Eugene H. Studier

Biology of Myotis thysanodes and M. lucifugus (Chiroptera: Vespertilionidae)—I. Thermoregulation

Abstract 1. 1. Thermoregulatory patterns and levels of controlled body temperature (Tb) in adult female Myotis thysanodes and M. lucifugus throughout their stay in maternity colonies are significantly affected by stage of reproduction and even more by stage of pregnancy, but are not affected by abundance of body fat or age. 2. 2. It is impossible to distinguish regulating bats from conforming bats in ambient temperatures (Tas) above 20–24°C, with bats of both species becoming partially hyperthermic above these Tas. 3. 3. Minimum Tb required for initiation of flight averages 30·3 and 24·3°C, for M. lucifugus and M. thysanodes, respectively, while neonates of these two species begin to regulate at about 9 1 2 and 4 1 2 days after birth, respectively. 4. 4. Behavioral aspects of thermoregulation may be as important as physiological thermoregulation in the biology of these species.

Evaporative water loss in bats

Abstract 1. 1. There is no difference in rate of evaporative water loss ( EWL ) between adult male and female Natalus stramineus, Glossophaga soricina , and Myotis nigricans irrespective of the reproductive conditions of the females. EWL in pregnant Artibeus cinereus is significantly less than other adults. 2. 2. EWL in bats is related to body weight ( W ) by the equation log EWL = log 0.398 + 0.672 log W , where EWL is g of water/animal per day and W is g. 3. 3. EWL increases with level of activity in torpid, active, and flying bats. 4. 4. EWL in active bats is inversely or directly related to ambient temperature ( T a ) at temperatures below the thermal neutral zone ( TNZ ) in different species. Above the TNZ, EWL is directly related to T a and water vapor pressure ( WVP ). Below the TNZ, EWL is inversely related to WVP . 5. 5. Depending on the species, grouping may result in significant increases, decreases or no difference in EWL .

Energy utilization and water requirements of captive Myotis thysanodes and Myotis lucifugus (Chiroptera).

Abstract 1. 1. Ten captive Myotis thysanodes ingested an average of 5·05 kcal/day and egested 0·47 kcal/day with a mean energy utilization of 90·8 per cent. 2. 2. One captive M. lucifugus ingested 4·15 kcal/day and egested 0·37 kcal/day with an energy utilization of 91·2 per cent. 3. 3. M. thysanodes gained an average of 2·77 cm 3 /day of water and lost an average of 2·86 cm 3 /day. This represents a water turnover of almost half the total body water. 4. 4. The M. lucifugus gained 1·97 cm 3 /day of water and lost at least 1·47 cm 3 /day representing a water turnover of about one third of the total body water. 5. 5. It is suggested that for small mammals in general that the energy utilization approaches or exceeds 90 per cent efficiency.

BIOLOGY OF MYOTIS THYSANODES AND M. LUCIFUGUS (CHIROPTERA: VESPERTILIONIDAE)-II. BIOENERGETICS OF PREGNANCY AND LACTATION

Abstract Through bomb calorimetry of known-age young bats, we have determined the energy cost of pregnancy and lactation in Myotis thysanodes and M. lucifugus finding that: 1. 1. Energy demand during pregnancy is hyperbolic. 2. 2. A very rapid increase in energy involved in embryo growth occurs during late pregnancy when the mothers are no longer homeothermic. 3. 3. This increased energy demand occurs earlier pre-partum in M. thysanodes than in M. lucifugus. 4. 4. Energy utilized during late embryo growth in M. lucifugus (130 cal/day) is significantly greater than in M. thysanodes (78 cal/day). 5. 5. Lactation in M. thysanodes requires at least 346 cal/day and is much more energy demanding than is pregnancy.

Diurnal Body Weight Loss and Tolerance of Weight Loss in Five Species of Myotis

Dawn to dusk weight loss of Myotis leibii and M. yumnnensis, caged singly, and M. lucifugas, M. thysanodes, and M. velifer, caged singly and in groups of four, was determined in their natural roosting environments. Individual weight losses ranged from 6.4 to 21.9 per cent of initial body weight, whereas weight loss of grouped bats ranged from 9.9 to 16.2 per cent. Roosting conditions, temperature and relative humidity, are reflected in daily weight loss. Grouped M. thysanodes lost significantly less weight than individually caged bats. There was no difference in weight loss of individual and grouped M. lucifugas and M. velifer. Weight loss at which half of the individuals of each species except M. leibii died ranged from 22.8 to 32.3 per cent of initial body weight.

