Showing papers in "Oecologia in 1973"

Behavioral implications of mechanistic ecology : Thermal and behavioral modeling of desert ectotherms and their microenvironment.

Abstract: Mechanistic principles from engineering, meteorology, and soil physics are integrated with ecology and physiology to develop models for prediction of animal behavior. The Mojave Desert biome and the desert iguana are used to illustrate these principles.A transient energy balance model for animals in an outdoor environment is presented. The concepts and relationships have been tested in a wind tunnel, in a simulated desert, and in the field. The animal model requires anatomical information and knowledge of the thermoregulatory responses of the animal. The micrometeorological model requires only basic meteorological parameters and two soil physical properties as inputs. Tests of the model in the field show agreement between predicted and measured temperatures above and below the surface of about 2 to 3°C.The animal and micrometeorological models are combined to predict daily and seasonal activity patterns, available times for predator-prey interaction, and daily, seasonal and annual requirements for food and water. It is shown that food, water and the thermal environment can limit animal activity, and furthermore, the controlling limit changes with season. Actual observations of activity patterns and our predictions show close agreement, in many cases, and pose intriguing questions in those situations where agreement does not exist. This type of modeling can be used to further study predator-prey interactions, to study how changes in the environment might affect animal behavior, and to answer other important ecological and physiological questions.

The breakdown and decomposition of sweet chestnut ( Castanea sativa mill.) and beech ( Fagus sylvatica L.) leaf litter in two deciduous woodland soils

Abstract: Changes in the carbon, hydrogen, nitrogen and polyphenol content of chestnut and beech leaves were measured during the first year after fall. Chestnut leaves had an initial carbon, hydrogen and nitrogen content (by weight) of 48.71%, 5.56% and 0.77% respectively; beech had a similar carbon and hydrogen content (47.77% and 5.36%) but less nitrogen (0.56%). Both leaf litter types showed percentage increases in nitrogen content during the study period but only the beech showed absolute increases in nitrogen content of up to 66.7% of the initial weight present in the leaves. The percentage increases in the nitrogen content of chestnut litter were largely attributable to more rapid losses of non-nitrogenous leaf constituents while the weight of nitrogen present in the leaves remained relatively constant. The percentage carbon and hydrogen contents of the chestnut and beech litter showed changes of less than 1% throughout the year, indicating that carbohydrate losses were directly proportional to weight losses. Soil animals fed on chestnut leaves to a far greater extent than beech leaves; this difference did not appear to be directly attributable to differences between the nitrogen contents or C/N ratios of the two leaf litter species. The gross polyphenol contents of chestnut and beech litter showed an intraspecific inverse correlation with the feeding activities of soil animals on the leaves, but did not account for interspecific differences in leaf palatability since chestnut leaves were eaten when they contained higher polyphenol concentrations than beech leaves. However, there was an interspecific negative correlation between palatability and the presence of protocatechuic and gallic acids.

The food of brown and rainbow trout (Salmo trutta and S. gairdneri) in relation to the abundance of drifting invertebrates in a mountain stream.

Abstract: The diet of Salmo gairdneri and S. trutta in a Pyrenean stream was very similar, and was also similar to the percentage composition of the drift but not the benthos. There was a good correlation between diel changes in the amount of food (both numbers and biomass) in the stomachs and diel changes in the abundance of drifting invertebrates. The major feeding period was in the early hours of the night when the trout fed chiefly on benthic invertebrates in the drift. This was the only feeding period in experiments 1 and 2 (mean water temperatures 4.7 and 7.3° C) but in experiment 3 (10.8° C), there was a second feeding period in the day when terrestrial invertebrates and emerging aquatic insects formed a large proportion of the diet.

