Demography of the Puerto Rican Racer,<i>Borikenophis portoricensis</i>(Squamata: Dipsadidae), on Guana Island, British Virgin Islands

Hileman, Eric T.; Powell, Robert; Perry, Gad; Mougey, Krista; Thomas, Richard H.; Henderson, Robert W.

doi:10.1670/16-147

Cited by 8 publications

(9 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Annual survival of the insular Neotropical pitviper, Bothrops insularis , ranged from 0.55 to 0.79 with males and females having slightly higher survival in the wet season than the dry season (Guimaräes, Munguia‐Steyer, Doherty Jr., Martins, & Sawaya, 2014). An annual adult survival estimate is available for only one other West Indian snake, Borikenophis portoricensis , a largely ground‐dwelling, diurnally active, mildly venomous dipsadid native to the Puerto Rico Bank; it was 0.50 (95% CI) in males (0.34–0.66) and females (0.33–0.66) (Hileman et al, 2017).…”

Section: Discussionmentioning

confidence: 99%

Effects of body size, diet, and transience on the demography of the arboreal boid snake Corallus grenadensis on Carriacou (Grenada Grenadines, West Indies)

Henderson

Hileman

Sajdak³

et al. 2021

Population Ecology

Self Cite

View full text Add to dashboard Cite

Remarkably little is known about the demography of snakes in the family Boidae. This lack of information may be attributed, in part, to low population densities on the Neotropical mainland, rendering capture‐recapture methods impractical for many species. Conversely, islands support fewer species but snake densities can be much higher. Corallus grenadensis is an arboreal boid endemic to the Grenada Bank and, relative to mainland boids, can be amazingly abundant. As young, its diet is comprised largely of native Anolis lizards, a ubiquitous and abundant food source; it then undergoes an ontogenetic shift in diet to a less abundant resource, rodents. From 2015 to 2019, we marked 254 C. grenadensis and used capture–recapture models to estimate abundance, capture probabilities, survival, and the proportion of transients. We hypothesized that the transient effect would increase with body size (snout–vent length [SVL]), prompted by their ontogenetic shift in diet. Capture probabilities increased with sampling effort and decreased with increasing SVL. Abundance ranged from 96 to 141 individuals and annual resident survival was 0.71, 95% confidence interval (CI) = 0.54–0.83. The proportion of transients increased with increasing SVL, with the estimate being distinguishable from zero starting at ~810 mm SVL, coinciding with the size at which their dietary shift from ectothermic to endothermic prey begins. Ontogenetic dietary shifts are widespread in snakes and occur in at least 11 of 17 species of West Indian boids. Thus, the prominence of transients in our study may be indicative of its demographic and ecological importance among other snake species.

show abstract

Section: Discussionmentioning

confidence: 99%

Effects of body size, diet, and transience on the demography of the arboreal boid snake Corallus grenadensis on Carriacou (Grenada Grenadines, West Indies)

Henderson

Hileman

Sajdak³

et al. 2021

Population Ecology

Self Cite

View full text Add to dashboard Cite

show abstract

“…comm.). Although pre-hurricane data are lacking from Saba, density estimates of Alsophis antiguae (Parker, 1933) from Great Bird Island (20.2/ha; Daltry et al, 2017) and Borikenophis portoricensis (Reinhardt and Lütken, 1862) on Guana Island, British Virgin Islands (19/ha; Hileman et al, 2017) may be representative of a ‘healthy’ racer population on islands such as Saba and St. Eustatius (Hileman et al even believe their abundance estimate may be underestimated due to the small sample size). In an earlier study, Rodda et al (2001) surveyed B. portoricensis on Guana, where they estimated a density of 50/ha in early successional ( Leucaena leucocephala ) forest habitat, and even suggested this was an underestimate.…”

Section: Discussionmentioning

confidence: 99%

“…Quantitative assessments of racers are generally lacking (but see Daltry et al, 2017 and Hileman et al, 2017), as highlighted by Madden et al (2021), and to our knowledge, only one study has quantified the effects of hurricanes on A. rufiventris on St. Eustatius (Madden et al, 2021). Specifically, the authors documented a significant decline in encounter rates of A. rufiventris on St. Eustatius (16.0 snakes/hr in 2011 compared to 0.34/hr in 2018 and 0.41/hr in 2019) as a result of hurricanes Irma and Maria.…”

Section: Introductionmentioning

confidence: 99%

A Post-hurricane Quantitative Assessment of the Red-bellied Racer (Alsophis rufiventris) on Saba and Comparison with St. Eustatius

