The 2010 Deepwater Horizon (DWH) oil spill and associated response activities overlapped with habitats for multiple life stages of federally protected sea turtles in the northern Gulf of Mexico.Although most assessment efforts focused on documenting the presence, abundance, and exposure of sea turtles to DWH oil in marine habitats, oil also washed ashore on sand beaches used by nesting turtles, specifically in NW Florida and Alabama, USA.In addition, extensive and highly mechanized beach cleanup efforts were conducted in NW Florida as well as Alabama, Louisiana, and Mississippi.Thus, the DWH oil spill negatively affected sea turtle nesting directly (e.g.adverse effects of oil exposure) and indirectly (e.g.beach cleanup activities deterring nesting) in several ways.In this study, we used a before-after, control-impact statistical modeling approach to examine long-term (1997-2012) historical records of loggerhead turtle (Caretta caretta) nest densities in 2 segments of the Florida Gulf coastline, one that was heavily affected by the oil spill (NW Florida) and one that was relatively unaffected (SW Florida).Loggerhead nest densities on NW Florida beaches in 2010 were reduced by 43.7% (95% confidence interval: 10-65%) relative to expected nesting rates in the absence of DWH oil and cleanup efforts.When we applied this reduction to all nesting habitat in NW Florida, this equated to a loss of approximately 251 unrealized nests from the 2010 nesting season -a loss we attribute to direct (e.g.mortality) and indirect (e.g.deterrence of nesting) effects related to the DWH incident.

We used satellite telemetry to study behavior at foraging sites of 40 adult female loggerhead sea turtles (Caretta caretta) from three Florida (USA) rookeries. Foraging sites were located in four countries (USA, Mexico, the Bahamas, and Cuba). We were able to determine home range for 32 of the loggerheads. One turtle moved through several temporary residence areas, but the rest had a primary residence area in which they spent all or most of their time (usually >11 months per year). Twenty-four had a primary residence area that was <500 km2 (mean = 191). Seven had a primary residence area that was ≥500 km2 (range = 573–1,907). Primary residence areas were mostly restricted to depths <100 m. Loggerheads appeared to favor areas with larger-grained sediment (gravel and rock) over areas with smaller-grained sediment (mud). Short-term departures from primary residence areas were either looping excursions, typically involving 1–2 weeks of continuous travel, or movement to a secondary residence area where turtles spent 25–45 days before returning to their primary residence area. Ten turtles had a secondary residence area, and six used it as an overwintering site. For those six turtles, the primary residence area was in shallow water (<17 m) in the northern half of the Gulf of Mexico (GOM), and overwintering sites were farther offshore or farther south. We documented long winter dive times (>4 h) for the first time in the GOM. Characterizing behaviors at foraging sites helps inform and assess loggerhead recovery efforts.

We used satellite telemetry to study postnesting migrations of 42 loggerhead sea turtles Caretta caretta from 3 Florida rookeries.Postnesting migrations ended in neritic (< 200 m) waters of Florida, Alabama, Texas (USA), and of Mexico and the Bahamas.Most postnesting migrations were restricted to the continental shelf and were relatively direct.Migrations through oceanic areas (> 200 m) tended to be less direct, largely due to apparent influences of the Florida Current in the Atlantic and to looping travel paths (often along edges of mesoscale eddies of the Loop Current) in the Gulf of Mexico.The largest loggerheads tended to migrate to foraging grounds that were farthest from the nesting beach.Turtles spent more time near the surface (< 3 m) when migrating than they did during residency at foraging sites, and were likely swimming just below the surface.The substantial amount of time spent near the bottom in neritic areas and the looping travel paths in oceanic areas indicate that migrating loggerheads may have been foraging.We identified 4 migratory corridors.Two were on the continental shelf of the Florida Panhandle, 1 was along the northern coast of Cuba, and 1 was along the southeastern coast of Florida.Migrating loggerheads may be uniquely vulnerable to mortality factors because of where they travel and how they behave, particularly if they are concentrated in narrow (perhaps <10 km wide) migratory corridors.Characterizing the behavior and identifying the travel paths of loggerheads during postnesting migrations are necessary steps for implementing successful recovery efforts.

The effectiveness of recovery plans for threatened and endangered species has been questioned in academic and political domains. A comprehensive assessment of species recovery plans concluded that quantification and prioritization of threats have received insufficient attention, which contributes to the failure of some plans. On the basis of this assessment, we developed and implemented a detailed analysis of threats in the Recovery Plan for the Northwest Atlantic Population of the Loggerhead Sea Turtle (Caretta caretta), produced by the National Marine Fisheries Service and US Fish and Wildlife Service. The analytical approach that we designed and summarize here provides an objective process for quantifying known threats and prioritizing recovery actions in terms of their relative impact on population growth rate (lambda) of the loggerhead sea turtle. Although this process was developed for loggerhead sea turtles, it can be applied to other species.

The effectiveness of recovery plans for threatened and endangered species has been questioned in academic and political domains. A comprehensive assessment of species recovery plans concluded that quantification and prioritization of threats have received insufficient attention, which contributes to the failure of some plans. On the basis of this assessment, we developed and implemented a detailed analysis of threats in the Recovery Plan for the Northwest Atlantic Population of the Loggerhead Sea Turtle (Caretta caretta), produced by the National Marine Fisheries Service and US Fish and Wildlife Service. The analytical approach that we designed and summarize here provides an objective process for quantifying known threats and prioritizing recovery actions in terms of their relative impact on population growth rate (λ) of the loggerhead sea turtle. Although this process was developed for loggerhead sea turtles, it can be applied to other species.

Seasonal and habitat variation in diet digestibility of pine voles (Microtus pinetorum) in four apple orchards was estimated using regression equations and the Van Soest analysis of stomach contents. The estimated percent digestible energy of diets in the four orchards varied from 57 to 72% during the year but a uniform seasonal pattern was not found among orchards. Weights of stomach contents declined markedly during winter in all four habitats.

Regression equations for estimating diet digestibility in meadow voles (Microtus pennsylvanicus) were developed using laboratory digestion trials and chemical analyses of diets and stomach contents. These equations were used to obtain estimates of the apparent digestible dry matter (DDM) and apparent digestible energy (DE) in the diets of wild meadow voles. The estimated DDM and DE in the diets of two wild meadow vole populations varied between 62.9 and 75.2% and 62.0 and 74.2%, respectively, and were similar to those reported previously for pine voles (Microtus pinetorum).

A Van Soest analysis of feed and fecal samples from 24 digestion trials with pine voles (Microtus pinetorum) and 18 digestion trials with meadow voles (Microtus pennsylvanicus) was used to examine the digestive capabilities of these species and the effect of feed constituents on fiber digestion. The neutral detergent soluble fraction of feeds and forages (NDS) was the most readily available for voles. Percent neutral detergent fiber (NDF) digestibility was variable and inversely related (P = 0.0001) to the percent NDF of the diets for both pine and meadow voles. NDF digestibility was not related (P > 0.30) to the percentage of lignin in the NDF or acid detergent fiber (ADF). NDF digestion accounted for 15 and 21% of the dry matter digested by pine voles and meadow voles, respectively, on a high fiber diet (40% NDF).