We investigated methods for reducing highway-caused mortality of Mojave Desert Tortoises (Gopherus agassizii) using barriers at the Desert Tortoise Conservation Center, located near Las Vegas, Nevada. Experiments tested effectiveness of various barriers of different heights and made of different construction materials, sex-dependent behaviors including rate of escapes, appropriate height of a barrier, and adverse effects on other sympatric vertebrate species including potential entrapment. Informed by analyzing previous investigations, we tested captive adult desert tortoises (midline carapace length >= 180 mm) within enclosures made from 8 different common construction materials, quantified behavioral responses of individuals over several (4-14) days, and identified sex-dependent responses to these barriers. Both sexes pushed against see-through barriers more than solid barriers (58% males, 67% females) and males reversed direction of pacing more often than females (56%). Pen escapes related to pacing reversals and were generally by males. Direction reversals and escapes occurred mostly with wire mesh designs and low (20-cm) solid barriers. Frequency of body contact was not linearly correlated with larger mesh sizes. Solid barriers appear to offer the best deterrent but are more expensive. Animals that escaped in trials lasting several days were larger than average size and often escaped more than once. Tortoises escaped at weak points in barriers, such as gaps with the ground, pen corners, breaks in material, or by climbing over the barrier. In testing minimum effective barrier height for 3 types of barrier materials, none climbed over at 46 cm, 5 climbed over at 30 cm, and 19 others climbed over at lower heights. We observed native species interactions with our barrier enclosures (n = 70) and compared morphometric measurements of common desert reptiles vs. barrier dimensions. These data suggested that different barrier types preferentially affect specific sizes of animals although we observed no mortality. While solid barriers stop all reptiles, wire meshes entrap reptile species smaller than mesh size (such as Callisaurus draconoides and Uta stansburiana) and stop larger species (such as Dipsosaurus dorsalis and Coluber flagellum). Morphometric measures of juvenile tortoises indicated that they could pass through the 2 largest wire mesh sizes we tested.

In a study to reduce Mojave Desert Tortoise (Gopherus agassizii) mortality along roadways, we tested the feasibility of structures that discourage tortoises from 1) walking or “pacing” along barriers or 2) crossing areas where gates or openings occur. The diversion designs we tested (one straight and one curved structure, each 7.6 m long) deflected tortoises away from fences at nearly the same rate as tortoises who continued walking along barriers despite the diversion (36.8% vs. 35.7%). No “tortoise guard” structures that we tested, similar to cattle guard structures, were 100% effective at preventing tortoises from crossing the opening. We identified essential characteristics of an effective “tortoise guard” such as minimum gap sizes in the structure and a construction design that allowed a tortoise to climb out of a trench under the structure.

Phosphorus (P) is an essential nutrient for phytoplankton growth and biochemical processes. In shallow coastal lagoons, there is strong coupling between water column and sediments in terms of P dynamics. To better understand dynamics and bioavailability of P in Maryland coastal bays (MCBs), surface sediment samples were collected at 13 sites of MCBs in May, August, October, and December in 2013 to assess the major reservoirs using a six-step sequential P extraction procedure. The objectives of this study were (1) to determine the spatial/temporal variations of P species in MCB sediment and to assess the relationship of P species at various locations with material sources and sediment types, and (2) to assess the bioavailability of sedimentary P in the study area. The average percentages of fractions of P of four months (representing four seasons) in surface sediments were Det-P (33.5 +/- 4.36%) > total organic P (27.2 +/- 3.43%) > Fe-P (13.0 +/- 1.36%) > Al-P (12.2 +/- 1.25%) > authigenic P (11.1 +/- 2.86%) > L.Adsorp-P (3.0 +/- 0.38%). On average, bioavailable P in surface sediments accounted for 55.4% of total P and thus represented a significant proportion of the sedimentary P pools in MCBs. Total P (TP) in the surface sediment ranged from 309.8 to 1345.4 mu g/g with an average of 874.5 +/- 343.3 mu g/g. There was a strong positive relationship between TP and sediment grain size (mean phi) such that sites with the finest sediments (clay-silt) closest to the mouths of tributaries had significantly higher TP than sites with coarser grains.

