Larimer, Samantha C.

Pasachnik, Stesha A.

English

The University of Kansas: Journals@KU

12 Iguana Times Volume 9, Numbers 1 and 20730 h, temp 72°F, wind NE at 15 knots,seas 2–3 feetA group of Earlham College students yawn,rub their eyes, and awaken to the aroma of break-fast aboard the Bahamas Star. The boat has com-pleted the five-hour journey to a set of remoteislands located in the northern portion of theExuma Island chain of the Bahamas. Here stu-dents will learn the essentials of herpetologicalfieldwork while working with the endemic iguanas.Characteristic of lizards in general, the iguanasdo not start their day until the sun’s rays warm thesand on this group of three islands, known as theAllen’s Cays. Consequently, the students’ day willfollow the same pattern, initially by waiting for thefirst iguana to make its way onto the beach tobask. A leisurely breakfast is followed by the appli-cation of sunscreen and the packing of personalgear: sunglasses, more sunscreen, a towel, durableshoes, snorkeling equipment, Joy dishsoap (for anocean-friendly scrub), Neosporin for scratches (onpeople and iguanas), photocopied maps of theisland, and a Sharpie. Also loaded into the trans-port dinghy are rulers, scales, PIT-tagging equip-ment, large scissors, nooses, nets, pillowcases, andbait. These are the tools that the crew, headed byDr. John. B. Iverson, will use to capture and exam-ine Cyclura cychlura inornata. Dr. Iverson began this study in 1980, a year inwhich some of the students who are currently par-ticipating in the adventure were not yet alive, andthe rest were too young to have relevant recollec-Figure 1. Cyclura cychlura inornata on the beach at Allen’s Cays (photographs by Lynne Pieper, May 2001).Sun, Students, and Scratches:Research on Allen’s Cays IguanasSamantha C. Larimer1,2 and Stesha A. Pasachnik11Department of Biology, Earlham College, Richmond, Indiana 473742Current address: Department of Psychology, Cornell University, Ithaca, New York 1485013Iguana TimesMarch/June 2002tions. In this ongoing natural history study of theendangered iguanas (C.I.T.E.S, Appendix 2),Earlham College students annually get an oppor-tunity to be a part of this important researchendeavor, learning about the iguanas whose storythey’re helping to document. Issues regarding thisspecies’ habitat, learning about other nativespecies, the “challenge” of living on a boat in theCaribbean, and tourism are all parts of this expe-dition to the Exumas.Cyclura cychlura inornata is a large iguana,reaching more than 120 cm in total length andoften living for more than 30 years. Breeding pop-ulations, until recently, have occurred only onAllen’s Cays. Here, they are found predominantlyon Leaf Cay (4 ha) and U Cay (3 ha), although 11individuals have been recorded from Allen’s Cay(7 ha) (Iverson, 2000). The latter are all at least 10cm larger than the largest individuals on the otherislands. This is not only an amazing sight tobehold but also a phenomenon yet to beexplained, although one may speculate that a dif-ference in diet and/or reduced intraspecific com-petition might play a role. Between 1988 and1990, eight individuals were transferred toAlligator Cay (1.8 ha), located in the Exuma CaysLand and Sea Park, Bahamas. This was done as asafeguard against the Allen’s Cays populationbeing destroyed by a stochastic event such as ahurricane, an epidemic, or the introduction of aferal mammalian predator. Since their introduc-tion, these individuals have been very prolific andwere, at last count in 1998, close to carryingcapacity (Knapp, 2001).For 21 years, Dr. Iverson has been takinggroups of students to the Exumas from the smallliberal arts college in Richmond, Indiana, where heteaches biology. Collectively, these expeditionshave been able to gather data essential to under-standing the life history and survival of this species.Eventually he would like to be able to documentlife expectancies, age classification, mating sched-ules, reproductive parameters, causes of death, andthe means of their prevention. Basically, he wantsto know just about everything one can learn witha minimum amount of intrusion. As part of thislong-term data-collection project, temperaturerecorders (tidbits) are placed on the island in vari-ous habitats to monitor year-round environmentalconditions. Dr. Iverson recently (June 2001)launched a more intensive study of the iguanas’reproductive behavior and capacity by spendingthe month-long mating season on the islands.0830 h, and temps have risenIguanas become visible as dark masses pepper-ing the sandy shore. The crew is ready for the day,and 11 former or current students and Dr. Iversonhead to land to begin their work. Some memberswait for a ride in the dinghy; others, eager tobegin, load their bags into the boat and plungeinto the water to swim the 150 meters to shore.Fifteen minutes later, catching begins in earnest.Students work quickly, walking the beach singly orin pairs, and looking especially at sites whereiguanas aggregate while waiting for tourist hand-outs. Many of these iguanas have become accus-tomed to the tourists who travel in boatloads tosee them, leaving their vessels for 10 minutes inorder to throw some food scraps to these fascinat-ing creatures before taking off for another island.Figure 2.  