Abstract

Gopher tortoises (Gopherus polyphemus) occur in a variety of habitats, but are primarily associated with sandhill communities. In peninsular Florida, however, mesic flatwoods make up the largest area of habitat, and scrub often replaces sandhill on inland ridges. Tortoise ecology is poorly understood in these habitats and few data are available to guide management. We surveyed tortoise burrows and assessed vegetation in scrub, flatwoods, and pine plantations on flatwoods soils at Avon Park Air Force Range in south-central Florida. Densities of noncollapsed burrows in scrub (1.93/ha) and flatwoods/plantations (1.42/ha) were generally lower than is typical for sandhill (3.25–9.95/ha), although total abundance was high (>20,000) because of the large habitat area. In scrub, low burrow densities may be due to low abundance of food plants. Nonetheless, the burrow density in scrub was significantly higher than in flatwoods/plantations, where food was abundant but soils were poorly drained and burrows were often flooded. The percentage of collapsed burrows was significantly higher in scrub (53%) than in flatwoods/plantations (35%), although a higher percentage of the remaining (noncollapsed) burrows were active in scrub (23%) than in flatwoods/plantations (16%). These patterns (and data from a subsequent radiotelemetry study) suggest that tortoises in scrub maintain strong fidelity to individual burrows, and frequently abandon others, whereas tortoises in flatwoods share burrows and move among them regularly, but rarely abandon them. This sharing and continual reuse of available burrows suggests a possible limitation on suitable conditions for burrow construction in flatwoods, probably related to the high water table. We suggest that scrub and flatwoods may constitute suboptimal habitats for gopher tortoises, due to low abundance of food in scrub and poorly drained soils in flatwoods. Nonetheless, large numbers of tortoises may occupy scrub and flatwoods, necessitating better understanding of their ecology in these habitats.

Abstract

Maximilian's snake-necked turtle, Hydromedusa maximiliani, is an endemic and vulnerable long-lived freshwater turtle from eastern Atlantic mountainous rainforest regions of Brazil. Three scenarios (real population, optimistic population, and pessimistic population) based on the species' life-history data and carrying capacity estimates collected throughout 13 yrs were generated with VORTEX and subjected to sensitivity tests to verify the influence of demographic (mortality rate and inbreeding depression) and environmental (fire and deforestation catastrophes) parameters on population viability. The results showed significant differences among the viability scenarios, with extinction probability ranging from 6% to 99%. These analyses illustrate that environmental and demographic stochasticity can negatively impact populations of H. maximiliani and emphasize the necessity of protecting areas for long-lived organisms inhabiting regions impacted by humans.

Abstract

Seasonal and temporal-spatial distributions of green turtle (Chelonia mydas) nesting activity were assessed at Aldabra Atoll Seychelles, the second largest green turtle rookery in the Western Indian Ocean (WIO), based on morning counts of fresh turtle tracks conducted during 1980–2011. The datasets used in the analyses are derived from an average of 3–4 surveys per month at two index sites representing ∼30%–42% of total annual nesting during 1980–1989 and ∼58% during 1995–2011; and monthly surveys conducted at another two remote sites, which accounted for an additional 20% of annual nesting (total ∼78%) during 2002–2011. Turtles engaged in year-round nesting during the season defined as December to November and characterized by patterns of high intra- and interannual variation. In some seasons, nesting peaked primarily during February to May, and in others during May to September, but on average during 1995–2011, a clear unimodal pattern emerged with nesting activity greatest during February to September, peaking during April to June, and lowest in November–December. The two Primary Index Sites situated 2.2 km apart on the west coast and separated by a lagoon entrance had mean peak nesting dates that consistently differed by more than a month. Possible explanations for the differences are discussed. At Aldabra, the timing of the 1997–1998 ENSO event coincided with a disruption in normal nesting cycles during 1998 through 2002 and the highest levels of nesting recorded at Aldabra to date during the 2000–2001 season. Comparison of seasonal median peak nesting dates at five green turtle rookeries in the WIO suggests an inverse relationship with latitude among four of them, with those in the lower latitudes peaking during the austral autumn and winter and in the higher latitudes during the austral summer, an indication that temperature may be moderating nesting seasonality in the WIO.

often I sing when I'm all alone,
and no one can see me but me.
i think and wonder what i am
and how i came to be.

i can swim the ocean,
and it's deep and wide,
and in the house above me
abide.

maybe one day i'll fly like an eagle,
fly like a bird and go and go.
soar like an eagle,
walk like a lion,
although it won't be i know.

but i can swim the ocean,
and it's deep and wide,
and in the house above me
abide.

i guess the time has come for