Introduction A neotropical folivore, the green iguana (Iguana iguana) is exotic to southern Florida, where it has few known predators (Kryskyo et al. 2007) and limiting factors are poorly understood. At high densities (see Meshaka et al. 2007), this reptile may threaten native wildlife (Smith et al. 2006), including the imperiled Miami blue butterfly (Cyclargus thomasi bethunebakeri) (FFWCC 2010). Gravid female iguanas shun densely shaded areas for nesting and move to more open settings to nest (Bock and Rand 1989). Thus, hurricanes may create or maintain clearings favorable for iguana nesting. Here I suggest that Hurricane Wilma, the most severe Florida Keys hurricane since 1965 (Kasper 2007), was a catalyst for iguana proliferation. Until my study, the distribution of this reptile and its sympatry with the Miami blue in the Key West National Wildlife Refuge (KWNWWR) were unknown. Methods • Searched for iguana burrows and tracks on 14 islands, 12 with uplands, in the KWNWR during the iguana nesting season (Feb-March) • Trapped (42 trap nights) iguanas on 1 island in the Marquesas Keys • Necropsied captured females to obtain clutch sizes •Results • Iguanas present on 12 islands distributed over 28 linear km • All iguana burrows were in remnants of once- large clearings created by Hurricane Wilma • Burrow density varied greatly among islands: highest on east Man Key (31 burrows in < 0.2 upland ha) • Largest number of burrows (n = 62) on Long Beach (Marquesas) despite only a partial search • Gravid females (n=3) averaged 55.6 eggs (range = 42-61) • Iguanas were syntopic with the Miami blue and nested in all 8 areas harboring the butterfly Discussion In the KWNWR, Hurricane Wilma transformed what had once been a densely vegetated setting with little suitable iguana nesting habitat (Fig. 1) into an open landscape (Fig. 2) with an abundance of it. More than 5 years after the storm virtually all iguana burrows were found in remnants of clearings known to have been created by Hurricane Wilma (Wilmers pers obs.), suggesting that this hurricane was and continues to be an important Tom Wilmers, Florida Keys National Wildlife Refuges, Big Pine Key, FL 33043 Green Iguana Proliferation in the Key West National Wildlife Refuge: A Hurricane By-product and a Threat to the Imperiled Miami Blue Butterfly? No panacea: some imperfect measures: • Wait for another hurricane of Wilma’s magnitude --live vegetation will be limited and iguana numbers likely greatly reduced, concentrating survivors and increasing the effectiveness of intensive trapping and nest destruction • Trap nesting females February-March • Find and destroy nests • Collect stomach contents from 50 trapped iguanas to determine if blackbead is commonly eaten In the KWNWR, the Miami blue (left), one of the rarest butterflies in the world, lays eggs (right) only on blackbead leaves or buds. Iguana consumption of blackbead is unconfirmed but merits investigation. Literature Cited Bock, B.C. and A.S. Rand. 1989. Factors influencing nesting synchrony and hatching success at a green iguana aggregation in Panama. Copeia 1989 (4): 978-986. Cannon, P., T. Wilmers, and K. Lyons. 2010. Discovery of the imperiled Miami Blue Butterfly on islands in the Florida Keys National Wildlife Refuges, Monroe County. Southeastern Naturalist 9: 847-953. Florida Fish and Wildlife Conservation Commission 2010. Miami blue butterfly management plan. FFWCC, Tallahassee, FL. 41 pp. Kasper, K.N. 2007. Hurricane Wilma in the Florida Keys. National Oceanic and Atmospheric Administration (NOAA)/National Weather Service (NWS) Weather Forecast Office (WFO) Key West, Florida. Krysko,K.M., E.M. Enge, J.C. Donlan, and E.M Golden. 2007. Distribution, natural history and impacts of the introduced green iguana (Iguana iguana) in Florida. Iguana 14:142-151. Meshaka, W.E., H.T. Smith, E. G., and J.A. Moore. 2007. Green iguanas (Iguana iguana): The unintended consequence of sound wildlife management practices in a south Florida park. Herpetological Conservation and Biology 2:149-156. Rand, S.A. B. Dugan, and D. Vianda. The diet of a generalized folivore, Iguana iguana in Panama. J. Herpetology 26:211-224. Smith, H.T., W.E. Meshaka, and R. Engeman. 2006. Raccoon predation as a potential limiting factor in the success of the green iguana in southern Florida. Journal of Kansas Herpetology 20:7-8. Webster, P. J., G. J. Holland, J. A. Curry, and H.-R. Chang. 2006. Changes in tropical cyclone number, duration, and intensity in a warming environment. Science 16 :1844-1846. Distribution of green iguanas in the Key West National Wildlife Refuge, 2011. Yellow markers indicate islands where iguana burrows were found. Green Iguanas and the Miami blue butterfly In the KWNWR, the Miami blue lays eggs only on blackbead (Pithecellobium keyense) leaves and buds (Cannon et al. 2010). In their native range, green iguanas eat a variety of plants but may consume whatever plant is most abundant and common (Rand et al. 1990). Blackbead is the most common woody plant on 6 of the 8 uplands that harbor the Miami blue (Wilmers pers obs.). Whether green iguana eat blackbead leaves is unconfirmed and merits investigation. If it does eat blackbead, Miami blue eggs and larvae would be consumed. Miami blue numbers greatly fluctuate (Cannon et al. 2010) and at low numbers, iguana consumption of the butterfly’s eggs could lead to extirpation on one or more of the 8 islands that harbor the butterfly. The iguana population may increase unchecked in KWNWR until some a limiting factor is reached. Of great concern is a future hurricane of Wilma’s magnitude once again killing most of the blackbead, concentrating the butterfly and the reptile in the small patches that remain. The number and severity of hurricanes is expected to increase due to global warming (Webster et al. 2006). Why iguana eradication is likely an exercise in futility: • The size and remoteness of the occupied areas • Iguanas swim well and move between islands. • The largest island in the Marquesas is > 8 km long and thus is a reservoir for replenishment of animals removed from smaller islands • The reptile’s high reproductive rate and a lack of native predators • Trapping constraints: 1. inability to capture most age classes; 2. trap-shyness; 3. state law mandates checking traps every 24 hours but vagaries of weather preclude this; 4. dense, dead vegetation is mixed with live vegetation in the coastal strand; 5. enormous manpower needed even if traps were effective. Figures 1,2. The absence (left) and abundance (right) of iguana nesting habitat on Boca Grande Key before and 1 month after Hurricane Wilma. Notice the lone palm tree. East Man Key 2 months (left) after Hurricane Wilma and the same area 5 years later (right). Today, iguana nesting in the KWNWR is limited largely to remnant clearings created by this hurricane. factor for the reptile’s proliferation in the KWNWR. With few known iguana predators in Florida (Smith et al. 2006), as the vegetation grew after the hurricane the abundance of suitable nesting areas likely allowed the iguana population to grow exponentially. The green iguana’s origin in the KWNWR is unknown, but given their now wide distribution, it is untenable that they arrived at all islands as waifs transported by the hurricane. Instead, as their population expanded in the KWNWR, individuals from a source population likely swam to other islands, as occurs in their native range (see Bock and Rand 1998). The captured gravid females (left) were large. Mean clutch size was 55.6 eggs. Green iguana burrows (right) on east Man Key.