• A checklist of the iguanas of the world (Iguanidae; Iguaninae)

      Iguana Taxonomy Working Group (ITWG); Buckley, Larry J.; de Queiroz, Kevin; Grant, Tandora D.; Hollingsworth, Bradford D.; Iverson, John B.; Pasachnik, Stesha A.; Stephen, Catherine L.; Iverson, John B.; Grant, Tandora D.; et al. (2016)
      This annotated checklist of the world's iguanas (Iguanidae; Iguaninae) represents an update by the Iguana Taxonomy Working Group (ITWG) of its 2011 list. We recognize 44 extant species (19 subspecies across six species) in eight genera....
    • Age-dependent, negative heterozygosity-fitness correlations and local effects in an endangered Caribbean reptile, Iguana delicatissima

      Judson, Jessica L Martin; Knapp, Charles R.; Welch, Mark E. (2018)
      Inbreeding depression can have alarming impacts on threatened species with small population sizes. Assessing inbreeding has therefore become an important focus of conservation research. In this study, heterozygosity-fitness correlations (HFCs) were measured by genotyping 7 loci in 83 adult and 184 hatchling Lesser Antillean Iguanas, Iguana delicatissima, at a communal nesting site in Dominica to assess the role of inbreeding depression on hatchling fitness and recruitment to the adult population in this endangered species. We found insignificant correlations between multilocus heterozygosity and multiple fitness proxies in hatchlings and adults. Further, multilocus heterozygosity did not differ significantly between hatchlings and adults, which suggests that the survivorship of homozygous hatchlings does not differ markedly from that of their heterozygous counterparts. However, genotypes at two individual loci were correlated with hatching date, a finding consistent with the linkage between specific marker loci and segregating deleterious recessive alleles. These results provide only modest evidence that inbreeding depression influences the population dynamics of I. delicatissima on Dominica.;
    • Allen Cays Rock Iguana, Cyclura cychlura ssp. inornata. IUCN Red List of Threatened Species

      Iverson, John; Grant, Tandora D.; Buckner, Sandra (IUCN, 2019)
      Only two natural breeding subpopulations of the Allen Cays Rock Iguana have ever been known (U and Leaf Cays), with a combined population of less than 500 mature animals inhabiting only seven total hectares (0.07 km2). Those two subpopulations have recovered from near extinction in the early 1900s to current levels that are near the limit of the resources available on those two cays (carrying capacity). Human-assisted translocations to other Bahamian islands over the past two decades has decreased the number of large adults on the source cays, and although these moves have increased the number of subpopulations, without reproduction almost all are considered not viable....
    • Amblyrhynchus cristatus. The IUCN Red List of Threatened Species 2020

      MacLeod, A.; Nelson, K.; Grant, Tandora D. (2020)
      Marine Iguanas occur on the large islands of Española, Fernandina, Floreana, Genovesa, Isabela, Marchena, Pinta, San Cristobál, Santa Cruz, Santa Fé, and Santiago, the mid-sized islands of Baltra, Bartolomé, Pinzón, Plaza Norte, Plaza Sur, Rábida, and Seymour Norte, smaller key populations on Darwin, Roca Redonda, and Wolf, as well as many satellite islets of the Galápagos Archipelago, Ecuador. The estimated extent of occurrence is 56,647 km2 by minimum convex polygon and the area of occupancy is estimated at 42,155 km2 using a 2x2 km grid overlay within a coastal buffer 2 km from the shore. The population size is poorly known and crudely estimated as low as 33,000 total iguanas after a strong El Niño famine and as many as 350,000 after several years of La Niña abundant food conditions, with fewer than 210,000 mature individuals. Current taxonomy describes eleven subspecies. Only one subspecies has a genetically resilient effective population size, and only one more is close to the threshold to be considered healthy; the remaining are critically low to moderate. Overall population trend is unknown, but is subject to extreme fluctuations and reductions during El Niño events (10–90% mortality), which are predicted to intensify in the future with ongoing climate change. Marine Iguana populations have been reduced by invasive alien predators such as feral cats, rats, and free-roaming pigs and dogs on five of the 13 main islands (ca 30% of the total population)....
    • Amblyrhynchus cristatus ssp. cristatus. The IUCN Red List of Threatened Species 2020