Foraging theories evaluate how animals make choices in prey. Some important factors in prey selection are size of prey and distance to pursuit, which can be affected by prey availability, ease of capture, and the time for chasing, handling, and ingesting prey. We examined prey size selection in an ambush (sit-and-wait) predator, the Eastern Fence Lizard, Sceloporus undulatus, in Maryland and Delaware, USA. We tested whether animals selected prey by size by presenting two sizes of prey (crickets) in a choice test in the field and measured latency to attack prey through a series of presentations of mealworm prey at different distances, recording the distance and time to attack. Adult males preferred larger prey and female juveniles preferred smaller prey. Distances to pursue prey did not differ between sexes but males had a longer attack latency than did females. Mean sprint speed on a vertical surface correlated with maximum burst speed, body mass, and body condition; males were more likely to run than were females, particularly during the spring. We found that our ambush foragers show prey size preferences and demonstrate a distance beyond which they will pursue prey. Because prey size preferences were not predicted by body size alone and cut-off distances did not vary seasonally, factors affecting foraging behavior warrant further attention.

Resources to implement conservation actions are very limited compared to the potential needs in a given area, which means conservationists usually have to make difficult choices and establish priorities for action. Therefore, it is important to demonstrate the value of a proposed conservation area or project for it to be considered a high priority for funding. In this exercise, you will research the importance of a specific area for conservation, and through a short oral presentation, make the case for its value and high priority for funding. The exercise should give students an enhanced understanding of the different approaches and criteria used for priority setting in conservation, and a chance to practice their oral communication skills.

Edible seaweeds have not been thoroughly explored for food, medicinal, or industrial purposes in the United States. This study compared selected proximate constituents of three edible seaweed species (Ulva lactuca L., Fucus vesiculosus L., and Gracilaria tikvahiae McLachan) at two sites for possible future development as a food crop on the Delmarva Peninsula. Sampling was conducted bimonthly at Chincoteague Memorial Park, Virginia, and Indian River Inlet, Delaware, from 2005 to 2008. Proximate constituents of moisture, ash, dietary fiber, proteins, and fat were measured seasonally and calorific values were calculated. Data were analyzed using correlation, paired samples t‐tests and one‐ and two‐way ANOVA. Significant variations in the proximate constituents were found among seasons, species, and between sites. The brown seaweed (Fucus) at both sites had higher fiber, fat, and ash (mineral) content than the green (Ulva) or the red (Gracilaria). Ulva and Gracilaria had higher protein content than Fucus. Seaweeds from Delaware had more fat, ash, and protein than from Virginia, potentially because of the more polluted, nutrient rich environment at the Delaware site. Positive correlations between seaweed fat and protein content may indicate an increase in the synthesis of both components under optimal growth conditions. Species' physiology differences and the water quality at the two sites likely impacted proximate constituent values. This study contributed new information to the existing body of knowledge in the areas of nutrition and ecology of seaweeds and their potential as a cash crop.

The effects of fire on wetland vegetation in the mid-Atlantic region of the United States are poorly known, despite the historical use of fire by federal, state, and private landowners in the Chesapeake Bay Region. Prescribed fire is widely used by land managers to promote vegetation that is beneficial to migratory waterfowl, muskrats, and other native wildlife and to reduce competition from less desirable plant species. We compared vegetative response to two fire rotations, annual burns and 3-year burns, and two control sites, Control 1 and Control 2. We tested the effects of fire within six tidal marsh wetlands at Blackwater National Wildlife Refuge and Fishing Bay Wildlife Management Area in Maryland. We examined changes in total live biomass (all species), total stem density, litter, and changes in live biomass and stem density of four dominant wetland plant species (11 variables). Our results suggest that annual prescribed fires will decrease the accumulation of litter, increase the biomass and stem densities of some wetland plants generally considered less desirable for wildlife, and have little or no effect on other wetland plants previously thought to benefit from fire.

We observed the social behavior of a high-elevation population of the lizard Sceloporus jarrovi on Mt. Graham in southeastern Arizona during August 1985, the month prior to the fall breeding season when territoriality should be intense. This population displayed lower levels of female territoriality than reported elsewhere for this species. Aggressive levels of resident females as measured in staged encounters were significantly lower than male aggressive levels. Display and feeding rates showed significant between-sex variation, also. Home ranges of adult males and females did not differ in size but were significantly larger than home ranges of juveniles. Home range sizes in adult females at high elevation were significantly larger than those at low elevation. Overlap between female home ranges was much higher than overlap between male home ranges. The large number of overlapping females per male (xBAR = 3.75 +/- 2.4) made determination of potential mating opportunities difficult. Some variation in behavioral patterns may result from the different demography of high elevation populations (delayed maturity, smaller effective population size) relative to low elevation populations. Intraspecific variation may strongly affect the selective pressures on social structures and reproductive success patterns.