Madden

Mielke²

2021

Preprint

View full text Add to dashboard Cite

We estimated occupancy, abundance (lambda), detection probability, density/ha and abundance of a regionally endemic snake in the Colubrid family on the Dutch Caribbean island of Saba in 2021, four years after hurricanes Irma and Maria impacted the island. Line transect surveys were conducted at 74 sites covering 6.7 ha. The proportion of sites occupied was estimated at 0.74 (min 0.48, max 0.90), with occupancy varying between vegetation types and across elevational gradients. Similarly, lambda was estimated at 1.61 (min 0.7, max 3.7) but varied between vegetation types and elevational gradients. Detection probability was estimated at 0.15 (min 0.10, max 0.21). Using Distance sampling, we estimated 10.9 (min 7.3, max 16.2) racers/ha, with a total population estimate of 4,917 (min 2,577, max 6,362) across the entire study region (438.6 ha.) Based on anecdotal observations from Saban residents and prior literature describing the pre-hurricane population as “abundant” (at least 2.0 racers/hour), we posit that the population experienced a hurricane-induced decline but may have since recovered, though not to previous levels (1.28 racers/hour). Nevertheless, our results suggest that racer densities on Saba are currently higher than those on St. Eustatius. Despite this, given the species’ extremely limited extant range and the presence of invasive species on both islands, prevention of local extirpation should be a high conservation priority.

show abstract

“…Consequently, it is unclear whether high survival leads to increased body size, large body size leads to increased survival, or some other mechanism underlies variation in both size and survival. Given that our 14 study sites are separated by less than 20 km, variation in climatic conditions is likely to be small and certainly far less than that seen in range‐wide demonstrations of variation in survival (Jones et al., 2012) or body size (Hileman, King, et al., 2017; Hileman, Powell, et al., 2017). Study sites differ in the extent of human activity and may differ in predator abundance, but how these variables affect mortality awaits further investigation.…”

Section: Discussionmentioning

confidence: 99%

Sunning themselves in heaps, knots, and snarls: The extraordinary abundance and demography of island watersnakes

King

Stanford²,

Jones

2018

Ecology and Evolution

View full text Add to dashboard Cite

Snakes represent a sizable fraction of vertebrate biodiversity, but until recently, data on their demography have been sparse. Consequently, generalizations regarding patterns of variation are weak and the potential for population projections is limited. We address this information gap through an analysis of spatial and temporal variation in demography (population size, annual survival, and realized population growth) of the Lake Erie Watersnake, Nerodia sipedon insularum, and a review of snake survival more generally. Our study spans a period during which the Lake Erie Watersnake was listed as threatened under the U.S. Endangered Species Act, recovered, and was delisted. We collected capture–mark–recapture data at 14 study sites over 20 years, accruing 20,000 captures of 13,800 individually marked adults. Lake Erie Watersnakes achieve extraordinary abundance, averaging 520 adults per km of shoreline (ca. 260 adult per ha) at our study sites (range = 160–1,600 adults per km; ca. 80–800 adults per ha) and surpassing population recovery and postdelisting monitoring criteria. Annual survival averages 0.68 among adult females and 0.76 among adult males, varies among sites, and is positively correlated with body size among study sites. Temporal process variance in annual survival is low, averaging 0.0011 or less than 4% of total variance; thus, stochasticity in annual survival may be of minor significance to snake extinction risk. Estimates of realized population growth indicate that population size has been stable or increasing over the course of our study. More generally, snake annual survival overlaps broadly across continents, climate zones, families, subfamilies, reproductive modes, body size categories, maturation categories, and parity categories. Differences in survival in relation to size, parity, and maturation are in the directions predicted by life history theory but are of small magnitude with much variation around median values. Overall, annual survival appears to be quite plastic, varying with food availability, habitat quality, and other ecological variables.

show abstract

Demography of the Puerto Rican Racer,Borikenophis portoricensis(Squamata: Dipsadidae), on Guana Island, British Virgin Islands

Cited by 8 publications

References 25 publications

Effects of body size, diet, and transience on the demography of the arboreal boid snake Corallus grenadensis on Carriacou (Grenada Grenadines, West Indies)

Effects of body size, diet, and transience on the demography of the arboreal boid snake Corallus grenadensis on Carriacou (Grenada Grenadines, West Indies)

A Post-hurricane Quantitative Assessment of the Red-bellied Racer (Alsophis rufiventris) on Saba and Comparison with St. Eustatius

Sunning themselves in heaps, knots, and snarls: The extraordinary abundance and demography of island watersnakes

Contact Info

Product

Resources

About