Showing papers in "American Midland Naturalist in 1971"
TL;DR: Differences in the pattern of approach to prey indicated that the bass distinguished different types of prey and whether the prey was on the bottom or in mid-water, and the additional velocity of the upper jaw due to protrusion of the premaxilla was measured.
Abstract: The behavior of the largemouth bass, Micropterus salmoides, during prey capture was studied with high-speed cinematography. Differences in the pattern of approach to prey indicated that the bass distinguished different types of prey and whether the prey was on the bottom or in mid-water. The distance from the prey at which the final attack was initiated was greater when the bass was traveling toward the prey at a higher velocity. The allowable error in this initiation distance was about one-fourth the length of the bass's head. Attacks initiated beyond this margin of error usually failed. About 10% of all filmed attacks failed. Once the jaws began to open the sequential movements of the head elements appeared to be completely determined. Two different patterns were observed, however, depending on whether the bass swam over the prey or drew the prey toward itself, i.e., suction feeding. Rationalization of these differences is presented. During suction feeding, the usual alternative, the jaws were opened before there was appreciable expansion of the mouth cavity. The asymmetry between opening and closing movements was also important; for without differences between them the prey would be expelled as the jaws closed. The additional velocity of the upper jaw due to protrusion of the premaxilla was measured. This additional velocity was relatively greater for smaller bass and in the slower-moving attacks of the same fish. The significance of this additional velocity in the evolution of the protrusible upper jaw of fishes is discussed.
169Â citations
TL;DR: The trees recorded in the original land surveys of the township lines of northern Vermont and the lotting surveys within the townships of Chittenden Co (ca 1763-1802) have been used to study the composition and map the distribution of the presettlement forests.
Abstract: The trees recorded in the original land surveys of the township lines of northern Vermont (ca 1783-1787) and the lotting surveys within the townships of Chittenden Co (ca 1763-1802) have been used to study the composition and map the distribution of the presettlement forests Forest composition was measured in 1962 at 193 points in Chittenden Co where original survey data was available, and was compared to presettlement composition Several general regions of forest were delimited in northern Vermont based primarily on the distribution of pine, hemlock, spruce and fir A gradient of relative abundance of these conifer species was evident from pine in the Champlain Valley and Connecticut River Valley to hemlock on the midslope uplands and fir and spruce in the mountains and northeastern highlands of the state A map of probable presettlement vegetation of Chittenden Co was prepared based on geographical distribution of species of witness trees, elevation, soil-substrate types, topography, and early historical records The outstanding feature of the presettlement forest was the great abundance of beech Beech ranged from more than 60% of the species composition on the upland midelevation soils in Chittenden Co to 13% on the spruce-fir-dominated highlands in northeastern Vermont Average beech abundance in hardwood forests was about 40%, which is in accord with the findings of other studies based on witness trees in New York, Pennsylvania and north central states Beech made up over 40% of the trees in the presettlement forest, but in 1962 it comprised only 3-5% This is probably due to the slow but persistent pattern of regeneration of beech in stands by root sprouts and the formation of clones resulting in its maximum development in old-age, undisturbed forests Comparison of pre-settlement and present forest composition indicated no outstanding changes in the presence or absence of species within soil-substrate types or elevation belts, but there was a distinctive overall increase in the importance of pine, hardhack and poplar in the present forests on the intermediate elevations which reflects the stages of secondary succession on much abandoned farmland throughout Chittenden Co Surveyor bias for selection of some species over others as witness trees was investigated A study of stake-to-tree distances which could reveal possible selection due to greater distances to those species which were being favored did not indicate any bias and the surveyors apparently took the tree nearest the stake which met whatever diameter and state-of-vigor requirements the surveyors were using The number of witness trees per unit area in Chittenden Co was similar to the number used in studies in other areas in the north central states 153 1 The work reported in this paper was done as an MS thesis at the Botany Department, University of Vermont, Burlington This content downloaded from 1575539104 on Mon, 20 Jun 2016 05:52:35 UTC All use subject to http://aboutjstororg/terms 154 THE AMERICAN MIDLAND NATURALIST 85(1)
125Â citations
TL;DR: A trophic hypothesis, based on the nature of predatorprey relationships in each of the two types of ecosystem, is proposed to explain the distribution patterns of parasites.
Abstract: Approximately 30 species of larval and adult parasites were collected from 549 centrarchid fish and 7718 gastropod molluscs from an oligotrophic and two eutrophic lakes in southwestern Michigan. The distribution pattern indicates that centrarchids from the oligotrophic lake harbor a wide range of species of adult parasites and a comparatively smaller number of larval forms, many of which complete their life cycles in predatory fish. On the other hand, bass and sunfish from the two eutrophic lakes harbor a proportionately larger number of larval parasites, most of which culminate their life cycles in fish-eating birds and mammals. A trophic hypothesis, based on the nature of predatorprey relationships in each of the two types of ecosystem, is proposed to explain the distribution patterns of parasites.
