Garza - Heron

In these South American countries there is a great likelihood that range information is quite wrong due to the lack of funding and prominent professionals. Furthermore, many areas are only accessible to the most intrepid. I have documented species in my area of Costa Rica that were only known to exist in different elevations and climates over 50 miles away. With that said, and based on your in-depth commentary, it might be prudent to leave the name of this individual as Heron or Garza (in spanish) and leave the scientific name as Butorides sp. Naturally, I am completely amenable to any final suggestion you may have as you are an expert in this field. Thanks Liam.

Googling around, it appears the Green Heron range maps vary from site to site. Xeno-canto doesn't even show the range extending to Colombia. Here's what Birdforum says regarding the range of Green Heron in South America:
"Restricted to coastal N. Colombia and Venezuela. Also a few records from Ecuador, C. Colombia, and Suriname."

On eBird, it shows that Striated Heron is much more likely than Green at any rate. I think All About Birds' range map is a bit inaccurate.

That said, the two species in their juvenile plumage are very tough to differentiate, but particularly with a shot like this. An ID based on field marks would be unlikely.

I think this is so dark that it would be difficult to truly know which species it is.

Creo que con Garza estas bien.

Not to muddy the waters further but I would have guessed juvenile black-crowned night heron (also within the range) because of the posture and the thickness of the bill.(http://www.allaboutbirds.org/guide/black-crowned_night-heron/id) It is a difficult one with the distant and backlighting of the photo.

So which is it?

No it's not... look at the map on my link.

Green Heron is out of range for the mapped location.