Showing papers in "American Midland Naturalist in 1970"
TL;DR: In California the annual vegetation adjacent to natural-ized stands of Eucalyptus camaldulensis often is inhibited severely, and water-soluble toxins found in the litter inhibited herb growth in laboratory, green- house, and field experiments.
Abstract: In California the annual vegetation adjacent to natural- ized stands of Eucalyptus camaldulensis often is inhibited severely. Annual herbs rarely survive to maturity where Eucalyptus litter accu- mulates. In the ecotone between the trees and herbs a "bare zone," lacking both litter and significant herbaceous vegetation, often is encoun- tered. The occasional herb occurring in this zone is stunted less severely than those in the litter. Grassland of gradually increasing vigor begins at the edge of the bare zone. This pattern was not explained by differences in edaphic conditions, differential grazing, seed removal, or competition for light or nutrients. Competition for water was significant in the production of bare zones, but was not responsible for the lack of herbs in the litter zone. Here soil moisture levels were usually comparable to those in the grassland. Several volatile and water-soluble toxins were found in Eucalyptus tissues. Cineole and a-pinene, both highly toxic terpenes, were found adsorbed to colloidal soil particles of the litter and bare zones. Adsorbed terpenes were toxic to germinating seeds and seedlings. Water-soluble toxins found in the litter inhibited herb growth in laboratory, green- house, and field experiments. Of 10 isolated phenolic toxins, five were identified as caffeic acid, chlorogenic acid, p-coumaric acid, ferulic acid,
275Â citations
TL;DR: A total of 31,637 individuals, comprising 70 fish species and 37 families, were trawled in a Georgia estuary and population structure was influenced by seasonal changes in taxa, numbers of species and individuals, and average size of fishes.
Abstract: A total of 31,637 individuals, comprising 70 fish species and 37 families, were trawled in a Georgia estuary. Population structure was influenced by seasonal changes in taxa, numbers of species and individuals, and average size of fishes. Species-numbers diversity was studied in regard to seasonal variation and three zones. Four indices were compared. Seasonal variation was found with "equitability" and "evenness" but not with the ShannonWiener index or species "richness." A seasonal change in relative abundance resulted primarily from the influx of juveniles in the late summer and autumn. An apparent increase in diversity from sounds to small creeks based on three indices was not statistically significant. INTRODUCTION Trawl samples of fish collected throughout one annual cycle from three zones in a Georgia salt marsh estuary are analyzed in terms of seasonal cycles and four contrasting diversity indices. Establishing the normal cycle of diversity in this undisturbed estuarine system is part of an inventory designed to establish bases for the future detection, evaluation, and control of pollution that might result from new industries. Species-numbers diversity is generally a more sensitive and reliable index of environmental health than are individual "indicator" organisms. For example, Wilhm (1967) found that diversity of benthic stream invertebrates decreased with the degree of pollution. However. diversity may also be affected by normal downstream trends related to stream order (size) (Harrel and Dorris, 1968). It is important, therefore, that the pattern of diversity in time and space be determined, if possible, prior to the advent of stress. The behavior of diversity indices needs to be understood, since the various ratios proposed measure different components of diversity. As the indices are variously affected by sample size and seasonal phenomena, it is also necessary to analyze population dynamics, seasonal changes in taxa, numbers of species and individuals, and growth. METHODS Fishes were sampled at approximately three-week intervals from January 1967 to February 1968 at 14 stations in the -estuarine system of Sapelo and St. Catherines sounds. The Marine Inistitute's R/V Kit Jones sampled with a 20 ft (6 m) wide otter trawl having 1 ,4 in (32 mm) mesh in the bag. Each station was trawled for 15 minutes. 1 Contribution No. 182 of the Marine Institute, University of Georgia, Sapelo Island 31327. 382 This content downloaded from 157.55.39.83 on Sun, 09 Oct 2016 05:13:42 UTC All use subject to http://about.jstor.org/terms 1970 DAHLBERG AND ODUM: ANNUAL CYCLES IN FISH 383 A representative fish collection is maintained at the Marine Institute. To compare habitats the study area was arbitrarily divided into three ecological areas according to the size of tidal waters: (1) sounds -stations 1, 2, 3, 7, and 8; (2) larger creeks-stations 4, 5, 6, 9, and 14; and (3) smaller upper creeks-stations 10, 11, 12, and 13 (Fig. 1). The sounds are the widest and deepest of the aquatic habitats compared and have, primarily, sandy bottoms. The lumps of clay occasionally trawled are exposed by erosion of the bottom. The "upper creeks" are relatively narrow and shallow with sand bottom, and drain the extensive Spartina salt marshes characteristic of Georgia estuaries. A considerable amount of organic detritus, settles here, and sticks and logs are commonly found on the bottom. The "large creeks" are generally intermediate in location and physical characteristics. Four diversity indices were calculated. The Shannon-Wiener function is: H =-X Pi logPi (1) i=n where Pi is the proportion of individuals in the i-th species. This -J H 9 SAPELO ~~SOUNUND 0 I < X 1~~~~~~~~~~~~~2 #< jW Fig. 1.-Collecting stations in estuarine system of Sapelo and St. Catherines sounds. This content downloaded from 157.55.39.83 on Sun, 09 Oct 2016 05:13:42 UTC All use subject to http://about.jstor.org/terms 384 THE AMERICAN MIDLAND NATURALIST 83(2) formula has been used widely as a species diversity index, as suggested by Margalef (1957). The Shannon-Wiener function increases as both the number of species and the equitability of species abundance increase. It is desirable to consider indices that treat these aspects separately since the two components of diversity may react differently to certain types of stresses. For the "species richness" component of diversity we selected the following: D = (S-1)/log N (2) where S is the number of species and N is the number of individuals. Tbhis index was also used by Margalef (1969) in diversity studies. Relative species abundance was measured by two indices. Lloyd and Ghelardi's (1964) equitability index is:
111Â citations
TL;DR: A selective literature review summarized field and laboratory evidence for salt-tolerance limits for marine angiosperms, mangroves, and plants of coastal strand, salt desert, and salt marsh, finding no laboratory-based evidence which definitely showed any angiosperm to be an obligate halophyte, although some were shown to be facultative.
