Snails can survive passage through a bird’s digestive system

Aim Predation is generally viewed as a factor that limits the distribution of animal prey species. However, in certain instances, such as seed dispersal, predation may enhance the dispersal capability of prey species. In a prior study, we found that land snails are preyed upon by the Japanese white‐eye (Zosterops japonicus) and the brown‐eared bulbul (Hypsipetes amaurotis) in the Ogasawara Islands. In this paper we provide experimental and field evidence indicating that land snails could potentially be dispersed through bird predation. Location Hahajima Island of the Ogasawara Islands in the western Pacific. Methods Experimentation was first performed to test whether the land snail Tornatellides boeningi could remain alive after being swallowed and passed through the bird digestive system. Next, in order to investigate the potential role of internal bird transport and dispersal of this snail, we investigated the relationship between the distribution of population genetic diversity in the snail and the regional geographical abundance of predatory birds. The population genetic structure of T. boeningi and isolation by distance were inferred with Arlequin . The association between nucleotide diversity in T. boeningi populations and population density of predators was examined using a generalized linear mixed model. We conducted a likelihood ratio test for the full model and for another model that removed the fixed effect. Results Of the 119 snails fed to Japanese white‐eyes and 55 snails fed to brown‐eared bulbuls, 14.3% and 16.4% of the snails, respectively, passed through the gut alive. Additionally, one snail gave birth to juveniles after emerging from a bird’s gut. Significant heterogeneity among the populations of T. boeningi on Hahajima was indicated using AMOVA; however, there was no evidence of isolation by distance. A positive correlation was found between levels of mitochondrial DNA variation among and within T. boeningi populations and the density of Japanese white‐eyes in the wild. Main conclusions Bird predation appears to be a method of dispersal for T. boeningi, and our results suggest that bird‐mediated dispersal plays a role in land snail population structure.     

贵州宽阔水7种雀形目鸟类繁殖巢记述

2012~2016年每年的4~8月,在贵州宽阔水国家级自然保护区记录到7种雀形目鸟类的巢共20个,分别为绿翅短脚鹎(Hypsipetes mcclellandii)2巢、斑胸钩嘴鹛(Pomatorhinus erythrocnemis)2巢、灰背燕尾(Enicurus schistaceus)1巢、灰眉岩鹀(Emberiza godlewskii)4巢、褐顶雀鹛(Alcippe brunnea)3巢、褐胁雀鹛(A.dubia)7巢和黑颏凤鹛(Yuhina nigrimenta)1巢。对其巢、卵或雏鸟以及巢址等进行了描述。     

A seed parasitoid wasp prevents berries from changing their colour,reducing their attractiveness to frugivorous birds

1. Frugivorous and seed‐feeding insects may alter the traits of fruits, such as shape and size, which may influence fruit attractiveness to frugivorous birds. Consequently, trait‐mediated interactions may occur in systems where plants, seed‐dispersing frugivorous vertebrates, and frugivorous or seed‐feeding insects interact. We investigated colour manipulation in Ilex integra Thunb. berries caused by the seed parasitoid wasp Macrodasyceras hirsutum Kamijo and how that manipulation relates to fruit attractiveness for frugivorous birds. 2. In winter, the colour of I. integra berries varied from green to red, but most berries were greenish, indicating that the berries were immature. Berry dissection indicated that the number of live parasitoid larvae present within each berry was closely related to berry colour – the greater the number of live larvae, more intense is the green colour of the berry. However, the wasp larvae did not modify the shape or size of the berries. More than 98% of berries that were protected from the insects by gauze bags ripened and turned red. In the present study, berries with unfertilised seeds alone turned red. Field‐feeding preference tests showed that the brown‐eared bulbul Hypsipetes amaurotis Temminck preferred red berries to green berries. 3. We demonstrated that the seed parasitoid wasp manipulates the berry colour, but not its shape or size, in a density‐dependent manner. Because green berries suffered less from bird foraging, we believe that this colour manipulation helps the wasps to avoid being killed by the birds. The present study indicates that manipulation by wasps may reduce the level of mutualism between the tree and seed‐dispersing birds.     

Mitochondrial DNA suggests multiple colonizations of central Philippine islands (Boracay,Negros) by the sedentary Philippine bulbul Hypsipetes philippinus guimarasensis (Aves)

In this study, we have used fragments of three mitochondrial genes (Control Region, CR; transfer RNA for methionine, tRNA‐Met; NADH dehydrogenase subunit 2, ND2 for a total of 1066 bp) to reconstruct the phylogeographic history of the endemic Philippine bulbul (Hypsipetes philippinus) at the scale of the central area of the Philippine archipelago. The study includes two of the five recognized subspecies (guimarasensis and mindorensis), 7 populations and 58 individuals. Multiple phylogenetic and network analyses support the existence of two reciprocally monophyletic maternal lineages corresponding to the two named subspecies. Molecular clock estimates indicate that the split between the two subspecies is consistent with the Pleistocene geological history of the archipelago. Patterns of relationships within guimarasensis are biogeographically less clear. Here, a combination of vicariance and dispersal needs to be invoked to reconcile the molecular data with the geographical origin of samples. In particular, the two islands Boracay and Negros host mitochondrial lineages that do not form monophyletic clusters. Our genetic data suggest multiple independent colonization events for these locations.     

Habitat of the Golden Nightjar Caprimulgus eximius

The Ostrich communal breeding system involves several females laying in a single nest. Only the ‘major’ female and the territorial male, however, provide parental care from incubation to fledging of chicks. Eggs are turned and displaced frequently upon the onset of incubation, and the major female evicts excess eggs out of the nest when the number of eggs is above a specific threshold level. A previous study indicated that the major female ostrich recognises her own eggs and selectively evicts eggs of minor females based on size, shape and shell texture. Our aim was to investigate if accepted and ejected eggs differ in colour characteristics. We quantified colour by measuring egg reflectance spectra, which were subsequently analysed using a visual model approach. Within clutches, there were no significant differences in colour between accepted and ejected eggs. These results suggest that female ostriches do not discriminate against foreign eggs based on deviations in colour.     

Role of birds in dissemination of the thread blight disease caused byCylindrobasidium argenteum

The thread blight disease of broad leaved trees caused byCylindrobasidium argenteum occurred in laurel forests over 20 yr old after clear cutting in Kyushu. Finding fruit bodies of the causal fungus was possible but very difficult in the forests. In inoculation tests using spores and infected branches harvested in the forests, we succeeded in transmission only with branches. In the forests, the disease is transmitted almost entirely by contact with infected branches. During 1989 to 1992 we found four brown-eared bulbul nests containing branches infected with the disease. In one nest, mycelia of the fungus had been transmitted to the host tree. The occurrence of the disease in forests over 20-yr-old was considered to be due to the nesting of birds in trees which provided the necessary height and closed environment.