Nesting Habitat Creation Enhances Recruitment in a Predator‐Free Environment: Malaclemys Nesting at the Paul S. Sarbanes Ecosystem Restoration Project

Abstract

Aquatic turtles worldwide are plagued with habitat loss due to development and shoreline alteration that destroys the terrestrial–aquatic linkage which they must cross to reproduce successfully. Furthermore, nesting habitat loss can concentrate nesting, increasing nest predator efficiency. We describe how the Paul S. Sarbanes Ecosystem Restoration Project at Poplar Island created nesting habitat for Malaclemys terrapin (Diamondback Terrapin), and document nesting success in response to construction progress and the absence of raccoons and foxes, the primary nest predators. We monitored terrapin nests throughout the nesting seasons from 2002 to 2011 to determine overall and within‐nest survivorship. Female terrapins began nesting on the restoration project within 1 year but planned construction during the study eliminated some nesting areas and opened previously inaccessible areas. Overall, nest survivorship was considerably higher than mainland nesting areas due to the absence of raccoons and foxes on the island and within‐nest survivorship was similar. Egg size, hatchling size, and the frequency of shell scute anomalies were similar to other terrapin populations, suggesting normal developmental conditions on the island. We documented annual variation in hatchling size that correlated negatively with mean air temperature during the incubation season. Our results indicate that restored or created isolated island habitat can be located rapidly by terrapins and can become an important source of recruitment in regions where nesting habitat is limited and predation is high. Poplar Island illustrates how habitat loss and restoration can affect turtle populations by revealing the changes in nesting patterns and success in newly created, predator‐free habitat.

Turtles and Tortoises Are in Trouble

“…Dam construction harms turtle populations by disrupting gene flow, through habitat deterioration (especially of nesting sites) and by interrupting migratory routes [51,52]. Channelization of rivers and shoreline hardening may eliminate nesting and basking areas and alter the hydrodynamic processes that maintain critical nesting habitat [53]. At least 48% of the global river volume has been altered by flow regulation or fragmentation by impoundment structures [54].…”

“…It may also compromise their population genetics if some nest areas are better protected than others [103], although the longevity and high fecundity of many species may offset genetic issues [195]. Head-starting has been credited with increasing recruitment for populations of some species (e.g., Kemp's Ridley, Lepidochelys kempi [196]; Diamondback Terrapins [53]), but follow-up studies are needed. The long-term success of head-starting has not been widely evaluated quantitatively; deterministic and stochastic modeling suggest it will not save declining populations (e.g., [197]; [6] for marine turtles; [48,67,198] for freshwater turtles).…”

Population and Nesting Site Evidence for Diamondback Terrapins, Malaclemys terrapin, in Northeast Florida

“…Feinberg and Burke (2003) recorded highest depredated terrapin nest densities on man-made trails. Roosenburg et al (2014) demonstrated that terrapins will sometimes use artificially produced habitats for nesting with some success. The nesting activity associated with the Goffinsville and Holly Point boat ramps would not be possible without the construction associated with the ramps.…”

Between the bay and a hard place: Altered diamondback terrapin nesting movements demonstrate the effects of coastal barriers upon estuarine wildlife

“…Barriers such as roads and bulkheading can also lead terrapins to nest in marginal habitats (Roosenburg ) such as backyards and driveways. Such displacement is of particular concern as human development increases because it may lead to lower nest success (Roosenburg , Roosenburg et al ) and population declines.…”

“…The creation of artificial nesting habitats could also be used to offset the creation of barriers to natural nesting areas (Baldwin et al ). For example, Roosenburg et al () describe the restoration of an offshore island within the Chesapeake Bay, Maryland that has created productive nesting habitats for terrapins away from the complex threats present around mainland nesting sites. Knowing that terrapins will use artificial nesting habitats, we recommend their development in Barnegat Bay from washed dredge soils (Wnek et al ).…”