102Â citations
TL;DR: The female woodmice appeared to form a closed community in which the residents occupied home ranges of a characteristic and stable size and in which transient females were able to establish home ranges only when vacancies of a suitable size were present.
Abstract: This study attempts to determine whether or not social interactions among woodmice (Peromyscus leucopus) result in behavioral regulation of population density. Live-trapping and tracking on a 13-acre plot located in a southern Michigan oak-hickory woodlot provided data on the numbers of mice living on the plot and on the extent of each individual's home range. The home ranges tended to be exclusive of the ranges of others of the same sex (females exhibited this more strongly than males). The female woodmice appeared to form a closed community in which the residents occupied home ranges of a characteristic and stable size and in which transient females were able to establish home ranges only when vacancies of a suitable size were present. Male woodmice, on the other hand, did not appear to exhibit population regulation by limiting the number of immigrants.
86Â citations
TL;DR: Tadpoles of eight species of frog were tasted in a standardized procedure by 11 volunteers and suggested that palatability in tadpoles may correlate inversely with vulnerability.
Abstract: Tadpoles of eight species of frog were tasted in a standardized procedure by 11 volunteers. The tadpoles were rated in their palatability from "tastes good" to "highly unpalatable." It is suggested that palatability in tadpoles may correlate inversely with vulnerability.
79Â citations
TL;DR: Seasonal changes in standing crops of living and dead dry matter and tissue levels of chemical substances were determined for a Juncus effusus population to show that rates of net nutrient uptake and synthesis of pigments are not merely functions of net dry-matter production, but physiological characteristics of the species.
Abstract: Seasonal changes in standing crops of living and dead dry matter and tissue levels of chemical substances were determined for a Juncus effusus population. These data were used to determine rates of production, pigment synthesis and nutrient absorption during different parts of the annual growth cycle. The annual cycle began with the appearance of young shoots in late summer. Net productivity was greatest during early autumn and midspring. Little growth occurred during the winter and there was a rapid dieback of shoots in the summer. Tissue concentrations of most chemical constituents declined during spring growth and summer dieback. Uptake rates of mineral nutrients other than nitrogen were large during autumn growth, but slight during spring growth. The same was true of pigment synthesis. Energy accrual was generally proportional to dry-matter increases during both phases of growth. Results of this investigation and previous studies are discussed to show that rates of net nutrient uptake and synthesis of pigments are not merely functions of net dry-matter production, but physiological characteristics of the species. Quantities of chemical substances per unit area of stand did not necessarily follow the same patterns of change as did dry-matter standing crops. Dead Juncus effusus shoots decomposed rapidly, about 50% of the dry matter disappearing within 4 months. Mineral nutrients were lost more quickly than the degradation of dry matter. INTRODUCTION Herbaceous vegetation of fresh-water marshes often produces large quantities of biomass (Penfound, 1956; Westlake, 1963). Chemical analyses have been made on several marsh species (Straskraba, 1966; Lawrence, 1968; Boyd, 1968, 1970a). These data were used to estimate amounts of chemical constituents per unit area of plant stand and to compare the nutritive value of various species. In addition, a few studies have dealt with the dynamics of mineral nutrient uptake and biochemical synthesis during growth and nutrient losses during decomposition. Uptake rates and tissue concentrations of most minerals declined as the growing season progressed, but maximum mineral accrual per unit area of stand was obtained at or near the time of peak standing crop (Stake, 1967, 1968; Boyd, 1969, 1970b). Pigment concentrations followed a similar trend of change (Boyd, 1970b). Drymatter standing crops decreased during late summer and total quantities of nutrients per m2 declined even faster than dry matter (Boyd, 1969, 1970b). There is very rapid release of most minerals, particularly cations, from emergent macrophytes once the shoots fall into the water (Boyd, 1970c). These processes are obviously very important aspects of the physiological ecology of macrophytes and additional research is needed. The present study was undertaken to describe the patterns of change in tissue concentrations and quantities per unit area of minerals, pigments and energy in a Juncus effusus L. stand during a yearly 1 This research was supported by contract AT (38-1) -310 between the U.S. Atomic Energy Commission and the University of Georgia.
73Â citations
TL;DR: In the case of the giant sequoia forest, the change in character of vegetation and the openness of the low vegetation zone led to changes in species composition but not in total biomass of the avifauna as discussed by the authors.
