scholarly journals Contrasting anti-predation responses in the intertidal periwinkle Littorina sitkana: effects of chemical cue, body size and time of day

2013 ◽  
Vol 8 (1) ◽  
pp. 38-45 ◽  
Author(s):  
Hisae Ojima ◽  
Satoshi Wada
Keyword(s):  
Body Size ◽  
Time Of Day ◽  
Chemical Cue ◽  
Littorina Sitkana

The effects of age, sex, reproductive status and temporal factors on the time-use of free-ranging red kangaroos

1993 ◽  
Vol 20 (6) ◽  
pp. 785 ◽  
Author(s):  
DM Watson ◽  
TJ Dawson
Keyword(s):  
Body Size ◽  
Group Size ◽  
Time Use ◽  
New South ◽  
New South Wales ◽  
Time Of Day ◽  
Adult Males ◽  
South Wales ◽  
Free Ranging ◽  
Foraging Time

The effects of temporal (time of day and season) factors and size, sex, female reproductive state and group size on the diel time-use of free-ranging red kangaroos (Macropus rufus) was examined. Particular emphasis was given to the effects on their foraging behaviour, with foraging divided into cropping, chewing and searching components. The study was conducted in semi-arid western New South Wales from July 1991 to March 1992, a time of deepening drought conditions in New South Wales. Group size had very little influence on the time-use of M. rufus. It was negatively but only weakly correlated with the proportion of foraging time spent chewing (chewing intensity). No significant differences in time-use were found between size classes of adult males (large and medium-sized males), females with or without pouch young, or females with different-sized pouch young (no visible young, small pouch young or large pouch young). Differences occurred between adult males, adult females and subadult kangaroos. These differences were mainly associated with their chewing and searching behaviour and were related to body size; as body size increased the proportion of time spent chewing and the intensity of chewing increased while the proportion of time searching and the proportion of foraging time spent searching (searching intensity) decreased. Neither the proportion of time spent cropping or foraging nor the proportion of foraging time spent cropping (cropping intensity) or the proportion of active time spent foraging (foraging intensity) differed between any size/sex/reproductive class. Temporal effects had a considerable influence on time-use. M. rufus were most active at night and in the few hours after sunrise and sunset. Seasonal changes in time-use were largely a result of changes in daytime behaviour. M. rufus foraged less and rested more during the day in winter than in spring or summer. There was no increase in the intensity or proportion of time spent foraging or cropping at night to compensate for the reduction in diurnal foraging. It is hypothesised that temporal variations in time-use were related to variations in weather and vegetation conditions.

Body size of ectotherms constrains thermal requirements for reproductive activity in seasonal environments

2020 ◽  
Vol 98 (10) ◽  
pp. 651-659
Author(s):  
Jared W.H. Connoy ◽  
Jessica A. Leivesley ◽  
Ronald J. Brooks ◽  
Jacqueline D. Litzgus ◽  
Njal Rollinson
Keyword(s):  
Body Size ◽  
Thermal Inertia ◽  
Reproductive Activity ◽  
Time Of Day ◽  
Thermal Requirements ◽  
Heating And Cooling ◽  
Painted Turtles ◽  
Snapping Turtles ◽  
Nesting Behaviour ◽  
Preferred Body Temperature

Body size may influence ectotherm behaviour by influencing heating and cooling rates, thereby constraining the time of day that some individuals can be active. The time of day at which turtles nest, for instance, is hypothesized to vary with body size at both inter- and intra-specific levels because large individuals have greater thermal inertia, retaining preferred body temperatures for a longer period of time. We use decades of data on thousands of individual nests from Algonquin Park, Ontario, Canada, to explore how body size is associated with nesting behaviour in Painted Turtles (Chrysemys picta (Schneider, 1783); small bodied) and Snapping Turtles (Chelydra serpentina (Linnaeus, 1758); large bodied). We found that (i) between species, Painted Turtles nest earlier in the evening and at higher mean temperatures than Snapping Turtles, and (ii) within species, relatively large individuals of both species nest at cooler temperatures and that relatively larger Painted Turtles nest later in the evening compared with smaller Painted Turtles. Our data support the thermal inertia hypothesis and may help explain why turtles in general exhibit geographic clines in body size: northern environments experience more daily variation in temperature, and larger size may evolve, in part, for retention of preferred body temperature during terrestrial forays.