The annual cycle in the Djungarian Hamster Phodopus sungorus Pallas

Abstract: Bei einem im Labor (Erling-Andechs, 47° 58′N, 11° 11′E) gehaltenen Stamm von Phodopus s. sungorus wurden die unter naturlichen Lichtbedingungen auftretenden jahresperiodischen Veranderungen verfolgt. 1. Im ersten Winter farbten die meisten Hamster in ein weisliches Winterkleid um (Abb. 2, 5 und 14). Der Verlauf der Umfarbung wird beschrieben (Abb. 1). Bei der Masse der Tiere begann der Haarwechsel ins Winterkleid im Oktober oder November und war im Dezember abgeschlossen, die Ruckfarbung ins Sommerkleid begann im Januar oder Februar und war im Marz oder Anfang April beendet. Bei Ausentemperaturen gehaltene Hamster begannen fruher mit der Umfarbung ins Winterfell und gelangten spater wieder ins Sommerfell als bei Innentemperaturen gehaltene Tiere; die Winterfarbung war bei ihnen intensiver (Abb. 3 und 4). 2. Die Umfarbung ins Winterkleid konnte durch Haltung im Kunsttag mit kurzer Photoperiode schon im Sommer ausgelost werden (Abb. 6). Bei diesen Tieren trat die Ruckfarbung ins Sommerkleid schon im Herbst ein, ohne das die kunstlichen Beleuchtungsverhaltnisse geandert wurden. 3. Die Hamster zeigten einen ausgepragten Jahresgang des Korpergewichts. Das Maximum lag im Juli und August, das Minimum im Dezember oder Januar zur Zeit des Winterfelles (Abb. 7 und 8). 4. Die Hamster pflanzten sich nur zwischen Februar und November fort (Abb. 9). Junge wurden in 2 Fallen 18 Tage und in 27 Fallen 19 Tage nach dem Zusammensetzen der Alttiere geworfen. Die Jungenzahl pro Wurf betrug 1–9, im Mittel 5 (Abb. 10). Die durchschnittliche Wurfgrose eines ♀ war beim ersten Wurf deutlich kleiner als beim zweiten und fiel danach wieder ab (Abb. 11). 5. Die Wachstumskurven junger Hamster werden mit Angaben aus der Literatur verglichen (Abb. 12). ♂ ♂ waren im Mittel schwerer als ♀ ♀ (Tabelle 1). 6. Die Masse der ♂ ♂ zeigte im ersten Winter eine deutliche Hodenregression. Das Gewicht der Winterhoden betrug etwa 1/9 des Gewichts der Sommerhoden (Abb. 13). Ausstriche aus der Cauda epididymidis enthielten bei diesen Tieren keine Spermien. 7. Bei Tieren im Winterkleid trat tagesperiodische Torpiditat auf. Hierbei sank die Korpertemperatur bei einer Umgebungstemperatur von 6°C auf 19–20°C ab (Abb. 18). 8. Mehr als 10% der Hamster behielten im ersten Winter die Sommerfarbung bei (Abb. 2, 3 und 14). Bei ihnen blieben auch Hodengrose und Hodenaktivitat sowie das Korpergewicht im Sommerzustand (Abb. 15) und Torpiditat trat nicht auf. 9. Im zweiten Lebenswinter farbte nur ein kleiner Teil der Tiere ins Winterkleid um, die Winterfarbung war zudem weniger stark ausgepragt (Abb. 2). Auch die winterliche Hodenregression zeigten im zweiten Winter nur wenige ♂ ♂, sie war zudem weniger ausgepragt als bei jungeren Tieren (Abb. 16). Die Hoden beim gleichen Tier konnten starke Unterschiede in Grose und Aktivitat zeigen.—Die Fortpflanzungstatigkeit war nach dem zweiten Winter praktish erloschen. 10. Phodopus besitzt eine mittventrale Talgdruse. Die Aktivitat dieser Druse ist bei ♂ ♂ sehr viel starker als bei ♀ ♀, sie weist anscheinend einen Jahresgang auf.

The breakdown and decomposition of sweet chestnut (Castanea sativa Mill.) and beech (Fagus sylvatica L.) leaf litter in two deciduous woodland soils : I. Breakdown, leaching and decomposition.

