Norman G. Reichenbach

Population Dynamics and Conservation of the Peaks of Otter Salamander, Plethodon hubrichti

A study was conducted in 1991 on the population dynamics of the Peaks of Otter salamander, Plethodon hubrichti, a salamander with an extremely limited distribution. From a 10 m x 10 m site in central Virginia, a total of 250 P. hubrichti were collected with 42 recaptures. The population size for P. hubrichti was estimated to be 450 salamanders. There was a slightly clumpedalee y distribution of salamanders throughout the site. The overall growth rate for young of the year was 0.10 mm/d and 0.08 to 0.11 mm/d for older animals. Surface activity occurred primarily between 2100 and 2300 h in the spring, 2200 and 2400 h in the summer, and 2000 and 2300 h in the fall. There was a positive linear relationship between the percentage of surface-active salamanders and the number of days between rains. Salamanders were often observed on vegetation; the percentage of salamanders on vegetation increased in relation to un- derstory denseness. The median area for home ranges was 0.6 m2; with this limited movement, the potential for fragmentation of the population was discussed. An alternative study plot design was considered based upon the clumped distribution and limited movements. The use of three 4 m x 4 m plots instead of one 10 m x 10 m plot reduced the amount of field time by 20% while still obtaining similar information.

Effects of Timbering on Plethodon Hubrichti Over Twelve Years

Abstract Clearcuts have been shown to adversely affect salamander populations, whereas impacts from milder forms of timbering are more variable. We determined the effects of clearcuts and shelterwood cuts on populations of the Peaks of Otter Salamander (Plethodon hubrichti) using counts of surface active salamanders found during multiple night collections. Sampling was done prior to and then periodically after timbering for 12 yr. Overall, the long-term trends in mean number of P. hubrichti at reference and shelterwood cut sites were not significantly different. In contrast, means at clearcut sites declined 41% during the first year posttimbering and then declined over the next three years to a low of 75% below pretimbering means. The means stabilized at 45% below pre-timbering means for the remainder of the study. Immediately after timbering 41% of the salamanders moved from transects established at the edge of clearcuts to reference transects that were 3–9 m away. Clearcuts had less canopy closure and dead leaf cover than reference and shelterwood cuts which likely degraded habitat for salamanders. Therefore, clearcutting forests is not advisable because of adverse impacts on salamanders, but forms of timbering that retain a portion of the forest canopy may be acceptable if it can be shown that the timbering method does not reduce salamander populations.