      MacLeod, A.; Nelson, K.; Grant, Tandora D. (2020)
      The Fernandina Marine Iguana is found on the islands of Fernandina, Isabela, Tortuga, and very likely other satellite cays in the Galápagos Islands, Ecuador. The estimated extent of occurrence is 8,845 km2 by minimum convex polygon and the area of occupancy is estimated at 2,288 km2 . The population size is poorly known and crudely estimated at 20,000–160,000 total iguanas with fewer than 96,000 mature individuals. Overall population trend is unknown, but is subject to extreme reductions and fluctuations during El Niño events, which are predicted to intensify in the future with ongoing climate change. This iguana is threatened by invasive alien Black Rats, feral cats, and free-roaming pigs and dogs on Isabela Island. Fernandina Marine Iguanas are threatened by a region-wide increase in human population and visitation that has multiplied the impacts from stress, marine pollution, habitat degradation, and chance of further invasive species introductions and emergent diseases. Land-based tourist presence and intensity has been shown to have a significant overall negative effect on iguana health. The population is estimated to have been reduced by at least 20–40% over the last three generations (18–24 years) due to the impacts of invasive alien predators, oil spills and urban pollution, and cyclic feast/famine fluctuations. Without significant invasive species control, declines are projected to continue in the near future, with a per cent reduction of at least 20–40% estimated over the past two generations and one generation into the future. This subspecies qualifies for listing as Vulnerable.
    • Amblyrhynchus cristatus ssp. hassi. The IUCN Red List of Threatened Species 2020

      MacLeod, A.; Nelson, K.; Grant, Tandora D. (2020)
      The Santa Cruz Marine Iguana is found on the islands of Santa Cruz, Baltra, Seymour Norte, Plaza Sur, Plaza Norte, and very likely other satellite cays in the Galápagos Islands, Ecuador. The estimated extent of occurrence is 1,439 km2 by minimum convex polygon and the area of occupancy is estimated at 580 km2 . The population size is poorly known and crudely estimated at 2,000–13,000 total iguanas with fewer than 7,800 mature individuals. Genetic data indicate a small effective population size. Overall population trend is unknown, but is subject to extreme reductions and fluctuations during El Niño events, which are predicted to intensify in the future with ongoing climate change. This iguana is threatened by invasive alien Black Rats, Norway Rats, feral cats, and free-roaming pigs and dogs. Santa Cruz Marine Iguanas are threatened by a region-wide increase in human population and visitation that has multiplied the impacts from stress, marine pollution, habitat degradation, and chance of further invasive species introductions and emergent diseases. Land-based tourist presence and intensity has been shown to have a significant overall negative effect on iguana health. The population is estimated to have been reduced by at least 30–40% over the last three generations (18–24 years) due to the impacts of invasive alien predators, oil spills, low effective population size, and cyclic feast/famine fluctuations. Without significant invasive species and pollution control, declines are projected to continue in the near future, with a percent reduction of at least 20–30% estimated over the past two generations and one generation into the future. This subspecies qualifies for listing as Endangered
    • Amblyrhynchus cristatus ssp. godzilla. The IUCN Red List of Threatened Species 2020

      MacLeod, A.; Nelson, K.; Grant, Tandora D. (2020)
      The Punta Pitt Marine Iguana is found only on the northern and eastern part of San Cristóbal Island and very likely the satellite islets in this region in the Galápagos Islands, Ecuador. The estimated extent of occurrence is 257 km2 by minimum convex polygon and the area of occupancy is estimated at 188 km2. The population size is poorly known and was crudely estimated at 50–400 total iguanas on the entire island in 2004. A more recent mark-resight study calculated 147 mature adults at the largest subpopulation of this new subspecies designation. Genetic data indicate a critically low effective population size. Overall population trend is unknown, but is subject to extreme reductions and fluctuations during El Niño events, which are predicted to intensify in the future with ongoing climate change. This iguana is threatened by invasive alien Black Rats, Norway Rats, feral cats, and free-roaming pigs and dogs. Punta Pitt Marine Iguanas are threatened by a region-wide increase in human population and visitation that has multiplied the impacts from stress, marine pollution, habitat degradation, and chance of further invasive species introductions and emergent diseases. Land-based tourist presence and intensity has been shown to have a significant overall negative effect on iguana health.
    • Amblyrhynchus cristatus ssp. hayampi. The IUCN Red List of Threatened Species 2020

      MacLeod, A.; Nelson, K.; Grant, Tandora D. (2020)
      The Marchena Marine Iguana is found only on the island of Marchena in the Galápagos Islands, Ecuador. The extent of occurrence and area of occupancy is estimated at 140 km2 . The population size is poorly known and estimated at 1,000–40,000 total iguanas, with fewer than 6,000 mature individuals. Genetic data indicate a critically low effective population size. Overall population trend is unknown, but is subject to extreme reductions and fluctuations during El Niño events, which are predicted to intensify in the future with ongoing climate change. Marchena Marine Iguanas are threatened by a region-wide increase in human population and visitation that has multiplied the impacts from marine pollution, habitat degradation, and chance of invasive species introductions and emergent diseases. This subspecies qualifies for listing as Endangered.
    • Amblyrhynchus cristatus ssp. jeffreysi. The IUCN Red List of Threatened Species 2020