Abstract: Weight losses from sweet chestnut and beech leaves, attributable to biotic and abiotic breakdown processes, leaching and microbial decomposition have been studied using tethered leaves and litter bags. The experimental sites were two adjacent areas of deciduous woodland. In one area (the Castanea site) a mor-like moder humus form has developed under a stand dominated by coppiced chestnut, in the other a mull-like moder underlies a stand of coppiced beech (the Fagus site).Chestnut leaves in the Castanea site are primarily comminuted by abiotic processes (wind, rain, hygroscopic movements, etc.) and soil animals make a relatively small contribution to leaf litter breakdown. After 31 months in the field 36.03% of the initial weight of chestnut leaves remained in the fine mesh bags against 22.82% in the coarse mesh bags. Weight losses from the coarse and fine mesh bags containing beech litter were not significantly different after 31 months when a mean weight of 57.10% of the litter remained.In the Fagus site, leaf litter breakdown was mainly due to the feeding activities of earthworms. However, chestnut leaves were more readily selected than beech leaves. After 8 months in the field nearly 45% more chestnut leaf material had been lost from the coarse mesh bags than from the fine mesh bags. Weight losses from the coarse and fine mesh bags containing beech litter were not significantly different after 31 months, when a mean weight of 43.30% of the litter remained.The leaching and decomposition rates of either type of leaves were not significantly different in the two sites. Chestnut leaves in fine mesh bags lost weight at twice the rate of beech leaves under similar conditions during the first 20 months of the study; however, most of the weight losses from beech and up to 75% of the losses from chestnut were attributable to leaching rather than to microbial decomposition. The rates of weight losses from the chestnut litter in fine mesh bags declined over the last year of the study, but beech maintained approximately constant weight loss rates for 31 months in the field. This difference may be due to different rates at which similar proportions of water soluble materials were leached from the leaves.A major defect in the litterbag technique is demonstrated. The litter bags maintain the micro-environmental characteristics of the surface litter layers and do not follow the breakdown and decomposition pattern of the leaf litter year class from which the experimental material was drawn.

Alkaloid and predation patterns in colorado lupine populations

Abstract: Colorado populations of herbaceous perennial lupines show three distinct patterns of amounts, kinds, and individual variability of inflorescence alkaloids. These patterns, interpreted as alternative chemical defense strategies, can be related to the susceptibility of populations to attack by larvae of a small flower-feeding lycaenid butterfly, Glaucopsyche lygdamus.

Ecology of coral reefs in the Gulf of Aqaba (Red Sea) influenced by pollution

Abstract: 1. This paper summarizes observations performed during 1966, 1968, and 1972, on coral reef flats 7 km south of Eliat (Gulf of Aqaba, Red Sea). The aim of this research was to describe the change in numbers of living coral colonies found on the coral tables in connection with pollution occuring in this habitat. A transect technique, developed by Loya and Slobodkin (1971) was used in this research. 2. In each of the three years, 19 ten metre transects were performed in various directions, on the same coral tables. 3. In 1966, 541 living coral colonies were counted in a total of 190 m of transects. At the identical place, this number had decreased to only 195, in 1972. The decrease in corals was found to be accompanied by a prominant increase in algae growth, that expend and develop, thus covering the coral specimens. 4. Especially sensitive to algal development are the branching micropolypal, coral species, that are the representatives of the genera Acropora, Seriatopora, and Stylophora. Of the above three genera counted in 1966, only 10 out of 192 colonies were found intact, in 1972. 5. The high mortality of corals in this locality occured during the years in which an oil terminal plus a mineral and phosphate loading harbour were developed at Eilat. 6. The frequent oil spills, together with the phosphate dust that reaches the sea, seem to be the factors that cause eutrophication in the shallow lagoon waters of the coral region, and thus the development of algae on the coast of corals is stimulated.

Seasonal changes in thermogenesis, organ weights, and body composition in the white-footed mouse,Peromyscus leucopus.