Factors Affecting Reaction-Time Testing and the Interpretation of Results

1991 ◽  
Vol 73 (3_suppl) ◽  
pp. 1195-1202 ◽  
Author(s):  
Simo Taimela
Keyword(s):  
Body Size ◽  
Reaction Time ◽  
Color Vision ◽  
Choice Reaction Time ◽  
Simple Reaction Time ◽  
Time Of Day ◽  
Low Grade ◽  
Related Factors ◽  
Factors Affecting ◽  
Testing Schedule

The aim of this study was to identify factors that might affect reaction-time (RT) testing and interpretation. Simple reaction time and choice reaction time were measured in a cohort of 893 white young men. Age, body size, color vision, and intelligence (IQ) were analyzed as subject-related factors. Effects of time of day of test and different examiners were analyzed in relation to testing facilities. All factors were statistically correlated to RTs; however, the relationships between age and RTs and between height and RTs were noticeably weak and apparently insignificant in practice. A defect in color vision was notably associated with slow choice RT and with mistakes on the test. As the choice was coded by color in the choice RT test, the result was expected. Low IQs were significantly related with slow RTs. Slow RTs have been correlated with low-grade IQs in previous studies also. Lower grades and greater variation in RTs were recorded just before meals or if testing was done outside the daily testing schedule. The examiner supervising the RT testing significantly affected the results. It was concluded that the introduction for tests should be given impersonally using a tape recorder or comparable equipment.

scholarly journals Niche differentiation mechanisms among canopy frugivores and zoochoric trees in the northeastern extreme of the Amazon

2020 ◽  
Vol 50 (3) ◽  
pp. 263-272
Author(s):  
Felipe TODESCHINI ◽  
José Julio de TOLEDO ◽  
Luis Miguel ROSALINO ◽  
Renato Richard HILÁRIO
Keyword(s):  
Body Size ◽  
Seed Size ◽  
Tropical Rainforest ◽  
Species Coexistence ◽  
Time Of Day ◽  
Fruit Weight ◽  
Time Of Arrival ◽  
Niche Segregation ◽  
Fruit Morphology ◽  
Fruit Consumption

ABSTRACT Frugivores and zoocoric trees represent an important proportion of tropical rainforest biodiversity. As niche differences favor species coexistence, we aimed to evaluate morphological and temporal niche segregation mechanisms among zoochoric trees and canopy frugivores in a tropical rainforest in the northeastern extreme of the Brazilian Amazon. We tested the effects of fruit morphology, tree size, frugivore body size and time of day on fruit consumption. We recorded the frugivore species that fed on 72 trees (44 species, 22 genera) and whether these frugivores swallowed the seeds. We monitored trees only once from 07:00 to 17:00 h between January and September 2017. We observed fruit consumption in 20 of the 72 trees. Seventy-three frugivore individuals from 22 species visited the trees. Heavier fruits were consumed by larger frugivores, while seed size was inversely correlated with frugivore size. Narrower fruits and fruits with smaller seeds had greater probability of having their seeds ingested, and larger frugivores were more prone to ingest seeds. Trees bearing fruits with smaller seeds were visited by a greater number of frugivores. Taxonomic groups differed in the time of arrival at fruiting trees. None of the evaluated variables (fruit weight and size, and seed size) affected the richness of frugivores that visited the trees. We concluded that, in the studied forest, fruit morphology (weight, size and seed size) is a niche segregation mechanism among zoochoric trees, while body size and time of day are niche segregation mechanisms among frugivores.

Acoustic Observations of Patterns of Aggregation in Haddock (Melanogrammus aeglefinus) and Their Significance to Production and Catch

1992 ◽  
Vol 49 (1) ◽  
pp. 23-31 ◽  
Author(s):  
Paul R. Boudreau
Keyword(s):  
Body Size ◽  
Spatial Scales ◽  
Time Of Day ◽  
Melanogrammus Aeglefinus ◽  
Biomass Density ◽  
Dual Beam ◽  
Local Aggregation ◽  
Catch Rates ◽  
High Degree ◽  
Haddock Melanogrammus Aeglefinus

A dual-beam acoustic system was used to collect detailed information on density and body size over a 24-h period in an area of the Scotian Shelf occupied by a population of large spawning haddock (Melanogrammus aeglefinus). The acoustic sampling showed a persistent gradient of decreasing density with distance from bottom with 50% of the fish < 2.5 m off bottom. Horizontally (scale of hundreds of metres), there was a high degree of local aggregation which changed dramatically over 24 h. Highest aggregation was in daytime, with fish more dispersed throughout the water column at night. The differences in the degree of aggregation with time of day appear to be sufficient to explain diel changes in net catch rates. On larger geographic scales (tens of kilometres), fish density was relatively uniform. Acoustics provide a method for studying the relative importance of aggregation on these various spatial scales to estimates of abundance. Haddock biomass density was also related to organism body size, as has been observed for other species in both aquatic and terrestrial situations, suggesting that haddock population density is determined by trophic interactions similar to those that underlie production of other populations of organisms.

Cortisol Response to Stressful Task and Time of Day

2002 ◽  
Author(s):  
Jacquelyn J. Graven ◽  
Tracy A. Manners ◽  
James O. Davis
Keyword(s):  
Time Of Day ◽  
Cortisol Response ◽  
Stressful Task
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