Abstract: Thirty species from the montane forest formation com- prised most of the breeding bird population of a giant sequoia forest, with a density ranging from 188 to 311 pairs per 100 acres (40 ha). When some 22 tons of living and dead trees per acre in the brush or sapling layer of this forest were eliminated by cutting, piling and pre- scribed burning, the change in character of vegetation and the openness of the low vegetation zone led to changes in species composition but not in total biomass of the avifauna. This was true because thickets of small trees were the least important vegetation for bird feeding or nesting; the upper canopy and understory were most important, followed by the ground and trunk categories. Two species of ground-feeding and. nest- ing birds and a third ground-nesting species disappeared after treatment. Nesting flycatchers and robins increased in numbers. Compared with results from areas where wildfires or logging operations have made sub- stantial changes in cover type and set succession back severely, this degree of habitat modification resulted in relatively small avifaunal changes.
57Â citations
TL;DR: The results of this study show that invasion and rapid encroachment of S. pyramidatus on C. dactyloides are pri- marily due to an allelopathic effect, with competitive mechanisms and mechanical disturbance probably accentuating this effect.
Abstract: Field observations of stands of Sporobolus pyramidatus indicated a reduction of growth of S. pyramidatus in the center of the stands. Associated species were either reduced in growth or eliminated from these stands. Rapid encroachment of S. pyramidatus on Cynodon dactylon was also observed. Experiments were designed to determine if the observed vegetational patterning was a result of allelopathy. Early studies eliminated shading and soil factors as causal agents. Experiments with field soil taken from around S. pyramidatus plants indicated that phytotoxins were present and were relatively stable in the soil. Decaying shoot material exerted the most phytotoxic effect on growth and germination of the test species; however, C. dactylon was adversely affected by all factors tested except leaf leachate. Buchloe dactyloides was inhibited by field soils and, by decaying shoots. The decaying shoots of S. pyramidatus inhibited the growth of its own seedlings. There was also an indication that the leaf leachate and root exudate of S. pyrami- datus may be responsible for its own decline. Para-coumaric acid and ferulic acid were extracted from S. pyrami- datus shoot residue in large quantities. Both compounds were very inhib- itory to germination of Amaranthus palmeri seed. The results of this study show that invasion and rapid encroachment of S. pyramidatus on C. dactylon and possibly on B. dactyloides are pri- marily due to an allelopathic effect, with competitive mechanisms and mechanical disturbance probably accentuating this effect. S. pyramidatus is more inhibitory to C. dactylon than to itself, thus allowing it to invade new areas before it eliminates itself.
53Â citations
TL;DR: Density of pitfall traps in a sampling area was critical in determining the number of beetles captured, and Comparisons of beetle catches between two spaced-grid sampling areas with different can densities indicated a close relationship between beetle-catch density and pitfall-trap density.
Abstract: Population sampling of five species of desert tenebrionid beetles, Eleodes armata, Centrioptera muricata, Centrioptera variolosa, Cryptoglossa verrucosa and Pelecyphorus adversus, was conducted using pitfall traps for 15 months at South Mountain Desert Park, Phoenix, Arizona. Decreases in beetle catch were observed during extreme summer climatic conditions (sustained drought and above-average temperatures) and throughout the colder winter months. The reduced catch was attributed to decreased surface activities and/or increased mortality rates. Increases in number of beetles collected in pitfall traps resulted from general density increases during seasonal periods of population eclosion. Localized elevations in beetle density may have been mediated through the aggregating influences of reproductive chemical pheromones. Beetle associations with desert vegetation reduced their overall population mobility and increased their likelihood of capture in pitfall traps placed near these plants. Some factors such as differential surface illumination due to changing moon phase and remova,l of beetle catch from the sampling area did not significantly affect the number of tenebrionids collected. Density of pitfall traps in a sampling area was critical in determining the number of beetles captured. Comparisons of beetle catches between two spaced-grid sampling areas with different can densities indicated a close relationship between beetle-catch density and pitfall-trap density.
50Â citations
TL;DR: The great edible land crab reacted differently to increases in temperature in that the length of its period increased slightly, producing a Ql0 of 0.996, and the rhythms were found to be essentially independent of temperature.
Abstract: Spontaneous locomotor behavior of four species (Gecarcinus lateralis, Cardisoma guanhumi, Ocypode quadrata, Coenobita clypeatus) of land crabs was studied in the field and in controlled conditions in the laboratory. All were found to be predominantly nightactive, and these locomotor rhythms persisted in constant temperature and in both constant darkness or constant illumination of various intensities for periods of over 3 months. No difference in the circadian period length of the rhythm could be distinguished at constant light intensities between 5 and 50 ft-c. The rhythms could be rephased by subjecting the crabs to artificial light cycles offered out of phase with the natural one. The effect of various constant temperatures (all within the ecological range) on the period lengths of rhythms in two species of crabs was tested; the rhythms were found to be essentially independent of temperature. The great edible land crab reacted differently to increases in temperature in that the length of its period increased slightly, producing a Ql0 of 0.996. I
47Â citations
TL;DR: Experiments showing that the predatory lunge can be elicited by purely visual stimuli are reported here for the first time and the predatory behavior of D. longipes is compared with that reported for other species and the differences are assessed in terms of adaptive function.