Abstract: 1. Seasonal adjustments in wild-caughtPeromyscus leucopus include autumn increases in basal metabolic, nonshivering thermogenesis, and interscapular brown fat and decreases in weights of gonads, liver, adrenal glands, and total lipid. Body weight and nonextractable dry weight do not change. 2. Basal metabolic rate, nonshivering thermogenesis, and interscapular brown fat increase following initial cold exposure in mid-September and are maintained at similar levels through January. 3. There is a positive correlation between nonshivering thermogenesis and interscapular brown fat, and negative correlations for both nonshivering thermogenesis and interscapular brown fat with body weight. 4. These seasonal changes in wild-caughtP. leucopus are compared with laboratory studies on the effects of chronic exposure to differences in temperature and photoperiod on these characters. It is concluded that disparities between the effects of cold acclimatization and cold acclimation could result from the influence of additional environmental cues, such as photoperiod, in cold acclimatized mice.

A quantitative approach to the mortality resulting from traffic in a population of Bufo bufo L.

Abstract: During the breeding migration of Bufo bufo in 1971 the number of females was counted, killed by traffic on an asphalt road with about 10 cars/hour. By counting egg-strings the total number of females was estimated too. By comparing both data it appeared that 30% of the females passing the road were run over. For the males a similar percentage is expected.

An energy budget for adultBrachionus plicatilis Muller (Rotatoria).

Abstract: An energy budget is presented for adultBrachionus plicatilis Muller, a brackish water rotifer. At 20°C the hourly consumption ofDunaliella salina by an individual rotifer was found to be 332.79±93.25 cal. The assimilation rate was 64.43±9.95 cal per hour when measured, and 62.88 cal per hour when calculated fromP+R. The difference between these two values is 2.4%. Respiration rate per individual per hour was 26.375±2.4 cal and egg production cost 36.5 cal per hour. The amount of faecal matter produced in an hour was obtaineb by subtraction (C-A). Ecological efficiencies are calculated and discussed in relation to those of animals of similar feeding habits.

Experimental studies of migration in bugs of the genus Dysdercus.

Abstract: Using a tethered flight technique, migration was studied in the African cotton stainer bugs Dysdercus fasciatus Sign., D. nigrofasciatus Stal, and D. superstitiosus (F.) (Heteroptera: Pyrrhocoridae). The flight system of males of all three species matures in 4-6 days post-eclosion, and flight can continue throughout life. Fed females of D. fasciatus do not fly, but rather histolyse the flight muscles and develop oocytes. Fed females of D. nigrofasciatus and D. superstitiosus exhibit some flight at 4 days post-eclosion, but flight is essentially absent at 6 days when flight muscle histolysis and oogenesis are in progress. Starved females of all three species undertake considerable flight and do not histolyse the flight muscles or develop oocytes. In starved pairs coupling frequency is lowered permitting increased migration. The three species are thus facultative migrants using starvation as a releasing cue. D. fasciatus feeds on baobab (Adansonia) fruits which are seasonally abundant and is the most opportunistic species with the highest reproductive potential and no flight in the presence of food. D. nigrofasciatus feeds on a variety of herbaceous annuals and perennials; it follows an intermediate migration and reproductive strategy. Finally D. superstitiosus is the most catholic in its food habits and has the lowest reproductive potential. Both of the latter species retain some flight capacity even when fed, presumably so that individuals can locate suitable host plants.

Adaptations for leaf eating in the great basin kangaroo rat, Dipodomys microps.

Abstract: Dipodomys microps forages in saltbush (Atriplex confertifolia), gathering the leaves into its external check pouches and returning them to the burrow to be cached or eaten. The leaves are available throughout the year and contain 50–80% water. D. microps can survive on these leaves in the laboratory without other food or water, but it is unusual among kangaroo rats in that it quickly succumbs when placed on a diet of air-dried seeds without water or succulent plant material. Its mean urine concentration on the seed diet was 2827 mOsm/l, which is lower than any previously reported for the genus. On the other hand, D. merriami, which occurs with D. microps and is well known as a seed specialist, cannot survive on the saltbush leaves, although it is capable of living on a seed diet without water or green vegetation.

