Snowy Owl Research Articles

Modelling biodiversity is an essential part of its protection

Modelling biodiversity is an essential part of its protection Professor Guillaume Blanchet from Université de Sherbrooke considers why modelling biodiversity is an essential part of protection and how we can model biodiversity better. The snowy owl is one of the most charismatic animals in the world, maybe in part because of the immense success of Harry Potter, which has a snowy owl as a pet. Even if it is a well-known species and one that almost everyone has little to no trouble spotting in the sky if it flies (even high up) above our head, scientists are still finding it very challenging to draw on a map where it lives and reproduces. To show how much trouble even the best scientists in the world have in defining where the snowy owl is found, I present here two expert maps suggesting where the snowy owl may be found.

A Worldwide Review of Snowy Owl Feeding Ecology: The Importance of Lemmings and Voles in a Changing Climate

We compared Snowy Owl feeding ecology from 15 breeding season studies throughout Nearctic and Palearctic circumpolar regions. We used raw data and information theory to assess the owls’ feeding niche. Combined studies yielded 59,923 prey items, of which 59,585 were used for calculations. Overall, mean food niche breadth (FNB) was narrow: H′ = 1.95; R = 1.60, D = 0.526. In 10 of 15 studies, lemmings were > 71.8% of the owls’ diet. In four studies, Lemmus was > 90% of the diet, and in three studies Dicrostonyx was >90% of the diet. In three other studies, Lemmus represented 71.8%, 73.8%, and 84.0% of the diet. In one study, Lemmus and Dicrostonyx were about equal: 49.1% and 47.5%. In the four remaining studies, Microtus and Clethrionomys voles were important. In contrast, of 5888 winter prey items from seven North American studies, the mean FNB (H′ = 4.61) was twice that of 15 breeding season scores, FNB (H’ = 1.95). The Snowy Owl is primarily an obligate lemming predator for breeding. Changes to population ecology and distribution of lemmings due to climate change will have direct affects and effects on the Snowy Owls’ reproductive output. The conservation of Snowy Owls is the conservation of lemmings.

A Safe and Effective Atovaquone-Proguanil Therapeutic Protocol for the Treatment of Avian Malaria by Plasmodium relictum in Snowy Owl (Bubo scandiacus).

Avian malaria is a re-emerging threat to avian species worldwide. It is sustained by several protozoan species belonging to the genus Plasmodium, mainly Plasmodium relictum. The even wider diffusion of the disease, probably because of the increase in the areas covered by their mosquito vectors, may pose new risks for avian species lacking natural resistance (especially those from artic or sub-artic environments) or those hosted in structures like zoos and wildlife rescue centers. With that premise, this study describes the efficacy and safety of a therapeutic protocol to treat avian malaria in three snowy owls (Bubo scandiacus) hosted in a wildlife rescue center in Apulia, south of Italy, and affected by avian malaria by P. relictum. The protocol consisted of administering 10/4 mg/kg atovaquone/proguanil per os once a day for three consecutive days, repeating this seven days later. Seven days after the end of the treatment, P. relictum was not detected in the birds' blood and no adverse effects were observed during the 60 days of monitoring after the end of the treatment. Therefore, a therapeutic regimen of 10/4 mg/kg/day may be considered safe and effective in a valuable and endangered species such as B. scandiacus.

Determination of Coagulation Parameters by Whole Blood Dynamic Viscoelastic Coagulometry in Strigiformes.