Abstract: Spiders belonging to the family Dinopidae catch their prey in small rectangular nets of hackled silk held at the corners by the first two pairs of legs while the net and the spider are supported by a scaffolding of silk. Dinopis longipes F. Cambridge employs the net to catch prey animals moving on a nearby substrate by thrusting the net against them. This form of prey capture has not been described for other species of dinopids and is described in detail and illustrated. Once the prey has been picked off the substrate, attached to the net, it is wrapped in silk and then bitten. Experiments showing that the predatory lunge can be elicited by purely visual stimuli are reported here for the first time. The predatory behavior of D. longipes is compared with that reported for other species and the differences are assessed in terms of adaptive function.
TL;DR: First- and 2nd-year survival and height growth of regenerated white fir and douglas fir seedlings were studied in typical microenvironments on exposed slopes and ridge tops at an eleva- tion of 1300 m in the Sierra Nevada of California.
Abstract: First- and 2nd-year survival and height growth of natu- rally regenerated white fir and douglas fir seedlings were studied in typical microenvironments on exposed slopes and ridge tops at an eleva- tion of 1300 m in the Sierra Nevada of California. Microsites were described by measuring soil moisture at several depths and potential evaporation at lst-year seedling height. Seedlings survive the summer drought apparently by attaining a type of dormancy in a suitable microsite. Survival was greatest in part shade and in full sun providing squaw carpet (Ceanothus prostratus) mats were present. In these microenvironments soil moisture reaches ten- sions of 15 atm and greater, but the reduced potential evaporation at the seedling tops probably compensates for the lack of soil moisture. The ,growth of natural regeneration is initially quite slow; however, mortality is essentially over by the 2nd year after germination. The' all-age group structure of the mixe'd conifer stands on these sites is apparently related to the occurrence of microenvironments suitable for seedling establish- ment.
TL;DR: The afterripening requirement and the relatively low temperature requirement for germination insure that germination does not occur during the summer, which can be interpreted as ecological adaptations to the seasonally-arid glade habitat.
Abstract: Leavenworthia stylosa Gray, L. uniflora (Michx.) Britt., and L. torulosa Gray are winter annuals that grow in shallow rocky soils of middle Tennessee cedar glades. Seeds of these species are dispersed in May, but germination is delayed until September and October. This study investigates reasons for the failure of these winter annuals to germinate during the summer. At maturity, practically all of the seeds are dormant, and germination during late spring and early summer (May and June) apparently is prevented by an internal dormancy mechanism(s). Dormancy in many of the seeds is overcome by a short period of after-ripening so that, in nature, a certain percentage of the seeds are nondormant (but quiescent) during July and August. During the quiescent period, nondormant seeds will germinate at constant temperatures ranging from 10 to 20 C but not at higher constant temperatures or at alternating temperatures that occur in nature during this time, even if the soil is kept continuously moist. By autumn most of the seeds have after-ripened and with the arrival of lower autumn temperatures, seeds germinate as soon as moisture conditions permit. The afterripening requirement and the relatively low temperature requirement for germination insure that germination does not occur during the summer. These germination-regulating mechanisms can be interpreted as ecological adaptations to the seasonally-arid glade habitat.
TL;DR: Field studies indicated a different pattern of vegetation around the A. psilostachya, and initial experiments suggested that the patterns were due neither to mineral nor physical properties of the soil nor to competition, but probably due to the interaction of organic compounds released by leaf leachate, root exudate and decaying materials.
Abstract: Ambrosia psilostachya (western ragweed) is a charac- teristic species found in the first stage of old-field succession and it persists through the later stages. Previous workers found that A. psilostachya was inhibitory to nitrogen-fixing algae and bacteria as well as to nitrifying bacteria. Field studies indicated a different pattern of vegetation around the A. psilostachya, and initial experiments suggested that the patterns were due neither to mineral nor physical properties of the soil nor to competition. The root exudate, leaf leachate and decaying leaves of A. psilostachya inhibited many of the early invaders of aban- doned fields. Andropogon ternarius, a bunch grass, was inhibited by de- caying material and root exudate of A. psilostachya. T'ridens flavus and Leptoloma cognatum, two species found more commonly near A. psilo- stachya in the field, were stimulated by leaf leachate and field soil collect- ed near A. psilostachya. Tridens flavus was also stimulated by root exudate of A. psilostachya. The differential patterns created by the A. psilostachya were probably due to the interaction of organic compounds released by leaf leachate, root exudate and decaying materials. The possibility of volatile materials from A. psilostachya affecting growth of associated plants was suggested. Two phytotoxins were isolated from overwintered A. psilostachya leaves but attempts to identify them were not suc- cessful.
