Study On The Breeding Ecology And Environmental Adaptability Of Ardea Cinerea

Ardea cinerea belongs to Ardeidae of Ardea family,which is a very common wading bird in Eurasian and African wetlands.A.cinerea is widely distributed in China,almost all over the country.Before 2010,A.cinerea bred in Northeast China and overwintered in south-central China and they were common winter migratory birds in Henan Province.After 2010,A.cinerea overwinter in the whole wetland of the Yellow River in Henan Province.In spring and summer,more than 100 individuals breed in the National Nature Reserve of Yellow River Wetland Birds in Xinxiang every year,nesting in reeds and forming a stable breeding population.The A.cinerea in the reserve has changed from winter migratory bird to resident bird.Although there have been some reports on the breeding ecology of A.cinerea,the research is mainly carried out in their original breeding areas.So far,the reproductive ecology of A.cinerea in wintering areas has not been studied yet.In order to understand the reproduction situation of A.cinerea in the Yellow River Wetland Bird National Nature Reserve in Xinxiang and their adaptation to the environment,a series of studies have been carried out in the Chenqiao Wetland in the reserve.The reproduction situation of A.cinerea was observed and studied in detail from February 2016 to October2018.During the three-year observation period,58,74 and 81 pairs of breeding A.cinerea were observed,respectively.Research methods:1.Observed the reproduction and foraging behavior of A.cinerea directly with telescope,and recorded the exact time and environmental temperature of all kinds of behavior.2.The following nest data were measured after the boat approached the nest:nest outer diameter,nest inner diameter,nest height,nest depth and environmental factors of nest area:water depth around nest,water distance around nest,distance between nest and village,distance between nest and road,distance between nest and farmland,reed height around nest,reed coverage around nest,reed diameter around nest,reed density around nest.3.Set up nest control area and measured its environmental factor data(the data were the same as nest area).4.The number of nest eggs,egg diameter,egg weight,hatching number and survival number were recorded,and the growth value of nestlings was measured.5.The quadrats were set up to investigate the food richness of A.cinerea.6.The measured data were analyzed by SPSS13.0 to study the nest site selection of A.cinerea.7.Compared the results with the reproduction of A.cinerea in different areas,the environmental adaptability of herons was discussed.Result:1.Occupying area,courtship and mating:Every year in mid and late February,A. cinerea flied from the Yellow River wetland in Xinxiang to the Chenqiao wetland one after another.Male birds had occupying area behavior,but the process was short.When courting,males showed themselves to females and combing feathers for female birds.The mating activities were usually 4:00~8:00 in the morning and 14:00~16:00 in the afternoon.2.Nesting:After successful matching,both males and females took local materials to build nests together.Began nesting in reeds at the end of February.According to observation,the nesting period was6-9 days.With the increase of nesting days,the number of daily sampling increased.There were two peaks in the number of daily sampling:7:00~9:00 and 15:00~17:00.The nest of A.cinerea was shallow disc and rough in structure.Nest material included reed stems and leaves,grass roots,branches,plastics,cloth strips,nylon rope and so on.Nest data:the outer diameter of the nest was 54.36�7.65 cm,the outer diameter was47.34�6.78 cm,the inner diameter was 40.4�6.29 cm,the inner diameter was 35.23�5.58 cm,the height of the nest was 55.7�9.94 cm and the depth of the nest was 11.35�3.23 cm.The results of single sample T test for nest data showed that the sig values of both sides were>0.05,and there was no significant difference between the sig values of 2016,2017 and 2018 and the overall mean.Data of environmental factors in nest area:water depth around nest was 161.55�52.39 cm,water distance around nest was 34.79�29.38 m,distance between nest and village was 284.13�178.58 m,distance between nest and road was98.98�46.53 m,distance between nest and farmland was 234.76�89.75 m,reed height around nest was91.7�15.83 cm,reed coverage around nest was 62.8�14.38%,reed diameter around nest was 4.91�0.19mm,reed density around nest was 115.75�17.55 P/m~2.The data of environmental factors in the control area were as follows:the water depth around the nest was 105.49�35.98 cm,the water distance around the nest was 15.78�7.34 m,the distance between the nest and the village was 312.35�114.66 m,the distance between the nest and the road was 122.69�47.66 m,the distance between the nest and the farmland was293.98�91.74 m,the height of the