Factors that limit the range expansion of introduced species can offer insights into the basic ecology of these species and inform conservation of associated endemic species. North American red ...squirrels (Tamiasciurus hudsonicus (Erxleben, 1777)) were recently introduced to the island of Newfoundland, Canada, where they have been implicated in the decline of two endemic bird subspecies. During the summers of 2016 (following conifer masting) and 2017 (following nonmasting), we conducted surveys with 1960 point counts and playback to assess red squirrel distribution and habitat use across a 257 km
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montane landscape in western Newfoundland. We used generalized additive models with stepwise model selection to assess the relationship between land cover and red squirrel occurrence each summer. Red squirrels were most common at low elevations and were not detected at elevations above ∼500 m. Their occurrence was negatively associated with the presence of water, coniferous scrub, and 10- to 30-year-old fir–spruce but positively associated with the presence of 30- to 70-year-old fir–spruce and >70-year-old fir. Red squirrel presence was related to more land cover variables in 2016, after a masting year. The absence of red squirrels from forests at higher elevations apparently resulted from lack of suitable habitat rather than incomplete range expansion. Climate- or silviculture-induced changes in vegetation may alter mid- and upper-elevation habitat suitability.
Introduced species are known for inducing changes in ecosystems and for their impacts on endemic island species. North American red squirrels ( Tamiasciurus hudsonicus ) were introduced to ...Newfoundland, Canada, during the 1960s and have been hypothesized as a cause of the precipitous decline of the Newfoundland Gray-cheeked Thrush ( Catharus minimus minimus ). To test the prediction that the impacts of squirrels led to range contraction by thrushes, we completed 1960 point count surveys for squirrel and thrush over two years (2016 and 2017) in western Newfoundland. Thrushes and squirrels were strongly segregated by elevation, with thrushes now being commonly detected at only high elevation, squirrels being detected most frequently at low elevation, and both species being rare and inversely likely to be present at intermediate elevations. We evaluated local (5.5 ha) and landscape (490.8 ha) scale habitat affiliations of thrushes using landcover data from a provincial forest resource inventory to assess the potential for synergistic impacts on thrush of squirrel invasion and forest management. Gray-cheeked Thrushes were associated with regenerating (10–30 years post-harvest) clear-cuts, conifer forest, and tall scrub at the local scale, but avoided tall scrub, regenerating stands, and second growth forest at the landscape scale. Regenerating clear-cuts and modified strip cuts were selected by thrushes at a local scale. Breeding Bird Survey data show that Gray-cheeked Thrushes were abundant at lower elevations prior to the expansion of squirrels across Newfoundland, so our finding of strong elevational segregation adds to the growing body of evidence suggesting that the introduction of squirrels played an important role in the sudden decline and range contraction of this insular songbird subspecies. Management for squirrels should include efforts to prevent spread upslope and to nearshore islands while more study is done on this and other hypotheses regarding the cause of Gray-cheeked Thrush decline, as well as on relevant aspects of the ecology of this little-studied thrush.
Purpose: The purpose was to determine the effect of a single-dose prophylactic ibuprofen use before a 164-km road cycling event in high ambient temperature on the circulating cytokine and leukocyte ...responses. Methods: Twenty-three men (53 ± 8 y, 172.0 ± 22.0 cm, 85.1 ± 12.8 kg, 19.6 ± 4.4% body fat) completed a 164-km self-paced recreational road cycling event in a hot, humid, sunny environment (WBGT = 29.0 ± 2.9°C) after consuming 600 mg of ibuprofen (n = 13) or a placebo (n = 10). Blood samples were obtained one to two hours before (PRE) and immediately after (POST) the event, and analyzed for concentrations of circulating cytokines interleukins (IL)-1β, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12, IL-13, GM-CSF, IFN-γ, and TNF-α and leukocytes (total leukocytes, granulocytes, monocytes, and lymphocytes). Results: Event completion time was 400.2 ± 74.8 min. Concentrations of all cytokines (except IL-1β, IL-2, IL-5, IL-12, GM-CSF, and IFN-γ) and of all leukocyte subsets increased from PRE to POST. Ibuprofen ingestion attenuated the increase in IL-10 (86% increase with Ibuprofen; 270% increase with placebo). Conclusions: Consuming 600 mg of Ibuprofen prior to a 164-km road cycling event in a hot-humid environment attenuates exercise-induced increases in the concentration of the anti-inflammatory cytokine IL-10, but does not alter the effect of the exercise event on concentrations of other circulating cytokines or leukocyte subset concentrations.