Abstract: The categories glycophyte, intolerant halophyte, faculta- tive halophyte, and obligate halophyte were defined in relative terms. An obligate halophyte was defined as a plant with optimal growth at moderate or high salinity and incapable of growth at low salinity. A selective literature review summarized field and laboratory evidence con- cerning salt-tolerance limits for marine angiosperms, mangroves, and plants of coastal strand, salt desert, and salt marsh. Extensive field observations, corroborated by several workers, were considered very strong, but not conclusive, evidence in defining tolerance limits of species. Even from field observations, however, very few species appeared to be restricted to salinities above 0.5%. Laboratory techniques were not consistent and seldom approximated natural conditions. Neverthe- less, no laboratory-based evidence was found which definitely showed any angiosperm to be an obligate halophyte, although some were shown to be facultative. Ability to reproduce, rather than short-term growth, Reviews by Uphof (1941), Chapman (1960), and Bernstein (1962) cover aspects of geographic distribution, taxonomic relationships, ecol- ogy, and physiology of halophytes. This paper examines only the litera- ture dealing with the range of salt tolerance of angiosperms from several habitats. The term halophyte, alone or coupled with a number of modifiers, has been defined in several contradictory ways. Some of these defini- tions will be reviewed here, and a single set of terms and definitions to be used as a basis for the rest of the paper will be presented. Schimper (1903) defined a halophyte as a plant which lived normally in saline habitats, but which could ". . . thrive on ordinary soil, for instance on garden-soil, without any addition of common salt." Schimper did not define a saline habitat, but his discussion implied it to be one with more than 2% NaCl. Warming (1909) similarly avoided implying that halophytes were restricted to saline habitats. Stocker (1928) defined halophyte and saline habitat more precisely: a normal glycophyte (non-halophyte) is able to tolerate up to 0.5% NaCl and a halophyte is able to tolerate, at any stage of its life, a salt concentration greater than 0.5%.
95Â citations
TL;DR: The individual and social behavior of 73 captive opossums, Didelphis marsupialis virginiana, was studied to provide an account of the behavior of the opossum, and to learn the extent to which behavioral and associated structural features may have contributed to its success.
Abstract: The individual and social behavior of 73 captive opossums, Didelphis marsupialis virginiana, was studied. The patterns of behavior seen in Didelphis appear generalized, correlating with the opossum's primitive morphology and taxonomic status. Diverse locomotor patterns, arboreal modifications, and highly unselective food habits explain in part the diversity of habitats frequented by Dudelphis in North America. A well developed attitude of passive defense is seen in interspecific encounters and the adaptive significance of such behavior is considered. Social behavior is poorly developed and, with the exception of mating, most intraspecific encounters between adults are agonistic in nature. Although marsupials are usually not successful in competition with placentals, the opossum is an obvious exception. Presumably, its generalized behavior has allowed Didelphis to exploit a variety of food sources and habitat types. This, together with a high reproductive potential, may account for the evolutionary persistence of the species, and its current ecological success. INTRODUCTION The opossum, Didelphis marsupialis (Family Didelphidae) is the only marsupial native to the United States. Morphologically, Didelphis resembles members of the Upper Cretaceous didelphid stock which underwent adaptive radiation in South America and from which all extant marsupials evolved (Simpson, 1945; Clemens, 1968). Although marsupials are usually not successful in competition with placentals, Didelphis is notable for its persistence, particularly in the eastern United States (Hamilton, 1958). This success may be due, in part, to the opossum's generalized morphology (Haines, 1958); but other aspects of its biology must also be involved. Despite the unique taxonomic position of Didelphis, little attention has been given to the details of its behavior. With the exception of studies on the ontogeny of behavior in pouch young (Langworthy, 1925, 1928), on reproductive behavior (Reynolds, 1952), and on defensive behavior (Francq, 1969), most information on the behavior of the opossum is of an anecdotal nature. The present study attempts to provide an account of the behavior of the opossum, with the specific objective of learning the extent to which behavioral and associated structural features may have contributed to its success. In addition, the primitive status of the opossum makes its behavior of exceptional interest from the broader standpoint of the origin and evolution of mammalian patterns of behavior in general. METHODS AND MATERIALS Opossums were captured in the vicinity of Ithaca, Tompkins Co., New York. A total of 76 individuals (33 males and 43 females) of the 1 Present address: Department of Biology, Fairleigh Dickinson University, Madison, New Jersey 07940.
86Â citations
85Â citations
TL;DR: The behavior and ecology of a population of individual- ly marked Microcavia australis was studied in a xerophytic thornbush habitat in Buenos Aires Province, Argentina, from April 1966 to October 1967.
