| Under natural environment, the condition of food resources distribution in space and time are often very unequal, so the food hoarding of many animals are happen during food rich season,which is a response for food shortages. The phenomenon of stealing food is very common in hoarding food animals. The hoarding food can be stolen by intraspecific or interspecific competitors, which are one of the main reasons for the loss of hoarding foods. Meanwhile, it is the main driving factor for the evolution of selection on the food storage behavior. Consequently, the study on the hoarding food strategy which avoid being stolen would be useful in uncovering the underlying mechanisms for the evolution of the hoarding food behavior,and protecting the hoarding food birds.The Varied Tit has obvious behavior of hoarding food at autumn, and the storage mode is scattered. During October 2014, at liaoning province, dalian, fairy cave national nature reserve (E 122°53’24"～123°03’30", N 39°54’00"～40°03’00"), in the experimental zone, we chose seven appropriate respectively separated greater than 1000 m areas. After that, we artificially placed Korean pine seeds, guided and set up seven fixed varied tits feeding points. Then, with mist net method, we traped varied tits at the fixed feeding points, and released these bird after bird banding and taking the blood. As shown in table 1. In this study, we artificially served the food in seven places and set the food source in the center(The fixed varied tits feeding points). According to the distance from the cache site to the food source, the high pilferage risk area, medium pilferage risk area and low pilferage risk area was divided to study the change of hoarding food ratio of varied tits, according to the presence or absence of potential pilferers. We took into account the time and energy’s costs and profits of feeding and storage process to examine the strategy of varied tits in avoiding being stolen food storage strategy.(1) The results showed that the trend in hoarding food strategy of varied tits was roughly similar whether there was potential thieves prey or not. Foods were mainly stored in the medium pilferage risk area, with the high pilferage risk area and low pilferage risk area storage food ratio was relatively low. The presence of interspecific and intraspecific potential pilferers had different and obvious influence on the hoarding food strategy of varied tits. The presence of interspecific and intraspecific potential pilferers decreased the food storage ratio of high pilferage risk area (interspecific potential pilferers:F2,118=3.174, P<0.05; intraspecific potential pilferers:F2,118=90.475,P<0.05),and increased that of low pilferage risk area (interspecific potential pilferers:F2,118=220.440, P<0.05; intraspecific potential pilferers:F2,118-15.651,P<0.05). Furthermore, when there was interspecific potential pilferers, the food storage ratio of medium pilferage risk area would be lower (F2,118=143.749, P<0.05), but if there was intraspecific potential pilferers, the food storage ratio of medium pilferage risk area would not change (F2,118=0.776, P> 0.05). This means that the varied tits recognized and prevented from stealing food of interspecific pilferers more than intraspecific potential pilferers.(2) In addition, in the three different situations, the male and the female varied tits’s hoarding food strategies were obviously different. As shown in table 2.When there was no potential pilferers, and there was intraspecific potential pilferers, the male varied tits would took notice and prevented stealing food more than the females(There was no potential pilferers:high pilferage risk area t=4.962, P<0.05; medium pilferage risk area t=-0.89, P>0.05; low pilferage risk area r=-2.166, P<0.05);(There was intraspecific potential pilferers:high pilferage risk area t= 0.152, P>0.05; medium pilferage risk area r=2.352, P<0.05; low pilferage risk area t=-2.287, P<0.05).While there was interspecific potential pilferers, the results show that no significant difference was observed in the hoarding food strategy of the male and female varied tits.(high pilferage risk area t=1.361, P>0.05; medium pilferage risk area t=-0.194, P>0.05; low pilferage risk area t=-1.599, P> 0.05).(3) when varied tits(n=40) hoard food, five Habitats can be chose.The overall trend of the choice is that Grass and Alcoves will be preferred chose by varied tits,Shrubs roots and Bark cracks are secondly chose and the Mosses will be chose at last. If no potential pilferers condition as comparitive group, when there was potential pilferers, the storage food rates of Moss which is farthest from the feeding points, will rise(intraspecific potential pilferers:F2,118=237.794, P<0.05; interspecific potential pilferers:F2,118=199.066, P<0.05). Further analysis shows that:when varied tits hoard food, and choiced the five Habitats, the influence from interspecific potential pilferers biger than intraspecific potential pilferers’s influence,which is mean when face interspecific pilferers,the varied tits will cost more time and effort to avoid food stolen.(4) When there is different potential pilferers, the Habitats chose of different male and female varied tits is different (female=15,male=25). 1.when there is no potential pilferers,and female as comparitive group, the male varied tits’s storage feeding rates of Crevice was lower (t=6.384,P<0.05), storage food rates of Bark cracks was rise (t=-3.867, P<0.05), and storage food rates of the other three Habitats was no significant difference (Shrubs roots:t=0.468, P>0.05; Grass:t =0.466, P>0.05; Mosses:t=-0.835,P>0.05). Because of the storage food rates of Bark cracks was rise,whice can reduce the effects of winter snow for food storage regain used, so when there is no potential pilferers, the male varied tits will cost more time and effort to avoid the influence of seasonal factors.2. when there is intraspecific potential pilferers,the male and female varied tits’s storage food rates of five Habitats was no significant difference (Bark cracks:t=1.485, P>0.05; Shrubs roots:t=0.666, P>0.05; Grass:t=0.196, P>0.05; Alcoves:t=-1.841, P>0.05; Mosses:t=-1.915, P>0.05).3. when there is interspecific pilferers,and female as comparitive group, the male varied tits’s storage feeding rates of Bark cracks was lower (t=2.877,P<0.05), storage food rates of Grass was rise (t=-6.995,P<0.05), and storage food rates of the other three Habitats was no significant difference (Shrubs roots:t=0.341, P>0.05; Alcoves:t=0.521, P>0.05; Mosses:t=-1.985, P>0.05). Because of the storage food rates of Grass was rise, whice can better avoid food stolen, so when there is interspecific pilferers, the male varied tits will ignore the influence of seasonal factors,and cost more time and effort to avoid the food stolen by interspecific pilferers. |
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