Black-throated green warblers were the dominant birds in all mature spruce forest habitats on Mt. Desert Island. As the figure indicates, their abundance was nearly proportional to the foliage volume above 20 feet. Their abundance did fall
off slightly in the two plots, C and E, in which very tall trees were present. Black-throated greens seldom use these tall tree tops for feeding,
so that the amount of foliage suitable for black throated greens should be slightly reduced from the amount calculated for plots C and E. Blackburnians, which require foliage near the tops of the trees, were present in small numbers in
both plots which had trees of height greater than 60 feet. A true understanding of their population control on Mt. Desert Island probably cannot be acquired without considering competition with other species. It is reasonable that the black
burnian can only persist where the forest is sufficiently old that the feeding zone of the dominant black-throated green stops well before the tree tops in which the blackburnian prefers to feed.
Black-throated green warblers were the dominant birds in all mature spruce forest habitats on Mt. Desert Island. As the figure indicates, their abundance was nearly proportional to the foliage volume above 20 feet. Their abundance did falloff slightly in the two plots, C and E, in which very tall trees were present. Black-throated greens seldom use these tall tree tops for feeding,so that the amount of foliage suitable for black throated greens should be slightly reduced from the amount calculated for plots C and E. Blackburnians, which require foliage near the tops of the trees, were present in small numbers inboth plots which had trees of height greater than 60 feet. A true understanding of their population control on Mt. Desert Island probably cannot be acquired without considering competition with other species. It is reasonable that the blackburnian can only persist where the forest is sufficiently old that the feeding zone of the dominant black-throated green stops well before the tree tops in which the blackburnian prefers to feed.
การแปล กรุณารอสักครู่..