Biology of Myotis thysanodes and M. lucifugus (Chiroptera: Vespertilionidae)—III. Metabolism, heart rate, breathing rate, evaporative water loss and general energetics

Abstract 1. 1. Oxygen consumption (OC), weight specific oxygen consumption (VO). heart rate (HR), breathing rate (RR) and evaporative water loss (EWL) differ in adult female Myotis thysanodes and M. lucifugus and are significantly related to thermoregulatory performance (regulating or conforming) and to reproductive condition but not to body composition, spleen or adrenal weights or age class. 2. 2. Multiple regression equation models of these physiological parameters as possible linear or exponential functions of ambient temperature (Ta), body temperature (T), T, to T differential, weight, and each other are presented. 3. 3. The relations of the physiological variables to Ta is curvilinear with OC, VO, RR and oxygen pulse (cm3 of oxygen consumed/heart beat) reaching minimal levels at similar optimal Ts which exceed normally controlled T1. HR becomes minimal at Ts approximating normally controlled Tl and EWL reaches minimal values at Tas lower than controlled T1. Evaporative heat loss equals metabolic heat production at Tas which exceed normally controlled T. 4. 4. Roosting energy budgets differ in the two species and are functions of reproductive status and thermoregulatory performance. The ability of regulating individuals to conform at low Tas conserves a large portion of the roosting energy budget.

Diurnal fluctuation in weight and blood composition in Myotis nigricans and Myotislucifugus

Abstract 1. 1. Body weight and percentage body water of naturally roosting Myotis nigricans did not change significantly during roosting hours, although hematocrit increased significantly from 53·7 to 56·3 per cent erythrocytes. 2. 2. Hematocrit and percentage body water of naturally roosting M. lucifugus did not change significantly under similar conditions, although body weight loss exceeded 16 per cent of initial body weight. 3. 3. Relative spleen weight increased significantly during the middle of the roosting period in M. nigricans, but returned to nearly its original value. 4. 4. In M. lucifugus relative spleen weight increased significantly during the latter half of the roosting period. 5. Relative kidney weight did not change significantly in either species. 5. 6. Serum sodium levels inM. nigricans and M. lucifugus increased significantly from 126 to 172 m-equiv./l., and 140 to 165 m-equiv./l., respectively. 6. 7. Serum chloride levels in M. lucifugus fluctuated from 140 to 153 m-equiv./ 1., while potassium levels increased from 3·96 to 5·30 m-equiv./l., during the roosting period.

Fall metabolism in relation to ambient temperatures in three species of Myotis

Abstract 1. 1. A zone of thermoneutrality exists for adult female Myotis thysanodes in early September in an ambient temperature range of 32·5–34·5°C with minimum metabolism of 1·74 cm3/g per hr. 2. 2. A transition from a homeothermic to a non-homeothermic metabolism to ambient temperature relation is evident by late September in adult female M. thysanodes. 3. 3. In early September, some adult female M. yumanensis exhibit a homeothermic metabolism to ambient temperature relation while others exhibit a non-homeothermic relation. 4. 4. In early September, adult M. lucifugus occultus of both sexes exhibit a non-homeothermic relation. 5. 5. At ambient temperatures above 32·5°C, metabolism in M. thysanodes increases at a significantly more rapid rate than in M. lucifugus occulttus. 6. 6. A critical thermal maximum ambient temperature of 44·5°C has been found for each of these three species.

Tolerance and Initial Metabolic Response to Ammonia Intoxication in Selected Bats and Rodents

Metabolic rates, as measured by oxygen consumption, and tolerances of three bats, Tadarida brasiliensis, Myotis lucifugus , and Eptesicus fuscus , and the laboratory rat, Rattus , and mouse, Mus , were determined in increasingly concentrated ammonia in air mixtures. Rats and mice exhibited increased oxygen consumption when exposed to increased ammonia levels. Oxygen consumption in rats ranged from 0.8 to 1.2 cc/g/hr in environmental gradients ranging from normal air to 5000 parts per million ammonia (ppm ammonia), while mice exhibited a rise in oxygen consumption from 3.7 to 4.7 cc/g/hr in concentrations of 0–3000 ppm ammonia. Myotis lucifugus exhibited erratic responses in mixtures of 0–5000 ppm ammonia, and oxygen consumption fluctuated between 4.9 and 10.6 cc/g/hr. Similarly, in E. fuscus consumption fluctuated from 3.3 to 7.2 cc/g/hr in 0–7000 ppm ammonia. In neither species was oxygen consumption correlated to the change in ammonia concentration. Tadarida brasiliensis exhibited decreased oxygen consumption ranging from 8.8 cc/g/hr to 2.3 cc/g/hr in air containing 0–7000 ppm ammonia. Tadarida brasiliensis and E. fuscus lived for 2½ and 1½ hrs, respectively, when exposed to 7000 ppm ammonia, but for only 10–20 min at 10,000 ppm ammonia. Myotis lucifugus and laboratory rats lived for 30–45 min in 5000 ppm ammonia. Laboratory mice lived for 2½ hrs at 3000 ppm and 10–20 min at 5000 ppm ammonia.

A method for control of water vapor pressure and its effect on metabolism and body temperature in Mus musculus

Abstract 1. 1. A simple method for controlling water vapor pressures (WVPs) in an open-flow system is described. 2. 2. High WVPs (30 mm Hg) alter the normla homeothermic response to ambient temperature variation in laboratory mice such that metabolic rate becomes independent of ambient temperature, particularly at ambient temperatures above the thermoneutral zone. 3. 3. WVPs of 10 and 20 mm Hg do not affect the normal, metabolism-ambient temperature relationship.