February 2017

I saw an iguana, a male about 2 feet long, along the wall in back of our building the other day. I used to see several each day, especially on my walks to Old San Juan but there seem to be far fewer now. I wonder why that is.

The iguanas here are green iguanas, also known as the American iguana, of the genus Iguana. It is native to Central and South America and some of the Caribbean islands. It was accidentally introduced to Puerto Rico in the 1970s as a result of the pet trade. It has also been introduced into Florida, Texas, Hawaii, and the US Virgin Islands. Presumably, owners allowed their pet iguanas to escape. The reptiles found the conditions ideal; there are now as estimated 4 million on the island. Locally they are called Gallina de palo and are considered an invasive species. Populations densities of up to 225 iguanas per hectare have been observed. That’s about 58,000 per square mile. That’s a lot of iguanas.

The invaders, with no natural predators here, are altering the ecosystem, burrowing into and weakening dikes, disrupting power lines (and getting fried in the process), destroying native vegetation and ornamental plantings. Two years ago there was a professional golf tournament here. Iguanas on one of the greens became intrigued with the golf balls and butted them around with their snouts. I’m not sure how the rules of golf dealt with that situation. Iguanas are harmless so this is certainly better than running into a cobra on a golf course, as has happened to Australian golfers in Vietnam.

I’m not sure why anyone would want a pet iguana. On the positive side, they are docile and do not require an elaborate diet. They are colorful, often displaying reddish hues. On the negative side, they require special lighting and constant heat. And they are ugly, in a reptilian kind of way. I cringe every time I see one. They remind me of the monsters in the 1950s science fiction movies I used to watch – Godzilla, The Monster That Devoured Cleveland, and the like.

They are ugly for a couple of reasons. The spines along their back are formidable. The dewlap, the longitudinal flap of skin under the chin, can be attractive only to another iguana. The dewlap is thought to have a role in thermoregulation. They are arboreal but can fall to the ground – and land – from as high as 50 feet without apparent injury. An iguana, about three feet long, once landed about ten feet from me as I was walking across a shaded lawn. Scared the hell out of me.

The iguanas in Puerto Rico are one example of the world wide problem of introduced species that become invasive. The forests of Central New York, our summer home, are being altered by the two invasive insects. The hemlock woolly adelgid, introduced from Japan in the 1950s, feeds by sucking sap from native hemlock and spruce trees. The Emerald Ash Borer, a beetle introduced from China in the early 2000s, destroys ash trees when larval feeding girdles the tree and disrupts the flow of water and nutrients. Aquatic ecosystems there have been disrupted by the introduction of zebra mussels, native to Russian waters. They were first discovered in the Great Lakes in the 1980s and have spread quickly since then. I once worked with a team of aquatic scientists to analyze the effects of zebra mussel introduction to the Seneca River. See the Notes and Sources section for a full attribution.

Once an introduced species is identified as invasive, i.e., causing ecological and economic damages, the question of management and controls comes up. This has often proved difficult. Consider the case of the lamprey in the Great Lakes. The lamprey (which is a fish, not an eel) was introduced into the Great Lakes (and Lake Champlain, and the Finger Lakes in New York) sometime in the early twentieth century. This ugly fish swims upstream to breed; after two or three years, the adults emerge and swim downstream into the lakes. Their mouths are adapted to stick onto a prey fish and eat through the skin until it can suck blood and other body fluids from the host fish.

The population of lampreys exploded after their introduction and as a consequence, the numbers of commercially important fish like the lake trout dropped. Management efforts (use of lampricides, placement of nets to prevent upstream migration to spawn) reduced their population and the population of lake trout rebounded but not to pre-lamprey levels. The case of the lamprey illustrates one important fact in invasive species management: the intruder’s population might be reduced by various means, but it is next to impossible to achieve complete eradication. There will thus continue to be Burmese pythons in the Everglades, lampreys in the Great Lakes, and purple loose strife in wet meadows and marshes in the northeastern US.

So is there a management strategy for the iguanas in Puerto Rico? Maybe. It turns out that iguanas are edible, and in fact, in some countries are known as “chickens of the trees.” In Honduras, for example, iguanas are hunted and their population is dwindling. The Puerto Rico government has assisted a start-up business to slaughter iguanas and sell the meat to countries, like Honduras, where iguanas are a food source. The initial goal was 2,000 lbs of iguana meat a week.

How do you cook iguana? Here is one recipe.

IGUANA EN PINOL

1 Iguana – female 3 sour oranges (acid) 1 garlic bulb 4 lg. onions 1 tsp. black pepper (grain) 12 c. water 1 lb. dry corn (powdered) 1 tsp. REO PEPPER 3/4 bottle of pork grease Salt to taste The first day: After the Iguana has been killed, open the stomach and below, take out the eggs and intestines. Clean the eggs very well with the sour oranges. Put the eggs in the arms with the Iguana in all its skin. Later in the day cook the eggs in salt water for 10 minutes, then let them sit in the water until they are cold. Store them in refrigerator. Early the following day soak the Iguana in cold water. Skin it and wash it once more. Cut the Iguana into small pieces and cook it with 8 cups of water with salt, garlic, sliced onion, and black pepper. Grind it into a “Soft Mass” and mix it with the gravy. Cook the corn in water until soft, then brown it (not too darkly) and grind to a lumpy mass. Take 4 cups of this corn, mix with the gravy and Iguana and cook, stirring constantly until it is well cooked. In 2 1/2 cups of pork grease, fry 3 onions (chopped fine) until clear and light brown. Set aside a few onions. With the rest, add the powdered pepper, Iguana mixture, more salt, sour oranges, and, if necessary, more pork grease. Do not let get too dry. Form a large rounded shape in a serving dish and create an indentation in the center.

Iguana can also be served fried, stewed, curried, boiled, or pretty much any way you can cook chicken. It is said to taste a bit like chicken but with the consistency of crab meat.

There are rumors here in Puerto Rico that sometimes iguana meat replaces chicken in some local recipes. It is rumored that, while you think you’re eating chicken on a skewer (pincho de pollo) it might actually be pincho de iguana.

Is this why the numbers of iguanas seem to be decreasing? I don’t know, but I’m going to be real careful the next time I think of having a pincho de pollo.

 

Notes and Sources: See Wikipedia entries for Green Iguana, Lamprey, Godzilla, Hemlock Woolly Adelgid, Emerald Ash Borer, and Zebra Mussel for more information.

The iquana recipe is from www.cooks.com – search for iguana recipes. I haven’t tried this one yet.

The lake trout image is from Wikimedia Commons. The original link is http://www.nwrc.usgs.gov/world/images/lamprey.jpg

The Godzilla image is a poster advertising the 2014 movie of that name. The poster art copyright is believed to belong to the distributor of the film, Warner Bros., the publisher of the film or the graphic artist.

The zebra mussel paper I referred to is Water Quality Impacts and Indicators of Metabolic Activity of the Zebra Mussel Invasion of the Seneca River, published June 2007 in the JAWRA Journal of the American Water Resources Association. The authors were Steven W. Effler, David A. Matthews, Carol M. Brooks-Matthews, MaryGail Perkins, Clifford A. Siegfried and James M. Hassett