Relationship between wintering site and survival in a migratory waterbird using different migration routes.

When wintering at different sites, individuals from the same breeding population can experience different conditions, with costs and benefits that may have implications throughout their lifetime. Using a dataset from a longitudinal study on Eurasian Spoonbills from southern France, we explored whether survival rate varied among individuals using different wintering sites. In the last 13 years, more than 3000 spoonbills have been ringed as chicks in Camargue. These birds winter in five main regions that vary in both migratory flyway (East Atlantic vs. Central European) and migration distance (long-distance vs. short-distance vs. resident). We applied Cormack-Jolly-Seber models and found evidence for apparent survival to correlate with migration distance, but not with flyway. During the interval between the first winter sighting and the next breeding period, long-distance migrants had the lowest survival, independently of the flyway taken. Additionally, as they age, spoonbills seem to better cope with migratory challenges and wintering conditions as no differences in apparent survival among wintering strategies were detected during subsequent years. As dispersal to other breeding colonies was rarely observed, the lower apparent survival during this period is likely to be partly driven by lower true survival. This supports the potential role of crossing of natural barriers and degradation of wintering sites in causing higher mortality rates as recorded for a variety of long-distance migrants. Our work confirms variation in demographic parameters across winter distribution ranges and reinforces the importance of longitudinal studies to better understand the complex demographics of migratory species.

Toxoplasma gondii infection in white spoonbills (Platalea leucorodia) from Henan Province, China.

Toxoplasma gondii oocysts in the environment are a threat to humans and animals. This study is aimed to evaluate the prevalence of T. gondii in white spoonbills and isolate viable T. gondii from white spoonbills. In 28.6% (2/7) of white spoonbills, T. gondii antibodies were found in heart juice by the modified agglutination test (cut-off: 1:4). T. gondii DNA was detected in tissues of 42.9% (3/7) white spoonbills. One viable T. gondii strain, named TgSpoonbillCHn1, was isolated from the myocardium of a white spoonbill by bioassay in mice. DNA extracted from TgSpoonbillCHn1 tachyzoites was characterized by PCR-restriction fragment length polymorphism with ten markers and the virulence genes ROP5 and ROP18. The results revealed that it was ToxoDB#2 (Type III). The ROP18/ROP5 genotype combination predicts that this strain is avirulent for mice, which is supported by the infection experiments in mice. This is the first report of the isolation of viable T. gondii strain from white spoonbil. The prevalence of T. gondii in white spoonbills may be indicative of environmental contamination of oocysts. This report provides direct evidence of white spoonbill as an intermediate host of T. gondii.

Unexpected dietary preferences of Eurasian Spoonbills in the Dutch Wadden Sea: spoonbills mainly feed on small fish not shrimp.

After an historical absence, over the last decades Eurasian Spoonbills Platalea leucorodia leucorodia have returned to breed on the barrier islands of the Wadden Sea. The area offers an abundance of predator-free nesting habitat, low degrees of disturbance, and an extensive intertidal feeding area with increasing stocks of brown shrimp Crangon crangon, the assumed main prey of P. leucorodia leucorodia. Nevertheless, newly established and expanding colonies of spoonbills have surprisingly quickly reached plateau levels. Here we tested the often stated assertion that spoonbills mainly rely on brown shrimp as food, by quantifying the diet of chicks on the basis of regurgitates and by analysis of blood isotopes using stable isotope Bayesian mixing models. Both methods showed that, rather than brown shrimp being the staple food of spoonbill chicks, small flatfish (especially plaice Pleuronectes platessa) and gobies (Pomatoschistus spp.) were their main prey. Unlike shrimp, small flatfish have been reported to be rather scarce in the Wadden Sea in recent years, which may explain the rapid saturation of colony size due to food-related density-dependent recruitment declines of growing colonies. By way of their diet and colony growth characteristics, spoonbills may thus indicate the availability of small fish in the Wadden Sea. We predict that the recovery to former densities of young flatfish and other juvenile/small fish in the Wadden Sea will be tracked by changing diets (more fish) and an increase in the size of Eurasian Spoonbill colonies across the Wadden Sea.