Very fair question and there may well be subtle differences between the
foraging of these species but I don't know of them. I have long held the view
though that competitive exclusion is a concept, that is demonstrable in most
cases and is useful for teaching biology but is not an absolute certainty of
nature. It can depend on how hard you look to find or not find differences that
are or are not there. Why should it be that it is necessary for one species to
use an environment differently from another, whilst competition between
individuals of a species is still extreme? That seems fairly pointless. If the
resource is abundant, the need for specialisation may be lowered and different
species can easily share the same food source. There are also cases where even
within a species, there are subdivisions eg in birds when males and females
feed in different ways or insect larvae are very different from adults. No
doubt that are whole rows of publications on library shelves on this very topic.
Philip
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