Patterns of daily torpor and day-roost selection by male and female big brown bats (Eptesicus fuscus)

1994 ◽  
Vol 72 (4) ◽  
pp. 744-749 ◽  
Author(s):  
Ian M. Hamilton ◽  
Robert M. R. Barclay
Keyword(s):  
Energy Savings ◽  
Eptesicus Fuscus ◽  
Daily Torpor ◽  
Male And Female ◽  
Ambient Temperatures ◽  
Big Brown Bats ◽  
Roost Selection ◽  
East End ◽  
Reproductive Females ◽  
Juvenile Development

Daily torpor can provide significant energy savings, but in bats may reduce rates of fetal and juvenile development and spermatogenesis. We examined the use of torpor during the day by male and female big brown bats (Eptesicus fuscus) in the field during the female gestation, lactation, and postlactation periods. While both sexes used torpor, males used it significantly more often and used deeper torpor than did reproductive females, indicating that the costs of torpor are higher for reproductive females. We suggest that by using shallow torpor, females may gain some of the benefits of torpor while minimizing the fitness costs. The different patterns of torpor may be responsible for observed differences in day-roost location amongst males, reproductive females, and nonreproductive females. Males should choose roosts with lower ambient temperatures than do females in order to increase the energy savings of torpor. Males and nonreproductive females roosted away from the maternity colonies more often than did reproductive females. Within one maternity colony, males roosted in the west end of the colony, while females roosted in the east end. These patterns of roosting may be related to how the roost warms during the day.

scholarly journals ROOST SELECTION BY FOREST-LIVING FEMALE BIG BROWN BATS (EPTESICUS FUSCUS)

2006 ◽  
Vol 87 (2) ◽  
pp. 345-350 ◽  
Author(s):  
Craig K. R. Willis ◽  
Christine M. Voss ◽  
R. Mark Brigham
Keyword(s):  
Eptesicus Fuscus ◽  
Big Brown Bats ◽  
Roost Selection

Roosting behaviour and roost selection of female big brown bats (Eptesicus fuscus) roosting in rock crevices in southeastern Alberta

2002 ◽  
Vol 80 (6) ◽  
pp. 1069-1076 ◽  
Author(s):  
Cori L Lausen ◽  
Robert M.R Barclay
Keyword(s):  
Small Groups ◽  
Eptesicus Fuscus ◽  
River Valley ◽  
Big Brown Bats ◽  
Roost Selection ◽  
Adult Females ◽  
South Saskatchewan River ◽  
Pregnancy And Lactation ◽  
Physical Attributes ◽  
Selection Of

We studied big brown bats (Eptesicus fuscus) roosting in rock crevices along the South Saskatchewan River in southeastern Alberta. We documented roosting behaviour and roost selection. During pregnancy and lactation, individuals aggregated as several small groups or one large group (maternity colony). Postlactating females roosted alone more frequently. During postlactation, individuals periodically returned to roost with a group dominated by pups, between periods of roosting alone. We identified 72 roosts used by members of the colony. Adult females switched roosts frequently and few roosts (24%) were reused. During pregnancy and lactation, the colony roosted in a 1.25-km length of the river valley on the northwest side of the river. With the onset of postlactation, females began roosting on both sides of the river and within a longer section of the river valley, and roosts faced in a more southerly direction. Crevices selected as roosts were more vertical in orientation, were farther from level ground above, and had openings that were smaller than those randomly available. Roosts used during pregnancy, lactation, and postlactation differed in physical attributes; lactation roosts were deeper and had larger openings. Selection of crevices with particular attributes suggested that selection was based on microclimate and avoidance of predation.

