This paper attempts to investigate Emily Dickinson’s poetry with regard to its environmental sensibility, from the perspective of recently developed theories of ecopoetry. Some contemporary eco-critics criticize the frequent use of ‘personification’ as a sign of internalizing outer nature into a humanized construct of epistemological imagination; however, Dickinson shows that ‘personification’ can perform a double function of both developing a sense of intimacy with nature and identifying the boundary of human consciousness that cannot entirely subsume nature under its power. This study focuses mainly on Dickinson’s poetry dealing with birds, as they are representative natural beings that have been frequently addressed and personified in the history of Western literature. In her poems, Dickinson, like many other poets and writers before her, often personifies birds and endows them with human qualities. Although such a way of delineating birds appears to simply highlight the similarity between human existence and nature, Dickinson’s use of ‘personification’ often reveals the ultimate otherness of creatures different from human beings and thereby calls upon humility for the natural environment. Dickinson’s close encounter with nature allows her to establish intimate connections with its minute elements and to turn it into a ‘place,’ where she feels safe and comfortable. Simultaneously, Dickinson’s focused observation of the natural environment leads her to acknowledge the epistemological limit in comprehending the outer world and to recognize it as a ‘space,’ where she experiences the ultimate heterogeneity of natural elements.