No reference values are available in Strigiformes to evaluate blood coagulation using dynamic viscoelastic coagulometry (DVC) with the Sonoclot (Sienco, Boulder, CO, USA) analyzer. The objectives of this study were 1) to assess the feasibility of DVC in Strigiformes, 2) to calculate the index of individuality of each coagulation parameter, and 3) to assess interspecies variability and establish reference intervals, if relevant, based on the index of individuality. Fresh whole blood samples were obtained from healthy Strigiformes, including 13 barred owls (Strix varia), 10 great horned owls (Bubo virginianus), 6 snowy owls (Bubo scandiacus), and 7 eastern screech owls (Megascops asio), and analyzed with DVC with glass bead (gb) and kaolin clay (k) coagulation activators. Activated clotting time (ACT), clot rate (CR), and platelet function were determined immediately after collection using fresh native whole blood. Intraindividual variability was assessed with a second fresh native whole blood sample from 5 barred owls. Interindividual variability was assessed using a Kruskall-Wallis test. For the parameters gbACT (n = 35), gbCR (n = 34), and kACT (n = 27), no significant differences were detected between species (all P ≥ 0.05). Based on low index of individuality, global Strigiformes reference intervals were determined for gbACT (32.3-852.5 seconds; n = 35), gbCR (0-20.1 units/min; n = 29), and kACT (0-1570.3 seconds; n = 27). In conclusion, DVC can be used in Strigiformes and the gb coagulation activator would be more appropriate when basal individual values are not available in a tested individual.

Avian haemosporidian parasites in captive and free-ranging, wild birds from zoological institutions in Switzerland: Molecular characterization and clinical importance.

Avian haemosporidian parasites are widespread and infect birds from a broad variety of avian families with diverse consequences ranging from subclinical infections to severe and fatal disease. This study aimed to determine the occurrence and diversity of avian haemosporidia including associated clinical signs and pathomorphological lesions in captive and free-ranging, wild birds from two zoos and the near environment in Switzerland. Blood samples from 475 birds, including 230 captive and 245 free-ranging, wild individuals belonging to 42 different avian species from 15 orders were examined for the presence of avian haemosporidian DNA by a one-step multiplex PCR designed to simultaneously detect and discriminate the genera Plasmodium, Haemoproteus and Leucocytozoon by targeting mitochondrial genome sequences. Positive samples were additionally tested using a nested PCR targeting the cytochrome b gene of Plasmodium and Haemoproteus. The obtained amplicons were bidirectionally sequenced. This study revealed haemosporidian DNA in 42 samples, belonging to ten host species. The most commonly detected lineage was Plasmodium relictum SGS1, which was identified in 29 birds (Phoenicopterus roseus: n=24, Alectoris graeca: n=1, Lamprotornis superbus: n=1, Somateria mollissima: n=1, Spheniscus demersus: n=1, Tetrao urogallus crassirostris: n=1), followed by Haemoproteus sp. STRURA03 in six avian hosts (Bubo bubo: n=5, Bubo scandiacus=1), Plasmodium relictum GRW11 in four individuals (Phoenicopterus roseus: n=3, Spheniscus demersus: n=1) and Plasmodium elongatum GRW06 in one Alectura lathami lathami. A Phalacrocorax carbo was infected with Plasmodium relictum, but the exact lineage could not be determined. One mixed infection with P. relictum and Haemoproteus sp. was detected in a Bubo scandiacus. Only five individuals (Spheniscus demersus: n=2, Somateria mollissima: n=1, Bubo scandiacus: n=1, Alectoris graeca: n=1) showed clinical and pathomorphological evidence of a haemosporidian infection.

IN VIVO CONFOCAL MICROSCOPY FOR CHARACTERIZATION OF MYCOTIC KERATITIS IN OWLS (BUBO SCANDIACUS, STRIX VARIA) AND A WOODCOCK (SCOLOPAX MINOR): THREE CASES.

This case series describes the use of in vivo confocal microscopy in the diagnosis and treatment of mycotic keratitis in two owls (one Bubo scandiacus, one Strix varia) and one woodcock (Scolopax minor). Each bird was at increased risk of fungal infection due to recent injury or stress. Ophthalmic findings in all birds included blepharospasm, ocular discharge, ulcerative keratitis, white or yellow corneal plaques, and anterior uveitis. Fungal hyphae were identified in corneal samples from all three eyes examined cytologically and in all three eyes by using in vivo confocal microscopy. Aspergillus fumigatus was isolated from a corneal culture in one bird. Despite medical treatment, progressive ocular disease prompted enucleation in two birds. Fungal hyphae were detected by histopathology in one of the two enucleated eyes. In vivo confocal microscopy aided the diagnosis of fungal keratitis in all birds and was the only diagnostic method that allowed immediate, real-time quantification of the extent (area and depth) and severity of mycotic keratitis.