We constructed minimum convex polygon (MCP) home ranges for free-ranging desert tortoises from a natural population adjacent to the Desert Tortoise Conservation Center, near Las Vegas, NV. Home range area estimates were not significantly different from those estimated for other desert tortoises in the Mojave and Sonoran deserts. Male tortoises had significantly larger and more variable home ranges in a combined statistical analysis of this study with those of Burge (1977) and Barrett (1990). Bootstrap analysis of the MCP polygon areas suggested substantial autocorrelation of the tortoise sightings despite a mean interval between recaptures of 3.2 days, violating an assumption of nearly all home range estimation techniques and predisposing to underestimation of the true home range area. Extending the interval between recaptures would severely limit the number of points that could be obtained on an individual tortoise in a single activity season. We also created "by eye" minimum polygons to compare with MCP's for the same tortoises. This comparison suggests that MCP's for desert tortoises include, as substantial fractions of their total area (12-56%, mean = 35%), areas with no evidence that tortoises use them. Movements between resightings vary with the sex of the animal (male > female) and interval since previous sighting. The distance of movements was approximately exponentially distributed, with short movements more common than longer movements, predisposing home range estimates for desert tortoises to be autocorrelated. We urge the consideration of home range as an indicator of size of the areas traversed by a tortoise and the patterns of movement in different individuals, sexes, and/or populations with less emphasis on the biological interpretation of area as a resource or characteristic of the animal.

We constructed minimum convex polygon (MCP) home ranges for free-ranging desert tortoises from a natural population adjacent to the Desert Tortoise Conservation Center, near Las Vegas, NV. Home range area estimates were not significantly different from those estimated for other desert tortoises in the Mojave and Sonoran deserts. Male tortoises had significantly larger and more variable home ranges in a combined statistical analysis of this study with those of Burge (1977) and Barrett (1990). Bootstrap analysis of the MCP polygon areas suggested substantial autocorrelation of the tortoise sightings despite a mean interval between recaptures of 3.2 days, violating an assumption of nearly all home range estimation techniques and predisposing to underestimation of the true home range area. Extending the interval between recaptures would severely limit the number of points that could be obtained on an individual tortoise in a single activity season. We also created eye minimum polygons to compare with MCP's for the same tortoises. This comparison suggests that MCP's for desert tortoises include, as substantial fractions of their total area (12-56%, mean = 35%), areas with no evidence that tortoises use them. Movements between resightings vary with the sex of the animal (male > female) and interval since previous sighting. The distance of movements was approximately exponentially distributed, with short movements more common than longer movements, predisposing home range estimates for desert tortoises to be autocorrelated. We urge the consideration of home range as an indicator of size of the areas traversed by a tortoise and the patterns of movement in different individuals, sexes, and/or populations with less emphasis on the biological interpretation of area as a resource or characteristic of the animal.

We tested the effect of water stress on behavior of desert tortoises in semi-natural enclosures. Populations of adult and immature desert tortoises were established at relatively high density in 4.1 ha pens at the Desert Tortoise Conservation Center near Las Vegas, Nevada. Pairs of pens received different levels of food (sod and forb patches) and water supplementation. We postulated that the relatively high densities of tortoises and the different levels of resources created different levels of environmental stress on the populations. Behavior was systematically observed during June-August 1991 and April-September 1992 for differences due to treatment (food and water supplementation versus no food and water supplementation). Behavioral observations were collected during 30 minute focal periods and periodic scan censuses of pens. Animals in the unsupplemented treatments, particularly males, moved further during focal periods than animals with supplemented diets. Movement varied significantly among months. There were no differences in feeding rates among treatments, although monthly effects were important in both treatments. Some differences between years in feeding rates appear related to rainfall patterns and presumably changes in resource availability. Interactions among animals were highest in May and September and were more frequent in unsupplemented pens. Length of morning activity period was shorter in unsupplemented pens for all months. Within treatments, supplemented females were more visible and were seen for longer periods of time during a morning activity period. Home ranges were not significantly different between treatments but showed significant sex effects. Males have larger home ranges than females, and both have larger home ranges than immature animals. When stressed by lack of water and food resources, tortoises reduced the length of above-ground activity time but attempted to compensate for this decreased time by increasing amounts of movement and feeding while active.

