Expansion of sandhill cranes (Grus canadensis) in east Asia during the non-breeding period

Aim Historically, the distribution of Sandhill Cranes included much of North America and extending in summer into northeast Russia. In recent years, observations of sandhill cranes in Asia during the non-breeding period have been frequently reported. However, the distribution and abundance of sandhill cranes during the non-breeding period in Asia have rarely been summarized and studied. Our study aimed to analyze the status of sandhill cranes that have spread south into East Asia during the non-breeding period and to assess the possible impacts of their potential spread. Methods Based on opportunistic data collected in the field and occurrence data collected online over the past half century, we used Geographic Information System to visualize the spatial distribution changes and regression analysis to analyze and visualize the changes in the amount of individuals over time. Results In the last 50 years, the distribution of sandhill cranes during the non-breeding season in Asia spanned 31 degrees in longitude to the west and 15 degrees in latitude to the south. Their distribution in Asia has expanded to 17 provinces and municipalities in China, Japan and South Korea. The amount of cranes in the non-breeding period in Asia increased significantly from 1963 to 2017. According to the historical records in East Asia, sandhill cranes were mixed with five other species of crane groups. Main conclusions These results indicate that the range and amount of sandhill cranes have expanded. Sandhill cranes were mixed with five other crane species, which indicate their adaptability to a range of habitat types and food resources. The implications of these trends in sandhill cranes in East Asia for this and other crane species warrants further research.

Evidence of avian-mediated long distance dispersal in American tardigrades

Terrestrial tardigrades, commonly known as “water bears”, are part of a phylum of microscopic, aquatic invertebrates famous for cryptobiosis and space travel, but little is known about their modes of dispersal on Earth. Wind is assumed, but not truly demonstrated, to be the major method of global dispersal. Yet, some water bear distribution patterns cannot be explained by patterns of prevailing winds. Mammals and birds have been proposed as potential animal vectors. Importantly, most nearctic-neotropical migrant birds move north and south, with many crossing the equator, whereas prevailing winds move west to east or east to west but do not cross the equator. When multiplied by billions of birds over tens of millions of years, if the ectozoochory of tardigrades by birds is true then both regional and intercontinental patterns can be better explained. To test for the potential role of birds in tardigrade dispersal, the nests of 10 species for birds were examined. Seventy percent of nests were positive for tardigrades, demonstrating that some birds are in a position for transference. The carcasses of eight birds (six species) found dead from window strikes and a Sandhill Crane (Grus canadensis) found dead during routine surveys were also examined. Of the birds examined, 66% yielded tardigrades from two classes, three orders, and five species, including juveniles, adults, and eggs, suggesting that many bird species are potential vectors for many species of tardigrades. Our data support the hypothesis of avian-mediated long distance dispersal of tardigrades and provide evidence that further investigation is warranted.

Variables del microhábitat que influyen en la grulla cubana (Grus canadensis nesiotes) para seleccionar el sitio de anidación en un humedal de Cuba

La grulla cubana (Grus canadensis nesiotes), subespecie endémica de Cuba, está amenazada; se estiman tan sólo 550 individuos. La facilitación de zonas de nidificación quizá incrementaría el éxito reproductivo de la subespecie. Sin embargo, el poco conocimiento sobre los factores determinantes de la selección del área de nidificación limita cualquier intento de manejo. Aquí, caracterizamos la estructura de la vegetación alrededor de cuatro nidos y en puntos dentro del Gran Humedal del Norte de Ciego de Ávila, región central de Cuba. Medimos las variables estructurales de la vegetación que pudieran determinar la selección del microhábitat de nidificación. Hicimos 20 parcelas alrededor de los nidos y en cuatro puntos a 100 m de cada nido, en las que se midieron: altura, cobertura a 30 y a 100 cm del suelo y distancia entre hierbas (método vecino más cercano). Comparamos los datos entre nidos y puntos y calculamos un índice de selección. Las áreas alrededor de los nidos mostraron diferencias para la altura, cobertura y distancia entre hierbas. Solamente la cobertura 30 cm fue homogénea. Las distancias entre hierbas con mayor frecuencia estuvieron entre 5 y 10 cm. La altura, cobertura a 100 cm y la distancia entre hierbas forman parte del patrón de selección del sitio de nidificación de la grulla cubana en este humedal.

Time within reproductive season, but not age or inbreeding coefficient, affects seminal and sperm quality in the whooping crane (Grus americana)

All living whooping cranes (Grus americana) are descended from 16 or fewer birds that remained alive in the early 1940s, a bottleneck that puts the species at potential risk for inbreeding depression. Although AI is commonly used in the management of the captive population of this species, little is known about seminal traits or factors affecting sperm quality in the whooping crane. In the present study, semen samples were collected from 29 adult males (age 3–27 years) during the early (March), mid (April) and late (May) breeding season over 2 consecutive years. The effects of donor age, time within reproductive season and level of inbreeding on seminal characteristics were analysed using regression and information–theoretic model selection. Only time within reproductive season significantly affected seminal traits, with total numbers of spermatozoa and proportions of pleiomorphisms increasing across the season. We conclude that, even with a highly restricted number of founders, there is no discernible influence of inbreeding (at the levels described) on sperm output or quality. Furthermore, although there is variance in seminal quality, the whooping crane produces significant numbers of motile spermatozoa throughout the breeding season, similar to values reported for the greater sandhill crane (Grus canadensis tabida).

Haemosporida prevalence and diversity are similar in endangered wild whooping cranes (Grus americana) and sympatric sandhill cranes (Grus canadensis)

SUMMARYThe population growth of endangered whooping cranes (Grus americana) is not consistent with species recovery goals, and the impact of parasite infection on whooping crane populations is largely unknown. Disease ecology and epidemiology research of endangered species is often hindered by limited ability to conduct invasive sampling on the target taxa. Accordingly, we hypothesized that sandhill cranes (Grus canadensis) would be a useful surrogate species to investigate the health impacts of Haemosporida infection in whooping cranes. Our goal was to compare the prevalence and diversity of Haemosporida infection between whooping cranes and sandhill cranes. We detected an overall infection prevalence of 83·6% (n = 61) in whooping cranes and 59·6% (n = 47) and 63·6 (n = 22) in two sympatric sandhill crane populations captured in Texas. Prevalence was significantly lower in allopatric sandhill cranes captured in New Mexico (12·1%, n = 33). Haemoproteus antigonis was the most abundant haemoparasite in cranes, present in 57·4% of whooping cranes and 39·2% of sandhill cranes; Plasmodium and Leucocytozoon were present at significantly lower levels. The high prevalence of Haemosporida in whooping cranes and sympatric sandhill cranes, with shared parasite lineages between the two species, supports sandhill cranes as a surrogate species for understanding health threats to endangered whooping cranes.