| Urbanization and human activities have not only affected habitat but also the wildlife,for instance,the structure of avian community and behavioral adaptation.Bird is a indicator species that in the research of the relationship between urbanization and wildlife.Red-Whiskered Bulbul Pycnonotus jocosus is a common and successful urban colony species in Southern China.The distribution range of Red-Whiskered Bulbul is expanded both in rural and urban area in recent years due to the flexible reproductive strategies.Thus,this work that studied the effect of artificial materials and traffic noise on the reproductive strategies of Red-Whiskered Bulbul is of great significance to understand the interaction between urbanization and birds.We investigated the reproduction of bulbuls,conducted the playback experiments with the tape of traffic noise,and studied the effect of noise on nestlings' calls phenotype and nest predation through recording and photograph around Nonggang National Nature Reserve,south China,in 2018.The results showed that:1)The breeding season of Red-Whiskered Bulbul lasted from late March to early August there,the average clutch size was about 3.21±0.46 eggs(range 2-4 eggs,n=47),which was different with the population in other regions.25%bulbuls built nests on herbaceous plants,75%on the woody plants,and the height that above the ground varied among nests(2.10±1.07m,range 0.43-5.00 m,n=56).The most frequent nest tree species was Sterculia nobililis(44.64%,n=56),a new cultivated species there.2)Artificial materials(plastic,cotton and paper)were found in 48.84%nests of Red-Whiskered bulbuls.It seemed that the presence of artificial materials had not shown adverse effect on the nest characteristic(nest volume:P=0.873;nest materials quantity:P=0.466),clutch size(P=0.129),predation(P=0.634),reproduction(P=0.795)and nest infection rate(P=0.414).But when parents birds used both plastic and cotton,or paper as nest materials,the abundance of earwig(an ectoparasite predator)increased.Bulbuls might built nests with less effort due to the abundance of artificial materials.3)Red-Whiskered Bulbul chicks adjusted their calls phenotype to the traffic noise.The minimum frequency was increased when we played the tape of traffic noise,yet,the phenomenon might be merely a physical side effect.Nestlings only called with a higher maximum amplitude when they were 5 days old(P=0.056),Lombard Effect disappeared as they grow(P=0.790).In this experiment,the effect of two three-hour noise per day on bulbul chicks are reversible.4)Begging calls provided an important cue for predators.The nests with playback of louder begging calls(mean+2 SD)were more easily detected(P=0.018).However,in the area with various predators,even the prey kept their nests quiet and odorless,they might still be predated(33.33%,n=12).Mice,the most common predator for nestlings of Red-Whiskered Bulbul,showed an avoidance for these nests with traffic noise(P=0.005).Red-Whiskered Bulbul is a successful bird species under the selection pressure of urbanization.Although our results showed that new habitats and the abiotic factors did not cause any adverse effect on Red-Whiskered Bulbul.Traffic noise had two sides,it made nest predation risk increased because noise caused nestlings called louder,on the other,noise lowered predation by mice.There were still need more studies about how birds response the urbanization environment. |
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