I think herps are one of the best indicators of good biodiversity, so as a group we tend to find ourselves in places where there is a whole range of fauna and flora and take it all in as part of our interest. The small weather windows for herping is perhaps also a factor when taking in other stuff. For example my interest in dragonflies developed over the years on days when it got too hot at a site to observe herps, so I would start to watch the dragonflies instead. End of season and I'm looking for fungi, though I have almost zero knowledge of the huge variety of species, I still love to see a whole range of fungi in late Autumn.

I do think herpos rapidly get a good 'eye' for habitat and the features and plants that make it so too, so we are forever picking out the wildlife hot spots where it is hard to miss the diversity of species on offer.

One thing with twitchers is on the whole they are looking 'up', whilst we are looking 'down'. I use to have a school friend who was into ornithology, we saw twice as much walking together because we had both the ground view and tree/hedge/sky view covered. 

I do know a few sites where twitchers regular trudge their way from car parks to their hides, most will be interested in reptiles if they see them, though I can never get over the sight of massive tripods and telephoto lenses pointing at a single adder trying to warm up in the sun. 

Richard