Effect of frugivorous birds on the establishment of a naturally regenerating population of Chinese yew in ex situ conservation

The Chinese yew Taxus chinensis is catalogued as an endangered species in China because of the small size andsenescent status of most populations. Its lack of natural regeneration is the most important reason for its endangeredstatus. We investigated the regeneration of an ex-situ conservation population, which was introduced intothe Nanjing Botanical Garden Memorial Sun Yat-Sen in the 1950s, and evaluated the role of frugivorous birds on theestablishment of this regenerating population. Two hundred and thirteen individual yew seedlings and saplingswere found on the hillside in 2006, and the nearest seedling was found more than 10 m away from mother trees. Thespatial pattern of all seedlings and saplings occurred as a clumped distribution, which is typical for vertebratedispersedplants. Six bird species were seen ingesting whole “fruits” at yew trees in the present study and 745 visitsby avian frugivores were recorded. Red-billed blue magpie (Urocissa erythrorhyncha), Chinese bulbul (Pycnonotussinensis) and azure-winged magpie (Cyanopica cyana) were the most frequent visitors over the two years of thestudy. Comparing the flights of departure and perching habitats of the three main bird species, we inferred that U.erythrorhyncha would be the most important disperser. This regeneration population has had good developmentover the past 20 or more years;frugivorous birds have removed seeds to the hillside every year until now, and seedgermination and seedling growth continue to develop well under natural conditions. We suggest that the conservationsystem of the Chinese yew should be composed of yews, avian dispersers and habitats for seed germinationand seedling growth.

Endozoochory of frugivorous birds as potential dispersal of seed parasites from Pistacia chinesis:experimental evidence

The plant-disperser-fruit pest triads involve 3 interacting animals or groups(plants,vertebrates and seed parasites),and the dispersal of both seeds and seed parasites,which can both benefit from endozoochory via defecation or regurgitation by frugivorous vertebrates.However,we have very limited knowledge about the ecological and evolutionary consequences of these plant-disperser-fruit pest triads.Across central Northern China,several seed wasps(mainly Eurytoma plotnikov attack Pistacia chinensis fruits,and seed wasp larvae can develop,diapause and finally emerge as adults inside a seed during the following 1-3 years.In this study,we experimentally investigated whether frugivorous birds discriminated P.chinesis fruits with or without seed parasites,and whether bird endozoochory(by defecation or regurgitation)affected larval survival of seed parasites.The infestation rate by seed parasites was 37%of the P.chinesis fruit crop but with up to 48%of aborted fruits.We found that all 5 bird species can discriminate and then reject all unhealthy fruits(including aborted and insect-infested).However,4 of the 5 bird species,in particular bulbul species,consumed 15-41%of aborted and insect-infested fruits as complementary food only when these unhealthy fruits were provided.Moreover,all larva of seed parasites remained alive after bird defecation or regurgitation.In conclusion,our study demonstrates that endozoochory by frugivorous birds could lead to potential dispersal of seed parasites of P.chinensis but with a very low probability.

Dispersal of invasive Phytolacca americana seeds by birds in an urban garden in China

Although seed dispersal is a key process determining the regeneration and spread of invasive plant populations,few studies have explicitly addressed the link between dispersal vector behavior and seedling recruitment to gain insight into the invasion process within an urban garden context.We evaluated the role of bird vectors in the dispersal of pokeweed(Phytolacca americana),a North American herb that is invasive in urban gardens in China.Fruiting P.americana attracted both generalist and specialist bird species that fed on and dispersed its seeds.The generalist species Pycnonotus sinensis and Urocissa erythrorhyncha were the most frequent dispersers.Seedling numbers of P.americana were strongly associated with the perching behavior of frugivorous birds.If newly recruited bird species use seedling-safe perching sites,the P.americana will regenerate faster,which would enhance its invasive potential.Based on our observations,we conclude that the 2 main bird vectors,P.sinensis and U.erythrorhyncha,provide potential effective dispersal agents for P.americana.Our results highlight the role of native birds in seed dispersal of invasive plants in urban gardens.

Onto the sense of smell in macaws, amazons and toucans: can they use volatile cues of fruits to make foraging decisions?

Over the past decades,empirical evidence has been accumulated indicating that olfactory information plays a fundamental role in bird life history.Nonetheless,many aspects of avian olfaction remain poorly understood.Our purpose was to broaden the knowledge about the importance of the sense of smell in some neglected bird groups:psittaciformes and ramphastids,and to compare how the response varied between the species.Because of the lack of information about the use of chemical cues for locating food in fruit-eating species,we also aimed to delve into this question.We conducted a 3-choice(water/vinegar/papaya and banana juice)scent test in 5 Costa Rican native species:scarlet macaw(Ara macao),red-lored amazon(Amazona autumnalis),yellow-naped amazon(Amazona auropalliata),keel-billed toucan(Ramphastos sulfuratus),and yellow-throated toucan(Ramphastos ambiguus).Results revealed that macaws and toucans allocated significantly more time to interacting with the fruit scent container,indicating that these species can perceive the volatile chemicals emitted by ripe fruits and that they can use this information to make foraging decisions.However,amazons did not dedicate more time to interact with the fruit treatment.Our research provides thefirst evidence of the ability to exploit chemical volatile cues in macaws and toucans.

Inter-specific and intra-specific variability in fruit color preference in two species of Turdus

One of the main hypotheses proposed to explain the evolution of fruit color deals with a preference of avian frugivores for specific colors,mainly black and red,which are the most common fruit colors in many of the studied habitats.I analyzed fruit color preferences by wild birds belonging to 2 species of the highly frugivorous genus Turdus(Eurasian Blackbird Turdus merula Linnaeus,1758 and Redwing Turdus iliacus Linnaeus,1758)by means of captivity experiments with artificial fruits.Despite important within-individual(i.e.temporal)and among-individual variability,consistent patterns of species-specific color preferences emerged.Eurasian Blackbirds tended to prefer red over blue,green and black,whereas Redwings seemed to prefer black over the rest.Green was systematically avoided by both species,suggesting that it might signal unripeness of fruits.Both preferred colors have been previously reported as the most common among fleshy-fruited plants.The high variability,both within and between individuals,in preferences suggests that they can be subject to changes through experience and learning and,therefore,are not likely to drive the evolution of fruit color.The main differences between both species could be related to the most common fruit color they fed upon during the last months before capture.