Molecular Identification of Sarcocystis sp. (Apicomplexa, Sarcocystidae) in Offspring of Tengmalm's Owls, Aegolius funereus (Aves, Strigidae)

Background: Birds act as intermediate or definitive hosts of cyst-forming coccidia parasites of the genus Sarcocystis Lankester, 1882. However, the spectrum of species of Sarcocystis in birds and the role of the latter in the transmission of coccidia are still incomplete for many avian species, including the Tengmalm's owl Aegolius funereus (Linnaeus, 1758). During the research on Tengmalm's owls in Finland, some fledglings were found dead and subsequently parasitologically examined. Therefore, this study is focused on the morphological and molecular description of a Sarcocystis species found in the intestine of the Tengmalm's owl and its possible role as a definitive host.Methods: Eleven fledgling owls in the Kauhava region of west-central Finland were found dead and subsequently were submitted for necropsy and parasitologically examined through the flotation–centrifugation coprological technique for the presence of oocysts/sporocysts of the genus Sarcocystis by light microscopy. Wet mounts were used for the examination of muscle samples (breast, legs, and heart). Polymerase chain reaction (PCR) and nested-PCR were carried out using primers for 18S rRNA, 28S rRNA, ITS1 region, and CO1 genes.Results: All 11 examined owls were parasitized by numerous sporocysts and oocysts in the intestinal mucosa scrapings (prevalence, 100%). Sporulated oocysts and sporocysts measured 16.34–16.96 × 11.47–12.09 μm and 11.85–13.52 × 7.77–9.25 μm, respectively. The skeletal and heart muscles were negative for sarcocysts. Sarcocystis sp. ex Aegolius funereus (hereafter Sarcocystis sp. Af) is closely related to Sarcocystis strixi in the barred owl (Strix varia Barton, 1799) from the USA and Sarcocystis sp. isolate 5 in the European shrew (Sorex araneus Linnaeus, 1758) from the Czech Republic. Phylogenetic analysis allowed determining the relationship of the herein reported Sarcocystis sp. with its congeners.Conclusions: This work provided the first and most comprehensive record on Sarcocystis from owls obtained in Finland, thus highlighting the importance of molecular data in species identification.

Molecular identification of Sarcocystis funereus sp. nov. (Apicomplexa, Sarcocystidae) in offspring of Tengmalm’s owls Aegolius funereus (Aves, Strigidae)

The spectrum of species of Sarcocystis in birds and the role of the latter in the transmission of coccidia are still incomplete for many avian species including Tengmalm’s owl Aegolius funereus (Linnaeus, 1758). Therefore, this study is focused on the morphological and molecular description of a new Sarcocystis species found in the intestine of the Tengmalm’s owl and its possible role as definitive host. Ten fledgling owls from the Kauhava region of west-central Finland were parasitized by numerous sporocysts and oocysts in the intestinal mucosa scrapings (prevalence 100%). Sporulated oocysts and sporocysts measured 16.34−16.96 × 11.47−12.09 µm and 11.85−13.52 × 7.77−9.25 µm, respectively. Skeletal and heart muscles were negative for sarcocysts. Sarcocystis funereus sp. nov. is closely related to Sarcocystis strixi from the barred owl (Strix varia Barton, 1799) from the USA and Sarcocystis sp. isolate 5 from the European shrew (Sorex araneus Linnaeus, 1758) from the Czech Republic. This is the first and most comprehensive record on Sarcocystis from owls obtained in Finland, thus highlighting the importance of molecular data in the species identification.

High prevalence of Sarcocystis funereus sp. nov. (Apicomplexa, Sarcocystidae) in offspring of Tengmalm’s owls Aegolius funereus (Aves, Strigidae)