Long‐term population decline of a genetically homogeneous continental‐wide top Arctic predator

Genetic analysis can provide valuable information for conservation programmes by unravelling the demographic trajectory of populations, estimating effective population size or inferring genetic differentiation between populations. Here, we investigated the genetic differentiation within Snowy Owls Bubo scandiacus in North America, a species identified as vulnerable by the IUCN, to (1) quantify connectivity among wintering areas, (2) evaluate current genetic diversity and effective population size, and (3) infer changes in the historical effective population size changes from the last millennia to the recent past. The Snowy Owl, a highly mobile top predator, breeds across the Arctic tundra, a region especially sensitive to current climate change. Using single‐nucleotide polymorphism (SNP)‐based analyses on Snowy Owls sampled across the North American non‐breeding range, we found an absence of genetic differentiation among individuals located up to 4650 km apart. Our results suggest high genetic intermixing and effective dispersal at the continental scale despite documented philopatry to non‐breeding sites in winter. Reconstructing the population demographic indicated that North American Snowy Owls have been steadily declining since the Last Glacial Maximum c. 20 000 years ago, and concurrently with global increases in temperature. Conservation programmes should now consider North American Snowy Owls a single, genetically homogeneous continental‐wide population which is probably sensitive to the long‐term global warming occurring since the Last Glacial Maximum.

Fluorescence in European Owls

Fluorescence induced by ultraviolet light has been observed in many animals, from invertebrates to mammals. Fluorophores (chemical compounds responsible for fluorescence) have been studied in feathers of bird species; for example, porphyrins (one of the most abundant biological pigments) in feathers of some owl species produce red-orange fluorescence. We conducted a fluorescence study on 13 European owl species, and found fluorescence in all of them. Contrary to what was previously reported, we also found fluorescence in the snowy owl (Bubo scandiacus). We also investigated fluorescence of different body and feather areas of the owls, and found similarities between species and some differences depending on occupied landscape, nest and life type, activity period, and plumage colour.

Snowy Owls in central North America have regular migration and high philopatry to wintering sites though not always to home ranges

Snowy Owls in central North America have regular migration and high philopatry to wintering sites though not always to home ranges

A handful of duck radiuses: Peculiarities of the avifaunal exploitation at the Gravettian site of Maisières‐Canal (Belgium)

AbstractThe early Gravettian site of Maisières‐Canal (Belgium) was discovered in 1966, during the widening of the Canal du Centre. Emergency excavation allowed the discovery of an open‐air human occupation which yielded abundant archaeological material. A re‐examination of the well‐preserved faunal collections has expanded the bird assemblage from the 29 bones initially recognized to 78, which have been studied from an archaeozoological point of view. Six taxa were identified, including species regularly encountered in Upper Paleolithic sites, such as the snowy owl (Bubo scandiacus), the northern raven (Corvus corax), and the willow or rock ptarmigan (Lagopus sp.). Ducks (Anatinae) are by far the best represented taxa. Surprisingly, only radius fragments were recovered for ducks, most bearing breaks and tool marks. We paid special attention to this peculiar set of duck radiuses. We performed experiments on fresh duck wings to evaluate the impact of different actions on the radius. Based on our experiments, two main hypotheses emerged. This accumulation of duck radiuses may represent (1) the waste from the production of dry wings and/or (2) a supply of raw material for craft activities. However, neither of these two hypotheses can be conclusively confirmed. As well as exhibiting some discrepancies, the bird bone assemblage from Maisières‐Canal shares several characteristics with early Gravettian sites from central Europe.