Thermal energetics of female big brown bats (Eptesicus fuscus)

2005 ◽  
Vol 83 (6) ◽  
pp. 871-879 ◽  
Author(s):  
Craig K.R Willis ◽  
Jeffrey E Lane ◽  
Eric T Liknes ◽  
David L Swanson ◽  
R Mark Brigham
Keyword(s):  
Metabolic Rate ◽  
Body Mass ◽  
Thermal Conductance ◽  
Eptesicus Fuscus ◽  
Ambient Temperatures ◽  
Big Brown Bats ◽  
A Value ◽  
The Family ◽  
Thermal Energetics ◽  
The Relationship

We investigated thermoregulation and energetics in female big brown bats, Eptesicus fuscus (Beauvois, 1796). We exposed bats to a range of ambient temperatures (Ta) and used open-flow respirometry to record their metabolic responses. The bats were typically thermoconforming and almost always entered torpor at Tas below the lower critical temperature Tlc of 26.7 °C. Basal metabolic rate (BMR, 16.98 ± 2.04 mL O2·h–1, mean body mass = 15.0 ± 1.4 g) and torpid metabolic rate (TMR, 0.460 ± 0.207 mL O2·h–1, mean body mass = 14.7 ± 1.3 g) were similar to values reported for other vespertilionid bats of similar size and similar to a value for E. fuscus BMR calculated from data in a previous paper. However, we found that big brown bats had a lower Tlc and lower thermal conductance at low Ta relative to those measured in the previous study. During torpor, the minimum individual body temperature (Tb) that we recorded was 1.1 °C and the bats began defending minimum Tb at Ta of approximately 0 °C. BMR of big brown bats was 76% of that predicted for bats based on the relationship between BMR and body mass. However, the Vespert ilionidae have been under-represented in previous analyses of the relationship between BMR and body mass in bats. Our data, combined with data for other vespertilionids, suggest that the family may be characterized by a lower BMR than that predicted based on data from other groups of bats.

Sexual differences in the annual lipid cycle of the big brown bat Eptesicus fuscus

1989 ◽  
Vol 67 (8) ◽  
pp. 1891-1894 ◽  
Author(s):  
David H. Pistole
Keyword(s):  
Eptesicus Fuscus ◽  
Fat Deposition ◽  
Caloric Content ◽  
Basic Pattern ◽  
Mating Season ◽  
Male And Female ◽  
Big Brown Bats ◽  
Big Brown Bat ◽  
Pregnancy And Lactation ◽  
Males And Females

The annual lipid cycle in male and female big brown bats, Eptesicus fuscus, was studied in relation to the reproductive patterns for each sex. The basic pattern of lipid deposition and use was similar in males and females; however, there were differences between the sexes in the timing of these activities. Females began rapid fat deposition 1 month earlier than males. The beginning of rapid fat deposition in females is associated with the end of lactation and in males with the end of spermatogenesis and the peak mating season. Rates of fat use were similar between the sexes for the entire hibernation period, but the rate in females was more consistent than the rate in males. The caloric content of male bats did not differ throughout the year, but females had higher values during pregnancy and lactation than at other times of the year. Differences between the sexes in the timing of specific events within the annual lipid cycle appear to be adaptations for optimizing reproductive success.

Glucoprivation counteracts effects of testosterone on daily torpor in Siberian hamsters

1996 ◽  
Vol 270 (2) ◽  
pp. R398-R403 ◽  
Author(s):  
J. Dark ◽  
D. R. Miller ◽  
P. Licht ◽  
I. Zucker
Keyword(s):  
Energy Savings ◽  
Inhibitory Effect ◽  
Daily Torpor ◽  
Adult Males ◽  
Inhibitory Effects ◽  
Ambient Temperatures ◽  
Siberian Hamsters ◽  
Potent Inhibitory Effect ◽  
Hypometabolic State ◽  
Glucose Analogue

