Sorry if this a rushed note, but the hour is a little late. I've got nothing
definitive and no studies to quote off-hand at this late hour, but I can
offer my (and no doubt everyone else's) observations that Honeyeaters easily
travel long distances and would not necessarily be affected by a couple of
trees being removed, except for the fact that the "death by a thousand cuts"
principle comes into play sooner or later. However, they do like to "tree
hop" when foraging and the availability of food must be up to their needs,
which are very constant - nectar around every 45 mins (Prof. Harry Recher
did studies on this in the 1970's and there'll be something in an old
edition of Emu on this one and you can check out copies through the CSIRO or
Birds Australia sites). Food availability is important and being able to
point to research which indicates arboreal minima, etc., in this regard may
have some significance in your case. Pardalotes also travel long distances
when necessary but also seem to like to "tree hop" when foraging.
I've seen thornbills travel a couple of hundred metres, but never really
great distances. They seem to "tree-hop" via trees in close proximity
(couple of metres) where and when possible. This is no doubt very important
in assisting avoidance of predators and this is a point which can be
effectively raised. Fairy wrens and scrubwrens stay low and tree removal
would not necessarily be a problem unless it is extensive enough to harm the
local environment or if cover more suited to them is also removed, thus
exposing them to added predation.
The bottom line is that an argument can be best mounted if there is concern
that the local environment as a whole will be degraded by this tree-cutting
exercise, leading to spiralling reductions in biodiversity. It is difficult
to point to studies on Thornbills, for instance, and their arboreal
requirements and mount an effective case for keeping a tree or two against a
determined eco-criminal. Go for the big picture and perhaps back it up with
these smaller snippets if you can get hold of them.
Contact local campaign coordinators of Wilderness Society or similar groups
who will have suggestions for how you can effectively mount your case and
you may well pull it off. Consider getting a "stay of execution" on the
trees which will allow you to put things together.
Would like to offer more, but other duties beckon. Hope this helps. Good
Regards - Ricki