A reappraisal of the systematic affinities of Socotran,Arabian and East African scops owls (Otus,Strigidae) using a combination of molecular,biometric and acoustic data

We investigated phylogenetic relationships among Otus scops owls from Socotra Island, the Arabian Peninsula and East Africa using molecular, vocalization and biometric data. The Socotra Scops Owl Otus senegalensis socotranus, currently treated as a subspecies of the African Scops Owl Otus senegalensis, is more closely related to the Oriental Scops Owl Otus sunia and to the endemic Seychelles Scops Owl Otus insularis. Considerable mitochondrial genetic distance and significant morphological differentiation from its two closest relatives, as well as its distinctive vocalizations compared with O. insularis, strongly support recognition of Socotra Scops Owl as a full species. Unexpectedly, two taxa from the Arabian Peninsula, Pallid Scops Owl Otus brucei and African Scops Owl Otus senegalensis pamelae, represent very distinct lineages; O. brucei is basal to a clade that includes taxa found in the Indo‐Malayan region and on Indian Ocean islands. In contrast, O. s. pamelae occupies a well‐supported basal position within a clade of continental Afro‐Palaearctic taxa. The uncorrected‐p genetic distance between O. s. pamelae and its closest relatives (other populations of senegalensis from mainland Africa) is c. 4%. As O. s. pamelae is also well differentiated phylogenetically, morphologically and vocally from O. s. senegalensis, we recommend its elevation to species status, as Otus pamelae. Among mainland African O. senegalensis subspecies, Ethiopian populations appear to represent the most divergent lineage, whereas other lineages from Somalia, Kenya and South Africa are poorly differentiated. The large genetic distance between the Ethiopian haplotype and other African haplotypes (3.2%) suggests that the Ethiopian Otus may represent a cryptic taxon, and we recommend that more individuals be sampled to assess the taxonomic status of this population.     

Diet of the critically endangered Seychelles Scops Owl,Otus insularis

The only data previously recorded on the diet of the critically endangered, endemic Seychelles Scops Owl, Otus insularis, is from the stomach contents of a few museum specimens and analysis of one pellet. Data are presented on more than 400 prey items identified from pellets and video recordings of provisioning at two nests. Pellets comprised exclusively of invertebrate remains: Orthoptera (64%), Coleoptera (14%), arachnids (11%) and other invertebrates (11%). Similarly, 111 (76%) of all items identified during 145 provisioning visits at two nests were invertebrates. Seventy-three (66%) were identified to morphospecies and comprised Orthoptera (93%), arachnids (4%) and Lepidoptera (3%). The diet of scops owls inhabiting areas of different altitudes (180-700m asl) was similar. Identification of prey taxa and species suggests that a significant amount of foraging takes place from foliage and on tree trunks, not just on the ground.     

Unusual song of an individual Cyprus Scops Owl Otus cyprius (Aves: Strigidae)

Cyprus Scops Owl, Otus cyprius, has recently been split from Eurasian Scops Owl, Otus scops, partly because of song differences. Spectrographic analysis of a more recent O. cyprius song recording shows that it differs from that of O. scops in phrase length and frequency more than previously analysed recordings. The recorded song is also most unusual in possessing two phrases each containing 11 consecutive quiet notes; these two phrases are also remarkably similar in pattern, timing and amplitude. Previously only three consecutive quiet notes were known from O. cyprius though so far its multiple quiet note phrases have been little studied.     

Conservation of Scops Owl Otus scops in the Alps: relationships with grassland management, predation risk and wider biodiversity

The Scops Owl Otus scops is the most endangered and least studied owl in Europe, with widespread declines reported throughout Europe. The species is qualitatively associated with two threats: changes in agricultural practices and predation by Tawny Owls Strix aluco . We investigated these two threats to a population in the Alps, where land abandonment is causing widespread woodland expansion with unknown consequences. Predation risk and environmental indicators of the degree of agricultural change both predicted Scops Owl distribution. Furthermore, agricultural change also affected broader biodiversity, as estimated by the richness and diversity of bird and diurnal butterfly species. This resulted in a strong association between Scops Owl presence and wider biodiversity, which held at different spatial scales and justified a conservation focus on a single, threatened species. The persistence of Scops Owls in the Alps could be promoted through subsidies halting land abandonment and promoting extensive grassland management practices. Such interventions would have the additional advantage of yielding broader biodiversity benefits.     

