Flight is the key to postprandial blood glucose balance in the fruit bats Eonycteris spelaea and Cynopterus sphinx

Excessive sugar consumption could lead to high blood glucose levels that are harmful to mammalian health and life. Despite consuming large amounts of sugar‐rich food, fruit bats have a longer lifespan, raising the question of how these bats overcome potential hyperglycemia. We investigated the change of blood glucose level in nectar‐feeding bats (Eonycteris spelaea) and fruit‐eating bats (Cynopterus sphinx) via adjusting their sugar intake and time of flight. We found that the maximum blood glucose level of C. sphinx was higher than 24 mmol/L that is considered to be pathological in other mammals. After C. sphinx bats spent approximately 75% of their time to fly, their blood glucose levels dropped markedly, and the blood glucose of E. spelaea fell to the fast levels after they spent 70% time of fly. Thus, the level of blood glucose elevated with the quantity of sugar intake but declined with the time of flight. Our results indicate that high‐intensive flight is a key regulator for blood glucose homeostasis during foraging. High‐intensive flight may confer benefits to the fruit bats in foraging success and behavioral interactions and increases the efficiency of pollen and seed disposal mediated by bats.     

Abundance, biology, and human exploitation of bats in the Palau Islands

Three species of bats, Pteropus pilosus, P. muriannus pelewensis , and Embullonura semicaudata palauensis , were surveyed by observations, systematic counts, and interviews with local residents in the Palau Islands of Micronesia during a one-month period in 1991. Pteropus pilosus is presumed extinct, with no observations made this century. Pteropus m. pelewensis occurred throughout the archipelago. It is less colonial than other subspecies of P. muriannus , with most of the population appearing to roost solitarily or in small groups of a few bats. Colonies were uncommon and typically ranged in size from about 30–200 animals. Evidence of two larger roosting concentrations, one of which may have held as many as 3,000 bats, was also found. These fruit bats forage and roost in a variety of forested habitats and have diverse diets known to contain the fruits of 54 species, the flowers of 28 species, and the leaves of one species. At dusk, most bats began foraging within several kilometres of their day roosts, but some flew at least 12 km to reach feeding sites. The largest numbers of P. m. pelewensis roosted on rugged and fairly inaccessible limestone islands near the centre of the archipelago, near where most people also lived. We were unable to estimate population size or determine population trend in the island chain. The bats are heavily harvested for commercial export, with more than 180,000 animals shipped to the Mariana Islands from 1975–1994. Smaller numbers are also killed as a local food source. Emballonura s. palauensis , the only insectivorous bat in the islands, was seen at 65% of the evening count locations and was also widespread in the archipelago. Recommendations for managing bats in Palau include a prohibition on the export of fruit bats and the establishment of several protected areas.     

High activity enables life on a high-sugar diet: blood glucose regulation in nectar-feeding bats

High blood glucose levels caused by excessive sugar consumption are detrimental to mammalian health and life expectancy. Despite consuming vast quantities of sugar-rich floral nectar, nectar-feeding bats are long-lived, provoking the question of how they regulate blood glucose. We investigated blood glucose levels in nectar-feeding bats (Glossophaga soricina) in experiments in which we varied the amount of dietary sugar or flight time. Blood glucose levels increased with the quantity of glucose ingested and exceeded 25 mmol l(-1) blood in resting bats, which is among the highest values ever recorded in mammals fed sugar quantities similar to their natural diet. During normal feeding, blood glucose values decreased with increasing flight time, but only fell to expected values when bats spent 75 per cent of their time airborne. Either nectar-feeding bats have evolved mechanisms to avoid negative health effects of hyperglycaemia, or high activity is key to balancing blood glucose levels during foraging. We suggest that the coevolutionary specialization of bats towards a nectar diet was supported by the high activity and elevated metabolic rates of these bats. High activity may have conferred benefits to the bats in terms of behavioural interactions and foraging success, and is simultaneously likely to have increased their efficiency as plant pollinators.     

