I'm sure StuDH will take a look at your suggestions.
In the meantime I concur that probably one of the reasons for most viewed is the length of time they have been on the site (mine of the elephant hawk moth caterpillar being the most viewed and one of the first photos), and it also has something to do with folk accessing the site when looking for identification - it's the only example on the site. Likewise searching for
Grass Snake you are presented with a number of pics and may chooose which one to view.
carlj's suggestion sounds good, if it is possible to arrange.
Tink