Nest Site Selection And Feeding Habits Analysis Of Bar-headed Geese In Yanchi Bay,Gansu

The Bar-headed Goose(Anser indicus)belongs to the Anateriformes(Anatidae).In April and June of 2018 and 2019,the nest site selection and feeding habits of bar-headed geese in the Yanchi Bay National Nature Reserve in Gansu were studied.Survey methods such as fixed-point observation,sampling,and factor determination were used.t-test,chi-square test,factor analysis,stepwise discriminant analysis,and fecal microanalysis and other processing methods,explore the key factors for the selection of nested goose nest sites and foraging rules throughout the breeding period,not only for the protected area spotted goose Habitat protection provides the basis,and also provides basic data for exploring the mechanism of bird nest selection.The main results of this study are as follows:(1)The survey of camp nest habitat selection and breeding results showed that 332bar-headed geese nests were found during the study period,and there were 3 camp nest habitats during the breeding period,namely shallow water swamps,lake islands and mountain cliffs,and their nest site types There are three kinds of haystack nest,ground nest and bare rock nest.The average nest densities in the three camping habitats of shallow water swamps,lake islands and mountain cliffs were: 0.18 nests/m2(n = 204),0.59 nests/m2(n = 108)and 0.06 nests/m2(n = 20).Bar-headed geese have obvious selectivity for the three camping habitats(P <0.01).They prefer to choose the lake nesting habitat habitat,followed by the shallow water marsh habitat,and finally the cliff habitat.The number of nest eggs in the three camping habitats of shallow water swamp,lake center island and mountain cliff were 4.7 ± 2.7(n = 204),4.2 ± 1.9(n = 108),3.1 ±0.6(n = 20);hatching success rates are: 48.65%(n = 199),45.27%(n = 148),24.00%(n= 25);breeding success rates are: 66.67%(n = 42),74.28%(n = 35),36.36%(n = 11).There was no significant difference in hatching success rate and reproduction success rate between shallow water swamps and Huxin island habitats(P > 0.05);shallow water swamp and mountain cliff habitats had significant differences in hatching success rate(P < 0.05),and there was no significant difference in reproduction success rates(P>0.05);there is a significant difference in hatching success rate and breeding success rate between the lake island and the cliff habitat(P < 0.05).(2)Comparison of nest site and control plots shows that in shallow water marsh habitats,bar-headed geese prefer to choose nest sites with smaller haystack density and cover,larger water areas,and deeper water levels;lake island habitats Barred-headed geese prefer to build nests in sites with higher vegetation density,higher vegetation,larger coverage,and less bare land and hay.In cliff habitats,bar-headed geese prefer the southeast and southwest slopes to the sunny slopes.Nests on grassy beaches and near water sources.(3)Principal component analysis shows that the main factors affecting the selection of nested goose nest sites in shallow water marsh habitats are: water source factor,hidden factor,interference factor,and food factor;the main factors affecting the selection of nested goose nest sites in lake core island habitats The factors are: hidden factor,food factor,and interference factor.The main factors that influence the selection of nesting sites of bar-headed geese in the cliff habitat are: terrain factor,food and water source factor,and interference factor.(4)Stepwise discriminant analysis shows that the most important habitat factors affecting the selection of nest sites for bar-headed geese in shallow-water swamp habitats are haystack density and water area.The standardized canonical discriminant function is y = 0.728 × haystack density-0.628 × water area.;The most important habitat factors affecting the selection of nesting sites for bar-headed geese in the habitat of the small island in the center of the lake are the average height of vegetation,the proportion of bare land,and the proportion of hay.The standardized canonical discriminant function is y =-0.976 × vegetation height + 0.722 × bare Land ratio + 0.692 × hay ratio;the most important habitat factor affecting the selection of nesting sites for bar-headed geese in the cliff habitat is the distance from the grassy beach and the slope direction.The standardized canonical discriminant function It is y = 0.958 × distance from Caotan-0.626 × slope.(5)Microscopic analysis of feces showed that the bar-headed geese mainly feed on19 plants of 11 families during the breeding period,and the feed intake of different families is in order: Cyperaceae> Saxifragaceae> Water Ophiopogonaceae> Echinops Branch>Asteraceae>Primulaceae>Rugaceae>Amaranthaceae>Firceae>Ranunculace>Rosaceae.Cyperaceae plants are the main feeding objects,and they account for an average of 43.14% during the breeding period.With the exception of sedges,feeding preferences for other plants are different at different stages of the breeding period.In theearly stage of breeding,the leaves of P.trifolium were most consumed,with a relative density of 11.2%,followed by a sea-milk leaf with a relative density of 9.25%.In the middle period,the leaves of P.trifolium were the most,with a relative density of12.43%,followed by a red-brown yarrow leaf with a relative density of 12.01%.In the later period,the most common small eyed lettuce was eaten,with a relative density of9.13%,followed by the swamp stolons,with a relative density of 8.98%.In the final period,the sea leek leaves consumed the most,with a relative density of 8.97%,followed by the stems of A.cuspidatum and rush,both with a relative density of 6.82%.