https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1168&context=eeob_ag_pubs

Terrestrial habitat requirements of nesting freshwater turtles

Training and long-term memory of a novel food acquisition task in a turtle (Pseudemys nelsoni).

For long-lived, iteroparous organisms whose annual reproductive success is low and unpredictable, the ''bet- hedging'' life-history paradigm predicts that an increase in resource acquisition should result in an increase in stored lipids and not an increase in reproductive output. We tested whether reproductive patterns in a population of midland painted tur- tles (Chrysemys picta marginataAgassiz, 1857) are consistent with this prediction. Assuming that annual temperature var- iation is a proxy for variation in resource acquisition, we hypothesized that if harvested resources are generally sequestered for future reproduction, then there should be no relationship between clutch frequency (the number of clutches laid per season) and the temperature experienced when no follicular growth occurred. We hypothesized further that if tem- perature constrains clutch frequency by limiting the amount of energy that can be allocated to reproduction, then clutch frequency would be related only to the temperature experienced during the period in which follicular growth occurred (fall temperature). We found that clutch frequency was primarily related to fall temperature, which suggests that the amount of thermal energy experienced during periods of follicular development limits the amount of stored energy that can be allo- cated to developing follicles. This pattern of reproductive allocation is consistent with the bet-hedging paradigm. Resume ´ : Chez les organismes iteropares avie longue dont le succes reproductif annuel est faible et imprevisible, le para- digme du « pari sur l'avenir » des cycles biologiques predit qu'une augmentation de l'acquisition de ressources devrait en- trao ˆner un accroissement des reserves lipidiques plutot qu'une augmentation du rendement reproductif. Nous avons verifie ´ si les patrons de reproduction d'une population de tortues peintes du centre ( Chrysemys picta marginataAgassiz, 1857) s'accordent avec cette prediction. En assumant que la variation de la temperature annuelle est une variable de rechange pour la variation de l'acquisition de ressources, nous emettons l'hypothese qui veut que, si les ressources recoltees sont en general mises en reserve pour des reproductions futures, il n'y ait pas de correlation entre la frequence des pontes (le nom- bre de pontes produites par saison) et la temperature subie durant la periode sans croissance des follicules. Nous formulons une seconde hypothese selon laquelle, si la temperature restreint la frequence des pontes en limitant la quantited'energie destineeala reproduction, la frequence des pontes est reliee seulement a la temperature subie durant la periode de crois- sance des follicules (temperature d'automne). Nous trouvons que la frequence des pontes est principalement relieeala temperature de l'automne, ce qui laisse croire que la quantited'energie thermique presente durant les periodes de devel- oppement folliculaire limite la quantited'energie en reserve qui peut etre allouee aux follicules en developpement. Ce pa- tron d'allocation reproductive s'accorde avec le paradigme du pari sur l'avenir. (Traduit par la Redaction)

Proximate constraints on reproductive output in a northern population of painted turtles: an empirical test of the bet-hedging paradigm

We constructed an artificial nesting mound for Glyptemys insculpta (Wood Turtle) in the Great Swamp National Wildlife Refuge, NL The original nesting site was impacted by development and invasive plants. The new nesting mound was constructed from similar soil and was 100 m distant from the original site. The new mound was 50 m from stream habitat and in an old field where it received full sun for the entire day. The mound was 18 m long, 8 m wide, and had a maximum height of 1.5 m, with gently sloping sides. We encountered nest-searching female Wood Turtles on the impacted site during late May to early June for four years, 2007–2010. We carefully hand-carried females to the new nesting area and allowed them to choose whether or not to nest on the mound. We protected all nests from predators. Seventeen of 18 nests that were deposited and left on the nesting mound produced live hatchlings. Six clutches had 100% hatching success, with only one failing completely. At least nine different female Wood T...

https://bioone.org/journals/northeastern-naturalist/volume-18/issue-3/045.018.0305/Use-of-an-Artificial-Nesting-Mound-by-Wood-Turtles-Glyptemys/10.1656/045.018.0305.pdf

Use of an Artificial Nesting Mound by Wood Turtles (Glyptemys insculpta): A Tool for Turtle Conservation

There has long been interest in the influence of predators on prey populations, although most predator–prey studies have focused on prey species that are targets of directed predator searching. Conversely, few have addressed depredation that occurs after incidental encounters with predators. We tested two predictions stemming from the hypothesis that nest predation on two sympatric freshwater turtle species whose nests are differentially prone to opportunistic detection—painted turtles (Chrysemys picta) and snapping turtles (Chelydra serpentina)—is incidental: (1) predation rates should be density independent, and (2) individual predators should not alter their foraging behavior after encountering nests. After monitoring nest survival and predator behavior following nest depredation over 2 years, we confirmed that predation by raccoons (Procyon lotor), the primary nest predators in our study area, matched both predictions. Furthermore, cryptic C. picta nests were victimized with lower frequency than more detectable C. serpentina nests, and nests of both species were more vulnerable in human-modified areas where opportunistic nest discovery is facilitated. Despite apparently being incidental, predation on nests of both species was intensive (57% for painted turtles, 84% for snapping turtles), and most depredations occurred within 1 day of nest establishment. By implication, predation need not be directed to affect prey demography, and factors influencing prey crypsis are drivers of the impact of incidental predation on prey. Our results also imply that efforts to conserve imperiled turtle populations in human-modified landscapes should include restoration of undisturbed conditions that are less likely to expose nests to incidental predators.

Incidental nest predation in freshwater turtles: inter- and intraspecific differences in vulnerability are explained by relative crypsis

We studied nest-site fidelity (1995–2000) and nest predation (1997–2000), and nesting movements (1999–2000) in a population of Chrysemys picta marginata at Miller's Marsh on Beaver Island, Michigan. On average, turtles nested farther (mean = 122.3 m) from the marsh than turtles in previously studied populations, possibly because of the relatively large nesting areas (n = 5) of our study. Nest predation was 17.4% over all years and was independent of nest location (distance from water, road vs. field nests, nesting field). Many turtles showed nest-site fidelity between years in that they favored one or two nesting areas and had annual inter-nest distances (ID) that were positively skewed and significantly less (mean = 88.7 m) than IDs of randomly paired nests of different individuals. Radiotelemetry indicated that most turtles emerged during the mid-afternoon and nested during the evening hours. Nesting excursion duration averaged 11.6 h and 75% remained on land overnight after nesting. The use of...

Matthew R. Dugan

Papers

Nest placement, nest-site fidelity and nesting movements in midland painted turtles (Chrysemys picta marginata) on Beaver Island, Michigan