      MacLeod, A.; Nelson, K.; Grant, Tandora D. (2020)
      The Wolf Marine Iguana is found on the islands of Wolf, Darwin, and Roca Redonda in the Galápagos Islands, Ecuador. The estimated extent of occurrence is 1,058 km2 by minimum convex polygon and the area of occupancy is estimated at 16 km2 using a 2x2 km grid overlay. The population size is poorly known and estimated at 600–2,300 total iguanas, with fewer than 1,380 mature individuals. Overall population trend is unknown, but is subject to extreme reductions and fluctuations during El Niño events, which are predicted to intensify in the future with ongoing climate change. Wolf Marine Iguanas are threatened by a region-wide increase in human population and visitation that has multiplied the impacts from marine pollution, habitat degradation, and chance of invasive species introductions and emergent diseases. This subspecies qualifies for listing as Endangered.
    • Amblyrhynchus cristatus ssp. mertensi. The IUCN Red List of Threatened Species 2020

      MacLeod, A.; Nelson, K.; Grant, Tandora D. (2020)
      The San Cristóbal Marine Iguana is found only on the southern and western part of San Cristóbal Island and very likely the satellite islets in this region in the Galápagos Islands, Ecuador. The estimated extent of occurrence is 398 km2 by minimum convex polygon and the area of occupancy is estimated at 240 km2 . The population size is poorly known and was crudely estimated at 50–400 total iguanas on San Cristóbal in 2004, although this is under-estimated as a more recent mark-resight study calculated 300 mature adults at the largest subpopulation. Genetic data indicate a critically low effective population size. Overall population trend is unknown, but is subject to extreme reductions and fluctuations during El Niño events, which are predicted to intensify in the future with ongoing climate change. This iguana is threatened by invasive alien Black Rats, Norway Rats, feral cats, and free-roaming pigs and dogs. San Cristóbal Marine Iguanas are threatened by a region-wide increase in human population and visitation that has multiplied the impacts from stress, marine pollution, habitat degradation, and chance of further invasive species introductions and emergent diseases. Land-based tourist presence and intensity has been shown to have a significant overall negative effect on iguana health.
    •  Amblyrhynchus cristatus ssp. nanus. The IUCN Red List of Threatened Species 2020

      MacLeod, A.; Nelson, K.; Grant, Tandora D. (2020)
      The Genovesa Marine Iguana is found only on the island of Genovesa in the Galápagos Islands, Ecuador. The extent of occurrence and area of occupancy is estimated at 28 km2 . The population size is poorly known and estimated at 900–15,000 total iguanas, with fewer than 9,000 mature individuals. Genetic data indicate a moderate effective population size. Overall population trend is unknown, but is subject to extreme reductions and fluctuations during El Niño events, which are predicted to intensify in the future with ongoing climate change. Genovesa Marine Iguanas are threatened by a region-wide increase in human population and visitation that has multiplied the impacts from marine pollution, habitat degradation, and chance of invasive species introductions and emergent diseases. Land-based tourist presence and intensity has been shown to have a significant overall negative effect on iguana health. This subspecies qualifies for listing as Critically Endangered.
    • Amblyrhynchus cristatus ssp. sielmanni. The IUCN Red List of Threatened Species2020

      MacLeod, A.; Nelson, K.; Grant, Tandora D. (2020)
      The Pinta Marine Iguana is found only on the island of Pinta in the Galápagos Islands, Ecuador. The extent of occurrence and area of occupancy is estimated at 92 km2 . The population size is poorly known and estimated at 800–6,000 total iguanas with fewer than 3,600 mature individuals. Genetic data indicate a low to moderate effective population size. Overall population trend is unknown, but is subject to extreme reductions and fluctuations during El Niño events, which are predicted to intensify in the future with ongoing climate change. Pinta Marine Iguanas are threatened by a region-wide increase in human population and visitation that has multiplied the impacts from marine pollution, habitat degradation, and chance of invasive species introductions and emergent diseases. This subspecies qualifies for listing as Critically Endangered.
    • Amblyrhynchus cristatus ssp. trillmichi. The IUCN Red List of Threatened Species2020

