Jessica A. Homyack

Energetics of surface‐active terrestrial salamanders in experimentally harvested forest

ABSTRACT Environmental temperatures affect nearly all aspects of ectotherm physiology, including terrestrial salamanders. Therefore, habitat disturbances that alter temperature regimes may interact with physiological processes to affect energy budgets of salamanders or constrain surface activity and possibly lead to changes in population-level parameters. We hypothesized that warmer surface temperatures following harvesting of canopy trees could cause surface-active salamanders to expend more energy for metabolism, potentially leaving a smaller proportion of the energy budget available for reproduction or storage. From 2006 to 2008, we quantified temperature regimes of salamander refugia in a field experiment replicated at 4 sites that included plots subjected to a timber harvest and plots not manipulated during this time period. At each site, we quantified temperature regimes in regenerating forest stands which, approximately 10 years earlier, experienced a range of harvest intensity from shelterwood to silvicultural clearcut. Further, we compared energetic parameters including 1) calories required to maintain homeostasis across an active season, 2) abundance of available potential energy (i.e., invertebrate prey), and 3) a measure of growth and storage (i.e., body condition index) among silvicultural treatments for surface-active salamanders. For surface-active eastern red-backed salamanders (Plethodon cinereus), mean calories required for maintenance were approximately 33% greater in recently harvested forest compared to unharvested controls, but body condition was inconsistent among treatments, and invertebrate abundances were similar among treatments but differed by study site. In contrast, we did not detect a treatment effect in any energetic metric 8–14 growing seasons after harvesting. Given that surface-active salamanders in recently harvested forest may be forced to restrain behaviors associated with foraging and mating or trade-off growth or reproduction for increased basic maintenance costs, energetics may be an important but overlooked short-term contributor to observed changes in abundances, reproductive demography, or surface activities after timber harvesting. Managing for both the rapid recovery of understory vegetation and retention of large stumps and logs may help mitigate warming of microclimate for salamanders and should be considered further.

Site Characteristics of River Otter (Lontra canadensis) Natal Dens in Minnesota

Abstract Knowledge of the habitat and spatial characteristics of natal dens used by female river otters (Lontra canadensis) is limited to a few observations. Documentation of these characteristics in human-altered landscapes may improve management opportunities for this species. We monitored 8 adult (>2 y old) radio-marked female otters during the natal denning season (March–May) in southeastern Minnesota during 2003–2004 and quantified 10 micro- and 2 macro-habitat characteristics of dens. Females began denning in March, with a mean initiation date of 31 March, and used natal dens for a mean of 49 d (se = 3). Two females used man-made brush piles as dens, four used small limestone caves, one used a cavity in the roots of a big-toothed aspen (Populus grandidentata) and one used a beaver (Castor canadensis) bank-den. Dens were located a mean of 316 m (se = 79) from the nearest body of water and averaged 61 m (se = 15) of elevation higher than the nearest body of water. Seven of eight females placed dens outside of their normal activity areas, and all females appeared to select den sites that were protected from flood events. Our results suggest that to promote successful reproduction of river otter populations, managers should protect potential denning sites in upland habitats adjacent to bodies of water.

Canada Lynx-bobcat (lynx canadensis × L. rufus) Hybrids at the Southern Periphery of Lynx range in Maine, Minnesota and New Brunswick

ABSTRACT Hybridization between federally threatened Canada lynx (Lynx canadensis) and bobcat (L. rufus) was recently documented in the United States, but little is known regarding physical characteristics of hybrids compared to parent species. We report on the morphology and physical characteristics of five of seven Canada lynx-bobcat hybrids detected near the southern extent of the lynxs geographic range in Maine, Minnesota and New Brunswick. Hybrids displayed a range of physical characteristics, including features common to both lynx and bobcat, or that were intermediate in character. Observation of an adult female hybrid with three kittens, as well as placental scars in the reproductive tract of a second animal, suggest that hybrids may be reproducing successfully. We recommend that careful measurement, recording and photographing of key characteristics as well as genetic analysis of suspected lynx-bobcat hybrids be priorities for natural resource agencies where hybridization between these species may occur.

Effects of Repeated-Stand Entries on Terrestrial Salamanders and their Habitat

Abstract In recent years, silivicultural methods have shifted away from clearcut harvesting towards greater retention of overstory trees through part or all of a rotation. However, little is known about the effects of partial harvesting on wildlife populations. Thus, we examined effects of high-leave shelterwood management on terrestrial salamanders prior to and after an initial harvest and a subsequent overstory removal harvest (ORH) 13 years later. On an experimental research site in southwestern Virginia, we compared changes in salamander captures in this plot to a clearcut and control plot 1994–1996 and 2007–2009. Compared to contemporaneous estimates from an unharvested control, salamander captures were lower on shelterwood and clearcut plots 2-years after the initial harvest (1996) and lower on the shelterwood plot 1- and 2-years after the ORH (2008, 2009). Captures of the most common species, Plethodon cinereus (Eastern Red-backed Salamanders), followed similar trends with fewer captures in both harvested plots 2-years after the initial harvest (1996), but only the ORH differed from the control 2-years after the second partial harvest (2009). Abundance of woody debris was greater in the shelterwood following the ORH but was more decayed in the control plot. The regenerating clearcut (14 years post-harvest) had deeper leaf litter and denser understory vegetation than the ORH. These data are some of the first available describing effects of multiple harvest entries on terrestrial salamanders and suggest cumulative negative impacts on salamanders may occur from partial harvesting systems. More long-term monitoring of salamander populations is justified in silvicultural systems with multiple entries within a rotation.