| Parental care of birds is ostensibly a collaboration between parents,but it is a source of conflict.Because the considerable energy consumption during the reproductive stage reduces the survival and future reproductive chances of the parents,the parents want to shift the burden of parental care to the partner and benefit from it.So,the investment in parental care is the result of a trade-off between parents,and when one parent's investment decreases or disappears altogether,how the other response to a change in the original balance is a topic of great interest to behaviorists.For this reason,from march to July 2019,the removal experiment was conducted on random single parents of the great tit for simulating the change of chick input of the remaining parent by video recording the nest boxes.In terms of understanding the degree of compensation,and the parents brooding strategy changes after the returning the great tit,this article analyzes the changing of the great tit parental rearing behaviour,and the differences in the frequency of raising young,the proportion of feeding species,and the frequency of removing faeces of the remaining great tits after parent removal.Meanwhile,great tits cooperative breeding behaviour was observed.The results are as follows:1.Comparison of parental input in the great titA total of 24 nest-parent rearing behaviours were recorded from 7:00 am to 10:00 am at the age of 10 days.After extracting the feeding frequency and feeding type of each parent bird video,as well as the number of times removing feces,the paired t-test was used to compare the frequency of raising chicks and the number of removal of feces between male and female parents.The chi-square test analyzed the ratio of adult and larval feeding.The results showed that males and females had the same feeding frequency and removal feces times(Feeding frequency: t=1.428,df=23,P=0.167;Number of removal of feces: t=1.221,df=23,P=0.235),However,the proportion of larvae in the diet of females was significantly higher than that of males(P<0.000).So,when great tits raise chicks in their natural state,both parents invest the same effort in raising chicks and removing feces,but female supply higher food quality than males.2.Male compensation type analysisA total of 24 nests of great tits were recorded,including 13 nests for removing the males and 11 nests for remove the females.The recording time is 7:00-10:00 am when the chicks are 11 days old.Compared the data on 11 days' single parenting with 10 days' two parents,males have a higher frequency of raising their young when removing their partners(t= 3.706,df=9,P=0.03).There was no significant difference in the total frequency of parental rearing(t=0.653,df=12,P=0.526).The same results were obtained after removal of feces(Remove fecal count when raising chicks by a single parent and Remove fecal counts when raising chicks by both parents: t=5.007,df=12,P<001,the number of feces removed by a single male and the total number of feces removed by both male and female: t=0.577,df=9,P= 0.578).The same results were obtained for the larval portion of the diet(P=0.632).Therefore,in the process of raising chicks by a single parent,male great tit raised the frequency of raising chicks and the number of feces removed,improved the quality of feeding ingredients,which fully compensated for the reduced input caused by female removal.3.Female compensation type analysisCompared the data of 11 days' single-parent rearing with that of 10 days' two-parent rearing,females raise their young more frequently when they are raised by a single parent(t=3.458,df=10,P=0.006).There was no significant difference in the total frequency of parental rearing(t=1.158,df=10,P=0.274).The same results were obtained after removal of feces(Fecal quantity removed when raising chicks by a single parent and fecal quantity removed when raising chicks by both parents: t=4.869,df=10,P=0.001.The number of feces removed by a male single parent and the total number of feces removed by male and female: t=1.175,df=8,P=0.274).The proportion of larvae in feeding was significantly lower than that in parental rearing(P<0.000).The results show that: Females fully compensate for the reduced input lost to females in terms of the frequency of raising young and the number of faeces removed,but the quality of feeding is reduced.4.The brooding strategy of the great tit after the parent returnsA total of 24 great tits were recorded,raising their young after parental removal and return.The recording time is during 7:00 and 10:00 am when the chicks are 12 days old.The brood frequency(Frequency comparison of male brooding: t=0.318,df=9,P=0.758;Frequency comparison of female brooding: t=1.268,df=8,P=0.240)?Number of removal of feces(Comparison of the number of feces removed by males: t=1.784,df=9,P=0.108;Comparison of the number of feces removed by females: t=0.308,df=8,P=0.766)was no significant difference before removal after returning the removed parent.The result suggests that the great tit quickly adjusts to its original brooding strategy.5.The first discovery of cooperative breeding of great titsAfter analyzing the chick-rearing behaviour of a total of 28 great tit nests,in three of the nests,three adult great tits shared a breeding nest,and each individual fed the chicks several times.This is the first time that the cooperative reproduction of great tit has been found. |
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