Temporal patterns of three sympatric pheasant species in the Nanling Mountains: N-mixture modeling applied to detect abundance

Background:The reliability of long‑term population estimates is crucial for conservation and management purposes.Most previous studies assume that count indices are proportionally related to abundance;however,this assumption may not hold when detection varies spatially and temporally.We examined seasonal variations in abundance of three bird species(Cabot’s Tragopan Tragopan caboti,Silver Pheasant Lophura nycthemera,and Whitenecklaced Partridge Arborophila gingica)along an elevational gradient,using N‑mixture models that take into account imperfect detection in our bird data.Methods:Camera‑trapping was used to monitor temporal activity patterns of these species at Guangdong Nanling National Nature Reserve from December 2013 to November 2017(4 seasons per year).For abundance analysis(N‑mixture modeling),we divided a year into 4 seasons,i.e.3 months per season,and performed the analysis by season.Elevation was incorporated into the N‑mixture model as a covariate that may affect abundance.We compared the N‑mixture model with a null model(no covariate model)and selected the better model based on AIC values to make an inference.Results:From 24 sampling sites,we obtained 6786 photographs of 8482 individuals of 44 bird species and 26 mammal species.Silver Pheasant was photographed much more frequently and showed higher temporal activity frequency than White‑necklaced Partridge or Cabot’s Tragopan.Silver Pheasant was camera‑captured most frequently in summer,and other two species in winters.All three species had two daytime activity peaks:between 6:00 a.m.and 10:00 a.m.,and between 5:00 p.m.and 7:00 p.m.,respectively.Our estimated abundance and detection probability from the N‑mixture model were variable by season.In particular,all three species showed greater abundance in summer than in winter,and estimated abundance patterns of all three species were more similar with observed cameratrapping counts in summers.Moreover,in winter,elevation had a positive impact on abundance of Silver Pheasant and Cabot’s Tragopan,but not on White‑necklaced Partridge.Conclusions:Our results demonstrate that the N‑mixture model performed well in the estimation of temporal population abundance at local fixed permanent plots in mountain habitat in southern China,based on the modeling of repeated camera‑trapping counts.The seasonal differences in abundance of the three endemic bird species and the strong effect of elevation on abundance of two species in winter were only indicative of variations in spatio‑temporal distribution within species and between species.In identifying suitable habitat for endemic pheasants,the positive elevational effect also suggests that more attention should be paid to conservation of areas with higher elevation in the Nanling Mountains.

Distribution of birds in the high-altitude area of Mount Everest

INTRODUCTION The Himalayas includes the world’s highest peak,Mount Everest(8848 m),and the altitude gradient of the southern slope of the mountain range changes rapidly,from Mount Everest to 100 km south,with the habitat shifting from glaciers to tropical rain forests at altitudes below 1000 m.This area is a global hotspot for bird distribution(Orme et al.2005),and the area is home to one of the highest concentrations of threatened birds in Asia.(Acharya&Vijayan 2010).Bird diversity research in this area has revealed that the eastern Himalaya mountain range,south slopes,and mid-lower altitude areas have higher levels of bird diversity than the western Himalaya mountain range,north slopes,and high-altitude areas,respectively(Acharya et al.2010,2011;Price et al.2011;Wang et al.2013;Romanov et al.2016).In addition,the adaptability of birds to high-altitude areas,such as the enhancement of the oxygen transport capacity of the Barheaded Goose(Meir&Milsom 2013)and changes in the flight characteristics of vultures(Sherub et al.2016)have also been investigated.However,most of these studies were carried out at altitudes below 5000 m.For the mountain range with the highest peak,at 8848 m,there are very few studies on the birds in large areas above the snow line,and bird data at very high altitudes mainly come from the sporadic records of early climbers(Swan 1961,1970).

Bird community comparisons of four plantations and conservation concerns in South China

Plantations of non-native,fast-growing trees are increasing in the tropics and subtropics,perhaps with negative consequences for the native avifauna.We studied bird diversity in 4 types of plantations in South China to deter-mine which plantation types are especially detrimental,and compared our findings with studies in nearby natu-ral forests to assess the magnitude of the negative impact.A total of 57 species was recorded.The mean capture rate of understory birds was 1.7 individuals 100-net-h-1.Bird richness and capture rate were lower in plantations than in nearby natural forests.Babblers(Timaliidae),primarily forest-dependent species in South China,were particularly under-represented in plantations.Species richness,composition and bird density,particularly of un-derstory birds,differed between plantation types.Plantations of Schima,which is native to South China,had the highest species richness according to point count data.Plantations of Acacia(non-native)supported the highest understory species richness and produced the highest capture rate of understory birds,probably because of their complex structure and high arthropod abundance.If bird diversity is to be considered,we strongly recommend that future re-afforestation projects in South China should,as far as possible,use mixed native tree species,and especially Schima,ahead of the other species.

