Whistle signal variations among three Indo-Pacific humpback dolphin populations in the South China Sea:a combined effect of the Qiongzhou Strait’s geographical barrier function and local ambient noise?

Geographic variations in the dolphin whistles could be useful in assessing association and isolation among populations.Whistle of free-ranging Indo-Pacific humpback dolphins(Sousa chinensis)among the Pearl River Estuary(PRE),Leizhou Bei(LZB)and Sanniang Bay(SNB)populations were investigated.A total of 2850 whistles with legible fundamental contour were extracted and 15 acoustic parameters were measured.Contrary to SNB,PRE and LZB had the same relative proportion of tonal type compositions with flat and sine representing the most frequent types.The generalized linear model analysis showed significant acoustic difference among populations and tonal types.All frequency parameters in SNB were significantly higher than those in PRE and LZB,where no significant variation was observed in most of the parameters either at the population level or within each tonal type.Canonical discriminant functions analysis showed a smaller difference between PRE and LZB than between PRE and SNB and between LZB and SNB.Compared with previous recordings,recent recordings demonstrated a consistent pattern of becoming higher in whistle frequency parameters in both LZB and SNB populations,suggesting that noise pollution in LZB and SNB increasing with time according to the acoustic niche hypothesis.Dolphin whistle’s geographic variations could be shaped by the combined function of the geographical barrier function of the Qiongzhou strait and local ambient noise.Considering the isolated condition and the relatively smaller population size of the humpback dolphin in the SNB,more effective and proactive conservation actions should be taken to prevent the extinction of small populations.

Differences and dynamics of multidimensional poverty in rural China from multiple perspectives analysis

Absolute poverty was completely eliminated in China in 2020.However,poverty measured by income does not fully reflect the actual situation.This paper analyses multidimensional poverty and its dynamics in rural China from perspectives of region,terrain,and geographical location during 2010–2018.We use the Chinese Family Panel Survey data,adopt the Alkire-Foster method and improve the multidimensional poverty index(MPI),calculating and comparing multidimensional poverty and its dynamics among 3009 rural households.In addition,the contribution of the indicator to multidimensional poverty is decomposed.The results indicate that multidimensional poverty has obvious regional differences,topographical differences,and geographical differences.Moreover,the targeted poverty alleviation policy has a significant impact on multidimensional poverty eradication,and the rate of decline of the MPI during 2016–2018 is significantly greater than that of 2010–2014.Education contributes more than 50%to the MPI.In general,the proportion of households with persistent multidimensional poverty is higher than temporary multidimensional poverty,and temporary multidimensional poverty is higher than no multidimensional poverty.These results obtained from a large scale,long time and multiple perspectives could offer new insights for the government to further consolidate the results of poverty alleviation while offering China’s experience to other developing countries.

Wing morphology covaries with migration distance in a highly aerial insectivorous songbird

According to classical prediction of aerodynamic theory,birds and other powered fliers that migrate over long distances should have longer and more pointed wings than those that migrate less.However,the association between wing morphology and migratory behavior can be masked by contrasting selective pressures related to foraging behavior,habitat selection and predator avoidance,possibly at the cost of lower flight energetic efficiency.We studied the handwing morphology of Eurasian barn swallows Hirundo rustica from four populations representing a migration distance gradient.This species is an aerial insectivore,so it flies extensively while foraging,and may migrate during the day using a‘fly-and-forage’migration strategy.Prolonged foraging flights may reinforce the effects of migration distance on flight morphology.We found that two wings’aerodynamic properties—isometric handwing length and pointedness,both favoring energetically efficient flight,were more pronounced in barn swallows from populations undertaking longer seasonal migrations compared to less migratory populations.Our result contrast with two recent interspecific comparative studies that either reported no relationship or reported a negative relationship between pointedness and the degree of migratory behavior in hirundines.Our results may thus contribute to confirming the universality of the rule that longer migrations are associated with more pointed wings.