Abstract: The behavior and ecology of a population of individual- ly marked Microcavia australis was studied in a xerophytic thornbush habitat in Buenos Aires Province, Argentina, from April 1966 to Octo- ber 1967. Another cavy, Galea musteloides, occurred in smaller numbers on the study area. Interactions between the two genera were amicable. Microcavia births occurred from August to April with most litters born in the September-December period. Gestation was 54 days. One female gave birth to four litters during the breeding season. Adult males have home ranges of approximately ?4 hectare, about twice the size of female home ranges. Microcavia is diurnal and may be active at any time of day. Most social interactions occur in the bare areas surrounding thorn- bush associations. Communal rolling sites are loci for olfactory com- munication. Interactions between adult males are agonistic and orga- nized by a straight-line dominance hierarchy. Males congregate around the home bush of a female near term; a conspicuous mating chase occurs at the post-partum estrus. Juveniles may suckle from lactating females other than the mother. Adult males associate with juveniles and respond sexually to them. Females maintain amicable relations with their daugh- ters until the birth of the next litter. Many behavioral similarities be- tween Microcavia and sciurid ecological equivalents, such as Citellus and Cynomys, are convergently evolved adaptations to open habitats. Microcavia social organization is more similar to that of rabbits (which also have a high reproductive potential and high mortality rate) than to sciurid ecological equivalents.
78Â citations
TL;DR: The behavior, distribution, and biotic relationships of the sand dollar Dendraster excentricus along the Pacific coast of California and Baja California, Mexico are studied in this paper.
Abstract: Observations were made on behavior, distribution, and biotic relationships of the sand dollar Dendraster excentricus along the Pacific coast of California and Baja California, Mexico. Populations occur on sandy bottom in bays, tidal channels, and along the outer coast. Orientation and feeding behavior, which are related to water movement, vary between populations in the different habitats. In sheltered bays, where there is relatively little water movement, sand dollars remain in shallow water, frequently move, and lie flat on the bottom where they feed on deposited material. In tidal channelsand protected areas of the outer coast, habitats with moderate water movement, adults are more stationary, usually are in an inclined position, and feed primarily on suspended material. Density estimates and aggregation values are greatest in these populations. In outer-coast areas consistently exposed to heavy seas, where water movement is greatest, sand dollars are usually buried, and presumably feed on deposited material. Two types of distribution patterns occur in populations along the protected outer coast. In one type, the populations run parallel to shore as dense bands, and maintain a characteristic pattern that is reformed when disrupted by occasional heavy seas. Usually juveniles are most abundant shoreward, and move seaward with age. The outer margin of these populations is well-defined in 4-12 m of water, and here the largest individuals and greatest densities occur. Most of our observations are of these populations. The other type of distribution is similar, except that it extends into deeper water, and below about 10-15 m; individuals become progressively smaller with depth. Various other organisms coexist with the sand dollars, many of them using the inclined sand dollars as shelter or a hard substrate. Known predators include fishes, crabs and sea stars. Fouling by the barnacle Balanus pacificus also may contribute to sand-dollar mortality. At present, separate taxa for the ecologically different populations of D. excentricus are not justified.
75Â citations
TL;DR: Desert iguanas in the Coachella Valley of California fed primarily on annual plants in the spring and shifted almost entirely to the leaves of desert perennials during the summer and turned over water more rapidly when maintaining weight on natural vegetation in Palm Desert.
Abstract: Desert iguanas in the Coachella Valley of California fed primarily on annual plants in the spring and shifted almost entirely to the leaves of desert perennials during the summer. Insects and fecal material always comprised a small portion of the diet. In summer at Palm Desert these lizards obtained about 1.0 liters of water per kg of dry food which contained 364 meq K+, 34 meq Na+ and 105 meq Cl-. In spring the foods were more succulent but contained virtually the same concentrations of electrolytes. At Thousand Palms the summer diet was drier and contained higher concentrations of cations. In summer desert iguanas turned over about 30 ml of water/(kg x day) when maintaining weight on natural vegetation in Palm Desert. Lizards that gained weight rapidly or exploited irrigated areas containing succulent vegetation turned over water more rapidly. Production of metabolic water was estimated at about 3.6 ml/ (kg x day) from behavior- al observations combined with available data on metabolic rates of desert iguanas. Turnover of potassium, sodium and chloride was estimated at 9.6, 0.9 and 2.7 meq/ (kg x day), respectively.
72Â citations
70Â citations
TL;DR: The sounds of black-tails, white-tailed, and Gunnison's prairie dogs were studied in Colorado and Wyoming from February 1964 to June 1966.
Abstract: The sounds of black-tailed, white-tailed, and Gunnison's prairie dogs were studied in Colorado and Wyoming from February 1964 to June 1966. Observations, photographs, and tape recordings were made in the field and were supplemented by data collected from captive prairie dogs. The sounds of black-tailed prairie dogs were named and had the usual function as follows: ( 1 ) "repetitious barks" alert; (2) "chuckle" alert; (3) "chatter barks" threat; (4) "wee-oo" contact; (5) "snarl" threat; (6) "growl" threat; (7) "scream" distress; (8) "raspy purr" pleasure; and (9) "tooth chatter" threat. The sounds of white-tailed prairie dogs were: (1) "repetitious barks" alert; (2) "chuckle" alert; (3) "laughing barks" contact; (4) "snarl" threat; (5) "growl" threat; and (6) "scream" distress. The sounds of Gunnison's prairie dogs were: (1 ) "repetitious barks" alert; (2) "rapid barks" apprehension; (3) "chuckle" alert; (4) "raspy chatter" contact; (5) "snarl" threat; (6) "growl" threat; (7) "scream" distress; and (8) "tooth chatter" threat.