TL;DR: A great majority of groves are undergoing a gradual decrease in density of giant sequoias due to low levels of regeneration, which began long before the influence of Western civilization on the groves.
Abstract: The vegetation of the giant sequoia groves is dominated by Abies concolor, with Pinus lambertiana as a characteristic associate. Sequoiadendron giganteum is of small importance in relative density, but includes the majority of basal area of canopy species within the groves. Despite its great basal area, crown coverage of Sequoiadendron seldom exceeds 5%. Libocedrus decurrens is an important associate in lower-elevation groves, particularly following fire disturbance. Groundcover vegetation is extremely variable. Present grove boundaries appear to be remarkably stable. There is no evidence of any change in grove boundaries during the last 500 years or longer. A great majority of groves are undergoing a gradual decrease in density of giant sequoias due to low levels of regeneration. This decline in density began long before the influence of Western civilization on the groves.
TL;DR: In contrast to other cave animals, metabolic rate of amphipods was not reduced in cave populations as compared to surface populations and in the genus Stygonectes the cave-limited S. emarginatus and S. spinatus had no lower standard metabolic rate than a surface seep population of S. tenuis potamacus.
Abstract: In contrast to other cave animals, metabolic rate of amphipods was not reduced in cave populations as compared to surface populations. In the genus Stygonectes the cave-limited S. emarginatus and S. spinatus had no lower standard metabolic rate than a surface seep population of S. tenuis potamacus. Cave ecotypes of Gammarus minus showed no lower standard or routine metabolic rate and no higher activity level or locomotor efficiency than surface spring ecotypes. One possible reason for these results is that the caves in which these amphipods were found are probably not food limited.
TL;DR: Studies were conducted on the reproductive biology of eight species of bats in central Iowa in 1967, 1968 and 1969, finding parturition began approximately 1 week earlier than in other species and the period of lactation varied from 5 to 6 weeks in all species; most young were foraging 4 to 5 weeks after birth.
Abstract: Studies were conducted on the reproductive biology of eight species of bats (Myotis lucifugus, M. keenii, Lasionycteris noctivagans, Pipistrellus subflavus, Eptesicus fuscus, Lasiurus borealis, L. cinereus and Nycticeius humeralis) in central Iowa in 1967, 1968 and 1969. Populations were sampled using mist nets; individual bats were marked and released at the site of capture. Parturition began by the 2nd or 3rd week of June and extended into the 1st week of July. In tree bats (Lasionycteris and Lasiurus) parturition began approximately 1 week earlier than in other species. The period of lactation varied from 5 to 6 weeks in all species; most young were foraging 4 to 5 weeks after birth. Population densities reached their maximum in August when young bats were volant and adults of some species may have been migrants. Adult male Lasionycteris were captured only in June and September, while adult females were abundant throughout the warm season, No adult males of L. cinereus, N. hum.eralis or P. subflavus were taken. Adult males of E. fuscus outnumbered females 10:1 in June and July although the sexes reached approximately equal numbers in late summer and early autumn. Adult females of M. lucifugus and M. keenii outnumbered males by approximately 2: 1.
TL;DR: Experiments in an artificial stream indicate that washout rate is density- dependent, at least in G. minus, with some density-independent washout occurring under extreme environmental conditions.
Abstract: In several cave-stream populations of Stygonectes spinatus and Gammarus minus, but not Asellus holsingeri, there was a large drop in abundance during spring high water. A long-lasting rather than short-term distributional change, this drop in abundance occurred despite the fact that the amount of food available is greatest during spring high water. Stygonectes species are less abundant than G. minus, largely because of the former's higher washout rate. This explains the rather difficult-to-grasp fact that the older cave species are less common. Experiments in an artificial stream indicate that washout rate is density- dependent, at least in G. minus, with some density-independent washout occurring under extreme environmental conditions. Washout is increased by increasing current velocity, increasing density, decreasing the size of the animals, or reducing the amount of available food.
TL;DR: A restricted concept of the family Microcotylidae (Mono- genoidea) is discussed and five new microcotyline species are described from fishes of southern.
Abstract: A restricted concept of the family Microcotylidae (Mono- genoidea) is discussed. Microcotylinae s.s. has typical forms with a long tail-like haptor: Bradyhaptorinae subfam. n., with an exceptionally short haptor but with a steep size-gradient in its clamps; Caenomicrocotylinae subfam. n., all genera with a metahaptor; and Bychowskicotylinae sub- fam. n., for Bychowskicotyla mormyri (Lorenz) comb. n., in which the later-formed larger clamps show an incipient asymmetrical modification. Five new microcotyline species are described from fishes of southern
TL;DR: The characters of Rhyacotriton are discussed relative to their evolu- tionary significance, and specializations mainly relate to heterochronic modes of evolution, favored by selection pressures associated with life in torrential streams and possibly related to such differential development as the early establishment of feeding and locomotor systems and the retardation of lung development.