Home range and movement patterns of Sokoke Scops Owl Otus ireneae

Virani, M. 2000. Home range and movement patterns of Sokoke Scops Owl Otus ireneae. Ostrich 71 (1 & 2): 139–142.

A radio-telemetric study of the endangered Sokoke Scops Owl Otus ireneae was conducted between July and December 1993. The aims were to determine the species' home range and movement patterns with respect to time and moon phases. Information gathered would then be used to formulate a rational conservation plan to ensure their survival. Six adult owls (from three adjacent pairs) were monitored during the study period. Pairs held exclusive home ranges with little (2.6%) or no overlap with their neighbours. Mean home range size (MCP) of individual owls was 8.8 ha while mean home range size of each pair was 11.0 ha. Peak owl activity took place immediately after dusk and prior to dawn. Periods of lulls occurred between 23h00 and 03h00. Movement per unit time was negatively correlated with distance from roost. The owls tended to forage further from their roosts on nights with decreased illumination from the moon. Maximum owl distances from roosts were attained between 00h00 and 02h00.     

Turnover of territorial Scops Owls Otus scops as estimated by spectrographic analyses of male hoots

In this study we assessed territory turnover of the European Scops Owl Otus scops, a migratory nocturnal raptor, using sonagrams of hoots recorded in the same territories in the 1993 and 1994 breeding seasons. Three structural parameters of the hoot (duration, inter-note interval and frequency) varied considerably, and a Discriminant Function Analysis classified >90% of individual calls correctly. In order to investigate yearly turnover and site-fidelity of male Scops Owls, the discriminant functions derived from the hoot sample recorded in 1993 were used to classify hoots of individuals recorded in the same territories in 1994. Apparently, turnover rate of territory owners was high and rapid, because 55–78% of territories censused in 1993 were defended by a different male in 1994. The fast decline of our Scops Owl population, probably due to winter mortality, could be responsible for such a high turnover of territorial owners.     

Pervasive low-frequency vocal modulation during territorial contests in Eurasian Scops Owls (Otus scops)

In several animal species, including birds, individuals are known to produce low-frequency vocalizations during aggressive interactions with conspecifics. In this study, I investigated territorial interactions between male Eurasian Scops Owls Otus scops that occupied territories in a densely packed area. The single-note hoot of the Scops Owl is generally thought to be highly repeatable; however, extensive recording of male–male interactions identified previously unrecognized variation in the structure of hoots. Male Scops Owls gave hoots at a frequency lower than usual when engaging in short-distance contests with neighbouring males. Within-subject analysis revealed that the caller’s average hoot frequency was positively correlated with the distance from its rival. During contests, males gradually reduced their hoot frequency as they approached one another, perhaps reflecting changes in the degree of escalation. Furthermore, there is evidence that male Scops Owls have voluntary control of their hoot frequency also on a very short time scale. Males gave deeper hoots immediately after the rival initiated countersinging, and returned to their usual frequency range at the end of the interaction. This study confirms in part the findings of other authors’ experimental work, where male owls adjusted their vocal frequency when challenged by an opponent. However, that study suggested that vocal frequency would encode information about the caller’s bodyweight. In contrast, the results of the present study cannot exclude the hypothesis that the hoot of the Scops Owl is a variable, conventional signal that reflects the willingness to escalate the conflict. The reliability of the signal could be maintained by the risk of retaliation by the opponent, usually located a few metres from the caller.     

The survival rate of Lanyu Scops Owls Otus elegans botelensis

Few species of owls have been well studied in the wild and estimates of survival rates are available only for a few species in the temperate region. This paper reports the adult annual and monthly survival estimates of the Lanyu Scops Owl Otus elegans botelensis , a subtropical Asian species, based on a 13-year study of a colour-marked population. The estimated seasonal survival pattern was relatively stable, with an indication of lower survival during May-June, the time of egg-laying and chick-rearing. Female survival in this species was consistently higher than male survival by an estimated 7%, which may have resulted from differential costs in reproduction. Annual survival rates during 1986-96 showed no significant differences between years. Based on a model with constant survival and annual variation in recapture rate, average annual survival for all birds was estimated as 75%, which is higher than expected given the small body weight of the Lanyu Scops Owl. This survival and the stable monthly survival pattern are discussed in light of the mild subtropical conditions of Lanyu Island.     

