A Zoo in my Luggage (1960) by Gerald Durrell might be the Durrell volume that will oblige you conclude that they are all the same. 

This happened to me and I bought Birds, Beasts and Relatives shortly after wards, but chickened out of reading it for ages.

What is clear about A Zoo in my Luggage is that in its composition Durrell was writing about a part of himself that he didn’t like. It would be stretching it to say that this is his existential novel, yes.  But if anything it is his animal cruelty novel, and in that much it really does the business.

How does someone after all become a naturalist? Given that Durrel is travelling and the zoo is so essential to him, he refers to his animals as his stuff, and in doing so stuffs them into all sorts of confined spaces to port them about the globe.

Today you may not be able to FedEx a camel, or send any animal across the world in a box.  In fact I hear there are some quite strict laws regarding their captrue and transport altogether. 

But when Durrell was building his zoo in Jersey, in the Channel Islands, he had to do the best he could, with his determination as his main advisor.