Abstract: Rhyacotriton olympicus is a stream-dwelling ambystoma- tid salamander having a mosaic of primitive (mainly structural) and derived (mainly ecological, developmental and physiological) features. Aspects of the morphology and ontogeny of middle to late larvae are considered. Proportional relationships during ontogeny, and external and microscopic features of the skin of the head and body are recorded. Skulls are well developed at an early age, especially those parts con- cerned with feeding. The last bones to appear are, in order, orbito- sphenoids, prefrontals, lacrimals (from two ossification centers) and septomaxillaries, and formation of lacrimals and septomaxillaries seems to be associated with metamorphosis. Nasal and coronoid bones never form. The anterior part of the otic capsule develops from two centers of ossification. Changes in dentition are marked and involve increases in the numbers of tooth loci on all but the premaxillary bone, during the period of growth studied. The rate of increase is greatest on the dentary. Most larvae lack palatopterygoid teeth, and all lack coronoid teeth; these are derived features in the family. Mineralized gill rakers are few in number. The hyobranchial apparatus is similar to that of other amby- stomatids. The vertebral column develops early, but some caudal verte- brae are added during later stages of larval life. From 42-46 vertebrae comprise the column, usually with 16 trunk and three caudosacral verte- brae. Limbs and girdles are well developed at relatively early ages. Coloration is analyzed, and development of bright yellow ventral pigment in late larval life is documented. The characters of Rhyacotriton are discussed relative to their evolu- tionary significance. The specializations mainly relate to heterochronic modes of evolution, favored by selection pressures associated with life in torrential streams and possibly related to such differential development as the early establishment of feeding and locomotor systems and the retardation of lung development.
TL;DR: Adult males and pregnant females were difficult to capture in the late spring and summer and waterfowl nesting areas surrounded by deep channels or over 0.5 mile from areas frequented by skunks were relatively safe from skunk predation.
Abstract: Striped skunks were studied on and near a 2083-acre marsh in northwestern Ohio in 1967 and 1968. The breeding season ranged from 12 February to 25 March, and the young were born from mid-April to mid-May. Most young skunks became self-sufficient in midAugust. The adult sex ratio averaged 0.8 male per female. Seventy-one per cent of the skunks examined were under 1 year old. Daily activity usually began within 60 min after sunset. Adult males and pregnant females were difficult to capture in the late spring and summer. Decreasing barometric pressure was significantly related to skunk captures. The average straight line distance between capture locations was 0.5 mile for adult males and females and 0.2 and 0.4 miles for juvenile males and females, respectively. Home ranges varied from 31 to 114 acres. The density of skunks in late summer was 12 per square mile. Skunks temporarily used the numerous dens on the dikes. Most of the 93 blue-winged teal and mallard nests observed were destroyed by predators, but skunks destroyed only 13 %. Waterfowl nesting areas surrounded by deep channels or over 0.5 mile from areas frequented by skunks were relatively safe from skunk predation.
TL;DR: Polyergus lucidus Mayr nested in sunny, well-drained fields and had three types of external nest structure: a simple crater of discarded pellets, a hidden entrance at the base of a grass clump and a chambered mound.
Abstract: Polyergus lucidus Mayr nested in sunny, well-drained fields. Its nest structure resembled that of Formica pallidefulva nitidiventris Emery, its slave species. Three types of external nest structure were observed: a simple crater of discarded pellets, a hidden entrance at the base of a grass clump and a chambered mound. Colonies occasionally became inactive and died out, probably because of an unknown disease. Adult sexual forms were present from early July until midSeptember; and mating flights occurred on hot, sunny afternoons between late July and mid-September. Alates normally flew without mating, but queens occasionally mated on the ground near the nest. Myrmica americana Weber preyed upon P. lucidus and its slaves as well as P. breviceps Emery. Acanthomyops claviger (Roger), Solenopsis molesta (Say), Monomorium minimum (Buckley), Lasius neoniger Emery and Formica fusca Linnaeus also harassed P. lucidus. Camponotus pennsylvanicus (De Geer) ambushed returning columns of P. breviceps.
TL;DR: Preliminary findings of the social behavior and interactions of Sceloporus undulatus (the fence lizard) and S celoporus graciosus (the sagebrush lizard) where they are sympatric in southern Utah are reported.