We tested whether 1) glucose availability is a signal for initiation of torpor in male hamsters and 2) glucoprivation can override the inhibitory effects of androgens on daily torpor. Male hamsters maintained at ambient temperatures of 8-16 degrees C were injected with 2-deoxy-D-glucose (2DG), a glucose analogue that interferes with cellular glucose oxidation. 2DG (2,000-2,500 mg/kg body mass) induced torpor within 1 h of treatment in normal adult males in reproductive condition and in those bearing testosterone (T)-filled capsules that produced supraphysiological blood T concentrations; body temperatures were reduced from 37 to 25 degrees C for several hours. Latency to torpor was increased and duration of torpor was decreased in the T-treated hamsters. Food intake decreased substantially both on the day of torpor and on the succeeding day. Glucoprivation appears to counteract the potent inhibitory effect of androgens on torpor and induces a hypometabolic state that results in overall energy savings.

The influence of roost closure on the roosting and foraging behaviour of Eptesicus fuscus (Chiroptera: Vespertilionidae)

1986 ◽  
Vol 64 (5) ◽  
pp. 1128-1133 ◽  
Author(s):  
R. Mark Brigham ◽  
M. Brock Fenton
Keyword(s):  
Reproductive Success ◽  
Direct Observation ◽  
Foraging Behaviour ◽  
Eptesicus Fuscus ◽  
Maximum Distance ◽  
Radio Tracking ◽  
Site Specific ◽  
Big Brown Bats ◽  
Specific Factors ◽  
Foraging Flight

We used radio tracking and direct observation to determine the effect of roost closure on the roosting and foraging behaviour of big brown bats (Eptesicus fuscus) in maternity colonies near Ottawa. Individuals were site loyal, but after eviction they moved short distances to new roosts where they tended to produce fewer offspring. The time spent on the first foraging flight, the maximum distance travelled, and the use of feeding areas did not change with exclusion. The results suggest that bats roost to take advantage of site-specific factors that may increase reproductive success.

Investigation of Thermal Effects in Direct Driven Hydraulic System for Off-Road Machinery

2016 ◽  
Author(s):  
Niko Karlén ◽  
Tatiana Minav ◽  
Matti Pietola
Keyword(s):  
Energy Efficiency ◽  
Hydraulic System ◽  
Energy Savings ◽  
Mechanical Energy ◽  
Hydraulic Model ◽  
Energy Losses ◽  
Total Efficiency ◽  
Ambient Temperatures ◽  
Wheel Loaders ◽  
Save Energy

Several types of off-road machinery, such as industrial trucks, forklifts, excavators, mobile cranes, and wheel loaders, are set to be operated in environments which can differ considerably from each other. This sets certain limits for both the drive transmissions and working hydraulics of these machines. The ambient temperature must be taken into account when selecting the hydraulic fluid since the viscosity and density of the fluid are changing at different operating temperatures. In addition to the temperature, energy efficiency can also be a problem in off-road machinery. In most off-road machines, diesel engines are employed to produce mechanical energy. However, there are energy losses during the working process, which causes inefficiency in produced energy. For better energy efficiency, hybridization in off-road machinery is an effective method to decrease fuel consumption and increase energy savings. One of the possible methods to save energy with hybrids is energy regeneration. However, it means that the basic hydraulic system inside off-road machinery needs to be modified. One solution for this is to utilize zonal or decentralized approach by means of direct driven hydraulic (DDH) system. This paper aims to investigate a DDH system for off-road machinery by means of modelling and analyzing the effect of the temperature. In the direct-driven hydraulic system, the actuator is controlled directly by the hydraulic pump which is operated by the electric motor. Specifically, it is a valveless closed-loop hydraulic system. Thus, there will be no energy losses caused by the valves, and the total efficiency is assumed to be significantly higher. In order to examine the DDH system, a thermo-hydraulic model was created. Additionally, a thermal camera was utilized in order to illustrate the temperature changes in the components of the DDH system. To reproduce the action of the system in different circumstances DDH system was run at different ambient temperatures, and the component temperatures in the system were measured and saved for the analysis. The thermo hydraulic model was proven capable to follow the general trend of heating up.

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