maxillaria saragurense leaves yellowing
 

I I've had this species for about a year now. I keep it in a terrarium with a humidity between 70 and 80% water daily as it is mounted with no moss on cork bark. I have good root growth but the leaves are yellowing and dropping and I was curious if this is a deciduous species.

I'm not sure if it's deciduous, but according to orchidspecies.com, it's a cool to cold growing species. What temps are you growing it at?

Yeah I saw that too. I keep it from 70 to 81 typically in summer and 60 to 73 in winter. I bought it locally from a grower who's had it for some time in an outdoors grow tent made from a car port and I live in a pretty warm climate.

I believe "cool to cold" generally means 45-60 degree nights and 60-75 degree days. You might try fiddling with air circulation as well, it's a good idea to use a fan in a terrarium if you aren't already. Yellowing may be a sign of sunburn, it could also relate to water quality (are you using distilled/RO water?)... Maybe it's just reacting to the summer heat, and will be okay again in the winter.

If you got it from a local grower, maybe ask them for advice... Orchids can be quite adaptable (sometimes), growing under less-than-ideal conditions. What are your night temperatures like? Many of the higher elevation species will tolerate warm days (and your temps seem quite moderate) if they can cool off at night.