Hi SHvar, I know what the books say, but as a keeper and breeder of this species, I am not sure that they are such bird and treetop feeders.
There is no doubt that smaller individuals will spend lots of time in trees, But like most other monitors, larger individuals most likely spend much of their time on the ground and sheltering in trees. I also get the feeling that Lacies are far more bird feeders then salvadorri. Even our large adult lacies will attempt to take a flying bird. That is, leap in midair to catch a bird flying by, only to bang off the walls and fall to the ground. Also, lacies have particular behaviors in consuming eggs. Once you see one do this, you quickly understand, that eggs are a large part of their behavior. On the otherhand, Croc monitors did not exhibit any particular behavior towards birds and nests and eggs. In fact, even our largest Croc monitor was afraid of birds(any size) and would only eat them after they were dead.
Our croc monitors did exhibit strong behaviors in consuming large mammals and did not fear large mammals at all. But then neither did the lacies. I do fully understand, that prey preference is not species linked(with varanids), but more microhabitat linked. As in, each population will key on a particular common prey item in their area. I would imagine, smaller croc monitors consume about what other indo monitors in the same habitat consume. This is despite, what picture people paint. Lastly, from some experience and deciphering construction(the build of a croc monitor) they just may be varanid consumers. As in the kingsnake of varanids. FR