Life history and feeding habits of the marine nematode, Chromadora macrolaimoides steiner

Abstract: Chromadora macrolaimoides Steiner, a free-living nematode present in the aufwuchs assemblages of several marine macrophytes located in North Sea Harbor, Southampton, New York, was isolated from Enteromorpha intestinalis and established in laboratory culture, where its life history and feeding habits were studied. Under the experimental conditions (25 C and 26‰ S) the worm has an average generation time (22 days) and average life span (45 days) similar to other chromadorids which have been studied in the laboratory.

On the accuracy of some mark-recapture estimators

Abstract: The behaviour of the mark-recapture estimators of Petersen, Bailey (triple catch) and Jolly and Seber are examined theoretically and empirically by means of simulation techniques. The correlation between the parameter [Formula: see text] and its associated variance is shown to be significant for all the estimators. This correlation makes the estimated variance an insensitive measure of the accuracy of the estimate except at very high sampling intensities. Such sampling intensities are rarely achieved in experimental work and so the method of mark-recapture must be considered of very limited use. At the sampling intensities necessary to give a coefficient of variation of less than 0.05 it does not seem likely that the correlation between [Formula: see text] and its variance will produce serious underestimation but the minimum confidence limits [Formula: see text] are recommended.

The food of Ancylus fluviatilis (Müll.), a littoral stone-dwelling, herbivore.

Abstract: A. fluviatilis is a herbivore which usually ingests periphyton. Evidence derived from both field observation and laboratory experiments suggests that the limpet prefers diatoms and that within this group Gomphonema is apparently the most attractive genus. These food preferences were most clearly defined in satiated individuals.Snails had no apparent effect on algal community structures in the field situation and it is suggested that this may either result from adaptability of the periphyton with respect to grazing disturbances, or from low snail density and thus low grazing intensity.The food preferences of A. fluviatilis in particular, and other algal exploiters in general, are discussed in terms of plant defense mechanisms. It is argued that an animal's ability to cope with algal cell walls (either in a mechanical or chemical sense) may be one of the major determinants in the food preference behaviour shown by herbivores feeding on algae.

Chemische Strategie beim Nahrungserwerb der Diebsameise (Solenopsis fugax Latr.) und der Pharaoameise (Monomorium pharaonis L.)

Abstract: 1. Die Diebsameise (Solenopsis fugax) markiert ihre unterirdischen Gange, die sie in die Brutkammern benachbarter fremder Ameisenarten anlegt, mit einem Rekrutierungspheromon aus der Dufourschen Druse. 2. Beim Beutemachen in den fremden Brutkammern gibt sie aus der Giftdruse eine hochwirksame und lang anhaltende Repellentsubstanz ab. Sie kann dadurch nabezu ungestort in den fremden Brutkammern die Ameisenbrut angreifen. 3. Eine ganz ahnliche chemische Strategie setzt die Pharaoameise (Monomorium pharaonis) beim Nahrungserwerb ein. Auch sie legt Rekrutierungsspuren mit einem Pheromon aus der Dufourschen Druse und markiert Beuteobjekte mit einer Repellentsubstanz aus der Giftdruse. Auf diese Weise schaltet sie sehr erfolgreich Futterkonkurrenten an gemeinsamen Futterplatzen aus.

