Importance of microhabitat selection by birds for the early recruitment of endangered trees in a fragmented forest

Background:Remnant microhabitats are important for bird habitat selection and plant regeneration in the fragmented habitat.However,empirical information on the consequences of how microhabitat use by birds affects the early recruitment of plants is lacking.Methods:In this study,we evaluated whether microhabitat selection by the Black Bulbul(Hypsipetes leucocephalus)(J.F.Gmelin,1789)impacts the early recruitment of the endangered tree species,the Chinese Yew(Taxus chinensis(Pilger)Rehd),in a fragmented forest over a 4-year period(2011–2012,2018–2019).Results:Our results showed the main factors affecting H.leucocephalus microhabitat selection were distance to the nearest T.chinensis mature tree,herb cover and density,leaf litter cover,and vegetation type.Moreover,the results of logistic regression also highlighted the importance of elevation,distance to light gap and roads,tree cover in bird microhabitat selection.Furthermore,the seed emergence rate in microhabitats used by birds did not differ from the natural forest,which was related to five factors of bird microhabitat.The Random Forest model showed that seedling emergence rate was increased with leaf litter cover and distance to fallen dead trees,but decreased in relation to herb cover,slope,and elevation.Conclusion:Our results highlight the importance of remnant microhabitats in fragmented forests for sustaining forest ecology and optimal management.The contribution of microhabitats used by birds to plant recruitment provides insights into how frugivore species contribute to plant regeneration,which should be incorporated in future conservation and management practices of fragmented forests.

Brightness of melanin-based plumage coloration is a cue to oxidative stress in Himalayan Black Bulbuls(Hypsipete leucocephalus nigerrimus)

Background: Melanin?based coloration is often found to be associated with variations in physiological and behavio?ral traits that are essential in avian communication.However,the function of melanin?based traits to their bearers has been investigated less than that of carotenoid?based ones.It is commonly believed that expression of melanin?based pigmentation is genetically controlled.However,whether it could be modulated by physical condition has remained controversial.In this study,we demonstrate that the level of melanin?based plumage pigmentation could be nega?tively correlated with an individual's oxidative stress level.Methods: In this study,we used two groups of Black Bulbuls(Hypsipetes leucocephalus nigerrimus) obtained from a pet?shop in 2010 and 2011 to examine the correlation between the melanin?based plumage coloration and the ratio of lymphocytes to heterocytes,which is an indicator of the oxidative stress experienced by an individual.Results: We found a negative correlation between oxidative stress levels and expression of melanin?based pigmen?tation on the breast and scapular feathers,but the correlation only appeared in the 2011 group,individuals of which had higher oxidative stress level and brighter plumage(i.e.more melanins) than those of the 2010 group.Conclusions: Our data suggest that melanin?based plumage could reflect an individual's physical condition in certain situations.Therefore,melanin?based plumage coloration could have a function in Himalayan Black Bulbuls' communication.

Importance of plant and bird traits on the seed removal pattern of endangered trees across different forest patches in southeast China

Seed removal by birds has been recognized as an important part of seed dispersal process in patchy forest areas;however,few studies have focused on the contribution of both plant and bird traits to seed removal.In this study,field data of seed removal for Taxus chinensis was combined with the data of bird and plant traits for analysis.The relevant traits of plants and birds that influenced T.chinensis-bird interaction were identified in a remnant patchy forest in yew ecological garden,Fujian Province,southeast China.Twenty bird species were found to forage and remove the seeds of T.chinensis.The number of bird species varied in different forest patches;however,their contribution to seed removal showed no significant differences.Both bird and plant traits were found to affect seed removal.The seed removal rate was positively affected by bird traits,such as foraging frequency and wing length,but decreased with body weight.The plant traits,such as number of fruits,tree height,canopy density,and crown width,which are related to safe shelter and food resource conditions,increased the seed removal rate.Our results underline the functional importance of bird and plant traits in the seed removal from endangered trees in patchy forests.Therefore,future conservation strategies should prioritize and recognize the role of both plant and bird traits in seed dispersal in remnant patchy forests.