The Flight Behavior of Migrating Birds in Changing Wind Fields: Radar and Visual Analyses

This paper examines the influence of atmospheric structure andmotion (principally winds aloft) on the flight behavior andaltitudinal distribution of migrating songbirds. Bird migrationdata that I gathered using surveillance radars operated by theUnited States National Weather Service and the Federal AviationAdministration and a vertically directed fixed-beam marine radarmounted on a mobile laboratory are analyzed in relation to windsaloft. Migrating birds appear to fly at altitudes where windswill minimize the cost of transport and assist movements inseasonally appropriate directions. When migratory flights occurat altitudes that are higher than usual, a significant correlationexists between the altitude of densest migration and the altitudeof most favorable wind. Lower altitudes may be favored overslightly more favorable winds at much higher altitudes. Radardata on the flight behavior of migrating birds in the vicinityof frontal systems is also examined. The flight strategies ofmigrants (fly over the front, change the direction of flight,or land and terminate the flight) differ depending on seasonand the "thickness" of the front. Recent migration studies thatare related to atmospheric structure and motion are summarizedand related to atmospheric processes operating simultaneouslyat vastly different spatial and temporal scales.     

The Foraging Ecology of Migratory Shorebirds in Marine Soft-sediment Communities: The Effects of Episodic Predation on Prey Populations

This paper explores the extent to which life histories of infaunalprey have been molded and maintained by predation. It is arguedsuch relationships should be most evident for episodic predation,where the predation is predictable, intense and short-lived.Migratory shorebirds are used herein as model episodic predators.Four stop-over areas in North America, for which experimentaldata exist, are compared. Evidence exists that SemipalmatedSandpipers in the upper Bay of Fundy maintain the observed lifehistory of their major prey, the amphipod Corophium volutator.In southeastern Massachusetts, shorebirds significantly reducethe abundance of their prey but in a frequency-dependent fashion,precluding life history responses of the prey. For Grays Harbor,Washington and Delaware Bay, there is no detectable effect ofshorebird predation on the infauna. In three of the four studies,there is no apparent effect of early shorebird migrants in significantlyincreasing the required stop-over of later migrants by depressionof prey densities. The data support the characterization ofsoft-sediment communities as loosely organized assemblages whosespecific constitution is determined more by ecological combiningability than by specific evolutionary responses to associatedspecies.     

Social Spacing in Small Mammals: Patterns of Individual Variation

The pattern of social spacing in small mammals differs fromthat observed in many other vertebrates. Small mammals frequentlyhave non-exclusive territories and tolerate a large amount ofoverlap with other conspecifics. The determinant factors ofhome range or territory size in small mammals are not knownfor most species. We carried out a study of the determinantfactors of home range size in a model small mammal, the easternchipmunk, Tamias striatus. The population was studied for fiveyears. The effect of experimental perturbations on food supplyand population density offered strong evidence that the meanhome range size in the population was determined by resourceabundance. Changes in population density had little or no measurableeffect. We noted that even when mean home range size decreasedsignificantly in response to an increase in available food,a great deal of variability in individual home range sizes remained.We hypothesized that this pattern of variation among individualswas also resource related; large home ranges would be locatedin areas of low resource density and small home ranges wouldbe located in areas of high resource density. Our data to datedo not offer support for this hypothesis; however our researchhas shown that the data needed to convincingly reject the nullhypothesis are very complex. We discuss the evidence requiredto study patterns of individual variation, and how models ofoptimal territory size may be useful. Research that examinespatterns of individual variation are few in number, yet studiesof individual variation will ultimately provide the best insightson the dynamics of evolutionary ecology.     

Cardiovascular and Other Physiological Correlates of Hibernation in Aquatic and Terrestrial Turtles

Recent research has provided new insight into the physiologyof hibernation in freshwater, marine, and terrestrial turtles.In this paper I review what is known about the mechanisms thatpermit the hearts of these turtles to withstand several monthsof hypoxia or anoxia. I also report new research that indicatesthat a terrestrial turtle, unlike freshwater and marine species,does not experience hypoxia in its winter burrow and thus doesnot rely on glycolysis to supply ATP, at least under moderatewinter conditions.     

THE PSYCHOPHYSICAL RELATIONSHIP BETWEEN COLOR AND SALT CONCENTRATIONS IN CHICKEN FLAVORED BROTHS

Taste panelists evaluated the effect of color on salt perception in chicken flavored samples using magnitude estimation. Samples were colored to simulate commercial chicken broth. Five color intensities were added to 5 NaCl concentrations ranging from 0.34 to 0.66% (w/v). Color had no influence on salt perception. Panelists were able to perceive color differences among samples (P <0.001) and these were correlated with the objective color function cot⁻¹ (a/b) calculated from the L,a,b values obtained from the Gardner XL-23. Overall flavor preference was evaluated by a taste panel using the technique of magnitude estimation. NaCl concentrations ranged from 0.52 to 0.80% (w/v). Overall flavor preference was unaffected by color. A reduction in NaCl concentration from 0.80% (w/v) to 0.52% (a 35% reduction) did not alter flavor preference. A 50 member consumer panel using a paired comparison test found no difference in flavor preference between an uncolored sample containing 0.80% (w/v) NaCl and a colored sample containing 0.72% (w/v) NaCl.     

DISSIMILARITIES IN COGNITION OF FLAVOUR TERMS RELATED TO VARIOUS SENSORY LABORATORIES IN A MULTIVARIATE STUDY

A study of dissimilarities in cognitive perception of 20 common flavor terms was carried out by the Sensory Group of Norway. An average cognitive pattern of the flavor terms was revealed from multidimensional scaling (MDS) and cluster analysis (CLU). In general, small but interesting deviations between different sensory laboratories working with various food products were found by a multivariate pattern recognition technique based on principal component analysis (PCA). Suggestions for finding general reference standards for flavor terms are discussed.     

Distribution of planktonic ciliates in highly coloured subtropical lakes: comparison with clearwater ciliate communities and the contribution of myxotrophic taxa to total autotrophic biomass

SUMMARY 1. The planktonic ciliate communities of eleven organically coloured north and central Florida lakes representing a variety of trophic conditions were examined during 1979–80. The total abundance and biomass of ciliates were not significantly different from comparable clearwater lakes and only minor taxonomic replacements were noted at the order level.
2. Timing of population peaks of oligotrophic lakes was dissimilar to clearwater lakes of the same trophic state, but seasonality in meso-trophic and eutrophic lakes resembled patterns described for comparable clearwater lakes.
3. Various ciliate components were strongly correlated with chlorophyll a concentrations, but only moderately correlated to dominant phytoplankton groups. No significant correlations were found between ciliate components and bacterial abundance.
4. Myxotrophic taxa numerically dominated oligotrophic systems, particularly during midsummer, and accounted for a large percentage of the total ciliate biomass. Estimates of the ciliate contribution to total autotrophic biomass indicate that these zoochlorellae-bearing protozoa may account for much of the autotrophic biomass during midsummer periods in coloured lakes, and thus may lead to an overestimation of phytoplankton standing crops available to zooplankton grazers if chlorophyll a is used as a surrogate measure of algal biomass.