The Effects of Timbering on Plethodon hubrichti: Short Term Effects

Effects of two types of timbering on populations of the Peaks of Otter salamander (Plethodon hubrichti) were determined using average numbers found during multiple night collections. Sampling was done prior to, and for two years after, timbering on four sites in each of three treatments (clearcut, shelterwood cuts, and reference). The average numbers of P. hubrichti at the reference and shelterwood cut sites were stable over time while those at the clearcut sites showed a significant decrease post-timbering. Two years after timbering, 30% of the pre-timbering populations remained at the clearcut sites. Jolly-Seber population estimates on one clearcut site decreased from 43 to eight animals after cutting. In contrast, one reference site had a population estimate that oscillated around a mean of 71. Of the animals marked before timbering, significantly fewer were recaptured after timbering at the clearcut site (17.5%) relative to the reference site (39.0%). Juveniles appeared to be the size class affected to the greatest degree. Adults and juveniles on clearcuts most likely emigrated and/or died after treatment. While most investigators believe that timbering is harmful to salamanders, it is difficult to document the effects. Most studies use population censuses in timbered areas and compare these numbers to adjacent untimbered areas. Salamander populations in timbered areas are usually lower, and sometimes absent, when compared to untimbered areas (Blymer and McGinnes, 1977; Bury, 1983; Enge and Marion, 1986; Pough et al., 1987; Ash, 1988; Bury and Corn, 1988; Stiven and Bruce, 1988; Welsh, 1990; Raymond and Hardy, 1991; Petranka et al., 1993; Dupuis et al., 1995). It is thought that opening the forest canopy increases exposure of the forest floor to sun and wind. This dessicates the habitat, thus reducing habitat quality for salamanders. Plethodontid salamanders may be particularly sensitive to habitat changes due to timbering since they are lungless, requiring moist skin for gas exchange, and are fully terrestrial, requiring moist microhabitats for egg development (Pough et al., 1987). Salamander populations are not the only part of the forest ecosystem affected by timbering. Duffy and Meier (1992) reported that the herbaceous community may not recover to the same pre-timbering species diversity in 40-150 year logging cycles. Forest floor organic matter decreased exponentially to about 50% of the initial levels within 15 yr following timbering, then recovered over the next 50 yr to within 5% of pre-timbering levels (Covington, 1981). Seastedlt and Crossley (1981) reported that microarthropod decomposers were significantly less abundant two years after timbering. Many changes can occur with loss of the forest canopy, some of which would directly affect food availability to salamanders (Mitchell et al., 1996). There are drawbacks to most earlier assessments of the effects of timbering on salamander populations. Foremost is most earlier studies assume that the pre-timbering population levels in the treatment and reference (control) sites were similar. Since salamander populations may have clumped dispersion patterns (Kramer et al., 1993) this assumption may not be justified. In this study both pre and post-timbering population levels were assessed for an endemic species, Plethodon hubrichti. METHODS AND MATERIALS Initially 18 sites were searched at night for P. hubrichti. Only salamanders that were surface active were counted. No logs, rocks, or other debris were disturbed in order to minimize damage to the salamanders habitat. All sites were located within the range of P. hubrichti in the Glenwood district of the Jefferson Nation Forest off the Blue Ridge Parkway in Bedford and Botetourt counties, Virginia. From these 18 sites, 12 were selected based upon (1) having adequate numbers of P. hubrichti and (2) logistical constraints associated with timbering such as having harvestable timber or being sufficiently distant from a waterway to permit timbering. These 12 sites were randomly assigned to three treatments (four sites per treatment): reference (no timbering), shelterwood cut (partial removal of canopy), and clearcut (total removal of canopy). At these sites P. hubrichti were monitored one year prior to and two years after timbering. At one site from each treatment, salamanders were individually marked (toe clip) and measured (snout-vent length, SVL) for a mark/recapture study which provided a more detailed picture of how the populations of P. hubrichti were being affected by timbering. At each of the 12 sites, one 5 × 5 m plot was established. Plots at timbered sites were located at least 20 m from the edge of the timbered area which ranged from 0.6 to 1.2 ha. The size of the plot ensured that all sites could be surveyed during a single night, thus avoiding temporal variation (Kramer et al., 1993). In 1993 baseline population levels were established for all 12 sites during 10 night surveys. The four shelterwood cut and clearcut sites were timbered in May 1994. Following timbering, eight surveys were conducted in 1994 and eight in 1995. Average numbers of P. hubrichti were calculated per site for each year. A repeated measures ANOVA with Huynh-Feldt adjustments to the probability levels (SYSTAT, 1996) was used to assess impacts since the averages were repeated, non-independent, measurements taken over time on each site. The reference sites were compared pairwise with the shelterwood cut and clearcut sites. The interaction of treatment and time was the key model parameter considered since this would indicate whether the populations at the reference sites were changing differently from those at the timbered sites. If the interaction parameter was significant (P 40 mm) and juveniles ([less or equal]40 mm). Losses of salamanders due to mortality/emigration or reduced surface activity was analyzed using contingency tables to test for homogeneity between sites for animals marked before timbering and seen again after timbering versus the number of animals marked before timbering and never seen again. Growth rates (mm/day) were measured within a calender year by change in SVL divided by the time between recaptures. A two-way ANOVA with variables of treatment and year were used to analyze the data. The growth rates were not significantly correlated with size and therefore no distinction for size classes was made in the ANOVA. Movement rates (cm/day) were calculated by dividing the distance between recaptures by the time between recaptures within a calender year. When an animal was recaptured multiple times in a calendar year an average was calculated. The analysis was then similar to that for growth rates.

Energy Use, Life Histories, and the Evaluation of Potential Competition in Two Species of Garter Snake

The energy flow in syntopic populations of the greater snakes Thamnophis radix and T. sirtalis in Ohio ranged from 74,676 to 144,041/kJ/ha/yr. Important factors affecting this quantity were the high densities of the snakes (114 to 212 snakes/ha), the high annual reproductive rate (approximately 15 to 19 young/female), and the high growth rates of the newborn snakes prior to their first hibernation period. This large intake of energy was channeled primarily into secondary productivity, with calculated tissue production/assimilation ratios (P/A) averaging 74% for new- born snakes prior to their first hibernation period and then dropping to a yearly average of 14% for the adults of both species. The factors that allow for high P/A values were the low metabolic rates, the circadian oscillations in metabolic rates, the winter period of low temperatures, voluntary hypothermia during the day, and generally low activity levels. The garter snakes impact upon the food resources at the study site appeared to be minimal during the three years of this study. A 1 to 4 predator/prey biomass ratio was estimated to be sufficient for maintenance, growth, and reproduction. Since the calculated predator/prey ratios were much smaller than this value, interspecific exploitative competition for food resources is unlikely to be a major factor in the population dynamics of either species of garter snake at the site studied.

Management of an endangered species of snake in Ohio, USA

Abstract More species of snakes are becoming endangered yet information on their effective management is lacking. The present study assessed the general biology of the prairie garter snake, an endangered species in Ohio, USA, and the potential impact of mortality due to game management practices in a state wildlife area (automobile traffic and grass mowing operations). Alterations to the present management practices include alternatives such as rescheduling of mowing operations to coincide with the snakes periods of inactivity and using signs to caution motorists to avoid hitting snakes on the road. Future management of wildlife areas should not focus upon a single species or trophic level but rather consider both non-game and game species.

Response of the western spruce budworm to temperature and dose of a virus, a growth regulator, and an organophosphate

Pathogenicity of nuclear polyhedrosis virus (NPV) to western spruce budworm larvae, Choristoneura occidentalis Freeman, increased as temperature increased. In contrast, at temperature extremes, mortality increased for a specified dose of malathion or diflubenzuron, while at the optimal temperatures (20–25 °C), mortality decreased. Malathion was the fastest acting insecticide, followed by diflubenzuron and then NPV.