Rusty blackbirds (Euphagus carolinus), once common across their boreal breeding distribution, have undergone steep, range-wide population declines. Newfoundland is home to what has been described as ...one of just two known subspecies (E. c. nigrans) and hosts some of the highest known densities of the species across its extensive breeding range. To contribute to a growing body of literature examining rusty blackbird breeding ecology, we studied habitat occupancy in Western Newfoundland. We conducted 1960 point counts across a systematic survey grid during the 2016 and 2017 breeding seasons, and modeled blackbird occupancy using forest resource inventory data. We also assessed the relationship between the presence of introduced red squirrels (Tamiasciurus hudsonicus), an avian nest predator, and blackbird occupancy. We evaluated 31 a priori models of blackbird probability of occurrence. Consistent with existing literature, the best predictors of blackbird occupancy were lakes and ponds, streams, rivers, and bogs. Red squirrels did not appear to have a strong influence on blackbird habitat occupancy. We are among the first to model rusty blackbird habitat occupancy using remotely-sensed landcover data; given the widespread availability of forest resource inventory data, this approach may be useful in conservation efforts for this and other rare but widespread boreal species. Given that Newfoundland may be a geographic stronghold for rusty blackbirds, future research should focus on this distinct population.
Three options for anesthetizing the skin around the horn bud of dairy goat kids were explored. Forty-five <10-day-old Saanen goat kids from were randomly split into five treatment groups (topical ...anesthetic cream (TA), vapocoolant spray (VS), local anesthetic applied by jet injector (JI), control - no treatment but painful stimulus applied (C), sham - no treatment and touching sites with a finger. The painful stimulus was multiple needle pricks on the skin around the horn bud. The outcome variables measured were heart rate movement, and vocalization during treatment application and administration of a painful stimulus around the horn bud. Heart rates were greater during application of a VS compared to TA.Neither the TA nor the VS appeared to have any effect on the response to the painful stimulus. Kids in the JI group had a 96% reduced odds of expressing a marked pain response in comparison to TA group and an 83% reduction in the odds of a high movement grade during a painful procedure in comparison to the combined results of the other three treatment groups.
HZ-166 has previously been characterized as an α2,3-selective GABA
receptor modulator with anticonvulsant, anxiolytic, and anti-nociceptive properties but reduced motor effects. We discovered a ...series of ester bioisosteres with reduced metabolic liabilities, leading to improved efficacy as anxiolytic-like compounds in rats. In the present study, we evaluated the anticonvulsant effects KRM-II-81 across several rodent models. In some models we also evaluated key structural analogs. KRM-II-81 suppressed hyper-excitation in a network of cultured cortical neurons without affecting the basal neuronal activity. KRM-II-81 was active against electroshock-induced convulsions in mice, pentylenetetrazole (PTZ)-induced convulsions in rats, elevations in PTZ-seizure thresholds, and amygdala-kindled seizures in rats with efficacies greater than that of diazepam. KRM-II-81 was also active in the 6 Hz seizure model in mice. Structural analogs of KRM-II-81 but not the ester, HZ-166, were active in all models in which they were evaluated. We further evaluated KRM-II-81 in human cortical epileptic tissue where it was found to significantly-attenuate picrotoxin- and AP-4-induced increases in firing rate across an electrode array. These molecules generally had a wider margin of separation in potencies to produce anticonvulsant effects vs. motor impairment on an inverted screen test than did diazepam. Ester bioisosters of HZ-166 are thus presented as novel agents for the potential treatment of epilepsy acting via selective positive allosteric amplification of GABA
signaling through α2/α3-containing GABA receptors. The in vivo data from the present study can serve as a guide to dosing parameters that predict engagement of central GABA
receptors.
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