| The growth and development of altrices nestlings depend entirely on parental rearing behavior,requiring parents to invest a lot of time and energy,which may affect the survival and reproductive opportunities of the parents,so parents adopt different reproductive strategies to maximize return of their reproductive.The ecological environment of breeding area is one of the most important factors that affect parental reproductive strategy.Parents will adjust their reproductive strategies according to the ecological environment of breeding areas,such as reproductive investment and feeding strategy.Totally monitored 23 effective nests in Lanius isabellinus.The average clutch size is 5.12 ± 0.66,and the average brood size is 3.70 ± 1.33,the hatching rate is 69.00% and the fledging rate is 96.53 %.T test shows that the number of clutch size is significant larger than the brood size(t = 6.255,df = 24,p < 0.001),but there is no significant difference between brood size and fledgling number(t = 1.365,df = 24,p = 0.185).The rate of parental feeding is a standard to measure the parental reproductive devotion.The results showed that the feeding rate of the male parent was significantly higher than that of the female parent(t = 7.68,df = 270,p < 0.001).There was a significant change in the feeding rate of male and female parents during the incubation period.With the increase of the daily age,the feeding rate of the male parent decreased,while the female parent's feeding rate increased.The female parent's initial investment was mainly warm chicks,and the feeding rate increased with the increase of nestling age,while the male parent's feeding rate tended to decrease.This indicates that the Rufous-tailed Shrike has evolved different division of labor patterns to relieve reproductive pressure,and to adapt to the desert environment,males have higher reproductive input.As the number of nestlings increased,the feeding rate of male and female parents increased and the size of feeding food increased.At the same time,the fitting results of the body weight growth curve showed that there was no significant difference between the growth rate and the expected flying weight of the nestlings.Thisindicates that the number of litters in the Rufous-tailed Shrike will increase in order to ensure the maximum output.The visiting and feeding position of parents have far-reaching influence on nestling's begging behavior.The results of the analysis of the feeding position show that the position selected by the parents is predictable and relatively fixed.The results of the nestling obtaining location analysis showed that: nestlings on the straight direction for food frequency and direction on both sides have significant difference(Wilcoxon signed rank test: n = 22,Z = 4.107,P <0.001),more parents tend to pass food to straight line direction on chicks,among them,the nestlings nearest parent get the most food,nesting on both sides get food accounted for 23.34% during the total begging time.The feeding position of parents of the Rufous-tailed Shrike is relatively fixed and predictable,and the best obtaining location of nesting is relatively fixed.The distribution of nestlings in Rufous-tailed Shrike nests is mainly achieved by the best competition position among nestlings.Nestling begging intensity can measure the intensity of competition within the nest compatriots,when the number of nests and age of nestlings increases day by day,the nestlings will improve their begging intensity to get more food,and the earlier the nestlings are hatched,the more intensive begging they will be.The nestlings also weigh the energy they consume and gain,and adjust the begging intensity of the food flexible.The Asynchronous hatching strategy,which influence the nestling's begging intensity of Rufous-tailed Shrike,makes the nestlings in the nest of body condition level difference,The earlier hatching of nestlings have the higher feeding rate,the better body condition,but the most late hatch nestlings for feeding rate is the lowest food obtain and the highest mortality rate.The study of the weight growth curves of different hatching order of Rufous-tailed Shrike show that there is no significant difference in weights(N =5,f = 0.53,p = 0.93),but the time of arrival of the nestlings in the maximum growth rate is positively correlated with the order of hatching(N = 5,f = 0.900,p = 0.037).This shows that the competition of the Shrike siblings is relatively weak,and the order of food intake in turn weakens the grade difference caused by the hatching order,thus increasing the reproductive output of each litter.In short,in the desert environment,the male of Rufous-tailed Shrike has higher feeding investment.When the nestlings increase,the parents will increase their feeding rates.The nestlings of Rufous-tailed Shrike will adjust their begging state according to the begging intensity of their compatriots,and reduce the competition in the nests,thusincreasing the reproduction output of the nest. |
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