reed around the nest was 89.63�13.79 cm,the coverage of the reed around the nest was 62.99�13.53%,the diameter of the reed around the nest was 4.93�0.24 mm,and the density of reed around nest was 117.53�15.99 P/m~2.3.Nest site selection:The results of principal component analysis(PCA)of environmental factors data of A.cinerea nest area in Chenqiao Wetland showed that there were significant correlations among 9 variables in the nest site selection.The cumulative variance of the first four common factors accounted for 70.89%and the eigenvalues were greater than 1,which could explain 70.89%of the influencing factors of A.cinerea nest selection.The larger absolute value of the factor load was the data of the distance between nest and farmland,the distance between nest and village,the water depth around nest,the distance between the nest and the water in the first principal component.Therefore,the 4 data with higher absolute value of factor load were the main influencing factors in the A.cinerea nest site selection of Chenqiao Wetland.Comparisons between nest and control areas showed that A.cinerea were selective to nest sites.In the comparison of factor data between nest area and control area,the most significant differences were the distance between nest and road,the depth of water around nest,the distance between nest and farmland.Therefore,the distance between the nest and the road,the depth of water around the nest,the distance between the nest and the farmland were the main factors for nest site selection.In the two analysis results,the depth of water around the nest,the distance between the nest and the farmland were the main factors affecting the nest site selection of A.cinerea.4.Spawning,hatching and brooding:The spawning time span of A.cinerea population was very long,beginning on February 27 at the earliest and March 19 at the latest.Generally,they laid eggs in the morning and the next day.The A.cinerea began to hatch after laying its first egg,while the female hatched while laying eggs.The incubation period lasted from 24 to 27 days.The A.cinerea was a late adult bird with a brooding period of 30 to 50 days.The brooding process could be divided into three stages:the early stage,the middle stage and the late stage according to the growth of the chicks.In brooding,parent birds vomited to feed their chicks.The nest egg number,hatching number and survival number(n=80)of A.cinerea in Chenqiao Wetland were 3.54�1.01,3.14�0.88,2.79�0.85,respectively.The hatching rate was88.69%,the survival rate was 88.84%,and the reproductive success rate was 78.80%.And the measured egg data(n=283)were as follows:the egg length was 61.61�5.11 mm,the egg short diameter was 45.78�3.04 mm,and the egg weight was 60.45�4.45 g.The results of single-sample T-test of nest egg number,hatching number,survival number and egg data showed that there was no significant difference between reproductive efficiency and years.After flied out,A.cinerea nestlings lived around their parents'habitats,and then fed and survived on their own.When winter came,part of A.cinerea in the population overwintered in the Chenqiao wetland.More A.cinerea would choose to disperse in the whole Yellow River wetland to spend the winter.When the breeding season came again,A.cinerea would concentrate on the wetland of Chenqiao Town to breed.5.Feeding habits and food richness:It was found that the food of A.cinerea was mainly small fish,shrimp,frog and insect by observed the foraging behavior of parent birds and analyzed the food fragments of nestlings directly.The food richness of A.cinerea in Chenqiao Wetland showed that the main food were Misgurnus anguillicaudatus Cobitis sinensis,Abbottina rivularis,Opsariichthys bidens,Hypophthalmichthys molitrix,Pelteobagrus fulvidraco,Carassius auratus,Rhodeus sinensis G�nther,Pseudorasbora parva,Monopterus albus,Cyprinus carpio,Ctenopharyngodon idellus,Aristichthys nobilis,Rana limnocharis Boie,Rana chensinensis,bufo gargarizans,Shrimp,snails,shellfish and aquatic insects.6.Comparison of reproductive ecology in different regions:1)The reproductive initiation time of A.Cinerea in different regions was quite different,but the temperature of different regions was similar when the same behavior occurs.2)The size of nest was not directly related to latitude,but the depth of nest deepened with the increase of latitude.At similar latitudes,the nest size of terrestrial A.cinerea was larger than that of arboreal A.cinerea.Among all terrestrial nests,the nest size of Chenqiao Wetland was the smallest.3)The nest egg number,hatching number and survival number of A.cinerea in Xinxiang Yellow River Wetland were higher than those in other areas,and the eggs were larger and heavier than those in other areas.By comparing reproductive data,it was confirmed that A.cinerea has good environmental adaptability and reproductive status in Xinxiang Yellow River Wetland.