Spatial relationships among members of a population of wall lizards

Abstract: Summary Wall lizards occupied overlapping territories, the size of which seemed to vary directly with the dominance level of the individual Average territories of both males and females encompassed about 25 square meters The overlap in territories among males was about 8 percent, and among females, about 18 percent When both sexes were considered, overlap was 100 percent This spacing mechanism appeared to be effective in governing the number of resident males but less so in governing number of resident females In each of three years, females outnumbered males by 35 to one, probably because, among non-resident individuals, males were forced to move about more than females in order to avoid resident males, and as a consequence were subjected to greater predation pressure Of 47 lizards marked on the study area, 60 percent were resident; the remainder were apparently wandering in search of unoccupied habitat The number of resident lizards increased over the 5-year period of study from l0 to 21 individuals Over the same period the average snout-to-vent length of this population decreased from 707 mm to 682 mm among males and 632 mm to 573 mm among females, probably reflecting a younger age structure Correlated with these changes in population size was an increase in predation pressure from feral cats as reflected in the incidence of caudal autotomy among lizards

Zum Energieumsatz phytophager insekten im Buchenwald. I

Abstract: Die Bestimmung des Energieumsatzes der Curculioniden-Populationen vonRhynchaenus fagi L.,Strophosomus (Schonherr) undOtiorrhynchus singularis L. wurde in folgenden Schritten vorgenommen: Die Untersuchungen wurden beiR. fagi an allen Entwicklungs- und Reifestadien durchgefuhrt, beiStrophosomus sp. undO. singularis nur an den Imagines.

Der Gesteinsabbau durch Ätzmuscheln an Kalkküsten

Abstract: Verteilung und Populationsdichte der Atzmuscheln werden bestimmt durch Wassertiefe und Neigungswinkel der Kuste sowie besonders durch die Art des Substrates. Oolithische Kalke sind 2–3mal starker besiedelt als Dolomit.

Estimating growth and mortality rates from size data.

Abstract: A method is presented for estimating rates of individual growth and population mortality utilizing average individual size at two times during a year. The model assumes a constant rate of mortality, Brody-Bertalanffy growth, a stationary age distribution, and recruitment confined to one month each year. A hypothetical example is presented to show the interrelationships of the growth and mortality constants, size at recruitment, asymptotic size and average individual size. Three examples are presented using data from the literature: Flathead sole (Hippoglossoides elassodon), a sea urchin(Echinus esculentus), and the crown-of-thorns starfish(Acanthaster planci). The method appears to be a means of obtaining reasonable approximations of growth and mortality rates for a variety of organisms.

Studies on the food and feeding habits of soil oribatei in a black pine plantation.

Abstract: Food preferences and feeding behaviour of abundant species of oribatid mites in a black pine plantation have been studied by soil sectioning technique. It is suggested that Microtritia minima, Rhysotritia duplicata and Phthiracarus sp. play an important role in the mechanical breakdown of decaying litter and, by contributing to the humification process, help in the accumulation of plant nutrients. Due to poor mobility their contribution to fungal spore dissemination is insignificant.

Seed germination in relation to salt concentration in three populations of Prosopis farcta.

Abstract: Prosopis farcta (Banks et Sol.) Eig., is a widespread perennial shrub in a variety of habitats over a large geographic area in the Middle East. In iraq it occurs in non-saline deserts of the west and saline agricultural lands of the Mesopotamian Plain. The species is economically important as fuel for a sizable segment of the population in rural areas. Seeds were collected in three environmentally distinct habitats, with regard to annual precipitation and soil salt content. The seeds were germinated in various concentrations of sodium chloride and their germination, seedling radicle growth, and dark respiration studied. The results indicate that the three populations differend in their response to NaCl with the northern population being generally more sensitive than the other two populations. The three populations represent “salt ecotypes” of this very widely distributed shrub. The salt ecotypes seem to be of somewhat recent origin and apparently have been further spread by improper agricultural land-use which created vast saline areas.

Population Dynamics of Stored-Product Mites*

Abstract: Population fluctuation patterns were determined during 1959–70 in wheat bulks in 2 granaries typical of those used on Manitoba farms for 7 kinds of mites. The patterns were bradly similar in the 2 granaries. Outbreaks of all mites except Tarsonemus granarius and Aeroglyphus robustus were unaffected by the prolonged storage of grain; those of Acarus siro and Cheyletus eruditus occurred in unusually high numbers periodically every 2–5 years, whereas Glycyphagus destructor and Androlaelaps casalis were present in relatively low numbers from the first year of storage. A rise in T. granarius population corresponded with grain age and the succession of microfloral species. Tydeid mites occurred periodically.

