SOLVED. YA-ish 12 year old orphan has a dead uncle that leaves him his mansion [s]

[Sara]

I read this around 2009, it was a paperback and the cover made it look like an old book with vines and leaves covering it. It was a longer book and each chapter had an illustration. The boy is 12ish and is an orphan but finds out he has an uncle that was reclusive and died and left him his estate. He moves there in the summer and finds out the uncle took a trip on the Amazon River. It starts out seeming almost like a haunted ghost book. I remember the first chapter is about the mailman who has walked the same stretch for years and has never picked up mail for the mansion but then one day he is walking by and notices a letter ready to be mailed out. This may be a bit of a spoiler but there ends up being these furry worm things that kind of act like cats? I think the boy names one Tig when he rescues it from a hawk or something.

[Stephanie]

The Valley of Secrets by Charmian Hussey?

[Sara]

Stephanie wrote: "The Valley of Secrets by Charmian Hussey?

"

Yes that is it! Thank you so much!

[Lobstergirl, au gratin]

This is a popular book - requested 10x now.