A behavioral inventory of the desert tortoise was compiled from observations on confined tortoises in experimental pens and free-ranging tortoises within semi-natural enclosures. We describe 80 actions. Much of a tortoise's active time outside burrows is spent in feeding behavior. Display sequences have both visual and olfactory components. Aggressive and courtship sequences have similar beginnings but proceed differently as animals respond to each other. Aggressive behavior involves much headbobbing, sniffing, biting and ramming. A pushing match enables tortoises to assess body mass and determine dominance. Courtship behavior may involve trailing, circling of the female by the male, and biting and sniffing sequences before mounting. There is no rejection display by females of courting males. Comparisons between Gopherus species and related tortoise groups suggest a very conservative evolution of behavior within the Gopherus group.

We conducted tests on the behavioral responses of captive desert tortoises (Gopherus agassizii) to barriers and highway obstacles. Desert tortoises are slow-moving but persistent wan- derers in their natural habitat. Consequently, they move substantial distances when they meet a barrier that they cannot go around. Tortoises responded differently to solid and non-solid barriers when placed in small pens constructed of various materials. Our tests indicated that a screen mesh with small enough openings to exclude a tortoise's head was the most suitable barrier material. When tortoises were tested for 2 h periods or after an overnight stay in a barrier pen, rates of responses with barriers declined with time but tortoises continued movement along the barrier. In a choice situation, we found no preference by tortoises for following either solid or mesh barrier fences. Tortoises quickly walked past openings in a barrier which were too small to enter but easily escaped from a barrier pen within 30 min when openings of an appropriate size were available. We found tortoises willingly entered culverts under large highways and retreated from concrete highways barriers.

JAEGER, R. G. 1986. Pheromonal markers as territorial advertisement by terrestrial salamanders. In D. Duvall, D. Muller-Schwarze, and R. M. Silverstein (eds.), Chemical Signals in Vertebrates 4, pp. 191203. Plenum Publishing Corp., New York. ROUDEBUSH, R. E., AND D. H. TAYLOR. 1987. Chemical communication between two species of desmognathine salamanders. Copeia 1987:744-748. SIMONS, R. R., AND B. E. FELGENHAUER. 1992. Identifying areas of chemical signal production in the red-backed salamander, Plethodon cinereus. Copeia 1992:776-781. WATSON, P. 1986. Chemical communication in the courtship ritual of the red-spotted newt: investigations into the role of the genial gland pheromone. 1986 Abstracts of Joint Meeting of Herpetologists' League and SSAR, Springfield, Missouri, p. 115.

Variation in home range size among three populations of the saxicolous iguanid lizard Sceloporus merriami was studied in relation to density, food availability, behavioral patterns, and daily activity periods. These populations, separated by a maximum distance of 50 km, occur along an elevational gradient which spans the elevational range of the species in west Texas. The population with the smallest home ranges had the highest density, the lowest food availability, and the most restricted daily activity period. Within populations, males consistently had larger home ranges than females. No significant between-year variation in home range size was noted within a given area or sex. Intraspecific variation in home range size is not explained by any single factor, such as food availability or density, but appears to be complexly determined by the interaction of energetic, breeding, and activity constraints.

The life history and demography of a population of Yarrow's spiny lizard, Sceloporus jarrovi, was studied in the Pinalefio Mountains of southeastern Arizona from 1972-1974. Sizespecific clutch sizes and maximum female body size were smaller in the Pinalefio Mountains than in a population at similar elevation in the Chiricahua Mountains. A female of average snout-vent length (72 mm) in the population studied here had 5.6 ? 1.9 (SE) offspring. Males grew faster than females at all ages and were significantly larger. Survivorship of young and adults varied between years with average adult female survivorship being 36%. Winter (October-May) survivorship was higher than summer (June-October) survivorship. Adult population densities were highest in the spring and steadily declined through the summer. Sex ratios among yearlings, but not other age classes, differed significantly from an expected 1:1 ratio. Life tables based on average age-specific fecundity and mortality rates resulted in net replacement rates (RO) of about 1.0. The average generation time of the Pinalenio population was slightly longer than for a Chiricahua population. Possible differences in environments of the Pinalefio and Chiricahua mountains are discussed in relation to the observed differences.