chicks hatched.

The article discusses research on the different working efforts of Danish Little Owls Athene noctua. It references a study by Lars B. Jacobsen and colleagues, published in the 2009 issue of "Ardea." The researchers mention that the working effort of this particular species referred to the total linear distance between all observed consecutive telemetry fixes within an hour survey. They also argue that the peak of their working effort occurs during the post-hatching dependency period which is commonly characterized by males flying long distances and females with fewer inactivity periods.

The article discusses research on the use of habitat as well as the range size of the homes of Little Owl Athene noctua in the eastern region of Poland. It references a study by Grzegorz Grzywaczewski, published in the 2009 issue of "Ardea." In order to assess the behavior of this species, the author conducted radio tracking efforts in the agricultural area of the region of Lublin as well as the vicinities of the towns of Chelm and Krasnik. To examine the home range areas of the owl, he mapped the region using the Minimum Convex Polygon method.

This article discusses a study on a declining population of the little owl, Athene noctua, in Poland. The study analyzed habitat preferences of the species in order to evaluate causes of the population decline. It used geographic information system (GIS) methods in recording field surveys between 2000 and 2005. The study showed a higher proportion of built-up areas in the occupied territories compared with the random locations. It concluded that the little owl shows a high degree of habitat plasticity.

The dawn chorus is a striking feature of spring mornings and a characteristic behaviour of many bird species, particularly the passerines. Dawn singing has been considered a reliable signal of male quality for mate and rival assessment. Singing is presumed to be relatively costly at dawn both because air temperatures are relatively low and because birds have not fed overnight. Models of optimal daily routine predict the existence of a “dusk chorus” in nocturnal birds, although this prediction has received little empirical attention. Nocturnal birds at dusk may be energy-limited because of a lack of daytime feeding, and singing at dusk may thus ensure signal reliability. Here, we used an observational and experimental approach to study vocal behaviour at dusk and dawn in a nocturnal raptor, the little owl Athene noctua. We assess whether male little owls adjust their vocal behaviour according to feeding stage (i.e. period of the night), ambient air temperature and territorial context (i.e. spontaneous calling behaviour vs elicited calling by intrusion). Across different temperatures, we find that both spontaneous vocal activity and inter-individual variability in call duration increased at dusk, clearly indicating a dusk chorus phenomenon. Results from playback presentations suggest that food, rather than air temperature, is likely to be more constraining at dusk. We discuss how comparing dusk and dawn choruses in nocturnal and diurnal species can provide insights into both mechanistic and functional aspects of signalling behaviour. [ABSTRACT FROM AUTHOR]

We compared diets of little owls (Athene noctua) and long-eared owls (Asio otus) in the Minqin Desert in northwestern China. Based on prey numbers, little owls fed mainly on mammals (51.0%) and beetles (46.9%), whereas long-eared owl fed almost exclusively on mammals (96.4%). Based on biomass, both species fed mainly on mammals. Mus musculus, Cricetulus barabensis and Meriones meridianus were the three most common mammals taken by both species. Seasonal variation was found in the diets of both species. Food niche breadth was 3.4 for little owls vs 2.9 for long-eared owls. Dietary overlap between the two species was 49.6%, but varied from 4.0% in April to 96% in January. Dietary overlap of mammals was 97.9%, indicating that both owls fed on similar rodent assemblages. Mean mass of prey was 25.8 ± 22.7 g for long-eared owls and 15.5 ± 22.7 g for little owls. The mean length of tibias of mammals in pellets also indicted that, on average, long-eared owls (18.1 ± 5.6 mm) took larger prey than little owls (16.2 ± 4.7 mm). [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to describe normal ECG patterns and values in four species of conscious raptors (Eurasian kestrel, Griffon vulture, Little owl, and Eurasian Eagle owl). Electrocardiograms were carried out in 75 conscious birds belonging to four species of raptors. Lead II waveforms were analysed to determine amplitudes and durations of waves and intervals. Morphologic patterns of P-QRS-T deflections were analysed in the six limb leads. Rhythm, heart rate, mean electrical axis, presence of Ta wave, ST slurring, and P-on-T phenomenon were also studied. The influence of species, body weight and heart rate in electrocardiographic variables were statistically analysed (P <0.05). Sinus rhythm was present in all tracings, showing sinus arrhythmia in four cases. Ta wave was present in six tracings and P-on-T phenomenon in four. ST segment could be identified in all tracings, being mainly high above baseline. Significant differences between species were found for all the electrocardiographic parameters. The heart rate and body weight were also found to be a significant influence in most parameters. This study provides electrocardiographic data for four species of raptors that can be used to establish comparisons for clinical purposes. [Copyright &y& Elsevier]

River floodplains are dynamic and fertile ecosystems where soil invertebrates such as earthworms can reach high population densities. Earthworms are an important food source for a wide range of organisms including species under conservation such as badgers. Flooding, however, reduces earthworm numbers. Populations recover from cocoons that survive floods. If the period between two floods is too short such that cocoons cannot develop into reproductive adults, populations cannot sustain themselves. Both climate change and floodplain rehabilitation change the flooding frequency affecting earthworm populations. The present paper estimates the influence of climate change and floodplain rehabilitation on the viability of earthworm populations in a Dutch floodplain; the Afferdensche and Deestsche Waarden along the River Waal. This floodplain will be part of major river rehabilitation plans of the Dutch government. In those plans, the floodplain will experience the construction of a secondary channel and the removal of part of its minor embankment. To estimate the impact of these plans and climate change, we used a dataset of daily discharges for 1900–2003 for the River Rhine at the Dutch–German border. We perturbed this dataset to obtain two new datasets under climate change scenarios for 2050 and 2100. From the original and two projected datasets we derived the frequency distributions for the annual periods without inundations for the studied floodplain. We subsequently compared the duration of these inundation-free (dry) periods with the maturation age distribution for L. Rubellus as derived from a Dynamic Energy Budget model. This comparison yielded in which parts of our study area and under which climate conditions the populations would still be viable, be able to adapt or become extinct. The results show that climate change has almost no adverse effect on earthworm viability. This is because climate change reduces the flooding frequency during the earthworms growing season. Floodplain rehabilitation, on the other hand, reduces the part of the floodplain area where populations can sustain themselves. Before rehabilitation, only 12% of the floodplain area cannot sustain a viable earthworm population. After rehabilitation, this increases to 59%, 28% of which is due to more frequent flooding. Enhanced exposure to soil contaminants may further suppress earthworm viability. This could frustrate further nature development and the viability of earthworm-dependent species such as the badger (Meles meles) or little owl (Athene noctua vidalli species), which is an objective of the river rehabilitation plans in the Netherlands. [Copyright &y& Elsevier]