68Â citations
TL;DR: A total of 1485 lizards from southern California, Mexico, Baja California, and nearby islands along the Pacific Coast and in the Gulf of California was examined between March 1962 and May 1964 as discussed by the authors.
Abstract: A total of 1485 lizards from southern California, Mexico, Baja California, and nearby islands along the Pacific Coast and in the Gulf of California was examined between March 1962 and May 1964. Of these, 738 were collected from three plant communities in the San Jacinto Mountains. The lizards represented 7 families, 18 genera, and 26 species. The results suggest that differing prevalences of parasites at different altitudes may be attributed to: '(1) specificity to altitudinally zoned definitive or intermediate hosts; (2) presence of single or multiple poten- tial host species; (3) possible influence by humidity and temperature ranges of air and substrate, as indicated by altitudinal changes in plant communities. Significant differences in infection rates between the sexes occur only in haemosporozoan infections. There are two age group distributional patterns of parasites: high initial infection rates in young animals that show little or no decline with age, and a progressive increase of infection rates with host age. Hatchling lizards often acquire multiple protozoan infections almost immediately following hatching. Distributional patterns probably depend upon trans- mission sites, host behavioral changes with age, and vector seasonality. Certain flagellates show decreased infection rates in correlation with concurrent infection by pharyngodont nematodes, possibly dependent upon number of worms present. Seasonal fluctuation, where present, seems related to distributional patterns among host age groups, vector seasonality, changes in host phys- iology associated with reproduction, or the parasites' reproductive cycle. Host specificity exists at infraordinal, familial, generic, and specific levels, with coccidians, oxyurid nematodes, and some cestodes showing the most limited host distribution. Restriction to certain hosts is influ- enced by phylogeny, diet, habits, and habitat of hosts. The following parasites were found: at least seven flagellates Proteromonas, Monocercormonas, Hexamastix, Tritrichomonas, Chilo-
TL;DR: The gross anatomy of all the appendicular muscles is compared in 21 genera, representing all but one of the families (Scopi- dae) of the Order Ciconiiformes, and some functional considerations of these salient features and some general com- ments pertaining to cIconiiform taxonomy are included.
Abstract: The gross anatomy of all the appendicular muscles is compared in 21 genera, representing all but one of the families (Scopi- dae) of the Order Ciconiiformes. Nycticorax nycticorax is used as the type for which most muscles are described. In some cases the descrip- tions are based on Eudocimus albus. Salient features of other taxa, as they differ from the condition found in these genera, are given. Some functional considerations of these salient features and some general com- ments pertaining to ciconiiform taxonomy are included.
TL;DR: The prolonged breeding, egg-laying and incubation periods, with a short larval period and metamorphosis at a small size are adaptive to breeding in temporary ponds in this region.
Abstract: Sympatric populations of Ambystoma opacum and Ambystoma t. tigrinum were studied in ponds on the coastal plain of New Jersey. Ambystoma tigrinum bred during the "January thaw" and its eggs remained under ice for a month after deposition. Eggs were laid in the deepest parts of the ponds. The mean number of eggs per mass (44) was lower than reported elsewhere for A. t. tigrinum. Development of eggs was followed in the field. The cold temperatures extended the breeding season (60 days) and prolonged the incubation period (45-50 days). After hatching in March, the larvae metamorphosed in June (75 days) at 40.5 mm snout-vent (SV) length, 70.3 mm total length. The prolonged breeding, egg-laying and incubation periods, with a short larval period and metamorphosis at a small size are adaptive to breeding in temporary ponds in this region. Eggs of Ambystoma opacum hatched when the ponds filled in midwinter after an incubation period of 120 days. The larval period (135 days) was prolonged because of low environmental temperatures. Growth and proportional changes of the larvae were studied. Most of the growth occurred in the last 60 days of the larval period. Metamorphosis occurred at 38.0 mm SV, 67.7 mm total length, exceeding that attained by larvae in Maryland or North Carolina. Metamorphosis in A. tigrinum was triggered by extrinsic factors (pond drying), and that of A. opacum at least partly by intrinsic factors. Ontogenetic and diurnal changes in behavior and habitat selection were studied in both species. Ontogenetic behavioral changes were correlated with development of limbs and distinct species differences were observed. A. opacum exploited the open-water resources early in the year and inhabited the bottom or vegetation when tigrinum larvae utilized open water. Both species remained hidden in vegetation during the day and were active only at night when they fed. Specific differences in growth and development, and the successive occupation of different zones in the ponds permitted coexistence with little competition.
TL;DR: Habits of 27 opossums were studied by attaching small radio transmitters and trailing them on the University of Kansas Natural History Reservation in 1966 and parts of 1965 and 1967 as discussed by the authors.
Abstract: Habits of 27 opossums were studied by attaching small radio transmitters and trailing them on the University of Kansas Natural History Reservation in 1966 and parts of 1965 and 1967. Activity is normally nocturnal and during the day each animal stays in a den. Most of the 88 dens located were in underground cavities of hilltop limestone outcrops; others were among tree roots in cutbanks of gullies; relatively few were in miscellaneous situations such as hollow trees, old buildings, or burrows away from rock outcrops. The average sojourn at a den is 2.2 days and each opossum uses many different dens but returns frequently to each of several favorite dens. An adult opossum forages from its den over an area with mean radius of 620 m but tends to stay much closer to its den. Extent of movement and frequency of shift were not closely correlated with season or temperature. A newly independent, young opossum tends to stay within a relatively small area at first, and to extend its range by gradual stages. Of nine young opossums that were trailed, three were preyed upon by the horned owl.