      MacLeod, A.; Nelson, K.; Grant, Tandora D. (2020)
      The Santa Fé Marine Iguana is found only on the island of Santa Fé in the Galápagos Islands, Ecuador. The extent of occurrence and area of occupancy is estimated at 44 km2 . The population size is poorly known and estimated at 3,000–16,000 total iguanas with fewer than 9,600 mature individuals. Genetic data indicate a low to moderate effective population size. Overall population trend is unknown, but is subject to extreme reductions and fluctuations during El Niño events, which are predicted to intensify in the future with ongoing climate change. Santa Fé Marine Iguanas are threatened by a region-wide increase in human population and visitation that has multiplied the impacts from marine pollution, habitat degradation, and chance of invasive species introductions and emergent diseases. Land-based tourist presence and intensity has been shown to have a significant overall negative effect on iguana health.
    • Amblyrhynchus cristatus ssp. venustissimus. The IUCN Red List of Threatened Species2020

      MacLeod, A.; Nelson, K.; Grant, Tandora D. (2020)
      The Española Marine Iguana is found on the islands of Española, Floreana, Gardner-by-Floreana, Champion, and very likely their satellite cays in the Galápagos Islands, Ecuador. The estimated extent of occurrence is 1,184 km2 by minimum convex polygon and the area of occupancy is estimated at 308 km 2 . The population size is poorly known and crudely estimated at 3,700–37,000 total iguanas with fewer than 22,200 mature individuals. Genetic data indicate a small to moderate effective population size. Overall population trend is unknown, but is subject to extreme reductions and fluctuations during El Niño events, which are predicted to intensify in the future with ongoing climate change. This iguana is threatened by invasive alien Black Rats, feral cats, and free-roaming pigs and dogs. Española Marine Iguanas are threatened by a region-wide increase in human population and visitation that has multiplied the impacts from stress, marine pollution, habitat degradation, and chance of further invasive species introductions and emergent diseases. Land-based tourist presence and intensity has been shown to have a significant overall negative effect on iguana health. This subspecies qualifies for listing as Endangered.
    • Amblyrhynchus cristatus ssp. wikelskii. The IUCN Red List of Threatened Species 2020

      MacLeod, A.; Nelson, K.; Grant, Tandora D. (2020)
      The Santiago Marine Iguana is found on the islands of Santiago, Bartolomé, Pinzón, Rábida, and very likely nearby islets in the Galápagos Islands, Ecuador. The estimated extent of occurrence is 1,164 km2 by minimum convex polygon and the area of occupancy is estimated at 444 km2 . The population size is poorly known and estimated at 450–4,000 total iguanas, with fewer than 2,400 mature individuals. Genetic data indicate a critically low effective population size. Overall population trend is unknown, but is subject to extreme reductions and fluctuations during El Niño events, which are predicted to intensify in the future with ongoing climate change. Invasive Black Rats threaten this iguana more severely when compared to other subspecies, as the islands in its distribution have scarce food resources for rats. Santiago Marine Iguanas are threatened by a region-wide increase in human population and visitation that has multiplied the impacts from stress, marine pollution, habitat degradation, and chance of invasive species introductions and emergent diseases. Land-based tourist presence and intensity has been shown to have a significant overall negative effect on iguana health....
    • Biosphere reserve to transshipment Port: Travesty for Jamaica's Goat Islands.

      Grant, Tandora D. (2014)
      You know what is a huge bummer? Being a part of an amazing conservation success story to recover a species, only to reach the point where all those efforts appear lost. I know I’m not the only conservationist who has fought similar battles — many losing, but occasionally winning. I still have hope that reason will prevail and my colleagues and I can make further progress toward true recovery and the long-term goals of sustainability. The Jamaican Iguana (Cyclura collei) is a really big lizard that was thought to have been extinct for 40-something years when a small number of individuals were found in the rugged limestone interior of the Hellshire Hills on the southern coast of Jamaica…
    • Brachylophus gau. The IUCN Red List of Threatened Species 2020

      Fisher, R.; Hathaway, S.; Gray, K.; Grant, Tandora D. (2020)
      Gau Banded Iguanas are known to occur only on Gau Island, Fiji, and have an estimated extent of occurrence and area of occupancy of 220 km2 . Over 50% of the natural habitat of Gau has been degraded or converted due to illegal forest burning practices and free-roaming domestic goat competitors. The iguana population is suspected to have declined correspondingly during the last 30–45 years (three generations). There is continuing predation pressure on iguanas from invasive alien rats, feral cats, and free-roaming domestic pigs. Without conservation intervention, habitat degradation observed during the last 20 years is projected to cause a further 10–20% decline over the next 10–15 years.
    • Conditional female strategies influence hatching success in a communally nesting iguana