Testimonials to reconstruct past abundances of wildlife populations

Long-term monitoring of wildlife populations has greatly contributed to our current understanding of population dynamics and ecosystem functioning. Despite tireless field campaigns, however, only a fraction of the biodiversity has been monitored to date and the dynamics of potential key species have yet to be understood.Here, we propose a method based on testimonials of observations from field workers to reconstruct past abundances of unmonitored populations and fill data gaps.We contacted scientists who conducted field work at the Bylot Island field station, Nunavut, in the Canadian Arctic between 1991 and 2019 and collected 205 testimonials of past observations from 131 participants. We scored each testimonial based on its content and derived annual abundance indices for three highly fluctuating taxa, being lemmings, snowy owls and ermines. These indices were compared to standardized abundance estimates based on field sampling that were either available between 1993 and 2019 (lemmings and snowy owls) or 2007–2019 (ermines).Our results show that abundance indices based on testimonials correlate well with those from systematic sampling and can be used to detect ecological phenomena. Moreover, we show that abundance indices were not affected by the effort of participants in the field or the delay between the observations and the collection of testimonials. Finally, we use the received testimonials to generate the longest ermine time series of relative abundance in the Canadian Arctic, spanning 29 years.Monitoring programs and research stations often have access to a pool of past participants (e.g. field workers, ecotourists) whose observations can be localized in time. As we strive to gain a deeper understanding of ecosystem functioning, tapping the memories of these people can provide valuable information on the past abundances of unmonitored populations and help answer hypotheses that would otherwise require years of systematic monitoring.

Why Are Snowy Owls White and Why Have They Evolved Distinct Sexual Color Dimorphism? A Review of Questions and Hypotheses

Abstract Many Arctic animals are white throughout their life, or turn white seasonally, with no distinct sexual color dimorphism. Common knowledge assumes these animals are white for camouflage in snow-covered landscapes. Presumably, this camouflage adaptation provides concealment from predators, and conversely, concealment for predation. This adaptation appears to be independent of sex. These theories seem logical; however, natural selection could also favor white coloration for other reasons. The Snowy Owl (Bubo scandiacus) is unusual because in addition to being white, it also shows sexual color dimorphism. Both sexes exhibit delayed plumage maturation. As yearlings, males and females are heavily marked with brown bars and spots on a white-based plumage. Males and females are believed to become whiter as they age. Males become almost pure white, while females retain brown bars and spots. As adults, males and females are distinctly sexually dimorphic in coloration and plumage patterning. These traits are not consistent with most other species of white Arctic animals, or most other species of owls. Snowy Owls are thought to share a common ancestor with the genus Bubo, especially Great Horned Owls (Bubo virginianus) from North America. This separation took place approximately four million years ago. If true, the evolution of white-based plumage in Snowy Owls was probably the result of natural selection favoring camouflage color in snow-covered environments, as Snowy Owls evolved and expanded into Arctic habitat. However, natural selection in concert or compromise with sexual selection, likely drove the evolution of sexual color dimorphism, and delayed plumage maturation, as a result of a snow-free tundra, and 24 hr of daylight during the breeding season. Natural selection appears to have independently favored different male and female plumage coloration and patterning. I propose that adult females evolved white plumage, interrupted with brown bars and spots, predominately for camouflage. Likewise, I propose that adult males evolved white plumage for at least two social signaling strategies: (1) to advertise their relative age, social status, and genotypic quality to females, and (2) to advertise relative age and social status to other males.

Another mention of Meadow Vole (<i>Microtus pennsylvanicus</i>) found in pellets of Snowy Owl (<i>Bubo scandiacus</i>) in northern Ungava Peninsula, Canada

The examination of raptor pellets can be used to evaluate Arctic biodiversity. We found the remains of Meadow Vole (Microtus pennsylvanicus) and Ungava Collared Lemming (Dicrostonyx hudsonius) in pellets from Snowy Owl (Bubo scandiacus) nesting in the northern part of the Ungava Peninsula. We differentiated the two species by visual identification and geometric morphometric analysis of molar shape. The results of our study combined with historical data suggest that most commonly used range maps of Meadow Vole should be revised.