TL;DR: The life history, fecundity, behavior and feeding habits of the North American leech, Erpobdella punctata, are investigated and a comparison of E. punctata with its related forms is served.
Abstract: The life history, fecundity, behavior and feeding habits of the North American leech, Erpobdella punctata, are investigated. There is evidence of an upstream migration in early spring. The size distribution within populations indicates that growth to maturity took one year in a permanent pond, but two years in a stream, perhaps because the stream dried up in summer. It seemed that few survived to a second breeding season. Mortality in the stream was estimated at about 93%, 73% and 93% in the first, second and third years, respectively. Intraspecific and snail predations of cocoons were important causes of mortality. These leeches are scavengers and predators, rather than parasites. Courtship involved mutual stimulation and cocoons were laid primarily in May, correlating with a large increase in water temperature. Each individual laid approximately 10 cocoons, each with five eggs which hatch about 3-4 weeks after being laid. INTRODUCTION Erpobdella punctata (Leidy, 1870) is one of the most commonly encountered and widely distributed species of freshwater leeches in North America. Known since 1870, it remains the only substantiated American representative of the Holarctic genus Erpobdella de Blainville 1818 and occurs in Alaska, Canada, and most of the United States to Mexico. Apart from brief scattered references, little is known about such aspects of its biology as its breeding habits, fecundity, population structure or ecology. By contrast, close European and Asian relatives of E. punctata have been studied extensively by such workers as Bennike (1943), Brandes (1899), Brumpt (1899, 1900), Jijima (1882), Klekowska (1951), Luferov (1963), Mann (1953, 1955, 1956, 1958, 1961), Nagao (1957), Pawlowski (1955), Sandner (1951) and Soos (1966). The biological observations on E. punctata presented in this paper constitute an attempt to fill this void, serving for the comparison of E. punctata with its related forms. METHODS OF STUDY The intent of the study was to make detailed biological observations on small natural populations of the free-living erpobdellid, Erpobdella punctata. Two especially suitable study sites in the vicinity of Ann Arbor, Michigan, were chosen on the basis of the abundance of E. punctata and the ease with which they could be observed. One site was a small stream in Hudson Mills Park on the Huron River, approximately 2 mi NW of Dexter, and the other Earhardt Pond, located about 0.5 mi N of the Concordia Junior College, just outside
TL;DR: Parental mobility jeopardizes survival of the young and this may account for the maternal female's solitary and aggressive nature, and her inclina- tion to confine herself to excavated dens and similar retreats.
Abstract: Maternal and offspring behaviors of P. trowbridgi were studied in aquaria. Ovigerous females approaching hatching time were more aggressive than other adult crayfish. At hatching, the female as- sumed a posture with the abdomen well extended and waved the pleopods very actively. Individual broods hatched in 2 days or less and 14 of 16 broods hatched within a 4-day period. Incubation experiments showed that no damage was incurred by eggs removed from the pleopods, and that water circulation was necessary to avoid mass mortality of such eggs. After hatching, the young remained with the parent for 21 to 25 days. From 8 to 12 days were spent in Stage 1 and 11 to 14 days in dependent Stage 2. The second-stage young molted into Stage 3 from 11 to 16 days after independence. Transition to an independent existence involved depletion of food reserves, loss of the clinging reflex, reversed orientation on the pleopods, exploratory and feeding behavior, and the onset of aggression. Independent Stage 2 crayfish avoided each other and their parent. Their response to artificial shelter, and background color and pebbles in relation to light intensity, has survival value in their natural habitat. The critical phases of reproductive biology following mating are: egg-laying, hatching, molting into Stage 2, and exploration. Parental mobility jeopardizes survival of the young and this may account for the maternal female's solitary and aggressive nature, and her inclina- tion to confine herself to excavated dens and similar retreats.
TL;DR: Northern three-toed and hairy woodpeckers consumed 2 to 26% of the brood of an endemic population of the Engelmann spruce beetle, Dendroctonus obesus, and Predation was restricted to the second-year brood and decreased the survival of this age-class by 13 to 25%.
Abstract: Northern three-toed and hairy woodpeckers consumed 2 to 26% of the brood of an endemic population of the Engelmann spruce beetle, Dendroctonus obesus. Predation was restricted to the second-year brood and decreased the survival of this age-class by 13 to 25%. Factors to account for the disproportionate losses of firstand second-year brood in the endemic population and for differential losses of brood from the endemic and epidemic populations to woodpecker predation are suggested and discussed. INTRODUCTION Knowledge of interactions between woodpeckers and bark beetles is restricted to high-level or "epidemic" populations of bark beetles (Van Tyne, 1926; Hutchison, 1951; Massey and Wygant, 1954; Blackford, 1955; Yeager, 1955; Baldwin, 1960, 1968; Amman and Baldwin, 1960; Knight, 1958, 1960; Otvos, 1965). To obtain information on interactions between woodpeckers and low-level or "endemic" populations of bark beetles, studies in a subalpine forest supporting an endemic population of Engelmann spruce beetles, Dendroctonus obesus (Mann.) (=D. engelmanni Hopk.), were initiated in 1961 near Deadman Lookout in Roosevelt National Forest, Larimer Co., Colorado. The objectives of this paper are twofold: to present infornation on beetle mortality caused by woodpeckers in this forest, and to speculate on factors to account for differential mortality by predation from woodpeckers of brood in endemic and epidemic populations of the spruce beetle. METHODS Broods of endemic populations of the spruce beetle normally develop in the bark of wind-thrown spruce trees and logging slash (Massey and Wygant, 1954; Nagel et al., 1957). Therefore, 22 and 21 spruce trees, to serve as brood trees, were felled with a chain saw during the autumn of 1961 and 1962, respectively. Abundance was estimated by counting insects in samples of bark 6 inches (15.2 cm) square a total of 3 times throughout brood life: first, when 3Y2 to 4 months old; next when approximately 1 year old, and finally, prior to emergence as adults, when approximately 2 years old. Larvae younger than 3 /2 to 4 months of age were too small to count easily; delaying the first census did not appreciably bias measurements of mortality caused by woodpeckers because woodpeckers in the 1 This study was supported by cooperative aid grants from the Rocky Mtn. Forest and Range Expt. Sta. of the U. S. Forest Service and National Science Foundation grant GB-753. 2 Present address: Division of Natural Resources, Humboldt State College, Arcata, California 95521.