Bionomics of Cyclops strenuus abyssorum Sars (Copepoda: Cyclopoida)

Abstract: 1. The annual cycle of Cyclops strenuus abyssorum Sars in some lakes of the English Lake District is described. Esthwaite Water, Rydal Water and Grasmere, all enriched by sewage, and Buttermere, a relatively unproductive lake, were sampled most frequently. 2. There is only one effective generation in the year in each of these lakes. Individuals of this generation hatch from eggs laid in the spring. In the deepest of the four lakes (Buttermere), these individuals reach the adult stage in early winter, pass the winter in the planktonic zone and start laying eggs early in the following year. In the other three lakes, most individuals of the spring generation reach the fifth copepodid stage by mid-summer and then spend the next eight months in the profundal zone. They leave this zone in February or March to return to the planktonic zone, become adult and start breeding. In July a few individuals may mature in the planktonic zone and give use to a second small generation in the autumn. 3. A correlation between the time in mid-summer when stage V copepodids appear in the profundal zone of the three shallower lakes and amounts of dissolved oxygen in this zone is shown. Although a correlation of this kind is plausible, presence of stage V copepodids in a deep, well oxygenated lake (Thirlmere) suggests that a causal connection of this kind is too simple an explanation, and perhaps only coincidental. 4. Rates of development of the different instars were found experimentally at constant temperatures and used to estimate production. Production, biomass and fecundity were all higher in Esthwaite Water than in the other three lakes.

An examination of some statistical tests used in the analysis of mark-recapture data.

Abstract: Some statistical tests used in mark-recapture analysis are examined It is shown that the tests presently available are insensitive and are not adequate under certain conditions The most important of these is that a population stratified with respect to probability of capture may not, by present tests, be distinguished from a homogenous population

Winter nests of the hedgehog (Erinaceus europaeus L.).

Abstract: An account is given of the winter nests of the hedgehog (Erinaceus europaeus L.), and their importance in the life of this species. Nests were constructed for protection during hibernation, in sites chosen for the degree of support gained from surrounding objects. They were usually made mainly of dry leaves, specially selected and carefully built into a robust weatherproof structure, by a method appropriate both to the hedgehog and the materials used. Construction of winter nests was closely correlated with environmental temperature. The life history of hibernacula is reviewed and it is shown that nests may persist for well over a year, though the leaves of which they are made normally decay completely in a much shorter time. Nests built in brambles, with plenty of support last longer than those in less preferred sites. The construction of winter nests was strictly seasonal, but their decay was gradual, with rapid deterioration at the end of the winter. About 30% of nests persisted till the following winter, though were not re-occupied. Over half of the nests built were occupied for one month or less, though some were in continuous use for up to six months. New nests were built even in midwinter, but the likelihood of their being occupied immediately was affected by the weather. Hedgehogs rarely shared a nest, though empty nests were sometimes taken over by small mammals or Hymenoptera. Most hedgehogs that died in their nests during winter were juveniles perhaps too inexperienced to construct an adequately protective nest. The importance of the nest in a hedgehog's life, particularly during hibernation may be a significant feature in determining both its distribution and its habitat choice.

Experimental studies on the respiratory rates of mites (Acari) from beech-woodland leaf litter.

Abstract: Respiratory rates (oxygen consumption) of thirty-six species of mites from beech-woodland leaf-litter were measured at 10°C in a Cartesian Diver. The first published information on the respiratory rates of Prostigmata, and new information on the respiratory rates of adult and juvenile stages of Mesostigmata and Cryptostigmata are presented.