Disease prevalence in an urban raptor related to pest species: The case of Eurasian Scops Owl Otus scops infection by Gongylonema sp.

Urbanization is often associated with homogenization, including the homogenization of biodiversity and overpopulation by generalist species that can change community and disease dynamics. In Madrid, nestlings of Eurasian Scops Owl Otus scops frequently suffer necrotic oropharyngeal disease as a result of infection by Gongylonema sp., a parasitic nematode transmitted by adult owls to their offspring through the diet, more specifically through consumption of a pest species: the oriental cockroach Blatta orientalis. We studied how the presence of cockroaches and owl infection rates are affected by urban features such as green areas. We found that a higher number of birds were affected by the parasite in the initial period of the breeding season and in areas with greater surface area of green spaces. We suggest that urban management should promote the diversity of insects in green areas so that the owls diversify their dietary offer to their offspring, to reduce the prevalence of the disease and improve their breeding success in the city of Madrid, as this problem has not yet been described in other cities.     

Helminth Communities of Owls (Strigiformes) Indicate Strong Biological and Ecological Differences from Birds of Prey (Accipitriformes and Falconiformes) in Southern Italy

We compared the helminth communities of 5 owl species from Calabria (Italy) and evaluated the effect of phylogenetic and ecological factors on community structure. Two host taxonomic scales were considered, i.e., owl species, and owls vs. birds of prey. The latter scale was dealt with by comparing the data here obtained with that of birds of prey from the same locality and with those published previously on owls and birds of prey from Galicia (Spain). A total of 19 helminth taxa were found in owls from Calabria. Statistical comparison showed only marginal differences between scops owls (Otus scops) and little owls (Athene noctua) and tawny owls (Strix aluco). It would indicate that all owl species are exposed to a common pool of ‘owl generalist’ helminth taxa, with quantitative differences being determined by differences in diet within a range of prey relatively narrow. In contrast, birds of prey from the same region exhibited strong differences because they feed on different and wider spectra of prey. In Calabria, owls can be separated as a whole from birds of prey with regard to the structure of their helminth communities while in Galicia helminths of owls represent a subset of those of birds of prey. This difference is related to the occurrence in Calabria, but not Galicia, of a pool of ‘owl specialist’ species. The wide geographical occurrence of these taxa suggest that local conditions may determine fundamental differences in the composition of local communities. Finally, in both Calabria and Galicia, helminth communities from owls were species-poor compared to those from sympatric birds of prey. However, birds of prey appear to share a greater pool of specific helmith taxa derived from cospeciation processes, and a greater potential exchange of parasites between them than with owls because of phylogenetic closeness.     

Microsatellite Loci from Lanyu Scops Owl (Otus elegans botelensis) and their Cross-Species Application in Four Species of Strigidae

We developed six new microsatellite markers containing tetranucleotide repeat motifs (GATA/CTAT) for Lanyu scops owl (Otus elegans botelensis) from an enriched partial library. All these loci are polymorphic and conform to Hardy–Weinberg equilibrium. We cross-species tested these and 12 other microsatellite primer pairs previously developed from O. elegans on four other species of owls (O. lettia, O. spilocephalus, O. scops, and Ninox scutulata). Results showed that the degree of polymorphism decreased with increasing phylogenetic distance to O. elegans. Most loci (66.7, 83.3, and 100%) were polymorphic in the three Otus owls but only five (27.8%) were polymorphic in N. scutulata. These microsatellites should be very useful genetic markers in studying the mating system, population genetics, and conservation of other little studied Old World Otus owls.     

High frequency of extrapair copulation with low level of extrapair fertilization in the Lanyu scops owl Otus elegans botelensis

The genetic mating system is known for only a few species of owls. Most of them are genetically monogamous. The Lanyu scops owl Otus elegans botelensis breeds in high density in the forests of Lanyu (Orchid Island), southeast of Taiwan. Because extra‐pair copulations (EPCs) have frequently been observed, we suspected a high degree of extra‐pair fertilizations (EPFs). Through intensive field observations we quantified both within‐pair and extra‐pair copulations of this owl, and used a set of microsatellite loci to assign the parentage of 200 offspring from 108 families collected between 1999 and 2004. Among copulations for which we could identify both participants, 19.77% were EPC. However, no EPC was observed in the period just before egg laying. We found only two cases of parentage mismatch among 108 broods. The first case was most likely a case of brood usurpation, which would be the first case reported in the Strigidae. The second case was an EPF resulting in one offspring. Our study found that parentage mismatch in the Lanyu scops owls to be extremely low, therefore reproductive success can be estimated accurately by simply counting chicks in nests.     