TL;DR: Pardosa concinna spends its first winter within the cocoon, a novel behavior for a wolf spider as mentioned in this paper and no significant differences in the number of eggs per cocoon in Pardosa were noted when tundra and low-altitude data were compared.
Abstract: Pitfall jars were used to collect 16,342 specimens of spiders, phalangids, erythraeid mites, and ground beetles at 3500-4270 m (11,500-14,000 ft) elevation. Most alpine tundra arachnid species have biennial life cycles, but some are annuals. This biennial pattern also predominates near sea level at high latitudes (50?N+). Annual cycles are more typical of mid-latitude (40?N), low-elevation regions. Various species of alpine tundra Pardosa wolf spiders have either twoor one-year cycles; the length of life appears to be directly proportional to the net primary productivity of the various species habitats. Mating and egg-laying in Pardosa tend to occur later in the year in the alpine tundra than at low elevations. No significant differences in the number of eggs per cocoon in Pardosa were noted when tundra and low-altitude data were compared. The overwintering stages of alpine tundra spiders (young and penultimate juveniles) are the same as for sea level, except that no tundra species overwinter as adults, whereas many low-elevation species do. Pardosa concinna spends its first winter within the cocoon, a novel behavior for a wolf spider. Dramatic temporal changes in the abundance or activity of some carabid ground beetles were recorded from incidental data obtained on this group. INTRODUCTION Relatively little is known about the life histories of arachnids or carabid ground beetles in the alpine tundra. This is particularly true for North America. Since data concerning life histories at lower elevations and in the arctic tundra are relatively more extensive, more research at high altitudes is desirable. In particular, the effects of the seemingly less hospitable alpine tundra environment on life cycle lengths are worth investigating. METHODS AND MATERIALS Nearly all of this research was done between tree line (ca. 3500 m or 11,500 ft) and 4270 m (14,000 ft) elevation in the Front Range of the Colorado Rockies. The principal study areas were Mount Evans and Rocky Mountain National Park. These two areas are about 77 km (48 miles) apart in a north-south direction. Most of the collecting was done during 6 June 15 November 1967, but some was also done during 1966 and 1968. The 1967 frost-free season at 3750 m was 61 days long (fairly typical) with snow prevalent except in June to October. During the 1967 season pitfall trap jars, 53 mm inside diameter and 55 mm deep, were placed in the ground, their rims flush to the surface. Ethylene glycol (10 mm deep) was added as a preservative 1 Based on part of a thesis submitted in partial fulfillment of the requirements for the Ph.D. degree at the University of Colorado.
TL;DR: The succulents invading the salt pan appear to represent a cyclical invasion stage which disappears during periods of drouth, and which is not necessarily a primary stage of succession.
Abstract: Species-soil relationships were studied at Stink and Bitter lakes in South Dakota. The effect of high salt concentrations on species distributions was established. The sulfate dominated soils appear to have a vegetation similar to that of chloride dominated soils of Nebraska, with an index of similarity equalling 90.0%. The succulents invading the salt pan appear to represent a cyclical invasion stage which disappears during periods of drouth, and which is not necessarily a primary stage of succession.
TL;DR: Maintenance metabolic rates, based on food consumption experiments of captive rodents of 10 species, ranged from 1.6 to 4.0 times the estimated basal rate, while assimilation efficiencies of rodents living in the wild on natural diets were determined by the ash tracer method.