Eco-physiological studies on desert plants : VIII. Root penetration of Leptadenia pyrotechnica (Forsk.) Decne. in relation to its water balance

Abstract: 1. Leptadenia pyrotechnica (Forsk.) Decne. is a leafless tree growing under, adverse arid conditions in the valleys of the Eastern Desert in Egypt. 2. The plant cover in areas inhabited by this species is very low and amounts to only 1% in some localities. In such an open vegetation competition between roots is lacking and each root system monopolizes a huge volume of soil. 3. The root system of a small Leptadenia bush penetrates to a depth of 11.5 m and has a lateral extension of 10 m. The root system exploits about 850 m3 of soil. The distribution of the roots and their branching is closely related to the availability of the soil moisture in the different strata. 4. The available soil moisture is not uniform throughout the whole profile. Depending on the average available soil moisture at the different depths, the total available moisture in the soil volume occupied by the root system of Leptadenia bush is found to be about 23000 kg. 5. The annual water output by the studied bush is found to be 5700 kg. This means that the available water in the soil occupied by the root system is sufficient to supply the plant for a period of four years without replenishment by rainfall. 6. The present study shows that the plant can live safely for several years under the severe conditions of the desert. The plant possesses some characteristics which help it to keep its water balance positive through increased absorption.

Interspecific aggressive behavior in tropical reef stomatopods and its possible ecological significance

Abstract: Aggressive behavior may play a role in resource partitioning in two Eniwetok stomatopods Gonodactylus incipiens and Haptosquilla glyptocercus. These animals inhabit cavities in coral rubble which they defend vigorously. H. glyptocercus is the more aggressive species and is more than twice as abundant as G. incipiens in the habitat studied. The latter attains larger sizes and also occurs in habitats where H. glyptocercus is rare or absent. A third rarer species, G. falcatus, is also less aggressive than H. glyptocercus and is found in a different microhabitat.

[Nutritional and ecological aspects of the uptake of dissolved amino acids by Anemonia sulcata (Coelenterata, Anthozoa)].

Abstract: Anemonia sulcata resorbierte und akkumulierte tritiummarkierte l-Aminosauren aus Meerwasser, welche diesem in naturlicher Konzentration zugesetzt worden waren (70–700 nMol/l). Die Aufnahme erfolgte nahezu ausschlieslich ektodermal; der uberwiegende Teil der aufgenommenen und dann eingebauten Aminosauren befand sich auch nach langerer Inkubation im Ektoderm. Diese Tatsache ist auf unterschiedliche cytologische Differenzierungen von Ento- und Ektoderm zuruckzufuhren. Elektronenmikroskopische Aufnahmen zeigen, das nur das Ektoderm resorbierende Strukturen (Mikrovilli) besitzt. Die Aufnahmeraten waren (von naturlichen Konzentrationen ausgehend) fur die untersuchten Aminosauren verschieden hoch (2–10 μg/g Frischgewicht/h). Die aufgenommene Menge war von der Ausenkonzentration abhangig. Die Konzentrationen, unterhalb denen nur noch eine sehr geringe Aufnahme registriert werden konnte, schwankten fur die einzelnen Aminosauren zwischen 10 und 100 nMol/l. Eine Gruppe von Aminosauren (Phe, Lys, Leu, His, Pro) wurde vorwiegend in den Synthesestoffwechsel eingeschleust, eine andere (Gly und Ser) wurde uberwiegend oxydativen Prozessen zugefuhrt. Der Gehalt an freien Aminosauren von Tentakelgewebe wurde bestimmt. Die Konzentration von Glycin z.B. ist im Gewebe 107mal hoher als im Medium, aus dem noch resorbiert wird. Die Aufnahme erfolgt daher mit groster Wahrscheinlichkeit aktiv. Formale Berechnungen zeigen, das den Tieren durch die Aufnahme geloster organischer Verbindungen ein Energiegewinn erwachst; dieser liegt uber dem Energieverbrauch, der dem Sauerstoffverbrauch aquivalent ist.