Isolation of a recent Korean epizootic strain of Newcastle disease virus from Eurasian Scops Owls affected with severe diarrhea

Velogenic Newcastle disease virus (NDV) was recovered from two dead Eurasian Scops Owls (Otus scops) from a wildlife rescue center in Korea during 2005. Phylogenetic analysis based on the sequence of the partial fusion (F) protein revealed that the isolates had the highest level of homology to recent Korean NDV strains from poultry.     

Vicariance and dispersal in the differentiation of vocalization in the Ryukyu Scops Owl Otus elegans

The distribution of species and species diversity can be affected by vicariance or dispersal. To understand their role in shaping species distribution and population structure these two processes must be estimated within and among populations. I analysed large‐scale variation in the call structure of the Ryukyu Scops Owl Otus elegans. This owl is distributed over a 1200‐km range, and only inhabits islands. Within this range, I studied this species across 22 continental islands of the Ryukyu Archipelago and two oceanic islands. The study aimed to assess whether there is variation in the acoustic structure of Owl hoot calls within islands, among major groups of islands and across a large area comprising a major biogeographical barrier (the Kerama Gap). The acoustic structure of calls was homogeneous within islands and among major island‐groups. Acoustic differentiation, however, increased over longer geographical distances of up to about 1200 km. The acoustic structure of hoots of the Ryukyu Scops Owl populations was clearly divided into two groups, north and south of the Kerama Gap. It is suggested that the Kerama Gap acted as a biogeographical barrier and contributed to the differentiation between the two major island‐groups. It is likely that this difference developed during the fragmentation of a widespread ancestral population by vicariant isolating events. There was also evidence of an effect of dispersal on vocal differentiation in subspecies inhabiting the two oceanic islands.     

Identification of the intermediate host of Gongylonema sp., the etiological agent of the necrotic oropharyngeal disease of the Scops owl (Otus scops)

Since 1997, fledgling Scops owls (Chordata: Strigidae) have been brought to the Brinzal Owl Rescue Centre (Madrid, Spain) with severe lesions in their oral cavities. Lesions consist of the presence of proliferative necrotic material in the oral cavity resulting in white plaques, which can lead to death by starvation. This disease has been detected in owls only within the limits of the city of Madrid. The etiologic agent has been identified as Gongylonema sp. (Nematoda: Spirurida), a nematode genus that includes a coprophagous arthropod as intermediate host in its cycle. The aim of this study was to identify the intermediate host of the parasite. Our work was structured in four component phases: i) Diet study of newborn chicks; ii) trapping arthropods that could be intermediate hosts; iii) molecular detection of the parasite in the selected arthropods: and iv) molecular characterization of the detected parasites by amplifying the cox1 gene. Four male owls were radio-tagged in order to locate their nests and a camera trap was placed to identify the prey brought to the owlets. Secondly, the arthropods present in the hunting areas of the owls were sampled, identified and analyzed by real time PCR (rtPCR). Only oriental cockroaches, B. orientalis (Arthropoda: Blattodea), were positive by rtPCR detection of Gongylonema sp. (66.7%). The nematodes obtained from cockroaches had a 99.8% identity of the cox1 gene with the Gongylonema sp. isolated for the first time in a Scops owl. Furthermore, these sequences only showed an <89% identity with all the other Gongylonema sequences available in the GenBank database. We conclude that the oriental cockroach should be considered as an intermediate host of the etiologic agent of NOD.     