Abstract: Maintenance metabolic rates, based on food consumption experiments of captive rodents of 10 species, ranged from 1.6 to 4.0 times the estimated basal rate. The use of exercise wheels increased the energy expended for maintenance. Production, as evidenced by weight gain, comprised only a small part of energy flow. Assimilation efficiencies of rodents living in the wild on natural diets were determined by the ash tracer method. Omnivorous and granivorous species demonstrated better assimilation than foliage herbivores. Gravid and lactating females of most species exhibited increased assimilation. Food consumption in the wild, as measured by the mean weight of the stomach contents, varied inversely with the mean minimum temperature at the time of trapping. Gravid and lactating females were hyperphagic. Caloric values of the stomach contents of these species ranged from 4.6 to 5.7 kcal/g. The nitrogen indices indirect estimates of protein content of the food from the stomachs of omnivorous species were consistently larger than those of foliage herbivores. Only crude estimates of ingestion rates and energy expenditures for maintenance and productivity can be made at this time because we lack information regarding activity cycles and thermal environments encountered by these rodents. INTRODUCTION In order to describe the energy dynamics of rodent populations one must have some measure of: 1) the amount of energy expended for maintenance and production, 2) the assimilation efficiency, and 3) the caloric value of the food. Estimates of maintenance energy expenditure by small mammals living in the wild have been made from respirometry and food consumption experiments (Odum, Connell, and Davenport, 1962; McNab, 1963b). Estimates of production in wild populations have been made from growth and reproductive rates (Golley, 1960; Odum et al., 1962). Assimilation efficiencies of captive rodents have been measured by subtracting the feces production from the food intake (Golley, 1960; Smith, 1962; Jameson, 1965). The energy value of a variety of ecological materials including rodent foods has been determined by calorimetry (Golley, 1960; Odum et al., 1962; Pearson, 1964). We have calculated the maintenance energy expenditure, assimilation efficiencies, and the caloric value of the food utilized by rodents at several sites in North Dakota, Minnesota, and Wyoming. The species studied included: deer mice (Peromyscus maniculatus), meadow voles (Microtus pennsylvanicus), red-backed mice (Clethrionomys gapperi), meadow jumping mice (Zapus hudsonius), grasshopper mice (Onychomys leucogaster), feral house mice (Mus musculus), Ord kangaroo 1 Present address: Department of Biological Sciences, University of Idaho, Moscow 83843. 2 National Science Foundation Undergraduate Research Participant.
TL;DR: The courtship behavior, spermatophore, manner of egg deposition and egg mass suggest a close phylogenetic relationship between A. annulatum and the maculatum group.
Abstract: Adult Ambystoma annulatum migrate to the breeding pond only in association with at least 1.27 cm (0.5 in) of rain; they do not migrate prior to mid-September. Adults exhibit a complex pattern of migration in the study area. They engage in a mass courtship (Liebesspiel) very similar to that of A. maculatum. The spermatophore has a wide base, with a short stalk that supports the overhanging sperm cap. Egg laying begins on the night of courtship or the next and is usually completed within two days. Adults leave the pond soon after breeding but may remain active aboveground for at least a week. The courtship behavior, spermatophore, manner of egg deposition and egg mass suggest a close phylogenetic relationship between A. annulatum and the maculatum group.
TL;DR: Data on growth and development were collected from five litters (30 individuals) of Richardson ground squirrels born in captivity and foot length achieved adult size first, tail length next, tails length next and total length last.
Abstract: Data on growth and development were collected from five litters (30 individuals) of Richardson ground squirrels (Spermophilus richardsoni elegans) born in captivity. Hair first appeared on the head at 10 days of age and fully covered the body by day 25. Incisors erupted at 13-14 (lower) and 22-26 (upper) days of age. On day 14 trills were first noted. Eyes opened 21-24 days and ears opened 21-26 days after birth. Young were weaned at 28-35 days. Body weight increased at an instantaneous growth rate of 11.4% per day during the first weeks after birth and 2.0% at 10 weeks; 25% of body weight growth was completed by day 35, 50% by day 49, 75% by day 60 and 100% by day 100. Of the linear measurements foot length achieved adult size first (100% in 42 days), tail length next (100% in 56 days) and total length last (100% in 63 days).
TL;DR: Between 1964 and 1968, 20 species of Hirudinea were collected in Colorado, 12 of which are new records for the state, and the frequency, abundance, and altitudinal distribution are recorded for each species.
Abstract: Between 1964 and 1968, 20 species of Hirudinea were collected in Colorado, 12 of which are new records for the state. A wide variety of sites were visited in all 63 Colorado counties, including 87 lotic and 443 lentic stations. A total of 6726 leeches were collected from 32 lotic sites and 261 lentic sites. Some species are geographically or altitudinally restricted; others are widely distributed. Helobdella stagnalis is the most abundant and widely distributed leech in Colorado. Erpobdella punctata, Haemopis mar- morata, Glossiphonia complanata, Placobdella ornata, and Theromyzon rude are also widespread. Batracobdella phalera is found only in the foothills zone and montane zone, whereas B. picta occurs from the foot- hills zone into the alpine zone; both species are found in the western half of the state. Dina dubia is common in the northern half of Colo- rado, excluding the Great Plains, but Nephelopsis obscura is prevalent in the western half. The plains zone is characterized by Illinobdella moorei, Helobdella fusca, and Theromyzon tessulatum. Seven species show highly restricted distributions: Dina parva, D. fervida, D. lateralis, D. microstoma, Placobdella parasitica, Macrobdella decora, and Haemopis kingi. The frequency, abundance, and altitudinal distribution are recorded for each species. Erpobdella punctata has the greatest frequency and abundance for lotic species, and Helobdella stagnalis for lentic species; however, both are abundant in standing and running waters. Helobdella stagnalis has the greatest altitudinal range (1080-3099 m) for lotic leeches, and Glossiphonia complanata (1044-3610 m) for lentic leeches. Limiting factors are distinctive for lotic and lentic species. Small lakes and ponds between 1700 and 3300 m with abundant gyttja and f6rna and with color values greater than 20 contain the greatest number of species of any habitat.
TL;DR: Seasonal cycles in population are better defined and more regular as a result of decreased temperature (and increased duration of low temperatures) associated with increased latitude and Goertz (1964) found that a long period of below-freezing weather, snow cover, and frozen ground coincided with a population decline.