Background Birds act as intermediate or definitive hosts of cyst-forming coccidia parasites of the genus Sarcocystis Lankester, 1882. However, the spectrum of species of Sarcocystis in birds and the role of the latter in the transmission of coccidia are still incomplete for many avian species including Tengmalm’s owl Aegolius funereus (Linnaeus, 1758). During a research of Tengmalm’s owls in Finland some fledglings were found dead and subsequently parasitologically examined. Therefore, this study is focused on the morphological and molecular description of a new Sarcocystis species found in the intestine of the Tengmalm’s owl and its possible role as definitive host. Methods Eleven fledgling owls from the Kauhava region of west-central Finland were found dead and subsequently were submitted for necropsy, parasitologically examined through flotation-centrifugation coprological technique for the presence of oocysts/sporocysts of genus Sarcocystis by light microscopy. Wet mounts were used for the examination of muscle samples (breast, legs, heart). Polymerase chain reaction and nested-PCR were carried out by using primers for 18S rRNA, 28S rRNA, ITS1 region and cox1 genes. Results All eleven examined birds were parasitized by numerous sporocysts and oocysts in the intestinal mucosa scrapings (prevalence 100%). Sporulated oocysts and sporocysts measured 16.34 − 16.96 × 11.47 − 12.09 µm and 11.85 − 13.52 × 7.77 − 9.25 µm, respectively. Skeletal and heart muscles were negative for sarcocysts. The phylogenetic analysis revealed that Sarcocystis funereus sp. nov. is closely related to Sarcocystis strixi from the barred owl (Strix varia Barton, 1799) from the USA and Sarcocystis sp. isolate 5 from the European shrew (Sorex araneus Linnaeus, 1758) from the Czech Republic, but a valid species. Conclusions This work provided the first and the most comprehensive record on Sarcocystis from owls obtained in Finland, thus highlighting the importance of molecular data in the species identification.

Environmental conditions and call-broadcast influence detection of eastern forest owls during standardized surveys

Owls play crucial roles in the environment and provide ecosystem services making them important to monitor and study. However, standardized methods for most species do not exist, and we lack understanding of the effects of many environmental variables and call-broadcast on detection of owls during surveys. We performed a multispecies occupancy analysis of owl monitoring data collected from 2004 to 2013 across the state of Maine to examine the effects of environmental variables, conspecific and heterospecific call-broadcast, and general survey protocols on detection of 3 forest owls: Northern Saw-whet Owl (Aegolius acadicus), Barred Owl (Strix varia), and Great Horned Owl (Bubo virginianus). We found that environmental variables such as cloud cover, precipitation, temperature, time of night, and wind had species-specific effects on detection probability, and ambient noise decreased detection probability for all species. Snow cover did not affect detection of any species. We also found that conspecific call-broadcast increased detection of each species, while heterospecific call-broadcast had variable effects. Specifically, we found that Long-eared and Barred owl broadcast increased the detection of Northern Saw-whet Owl, and our results suggest additional heterospecific effects may exist. Our study showed that, compared to the protocol of the Maine Owl Monitoring Program, surveys simultaneously examining all 3 of our focal species can increase efficiency and lower disturbance by only broadcasting Long-eared and Barred owl calls during a 10-min survey. We recommend that future owl surveys take into account species-specific effects of conspecific and heterospecific call-broadcast, and use our results when designing survey protocols that include one or more of our focal species.

Genomic variation and population histories of spotted (Strix occidentalis) and barred (S. varia) owls

Spotted owls (SO, Strix occidentalis) are a keystone species inhabiting old-growth forests in Western North America. In recent decades, their populations have declined due to ongoing reductions in suitable habitat caused by logging, wildfires, and competition with the congeneric barred owl (BO, Strix varia). The northern spotted owl (subspecies S. o. caurina) has been listed as “threatened” under the Endangered Species Act since 1990. Here we present a comprehensive look at genetic variation to elucidate the population histories of SO and invading western BO. Specifically, we present an improved SO genome assembly, based on 10x and Bionano Genomics data, along with 51 high-coverage whole-genome sequences including 11 SO from two subspecies (caurina and occidentalis), 25 BO, 2 confirmed and 13 potential hybrids. We identified potential hybrids based on intermediate morphology and found them to be a mixture of pure BO, F1 hybrids, and F1 x BO backcrosses. Unlike previous studies reporting asymmetries in the species-specific genders of the parents of F1 hybrids, we did not observe any significant asymmetry. Within species, we found that Western BO genetic variation is not simply a subset of the genetic variation in Eastern BO, suggesting that the two groups have been genetically isolated for longer (thousands of years) than previously suspected (80-130 years). Similarly, we found evidence of substantial genetic differentiation between the two SO subspecies. Finally, our analyses suggest that Northern SO experienced a moderate population bottleneck around the end of the last glaciation, while BO population sizes have always been large.