Comparative urbanization of birds in China and Europe based on birds associated with trees

Urbanization effects on living organisms are spatially heterogeneous.Here we quantified the abundance of birds per tree in forested urban and rural habitats for 85,829 trees mainly in China and Europe.A population model was based on the assumption that:1)birds have a normally distributed habitat preference;2)an increase in population size linked to the habitat preference;3)a population size dependent on the habitat preference;and 4)the removal of a certain fraction of individuals giving rise to extinction.We tested for large-scale differences in the impact of urbanization on the frequency distribution of the difference in abundance between urban and rural habitats in China and parts of Europe.The difference in the frequency distribution of urban population density of birds in trees minus rural population density of birds in trees in China and Europe was statistically significant suggesting that the abundance of birds differed between trees in urban and rural habitats,but more so in China than in Europe.We hypothesize that more pronounced differences in China than in Europe may have arisen due to the Four Pests Campaign in 1958-1962 that resulted in death of hundreds of millions of birds(mainly tree sparrows Passer monfanus,but also numerous other less common species that were starting to become urbanized around 1960).Species that were less common in 1960 could not sustain reductions in population size in urban areas and hence these species are still rare or absent in urban areas today 60 years later.

Effects of ice storm on species richness and abundance of resident birds in subtropical forest in southern China

Between January and February 2008,a severe ice storm occurred in southern China.The storm damaged nearly 21 million hectares of forest lands with broken branch,trunk breakage,and stem bending of many trees.This natural disturbance provides a unique opportunity to study impacts of extreme climatic event on forest birds.Using hierarchical multi-species occupancy model(species richness;27 species)and N-mixture model(abundance;3 species),we investigated how the storm affected resident bird species in subtropical forest in southern China.We sampled birds at Chebaling National Nature Reserve in Guangdong Province,monthly for 1 year each before and after the storm by mist nets.To take into account variations in temperature between years and between months,we incorporated monthly mean temperature into the models as an additional covariate.Observed species richness was greater before the storm.Estimated species richness(from the hierarchical model)also tended to be greater before than after the storm although 95%Bayesian credible intervals of these estimates were overlapped.Temperature showed a negative effect on estimated species richness,indicating greater species richness during winter.Among three species captured the most,abundance of Chestnut Bulbul(Hemixos castanonotus)significantly decreased after the storm.Other two species,Grey Treepie(Dendrocitta formosae)and Huet’s Fulvetta(Alcippe hueti)showed insignificant responses to the storm.Our study indicates that the 2008 ice storm may not have a significant impact on species richness of resident birds in subtropical forest;however,the effect can be species-specific and negative to some species’population.

Lineages differentiation and population structure of the light-vented bulbul Pycnonotus sinensis in China based on mitochondrial DNA and microsatellite analysis

The light-vented bulbul Pycnonotus sinensis is a small resident passerine that is found widely in central and south China,North Vietnam,and some East Asian islands,including Hainan,Taiwan and the Ryukyu Islands.Its subspecies status has been under considerable debate.A total of 10 subspecies have been proposed,but only 4 are widely recognized,including 1 continental taxon,P.s.sinensis,and 3 insular subspecies:P.s.hainanus,P.s.formosae and P.s.orii.Two mitochondrial DNA genes and 9 microsatellite loci were used to investigate the genetic divergence of this species,to identify the evolutionary status of 2 insular subspecies(P.s.hainanus and P.s.formosae)and to uncover probable historical causes that shaped them.The results reveal that P.s.formosae has diverged significantly from the other 2 subspecies because of a substantial time of isolation for populations on Taiwan Island.There was no significant genetic differentiation between P.s.sinensis and P.s.hainanus.The notable morphological difference in P.s.hainanus might be attributed to a rapid,recent adaptation to the tropical environment of Hainan Island.The low genetic divergence between P.s.sinensis and P.s.hainanus might result from a recent divergence or gene flow between them.Two insular subspecies of light-vented bulbul populations might have diverged recently from their continental relatives through a complex evolution history owing to island isolation,ecological isolation,and possibly even hybridization.Both P.s.hainanus and P.s.formosae should be considered important conservation units because of their morphological and genetic distinctiveness.