Abstract: Northward dispersal in Sigmodon hispidus has not significantly affected early growth rate of young or size of young at birth. But there has been a significant increase in litter size in the northern population. Northern S. hispidus have the same size young, but more young per litter than the southern population. Maintenance of the size of young at birth in northern populations may be related, in part, to the development of thermoregulatory capabilities. In the northern population there was seasonal variation in litter size, growth rate (tail length), and size of young at birth (tail length and body weight). Litters of S. hispidus produced in cold weather months are significantly smaller than those produced in warm weather months. INTRODUCTION The northward dispersal of the hispid cotton rat (Sigmodon hispidus spp.) has been well documented over most of its geographical range (Patton, 1941; Rinker, 1942; Cockrum, 1948; Anderson and Berg, 1959; Jones, 1960, 1964; Mohlhenrich, 1961; Genoways and Schlitter, 1966). With increasing latitude, populations of S. hispidus encounter increased seasonal climatic variability and longer cold periods. Populations of S. hispidus show both seasonal cycles and irregular long-term fluctuations in density. Irregular fluctuations in population, frequently to "plague" proportions, have been reported in both southern and northern populations (for a review of the literature see Goertz, 1964). Odum (1955) demonstrated three well-marked long-term "cycles" in a southern population of S. hispidus hispidus, although in all years the autumn density of cotton rats was markedly greater than the spring density. He considered the latter type of variation a "northern-type" seasonal cycle in these populations. Northern-type cycles in density have also been observed in other southern populations of S. hispidus (Erickson, 1949; Dunaway and Kaye, 1964). In northern populations of S. hispidus, seasonal cycles in population are better defined and more regular as a result of decreased temperature (and increased duration of low temperatures) associated with increased latitude (Goertz, 1964; unpublished data). Variation in S. hispidus populations appears to be regulated by temperature (Baumgartner, 1945; Sealander and Walker, 1955; Dunaway and Kaye, 1964; Goertz, 1964). Goertz (1964) found that a long period of below-freezing weather, snow cover, and frozen ground coincided with a population decline. Similar declines had four factors in common: (1) high summer and autumn population density; (2)
TL;DR: There was a significant distributional difference for the mature larvae of Saratoga Lake and two physiological factors (food requirements, and oxygen require- ments) are discussed as possible causes for this behavioral difference.
Abstract: The diel vertical migrations of Chaoborus punctipennis Say (Diptera: Culicidae) were studied during two 24-hr sampling periods at Saratoga Lake, New York. Samples were taken at the surface, 4 and 8 m every 3 hr from 0700 to 1900, then every hour until 0600. A total of 33,349 larvae were collected during sampling, and each of these was categorized according to instar. The temporal distributions of the mature larvae (3rd and 4th instars) were analyzed to demonstrate pos- sible behavioral differences. There was a significant distributional difference for the mature larvae of Saratoga Lake. The behavior of the 3rd and 4th instars was similar until midnight. After midnight the 4th instars consistently showed a secondary peak in numbers while the 3rd instars failed to recover and decreased until sunrise. This decrease can be attributed to the fact that the 3rd instars leave the surface earlier and apparently reenter the sedi- ments sooner than the 4th instars. Two physiological factors (food requirements, and oxygen require- ments) are discussed as possible causes for this behavioral difference.
TL;DR: The stream snail, Pleurocera acuta, was studied during a 12-month period in Silver Creek, Madison Co., Kentucky; growth was rapid until October, slowed during the winter, then increased in early spring, and appears to have a two-year life span.
Abstract: The stream snail, Pleurocera acuta was studied during a 12-month period in Silver Creek, Madison Co., Kentucky. Substrate was important in the distribution of P. acuta; substrates high in car- bonate offered the most suitable habitats. Distribution was secondarily affected by water depth and current, with the largest populations in shallow areas of relatively slow flow. Overall population density was 38.4/M2, with densities up to 161/M2 in high-carbonate areas. Repro- duction occurred in July and August. Growth was rapid until October, slowed during the winter, then increased in early spring. The species appears to have a two-year life span. Population size varied in direct proportion with the concentrations of dissolved oxygen and alkalinity. The adult sex ratio is 1: 1; females average slightly longer than males. Apical erosion decreased downstream, as did the obesity index due to the increased length of noneroded shells. Shell width increased slightly in the lower part of the stream.
TL;DR: Net primary herbage production was measured in three upland and three lowland prairie community types in eastern North Dakota, finding that spring burning significantly stimulated herbageProduction and herbage caloric content in upland communities, whereas it did not affect, or slightly reduced, these parameters in lowland sites.
Abstract: Net primary herbage production was measured in three upland and three lowland prairie community types in eastern North Dakota. Peak herbage weights (harvest method) in 1965 ranged from 109 to 353 g/m2 in the lowland types, and from 223 to 348 g/m2 in the upland community types. Based solely on herbage production, efficiencies of energy utilization ranged from 0.09% in the SalicorniaSuaeda community-type to 0.28% in the Distichlis-Hordeum-Poa type. Corresponding weights during 1966 were lower; the degree of reduction ranging from 32-47% in the lowlands to 20-26% in the uplands. The differences in peak herbage weights for the two growing seasons may have resulted from higher rainfall in the early portion of the 1965 growing season. Spring burning significantly stimulated herbage production and herbage caloric content in upland communities, whereas it did not affect, or slightly reduced, these parameters in lowland sites. Six taxa composed 81% and 77% of the herbage caloric contents of unburned and burned upland plots, respectively. Forbs and small shrubs contributed 27-35% of total herbage energy. Burned and unburned lowland plots were dominated by four taxa; forbs and small shrubs contributing only 9-12% of the herbage caloric content in those communities.