Contrasting Patterns of Movement across Life Stages in an Insular Iguana Population

Moss, Jeanette B; Gerber, Glenn P.; Goetz, Matthias; Haakonsson, Jane; Harvey, Jessica C.; Laaser, Tanja; Welch, Mark E.

doi:10.1670/18-113

Cited by 6 publications

(8 citation statements)

References 29 publications

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“…The overarching scientific goal of the radio‐tracking study on Little Cayman was to characterize a poorly understood process in the life history of a critically endangered iguana species—natal dispersal (Moss et al, 2020). This would contribute to an improved understanding among conservation researchers of this cryptic early life stage, including how the behaviors exhibited by hatchlings may ultimately shape patterns of recruitment and admixture in otherwise stable adult populations.…”

Section: Performancementioning

confidence: 99%

“…During this field season, new insights into patterns of natal dispersal were gleaned from the combination of drone‐based tracking and manual triangulation. For instance the greater frequency and precision of tracking facilitated by the UAV early in the season helped to illustrate that patterns of movement can vary remarkably among neonates even over short time frames (Moss et al, 2020). Characterizing fine‐scale behavioral variation among neonates dispersing through different habitat types is of conservation importance because increased time spent in habitat such as mangrove has been shown to correlate with increased probability of survivorship (Knapp et al, 2010).…”

Section: Performancementioning

confidence: 99%

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A more precise way to localize animals using drones

Hui

Moss

et al. 2021

Journal of Field Robotics

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Radio telemetry is a commonly used technique in conservation biology and ecology, particularly for studying the movement and range of individuals and populations. Traditionally, most radio telemetry work is done using handheld directional antennae and either direction‐finding and homing techniques or radio‐triangulation techniques. Over the past couple of decades, efforts have been made to utilize unmanned aerial vehicles to make radio‐telemetry tracking more efficient, or cover more area. However, many of these approaches are complex and have not been rigorously field‐tested. To provide scientists with reliable quality tracking data, tracking systems need to be rigorously tested and characterized. In this paper, we present a novel, drone‐based, radio‐telemetry tracking method for tracking the broad‐scale movement paths of animals over multiple days and its implementation and deployment under field conditions. During a 2‐week field period in the Cayman Islands, we demonstrated this system's ability to localize multiple targets simultaneously, in daily 10 min tracking sessions over a period of 2 weeks, generating more precise estimates than comparable efforts using manual triangulation techniques.

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Section: Performancementioning

confidence: 99%

Section: Performancementioning

confidence: 99%

A more precise way to localize animals using drones

Hui

Moss

et al. 2021

Journal of Field Robotics

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“…A total of 81 unique tagged females were documented nesting on Little Cayman between 2015 and 2018. The smallest recorded gravid female in our dataset (28.3 cm in SVL and 1,080 g in mass) was inferred to be 2–3 years of age based on size trajectory analysis (Moss et al, ). Female SVL (2015 mean: 40.47 ± 4.35 cm; 2016 mean: 39.35 ± 3.04 cm; 2017 mean: 39.74 ± 3.85 cm; and 2018 mean: 42.19 ± 1.97 cm) was significantly positively correlated with clutch size ( t = 3.41, R 2 = .199, p = .001; Figure ).…”

Section: Resultsmentioning

confidence: 82%

“…Our hypothesis was that variation in social environmental preferences among nesting females would be explained by differential energetic constraints linked to reproductive timing and body size. While female rock iguanas nesting in aggregations aggressively defend nests against conspecifics (Iverson et al, ; Knapp & Owens, ; Wiewandt, ; Wilson et al, ), energy available for nest defense may be reduced substantially following long‐distance nesting migrations (Iverson et al, ; Moss et al, ; Pérez‐Buitrago et al, ) and physical nest excavation. Evidence for this trade‐off is clear in the related Iguana iguana , for which females are visibly emaciated postlaying (Rand & Rand, ) and, having little energy to devote to nest defense prior to departing a nesting area, suffer many instances of conspecific intrusion and ovicide (Rand, ; Rand & Dugan, ; Rand & Rand, ).…”

Section: Discussionmentioning

confidence: 99%

“…A promising system for investigating these dynamics is the West Indian rock iguana (genus Cyclura ), an insular lizard for which a range of nesting behaviors, including aggregative oviposition, have been documented (Carreras‐De León et al, ; Iverson et al, ; Pérez‐Buitrago, Sabat, & McMillan, ; Wiewandt, ). Much of the conversation surrounding communal nesting in Cyclura has focused on the constraining habitat features of Caribbean islands: predominantly karst limestone, with spurious distributions of deep, friable soil, access to which often demands long‐distance nesting migrations (Iverson et al, ; Moss et al, ; Pérez‐Buitrago et al, ). However, there is also considerable evidence that social factors (i.e., competition) could account for individual variation in nesting strategies.…”

Section: Introductionmentioning

confidence: 99%

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Conditional female strategies influence hatching success in a communally nesting iguana

Moss

Gerber

Laaser

et al. 2020

Ecology and Evolution

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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.

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Using recent genetic history to inform conservation options of two Lesser Caymans iguana (Cyclura nubila caymanensis) populations

Rogers,

Stenhouse,

Wilson

et al. 2024

Conserv Genet

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The Sister Islands rock iguana (Cyclura nubila caymanensis) is critically endangered and endemic to the Caribbean islands Little Cayman and Cayman Brac. The Cayman Brac population and indeed the entire species is under threat from habitat destruction, invasive species, and anthropogenic impacts on the island. We assessed the genetic diversity, estimated effective population sizes, and tested for differentiation of populations between these two islands to inform potential future translocation should this be needed for the Cayman Brac population. Two mitochondrial DNA markers (cytochrome b and NADH subunit 4) and seven DNA microsatellite markers were used to assess the genetic diversity, genetic structure, demographic history, and effective population size of the two iguana populations. Mitochondrial DNA showed no genetic differentiation between populations; however, we found little to moderate divergence with microsatellites. We compared multiple demographic scenarios and revealed that ongoing gene flow is likely. The demographic history implied a significant genetic bottleneck around 10,000 years ago, coinciding with the sea level rise at the close of the last glacial period, and the start of the Holocene. Estimates of current effective population sizes indicate a small-scale number of breeders on each island of similar magnitude to the census mature population size (between 100 and 800 individuals). The relatively low differentiation between populations supports the possible development of active genetic management plans to manage the declining populations of the Sister Islands rock iguana.

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Contrasting Patterns of Movement across Life Stages in an Insular Iguana Population

Cited by 6 publications

References 29 publications

A more precise way to localize animals using drones

A more precise way to localize animals using drones

Conditional female strategies influence hatching success in a communally nesting iguana

Using recent genetic history to inform conservation options of two Lesser Caymans iguana (Cyclura nubila caymanensis) populations

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