• 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....
    • Assessment and validation of miniaturized technology for the remote tracking of critically endangered Galápagos pink land iguana (Conolophus marthae)

      Loreti, Pierpaolo; Bracciale, Lorenzo; Colosimo, Giuliano; Vera, Carlos; Gerber, Glenn P.; De Luca, Massimiliano; Gentile, Gabriele (2020)
      Background: Gathering ecological data for species of conservation concern inhabiting remote regions can be daunting and, sometimes, logistically infeasible. We built a custom-made GPS tracking device that allows to remotely and accurately collect animal position, environmental, and ecological data, including animal temperature and UVB radiation. We designed the device to track the critically endangered Galápagos pink land iguana, Conolophus marthae. Here we illustrate some technical solutions adopted to respond to challenges associated with such task and present some preliminary results from controlled trial experiments and feld implementation. Results: Our tests show that estimates of temperature and UVB radiation are affected by the design of our device, in particular by its casing. The introduced bias, though, is systematic and can be corrected using linear and quadratic regressions on collected values. Our data show that GPS accuracy loss, although introduced by vegetation and orientation of the devices when attached to the animals, is acceptable, leading to an average error gap of less than 15 m in more than 50% of the cases. Conclusions: We address some technical challenges related to the design, construction, and operation of a custom made GPS tracking device to collect data on animals in the wild. Systematic bias introduced by the technological implementation of the device exists. Understanding the nature of the bias is crucial to provide correction models. Although designed to track land iguanas, our device could be used in other circumstances and is particularly useful to track organisms inhabiting locations that are diffcult to reach or for which classic telemetry approaches are unattainable.
    • Chemical signatures of femoral pore secretions in two syntopic but reproductively isolated species of Galápagos land iguanas (Conolophus marthae and C. subcristatus)

      Colosimo, Giuliano; Di Marco, Gabriele; D’Agostino, Alessia; Gismondi, Angelo; Vera, Carlos A.; Gerber, Glenn P.; Scardi, Michele; Canini, Antonella; Gentile, Gabriele (Springer Science and Business Media LLC, 2020)
      The only known population of Conolophus marthae (Reptilia, Iguanidae) and a population of C. subcristatus are syntopic on Wolf Volcano (Isabela Island, Galápagos). No gene flow occurs suggesting that effective reproductive isolating mechanisms exist between these two species. Chemical signature of femoral pore secretions is important for intra- and inter-specific chemical communication in squamates. As a first step towards testing the hypothesis that chemical signals could mediate reproductive isolation between C. marthae and C. subcristatus, we compared the chemical profiles of femoral gland exudate from adults caught on Wolf Volcano. We compared data from three different years and focused on two years in particular when femoral gland exudate was collected from adults during the reproductive season. Samples were processed using Gas Chromatography coupled with Mass Spectrometry (GC–MS). We identified over 100 different chemical compounds. Non-Metric Multidimensional Scaling (nMDS) was used to graphically represent the similarity among individuals based on their chemical profiles. Results from non-parametric statistical tests indicate that the separation between the two species is significant, suggesting that the chemical profile signatures of the two species may help prevent hybridization between C. marthae and C. subcristatus. Further investigation is needed to better resolve environmental influence and temporal reproductive patterns in determining the variation of biochemical profiles in both species.
    • 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.