Factors associated with returns of snowy owls to airports following translocation

AbstractHuman‐dominated environments often include ecological traps for wildlife, such as airports that may be perceived as suitable habitat by grassland birds but reduce fitness because of collisions with aircraft. Birds of prey are often attracted to airports where collisions with aircraft (i.e., bird strikes) are usually fatal for the birds and are a significant threat to flight safety. The snowy owl (Bubo scandiacus) is known for its nomadism, exhibiting unpredictable and highly variable movements during the nonbreeding season, including being a common visitor to airports, which often have high small‐mammal populations and mimic flat, open habitats used naturally by owls. Since 2009, the Federal Aviation Administration reported an average of 22 snowy owl deaths annually due to aircraft collisions throughout 55 North American airports. To aid in active management of owls at airports, we assessed relocation data of 42 telemetry‐tracked snowy owls from 2000–2020 in the United States and Canada. Owls that returned to the airport after relocation (33%) frequently crisscrossed and perched near runways where they were at risk of strikes. Adult females and immature males were more likely to return than the other sex and age classes, and returns were less likely to occur as the distance between the release site and the airport increased. Owls relocated in open habitats with a greater proportion of wetland and cropland (including grasslands and pasture) land cover classes were also less likely to return. We conclude that inclusion of multiple factors to limit return rates of relocated snowy owls from airport facilities can unspring the ecological trap presented by airports to these owls.

Nyctea scandiaca

This datasheet on Nyctea scandiaca covers Identity, Distribution.

Temporal changes in proportions of small mammals in the diet of the mammalian and avian predators in Slovakia

The paper presents a brief account of the temporal changes found in proportions of the mammal components in the diets of several species of predators (owls and carnivores) collected from various sites in Slovakia and originating in various periods (Late Pleistocene–Recent). The material collected from the Šarkanica Cave (Muráňska planina Mts.) contained bones in three layers, dated using the radiocarbon analysis (14C) to 18,000–21,000 years BP (18–21 Ka), showing relatively small differences in composition of the fossil diet of Bubo scandiacus with predominance of Lasiopodomys gregalis (73.3%) and Chionomys nivalis (6.9%). A similar type of material from the Nový 3 Cave (Belianske Tatry Mts.), dated to the period of 30 Ka, contained more numerous remnants of Lemmus cf. lemmus and Sorex tundrensis. Undated samples from the Nový 1 Cave and from the Šarkania diera Cave (Súľovské skaly Mts.), which differ in their higher abundance of Dicrostonyx cf. gulielmi, are probably dated from the colder period of the last glacial maximum. Three samples from caves in the Veľká Fatra Mts. dated from the Late Pleistocene (Upper Dryas) originated from carnivores, with differences in relative proportions of predominant prey species: Chionomys nivalis (80.0%) and Lasiopodomys gregalis (14.3%), while remains of Cricetus cricetus (0.6%) also appear there. Two examples of differences in the diet composition of Strix aluco in the Veľká Fatra Mts. are present in samples dated to the Holocene period: natural development of forest fauna in the environs of Dolný Harmanec and anthropogenic influence in the form of three deforestation periods in the Tlstá massif near Blatnica (both Veľká Fatra Mts.). A sample set of the diet of Tyto alba dated >500 years BP from a church in Žilina is compared with a recent sample set of this owl diet from the Turčianska kotlina Basin and from the Danubian Lowland (Tekovské Lužany). The main difference lies in the greater proportion of the murid rodents and the relatively lower abundance of Microtus arvalis in the sample from the 16th century. Similar results were found comparing samples of Tyto alba diet, taken from a cave near Hatiny (Slovenský kras Mts.) and expected to be 100 years old, with more recent samples from the Košická kotlina Basin. The collection from the Hatiny Cave differs from the recent material in the presence of Sicista trizona and Alexandromys oeconomus. The recent samples of the diet of Bubo bubo taken from the Horné Považie Basin differ from the samples dated back more than 70 years ago by a high proportion of the genus Apodemus and a predominant incidence of frogs, while the old samples come from the period of the communist influence of the agricultural production causing serious environmental changes in the countryside (1950s) and as a result, a greater volume of large prey species, Rattus norvegicus, Arvicola amphibius, Lepus europaeus, and Erinaceus roumanicus. Since 1990, the availability of large prey for Bubo bubo has decreased due to the decline of livestock farming and a consequent successional overgrowing of pasture land by trees.