RECENT BIOACOUSTIC PUBLICATIONS—from 1991 and a few from 1990 and 1989

ABSTRACT

The focus of this study was to determine whether individual vocal identification of Scops Owls Otus scops was possible and if there was a stability of the hoot-calls over a short time period in the same individuals. Spontaneous vocalizations of 13 owls were recorded in 2004 in Southern Tuscany, Italy. Visual analysis of spectrograms and quantitative multivariate analysis of six vocal features showed marked individual differences. In some owls a repertoire of two different hoot types was found. In 2005, 10 Scops owls were recorded three times in the same breeding season (2 hours and 10 days after the first session). Statistical analysis of data showed that 60% of owls did not change call features over time. However a slight but significant variability between successive vocal performances of the same owl was found in 40% of cases. This variability may decrease the recognition power by acoustic analysis. To overcome this obstacle I suggest a multi step qualitative/quantitative approach. A Difference Index (DI) was calculated to set a threshold between the slight intra-individual and the very high inter-individual variability. This method allowed the recognition of calls of each owl recorded over time in 2005.     

High frequency of extrapair copulation with low level of extrapair fertilization in the Lanyu scops owl Otus elegans botelensis

The genetic mating system is known for only a few species of owls. Most of them are genetically monogamous. The Lanyu scops owl Otus elegans botelensis breeds in high density in the forests of Lanyu (Orchid Island), southeast of Taiwan. Because extra-pair copulations (EPCs) have frequently been observed, we suspected a high degree of extra-pair fertilizations (EPFs). Through intensive field observations we quantified both within-pair and extra-pair copulations of this owl, and used a set of microsatellite loci to assign the parentage of 200 offspring from 108 families collected between 1999 and 2004. Among copulations for which we could identify both participants, 19.77% were EPC. However, no EPC was observed in the period just before egg laying. We found only two cases of parentage mismatch among 108 broods. The first case was most likely a case of brood usurpation, which would be the first case reported in the Strigidae. The second case was an EPF resulting in one offspring. Our study found that parentage mismatch in the Lanyu scops owls to be extremely low, therefore reproductive success can be estimated accurately by simply counting chicks in nests.     

Territoriality and the significance of calling in the Lanyu Scops Owl Otus elegans botelensis

Territories of Lanyu Scops Owls Otus elegans botelensis overlap in both breeding and non-breeding seasons. Results of radiotelemetry showed that neighbouring owls do not use the shared areas of their territories at the same time. Frequent countersinging apparently permitted individuals to avoid potentially costly encounters with neighbours. Non-territorial owls can forage and rest in occupied territories. Experiments using decoys and playbacks showed that intruding owls were tolerated within either core or peripheral territories in all seasons if they remained silent, while calling intruders almost always incited threats or attacks even in autumn. Tolerating silent owls that are not competitors for mates or for nest sites appears to be an energy-saving territorial strategy.     

Food and habitats requirements of the Eurasian Scops Owl (Otus scops) in Switzerland revealed by very high-resolution multi-scale models

In Europe, agricultural practices have progressively evolved towards high productivity leading either to the intensification of productive and accessible areas or to the abandonment of less profitable sites. Both processes have led to the degradation of semi-natural habitats like extensive grasslands, threatening species such as the Eurasian Scops Owl Otus scops that rely on extensively managed agricultural landscapes. In this work, we aimed to assess the habitat preferences of the Scops Owl using habitat suitability models combined with a multi-scale approach. We generated a set of multi-scale predictors, considering both biotic and abiotic variables, built on two newly developed vegetation management and orthopteran abundance models. To select the variables to incorporate in a ‘best multi-scale model’, we chose the best spatial scale for each variable using univariate models and by calculating their relative importance through multi-model inference. Next, we built ensembles of small models (ESMs) at 10 different scales from 50 to 1000 m, and an additional model with each variable at its best scale (‘best multi-scale model’). The latter performed better than most of the other ESMs and allowed the creation of a high-resolution habitat suitability map for the species. Scops Owls showed a preference for dry sites with extensive and well-structured habitats with 30–40% bush cover, and relied strongly on semi-extensive grasslands covering at least 30% of the surface within 300 m of the territory centre and with high orthopteran availability near the centre (50-m radius), revealing a need for good foraging grounds near the nest. At a larger spatial scale within a radius of 1000 m, the habitat suitability of Scops Owls was negatively related to forest cover. The resulting ESM predictions provide valuable tools for conservation planning, highlighting sites in need of particular conservation efforts together with offering estimates of the percentage of habitat types and necessary prey abundance that could be used as targets in future management plans to ensure the persistence of the population.