The Colombian Aviary is really one of the most world class venues in Colombia and certainly worth a visit.  You'll see hundreds of birds in a massive open air, natural aviaries in South America. The aviary park works as an international conservation partner collobarating with zoos around the world to run captive breeding programs for endangered species.  Although it's a 45 min car ride to get there, this is well worth visiting even if you only plan 4 hours including travel.  Tours are $39 per person including transportation, but larger groups can get significant discounts if you contact the aviary directly (because transportation is most of the cost).

Tour of the Colombian National Aviary in Cartagena