| The study of life history has always been a hot topic in the field of avian behavioral ecology,with a focus on understanding species differences and evolution in life history traits.Previous research has found temperature and precipitation to be significant drivers of avian life history.As global climate change poses an increasing threat,it has become increasingly important to examine the impact of temperature and precipitation changes on avian life history.Nest predation risk is another important factor driving avian life history trait evolution,and has long been a focus of research in avian biology.However,with increasing ecological complex,it is no longer sufficient to isolate the effects of biological or abiotic factors on avian life history traits.Therefore,it is an urgent need to study the combined effects of factors such as temperature,precipitation,and nest predation,on life history traits to better understand species differences and evolution in life history traits.In the early 21 st century,the life history syndrome hypothesis was proposed,leading to research focused on the correlation between individual behavior,morphology,physiology,and life history traits.Currently,most research in this field investigates the relationship between individual behavior and physiological factors such as hormone levels and the immune system.However,there is less research on the relationship between individual behavior and life history traits,and the nature of their relation remains uncertain and requires further exploration.Anti-predator behavior is crucial for bird survival and reproduction,and investigating the consistency between anti-predator behavior and life history traits can help deepen our understanding of how biological phenotypic vary,why they covary,and why phenotypic variation persists within populations.This study focused on the varied tit Sittiparus varius and aimed to explore several scientific questions related to the species’ life history parameters.Specifically,the study seek to investigate:(1)how environmental factors such as temperature,precipitation,and nest predation risk influenced varied tit life history traits such as first egg laying date,clutch size,and reproductive success rate,(2)whether the combined effect of multiple environmental factors made their impact on the varied tit’s life history traits more complex,and(3)whether there was a correlation between anti-predator behavior(as measured by flight initiation distance and nest defense strength)and life history traits in the varied tit.This study was conducted during the breeding seasons from 2017-2022 in the Xianrendong National Nature Reserve,Liaoning,China.Field investigations were carried out,and annual meteorological data were utilized to obtain the primary research findings.1.When faced with high predation risk(n = 76),the varied tit displayed an earlier first egg laying date in response to increasing environmental temperature(t =10.33,B =-13.63,SE = 4.24,P < 0.01).However,this trend was absent under low predation risk(n = 191,t = 1.78,B = 2.23,SE = 1.67,P = 0.18).2.When faced with high temperature conditions(n = 176),the varied tit displayed a later first egg laying date in response to increasing precipitation(t = 13.87,B = 14.42,SE = 3.87,P < 0.01).However,this trend was absent under low temperature conditions(n = 92,t = 2.79,B = 5.86,SE = 3.50,P = 0.09).3.When faced with low temperature conditions(n = 92),the reproductive success rate of varied tit gradually decreased as precipitation levels increased(t =34.52,B =-0.51,SE = 0.08,P < 0.01).Conversely,such a pattern was not observed under high temperature conditions(n = 176,t = 0.37,B =-0.04,SE = 0.06,P < 0.05).4.Nest predation risk was negatively related with breeding success rate(t =34.52,B =-0.87,SE = 0.08,P < 0.05).5.No significant correlation was observed between the flight initiation distance,nest defense behavior and the first egg laying date or clutch size of the varied tit.However,a positive relationship was found between flight initiation distance and reproductive success rate(n = 47,B = 0.08,P < 0.05),as well as between nest defense intensity and reproductive success rate(n = 51,B = 0.07,P < 0.01).The findings of this study suggest that temperature,precipitation,and nest predation risk can all impact the life history traits of birds.Specifically,the effects of temperature and precipitation on the life history traits of the varied tit are influenced by predation risk.Furthermore,the research confirms the consistency between some life history traits and anti-predator behavior.The study highlights the importance of conducting comprehensive studies that take multiple environmental factors into account to gain a deeper understanding of the evolution of avian life history traits.Finally,it emphasizes the need for long-term tracking investigations to validate consistency between behavior and life history traits,and the potential negative impacts of climate fluctuations on wild populations. |
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