Abstract: Sagebrush lizards (Sceloporus graciosus) were more wary and less prone to climb trees than fence lizards (Sceloporus undulatus). Males of both species were considerably more active than females in May. The evidence for species discrimination by the males was inconclusive, but males never confused the sex of a conspecific, and both sexes showed some ability to distinguish individual mates. Males courted females and defended territories both during and after the reproductive season. Mates may form long-term pair bonds. Some males of both species were polygynous; others monogamous. Frequency of assertion displays was correlated with distance traveled. Push-up displays of the two species were distinct. This paper reports preliminary findings of the social behavior and interactions of Sceloporus undulatus (the fence lizard) and Sceloporus graciosus (the sagebrush lizard) where they are sympatric in southern Utah. The study area was located in the Kolob section of Zion National Park, Washington Co., Utah, at an elevation of 6200 ft (1888 m). The area includes a small temporary stream bordered on the E by a steep sandstone slope with little vegetation cover, and on the W by a lava outcrop, supporting a heavy growth of scrub oak (Quercus sp.), maple (Acer sp.) and serviceberry (Amelanchier sp.). Although both sagebrush lizards and fence lizards are abundant on the study area, fence lizards are confined to an island of scrub growth associated with the stream. Sagebrush lizards are more widespread through the area and are the most abundant lizard at this elevation. In May 1969 the study area was divided into 24 quadrats (20 ft on each side) marked by numbered stakes to facilitate measuring lizard location and activity. In August 1969 26 quadrats were added, increasing the area to about %2 acre. All lizards residing on the 50-quadrat area were captured by hand or noose; each was marked by clipping various combinations of toes and by painting a distinctive design on its back according to standard proceduire (Tinkle, 1967). I measured the snout-vent length in mm of each lizard, then released it at the location of capture. I spent about 80 hr in periods ranging from 2 to 9 hr following the various marked individuals. In August lizards captured in May were recaptured, remeasured, repainted and released. Data were recorded on a Magnavox portable cassette tape recorder. I spent 16-27 May and 3-11 August 1969 in the field. Sagebrush and fence lizards, though similar in appearance in southern Utah, can be distinguished easily by the dorsal color of the head; that of a sagebrush lizard is patternless but that of a fence lizard includes several bold narrow stripes and bands. Adult sagebrush lizards also are smaller and stockier than fence lizards. The average snoutvent length of the adult sagebrush lizards I measured was 57 mm; of fence lizards, 66 mm. There seems to be no sexual dimorphism in
TL;DR: The population of this species increased and a high local population remained to the end of the study in September 1961, and ecological information obtained from 515 pine mice captured 1430 times at the western limit of their geographic range in North America is reported.
Abstract: Population variation, habitat, movement, disappearance, sex ratio, reproduction and size of 515 pine mice (Microtus pinetorum) captured 1430 times were studied between October 1959 and September 1961 in Payne Co., Okla. Pine mice were more numerous after a Sigmodon hispidus "crash" and in areas not occupied by Sigmodon. Savanna edge, upland woods, grass-forb and bottomland woods, in that order, were favored plant associations based on number of captures. Other variations in apparent habitat selection are given. Home ranges, longest distances traveled and captures were greater for males than for females, for adults than for subadults, and on one grid than on another. Females disappeared more rapidly than males. Population turnover was 93.3% per year. Sex ratio was 242 (47%) males to 271 females at all age levels, but was 17 (40%) males to 26 females for 7-16 g subadults. Adults of both sexes are apparently capable of breeding throughout favorable years. The height of the reproductive season is from October to May with curtailment of reproductive activity during the summer. Each female may have 1-4 litters per year with 1-5 (mean, 2.6) individuals per litter. Pine mice weigh 2.3 g at birth, 8% of the female's body weight, and weigh an average of 27.1 g and are 127 mm long as adults. Other reproductive, sex, age and weight variations are given. INTRODUCTION Six months and 5000 trap-nights after a study of rodent populations began in October 1959, near Lake Carl Blackwell, Payne Co., Okla., the first capture of a pine mouse (Microtus pinetorum) was made. Shortly thereafter the population of this species increased and a high local population remained to the end of the study in September 1961. This paper reports ecological information obtained from 515 pine mice captured 1430 times at the western limit of their geographic range in North America. METHODS Mice were captured by live-trapping, marking and releasing on two established grids and by snap-trapping on transects. Vegetation along snap-trap transects and at live-trap sites was sampled by a inodification of the line-intercept method of Canfield (1941). A detailed description of the methods has been given in two previous papers (Goertz, 1964, 1970). DESCRIPTION OF AREAS TRAPPED Elements of both the Grassland and Deciduous Forest Biomes are
TL;DR: The purposes of this investigation were to provide a quantitative description of the vegetation in an active fresh-water heron rookery and to investigate any changes in soil nutrients as possible limiting factors in the subsequent floral pattern.