John Iverson measures an iguana; size is just onebit of data he and the students gather for each individual(photograph by Lynne Pieper, May 2001).14 Iguana Times Volume 9, Numbers 1 and 2This feeding obviously is not a natural event, andits effects are something that Dr. Iverson hopes tosomeday understand. The massing behavior trig-gered by these handouts appears to have elimi-nated much of the territorial behavior that prob-ably characterized the iguanas’ ancestors. Also, thefood, though easy to obtain, is not kind to theseanimals’ digestive systems, often passing throughtheir guts less completely digested than their nor-mal diet of leaves and fruit (J.B. Iverson, unpubl.data). Whether this altered diet has an effect onthe life span of this species is something thatrecently collected data comparing iguanas fromdifferent sites will hopefully be able to determine.Because limited areas of each island receive visitsfrom tourists, detailed locality data will allow com-parisons of growth rates between individualsreceiving altered diets and those that are notaffected by tourism.In the short term, tourists are both helpful anda hindrance to the researchers. The familiarity ofthe iguanas with humans makes them initially easyto capture. Many can be approached easily, and thefriendliest individuals can be captured with a sweepof the net. Others are a bit more cautious, andneed to be lured with bait. Small rocks or shellsfound on the beach are sometimes enough, thefalling objects possibly mimicking ripe fruit fallingfrom a tree. For the most wary individuals, leftoverfood from the boat works well. Orange peels withtheir strong citrus smell and bright orange col-oration are favorites; however, grapes, apples,bread, and lettuce all work well. More renewablethan the food are “swing baits,” which wereinvented by Dr. Iverson and his crew a decade ago.Large red Legos® tied to string can be tossedrepeatedly to fall with just the right force to inter-est an iguana, and the red color is also thought toFigure 3. Too heavy for the scales, handling this huge iguana, caught after hours of stalking by boat Captain Bruce onAllen’s Cay, required two people, in this case John Iverson and Geoff Smith. For unknown reasons, iguanas on Allen’s Caytend to grow much larger than those on Leaf or U Cays (photograph by Lynne Pieper, May 2001).15Iguana TimesMarch/June 2002excite them. An added advantage of the swingbaits is that they can be pulled in slowly, luringreluctant individuals from the bushes to a net lyingon the ground, which is flipped over the distractedlizard. The struggling iguana is then extractedfrom the net. This is often a two-person task, espe-cially for larger individuals, and painful scratcheshave been known to result from the effort.Eventually, the lizard is placed into a pillowcase,which is tied and placed in the shade until pro-cessing. Variations on the catching theme arenumerous, with each student developing his or herown technique over the course of the week. Largenooses of heavy cord attached via fishing swivels toextendible golf ball retrieving rods are sometimesmore successful on particularly cautious animals.Their curiosity at the swinging cord often causesthem to sit patiently while the noose is adjusted.Occasionally the animals will virtually noose them-selves as they attempt to bite the cord.Regardless of capture technique, the baggedCyclura are taken to a workstation where they areprocessed. Each lizard is weighed, sexed, measured(both tail and snout-vent lengths are recorded),marked, and released. Marking is done in a varietyof ways. All captured iguanas are toe-clipped andmany, depending on size, are PIT-tagged. PassiveIntegral Transponders are tiny glass beads withwire coils inside. They are injected subcutaneously,allowing the animal to be identified with thesweeping of a reader which shows an identificationcode, much like the system used by supermarketsto ring-up prices on groceries. Together, these twomethods of marking provide very reliable identifi-cation (Iverson, 2000), even allowing dead anddecaying animals to be recognized. Prior torelease, the iguanas are marked temporarily withnon-toxic paint. This identifies them as previouscaptures and eliminates wasted time chasing ani-mals for which data have already been recorded.The response of tourists to this fieldwork variesfrom wanting to be a part of the effort to extremeanger. A few folks become quite offended by themarking of individuals, possibly because it destroysotherwise perfectly natural looking pictures.However, because they too want to help preservethese magnificent animals, others comment on theresearchers’ intrusive methods, and cite signs onthe islands that threaten dire consequences tothose who interfere with these vulnerable crea-tures. Dr. Iverson, in fact, was instrumental inputting up the very signs that the tourists quote,Figure 4. Students Colin Meeks and Stephen Jones “touch, catch, chase, and harass” a young iguana, ignoring the sign inthe background that