We visited Caroni Swamp Bird Sanctuary in March, which is a great time to see the scarlet ibis. The boat trip down the mangrove channels and into the more open part of the swamp is lovely and there are other things to see, such as crabs, oysters, the mangroves themselves, or even boas in a tree. Most of the channels are man-made and used to be used for irrigation, but after time, the routes to the sea and the man-made channels have allowed the fresh/salt water to mix and the mangroves have moved in. After some navigation in the swamp, the boat "parks" facing the island, along with several other boats, of course, and you set up to watch the birds roost for the night. At first there are a few egrets and maybe a heron or two, then some groups of egrets and tri-color herons, but then more and more, and larger and larger groups of scarlet ibis. They dot the trees like flowers, and it is a breathtaking sight to see them fly over in large groups.
This is very enjoyable trip regardless; however, it will be enhanced by a high quality pair of binoculars, because then you can see the fine details (such as the legs, beaks, and black wingtips) of the birds, and note the differences between the adults and juveniles which aren't deeply colored yet. If you are a photographer, you will want to have a telephoto lens and something for stability... the boat will be pretty still, but as the light fades it gets more challenging to get the shot in focus (we tried it through the binoculars with a smaller digital camera and it was ok, but we wished for better equipment -- there are not waves or spray to endanger the camera).
There are a variety of boat tour leaders, it probably doesn't matter much which you take if you just want to see the birds, but the boat captain/guide does give a narrative as you take the ride, and even within companies, the quality of narration can vary. You need to hire the tour as a permit is required to enter the sanctuary. They all leave at pretty much the same time, to give you time to tour a little and then end up in the viewing location right at sunset, so don't arrive late, though I do note that our boat "delivered" a couple to the rest of their group that had left without them in another boat. In addition to the above-mentioned photography equipment, a hat/sunglasses are a must since you are looking into the sun a lot at that time of day, and though we didn't have much trouble with mosquitoes that particular day, long pants and some repellent are good recommendations! One steps down into the boat/up onto the dock, and sits on open benches without backs, so travelers with physical limitations should keep this in mind -- others in our boat had brought cushions to sit on.
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