Abstract: An island rookery of approximately 8000 Ardeidaean birds in west-central Minnesota was mapped and divided into three areas of use: heavy, light and none. Quadrats, 1 m on a side, were used to sample these three areas for floristic composition, soil nutrients and pH, light regime and great blue heron nest concentration. The results support previous work on oceanic rookeries showing a reduction in plant density in areas of high avian activity. The distribution of 21 plant species discussed, with relation to the three areas of activity, is limited neither by the summer light intensity nor the concentration of nutrients measured during the winter. INTRODUCTION The purposes of this investigation were to provide a quantitative description of the vegetation in an active fresh-water heron rookery and to investigate any changes in soil nutrients as possible limiting factors in the subsequent floral pattern. Alpheraky (1905), Guthrie-Smith (1914, 1925), Wilson (1959), Fineran (1964, 1966) and Gillham (1956, 1963a and 1963b) have all reported on vegetational responses to high bird concentrations in oceanic colonies, but very little information is available with respect to fresh-water nesting sites. The mechanisms of these vegetational responses are somewhat dependent upon the type of avian aggregation. A tree-roosting or nesting colony influences the ground vegetation mainly through the accumulation of the droppings. On the other hand, ground-feeding and burrowing or tunneling nesters also graze, burrow and trample the area. Herons represent a tree-nesting colony. The physiological effect of guano on plant life is reported to result from an unfavorable osmotic balance set up in the soil by the accumulation of salts; salt concentration in seabird guano is often very high (Gillham, 1963b). The macronutrient soil constituents of these oceanic rookery areas have been well established. The soils, are characterized by: 1. A decrease in the C: N ratio as a result of the high influx of nitrogen, usually in the form of nitrates (Blakemore and Gibbs, 1968). Oceanic rookery soil nitrate content sometimes shows a 100-fold increase over control areas (Gillham, 1956). 2. An increase in phosphate content, almost solely as inorganic phosphate. A 30-fold increase has been noted here (Gillham, 1956). 3. A high concentration of soluble ions, namely sodium, potassium, ammonium, chloride, sulfate, nitrate and phosphate (Blakemore and Gibbs, 1968; Campbell and Claridge, 1966). 4. A decrease in the amount of exchangeable calcium and magnesium. This is due apparently to a displacement by ammonium ions during the leaching process (Ward, 1961; Blakemore and Gibbs, 1968). The hydrogen ion concentration of guano varies widely (pH: 5.8-
TL;DR: The increased importance of sugar maple in the stand was attributed to absence of major disturbance, climatic and soil changes in the past century, related to increased precipitation during much of the period, and selective cutting.
Abstract: All stems 2.6 inches (6.6 cm), or greater, in diam breast height (dbh) were tallied in an 18-acre (7.2 ha) forest on loessal soils of the Ozark Hills in Union Co., Ill. Understory and ground vegetation were sampled in 0.01and 0.001-acre (4 sq m) transects and quadrats. Stand density was 221 stems per acre and basal area was 130 sq ft. Sugar maple (Acer saccharum) was the leading species based on importance values of 38 species. The canopy strata included shagbark hickory (Carya ovata), black oak (Quercus velutina), northern red oak (Q. rubra), sugar maple and white oak (Q. alba). Sugar maple and shagbark hickory increased substantially in the canopy during an 11-year period from 1956 to 1967, while northern red oak and black oak decreased in importance value. The increased importance of sugar maple in the stand was attributed to absence of major disturbance, climatic and soil changes in the past century, related to increased precipitation during much of the period, and selective cutting. The stand was classified as western mesophytic (Braun, 1950).
TL;DR: Three hundred fifty-seven specimens of fish, amphibians, and reptiles representing 59 taxa and a variety of ecological relationships were surveyed for the fungus Basidiobolus ranarum.
Abstract: Three hundred fifty-seven specimens of fish, amphibians, and reptiles representing 59 taxa and a variety of ecological relationships were surveyed for the fungus Basidiobolus ranarum. B. ranarum was isolated from species occupying a broad range of ecological situations varying from totally aquatic to semiarboreal nd subterranean forms.
TL;DR: Adaptations which permit this plant to succeed in dry, exposed habitats are a capacity for water uptake through foliar trichomes, the capacity to resist rapid drying at low humidities, and the ability to endure extreme desiccation without incurring irreversible impairment of its metabolism.
Abstract: Tillandsia ionantha Planch is a Mexican and Central American epiphyte or saxicole. Because this species cannot impound water and debris among overlapping leaf bases as do many other bromeliad epiphytes and because it lacks a root system capable of significant absorption, it must rely on rapid mineral and water uptake over the shoot surface. Adaptations which permit this plant to succeed in dry, exposed habitats are a capacity for water uptake through foliar trichomes, the capacity to resist rapid drying at low humidities, and the ability to endure extreme desiccation without incurring irreversible impairment of its metabolism. It is not as insensitive to desiccation injury as some true poikilohydrous plants. When water deficits approach 7580%, irreversible metabolic injury occurs as evidenced by permanent impairment of photosynthesis and respiration and eventual death. Young seedlings are less capable of resisting desiccation than adult rosettes but they can endure at least a 65% water deficit without loss of function.