      Moss, Jeanette B.; Gerber, Glenn P.; Laaser, Tanja; Goetz, Matthias; Oyog, TayVanis; Welch, Mark E. (2020)
      The decision of females to nest communally has important consequences for reproductive success. While often associated with reduced energetic expenditure, conspecific aggregations also expose females and offspring to conspecific aggression, exploitation, and infanticide. Intrasexual competition pressures are expected to favor the evolution of conditional strategies, which could be based on simple decision rules (i.e., availability of nesting sites and synchronicity with conspecifics) or on a focal individual's condition or status (i.e., body size). Oviparous reptiles that reproduce seasonally and provide limited to no postnatal care provide ideal systems for disentangling social factors that influence different female reproductive tactics from those present in offspring‐rearing environments. In this study, we investigated whether nesting strategies in a West Indian rock iguana, Cyclura nubila caymanensis, vary conditionally with reproductive timing or body size, and evaluated consequences for nesting success. Nesting surveys were conducted on Little Cayman, Cayman Islands, British West Indies for four consecutive years. Use of high‐density nesting sites was increasingly favored up to seasonal nesting activity peaks, after which nesting was generally restricted to low‐density nesting areas. Although larger females were not more likely than smaller females to nest in high‐density areas, larger females nested earlier and gained access to priority oviposition sites. Smaller females constructed nests later in the season, apparently foregoing investment in extended nest defense. Late‐season nests were also constructed at shallower depths and exhibited shorter incubation periods. While nest depth and incubation length had significant effects on reproductive outcomes, so did local nest densities. Higher densities were associated with significant declines in hatching success, with up to 20% of egg‐filled nests experiencing later intrusion by a conspecific. Despite these risks, nests in high‐density areas were significantly more successful than elsewhere due to the benefits of greater chamber depths and longer incubation times. These results imply that communal nest sites convey honest signals of habitat quality, but that gaining and defending priority oviposition sites requires competitive ability.
    • Conolophus pallidus. The IUCN Red List of Threatened Species 2020

      Gentile, G.; Grant, Tandora D. (2020)
      The Barrington Land Iguana is only found on Santa Fé (Barrington) Island, Galápagos Archipelago, Ecuador, and has an estimated area of occupancy and extent of occurrence of 40 km2 . Based on the denuded landscape caused by non-native goats, historic human consumption, and low numbers of iguanas observed in the 1960s–1970s, it is estimated that the iguana population had been reduced by at least 50% up to a point three generations in the past (52 years) and probably continued until after the goats were eradicated in 1972. The most recent survey in 2005 estimated their population to be 3,500–4,000 mature adults and potentially stable, although it was unknown if they had neared carrying capacity. Molecular analysis also shows extremely low genetic variation and richness compared to sampled populations of the Common Land Iguana (Conolophus subcristatus). Heavy predation pressure on this congregatory nesting iguana by Galápagos Hawks may have affected the rate of population recovery since goats were eradicated (1972). The recent introduction to the island of >500 juvenile Española Tortoises that compete with iguanas for scarce food resources may have an impact on the future stability of the iguana population.
    • Conolophus subcristatus. The IUCN Red List of Threatened Species 2020

      Kumar, K.; Gentile, G.; Grant, Tandora D. (2020)
      The Galápagos Land Iguana has a mostly outdated population size estimate of ca 10,000 mature individuals, in 13 subpopulations that are fragmented from each other by vast lava flows or are on isolated islands. With the exception of Baltra where the subpopulation had been extirpated, subpopulations were considered healthy three generations ago in the 1950s. Since that time, iguanas have been nearly extirpated from most of southern Isabela and Santa Cruz, and have declined in northern Isabela. Juveniles are rarely observed in these remaining nine locations due to continued predation by feral cats. Iguanas are small in number but relatively stable on Fernandina and Plaza Sur. They have increased again on the small islands of Baltra and Seymour Norte (likely to carrying capacity on the latter), due to conservation efforts. Overall, considering the assumed population (current andformer) sizes on the larger islands, it is estimated the population has declined by at least 30% over the last three generations. A minimum estimate of 10–15% decline is projected during the future three generations, based on the presence of invasive alien predators in some subpopulations and impacting juvenile recruitment. The estimated extent of occurrence meets the Vulnerable threshold at 9,524 km2 and the area of occupancy is crudely estimated to be 540 km2 . Further research on fine-scale distribution is needed to clarify an accurate occupancy status of the subpopulations.