The Snowy Owl Scientist by Mark Wilson

The Snowy Owl Scientist by Mark Wilson

Structure of snowy owls muscles of the chest wall and shoulder girdle with elements of their biomechanics

Structure of snowy owls muscles of the chest wall and shoulder girdle with elements of their biomechanics

Density-dependent winter survival of immatures in an irruptive raptor with pulsed breeding.

Highly mobile predators can show strong numerical responses to pulsed resources, sometimes resulting in irruptions where large numbers of young invade landscapes at a continental scale. High production of young in irruption years may have a strong influence on the population dynamics unless immature survival is reduced compared to non-irruption years. This could occur if subordinate individuals (mainly immatures) are forced into suboptimal habitats due to density-dependent effects in irruption years. To test whether irruptive individuals had lower survival than non-irruptive ones, we combined necropsy results (N = 365) with telemetry (N = 185) from more than 20years to record timing and causes of mortality in snowy owls (Bubo scandiacus), which irrupt into eastern North America during winter following high breeding output caused by lemming peaks in the Arctic. Mortality was more than four times higher in irruption years than non-irruption years, but only for immatures, and occurred disproportionately in early winter for immatures, but not adults. Mortality was also higher in eastern North America, where owl abundance fluctuates considerably between years, compared to core winter regions of the Arctic and Prairies where populations are more stable. Most mortality was not due to starvation, but rather associated with human activity, especially vehicle collisions. We conclude that immature snowy owls that irrupt into eastern North America are limited by density-dependent factors, such as increased competition forcing individuals to occupy risky human-altered habitats. For highly mobile, irruptive animals, resource pulses may have a limited impact on population dynamics due to low subsequent survival of breeding output during the nonbreeding season.

Rapid assessment of West Nile virus circulation in a German zoo based on honey-baited FTA cards in combination with box gravid traps

BackgroundFor over a decade, monitoring of West Nile virus (WNV) in Germany has consisted of a bird monitoring programme as well as a mosquito-based surveillance programme employing CO2-baited encephalitis vector surveillance (EVS) traps for mass trapping and screening of mosquitoes. In contrast to the EVS traps, the Reiter/Cummings type box gravid trap collects gravid female mosquitoes, which have already taken a blood meal, increasing the likelihood of being infected with pathogens. The traps can be equipped with a honey-baited Flinders Technology Associates® (FTA) card to encourage sugar feeding by the trapped mosquitoes. FTA cards contain nucleic acid preserving substances, which prevent the degradation of viral RNA in the expectorated mosquito saliva and allows for testing the card for flavivirus RNA. This study aimed to assess the suitability of the method for WNV surveillance in Germany as an alternative to previous methods, which are expensive, time-consuming, and predominantly target host-seeking populations less likely to be infected with WNV.MethodsIn the Thüringer Zoopark Erfurt, snowy owls (Nyctea scandiaca) and greater flamingos (Phoenicopterus roseus) died of WNV infections in July and August 2020. In response, five Reiter/Cummings type box gravid traps were positioned during the daytime on the 10th, 13th, and 16th of September in five different locations. The FTA cards and mosquitoes in the chamber were collected, kept in a cool chain, and further processed for virus detection using a modified generic flavivirus reverse transcription PCR.ResultsA total of 15 trappings during September collected a total of 259 female mosquitoes, 97% of which were Culex pipiens sensu lato, as well as 14 honey-baited FTA cards. Eight mosquitoes tested PCR-positive for WNV. Four FTA cards tested PCR-positive for mosquito-borne flaviviruses, two of which were confirmed as WNV, and the remaining two confirmed as Usutu virus.ConclusionThe suitability of the FTA cards in preserving viral RNA in the field and rapid turnaround time from collection to result is combined with a simple, cost-effective, and highly specific trapping method to create an arbovirus surveillance system, which circumvents many of the difficulties of previous surveillance programmes that required the analysis of mosquitoes in the laboratory.Graphical