prohibits such activities — but it’s all in the name of science (photograph by John Iverson, March 2000).16 Iguana Times Volume 9, Numbers 1 and 2and the research he is undertaking has beenapproved by all of the appropriate permit-grantingagencies. Still, we were pleased that touristsacknowledge the protection afforded these animalsand are willing to take action.Although many people encountered in thefield are doing what they can to help protect theseanimals, many others are still causing harm, some-times unknowingly. Humans are the only signifi-cant threat to this species, whether it is in the formof feeding by tourists, poaching, or illegal exploita-tion for international trade. Each action has itsown serious effects. This species is protected undernational Bahamian Law, but enforcement is lack-ing because no warden works in the area and theseislands are extremely secluded (Iverson, 1999). Asfor the future, conservation plans include addi-tional studies of the introduced individuals onAlligator Cay and possible captive-breeding pro-grams at the Ardastra Zoo in Nassau and theNature Centre Different on Abaco (Iverson,1999). These are hopeful prospects, but actionstaken by individuals are even more important forthe preservation of this species. Taking time toreport illegal treatment of this species and educat-ing oneself and others are methods by whicheveryone can help save the endangered Allen’sCays Rock Iguanas.1800 h, temperatures are droppingThe crew piles into the dinghy to return to theboat for dinner. Many have spent the entire day onthe island and this will be the first time since break-fast that they will be back onboard. After dinner,Figure 5. After more than an hour of trying to coax thisiguana out of the brush using every type of bait available,student Chaundra Schofield was on the verge of giving upwhen the previously reluctant beast came running down toeat a grape out of the hand of a newly arrived Italiantourist. A quick sweep of the net and two people to helpdetangle it, and the year’s largest iguana from Leaf Cay wasin hand (photograph by Samantha Larimer, May 2001).Figure 6. Students James Rose and Brendan Gallaghermark an iguana with car touch-up paint to avoid recaptur-ing the same individual later that trip. The paint is eventu-ally shed with the skin and causes no permanent damage(photograph by Lynne Pieper, May 2001).17Iguana TimesMarch/June 2002students gather on deck to listen to Captain Ron,John, and alumni tell stories of past trips, laughingand gasping appropriately. Although most studentsparticipate in only one week of this long-termstudy, these stories allow them to grasp all thatgoes on in a research project of this intensity andduration. This undoubtedly is a new concept forsome, as each party is composed of a wide age-range of individuals with varied interests and back-grounds in science. For some, this will be theironly exposure to science-in-action (as opposed tomerely learning about it from books or television).Besides the interesting stories, students loung-ing on deck also entertain themselves with goodbooks, decks of cards, or by recording the day’sexperiences in their personal journals, jotting downrecollections and impressions of the day’s excitingevents. The iguana-catching process itself isthrilling. It gives students an opportunity to relivetheir childhood fantasies of exploration and adven-ture, their survival dependent upon outsmartingthe wild animals they stalk. However, students domore than work, taking occasional short breaks toexplore tide pools, go snorkeling, or try their luckat retrieving coconuts from trees. Finally, withheads filled with images of the day’s experiencesand eagerly anticipating tomorrow, the studentsmake their way to the bunks to rest in preparationfor the next day’s exhilarating activities, dreamingabout that one iguana that just couldn’t be caught,new capture techniques, a section of the island yetto explored, whether or not enough iguanas canbe captured to shatter last year’s record, …Note: Stesha Pasachnik and Samantha Larimer wereparticipants on trips in March 2000 and May 2001,respectively. They thank Bob Powell and John Iversonfor comments on this paper, and the latter for mak-ing such trips available to students. ReferencesIverson, J.B. 1999. Allen’s Cays Iguana, Cyclura cychlura inornata,p. 34–36. In A. Alberts (comp. & ed.), West Indian Iguanas:Status Survey and Conservation Action Plan. IUCN, Gland,Switzerland and Cambridge, UK.Iverson, J.B. 2000. Results of Allen’s Cays Iguana study (18–25 March 2000) http://www.earlham.edu/%7Ebiol/iverson/Iguana.html.Knapp, C.R. 2001. Status of a translocated Cyclura iguana colonyin the Bahamas. J. Herpetol. 35:239–248.Figure 7. An iguana, excited by a rock that fell onto thesand, comes running to investigate, only to fall prey to anet lying on the ground near the well-placed stone(photograph by Samantha Larimer, May 2001).

Sun, Students, and Scratchers: Research on Allen\u27s Cays Iguanas

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Sun, Students, and Scratchers: Research on Allen's Cays Iguanas

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