Intraday Blood Rheological Changes Induced by Ramadan Fasting in Sickle Cell Trait Carriers

The goal of the present study was to test whether fasting during the holy period of Ramadan may disturb blood rheology in sickle cell trait (SCT) carriers more than in a group of subjects with normal hemoglobin. Twenty African male students participated in the study: 10 SCT carriers and 10 subjects with normal hemoglobin (CONT). Biochemical parameters (plasma glucose and lipids levels), hematocrit, blood viscosity, and urine specific gravity were measured in the two groups on the 14th day of the Ramadan period (Ramadan condition) and 6 wks after the end of Ramadan (baseline condition). All the measurements were performed twice for each experimental day to measure intraday variation: 8:00 and 18:00?h. Plasma glucose level and lipid profile were not significantly different between the two groups. Although Ramadan did not affect the lipid profile, the plasma glucose concentration was lower during the Ramadan period compared with the baseline condition in the two groups. Hematocrit and urine specific gravity did not differ between the two groups and was greater in the evening than in the morning, independently of the condition. SCT carriers had higher blood viscosity than the CONT group. However, whereas blood viscosity remained unchanged through the day in the CONT group, whatever the condition, SCT carriers were characterized by a large increase of blood viscosity in the evening during the Ramadan period, indicating higher risk for microcirculatory blood flow impairments. Specific medical recommendations are needed for SCT carriers engaged in religious fasting.     

Early outflying and late homeflying in the Indian pygmy bat under natural conditions

The outflying and homeflying activity pattern of a colony of the Indian pygmy bat Pipistrellus mimus occupying a tunnel was studied under natural conditions. Before leaving the tunnel for foraging, the bats made circling flights outside to sample the environmental light conditions. The onset and end of activity was related to the times of sunset and sunrise respectively. The onset of flight during evening commenced after sunset from mid-September to mid-April, before sunset during the rest of the year. Onset of activity occurred at higher light intensities compared to light intensities prevailing during the return flight to the roost in the morning. The duration of activity time showed a curvilinear relationship with the duration of the night. The phase relationship between onset and end of activity, and sunset and sunrise, showed marked seasonal variations in the values of Ψ_onset, Ψ_end, and Ψ_midpoint. However, such changes in the phase angle properties did not obey Aschoff's seasonal rule. Based upon the data obtained on the onset and end of activity patterns for five species of bats, including the data from this study, we report that P. mimus is the earliest to set out for foraging in the evening and among the last to return home in the morning. This might be due to dusk and dawn peaks in activity of the prey insects.     

Isolation of Genetically Diverse Marburg Viruses from Egyptian Fruit Bats

In July and September 2007, miners working in Kitaka Cave, Uganda, were diagnosed with Marburg hemorrhagic fever. The likely source of infection in the cave was Egyptian fruit bats (Rousettus aegyptiacus) based on detection of Marburg virus RNA in 31/611 (5.1%) bats, virus-specific antibody in bat sera, and isolation of genetically diverse virus from bat tissues. The virus isolates were collected nine months apart, demonstrating long-term virus circulation. The bat colony was estimated to be over 100,000 animals using mark and re-capture methods, predicting the presence of over 5,000 virus-infected bats. The genetically diverse virus genome sequences from bats and miners closely matched. These data indicate common Egyptian fruit bats can represent a major natural reservoir and source of Marburg virus with potential for spillover into humans.     

Altered flower/fruit clusters of the kitul palm used as roosts by the short-nosed fruit bat, Cynopterus sphinx (Chiroptera: Pteropodidae)

The short-nosed fruit bat (Cynopterus sphinx) creates bell-shaped cavities in flower/fruit clusters of the kitul palm (Caryota urens) by chewing and severing flower and fruit strings. These cavities (stem tents) in which the bats roost are usually about one metre deep and 30 cm in diameter. We observed groups of bats roosting in fully-formed stem tents during the daytime, and the construction and subsequent occupancy of newly formed tent cavities. Stem tents are similar in principle to leaf tents except, instead of being formed when bats chew veins and the surrounding tissues of leaves, stem tents are formed in C. urens when bats completely cut several of the central flower/fruit strings. Flower/fruit strings are mostly severed when they are in an immature stage, at times when they are thin and widely spaced. Once these strings thicken and become heavily-laden with mature fruits, bats cannot penetrate the cluster to sever them. Our observations suggest that a single male enters an immature flower or fruit cluster either from below or the sides and severs the central strings along the peduncle. In early phases of stem-tent construction, C. sphinx severs flower/fruit strings at a rate of about one or two per day, and cluster alteration may continue upwards to two months. Only one immature flower/fruit cluster on a C. urens tree is available for alteration by bats at any given time. That this bat does not roost in the fruit/flower cluster during the day, when a tent is under construction, and the accumulation of chewed flower and fruit strings beneath such a cluster in the morning, suggests that tent construction by C. sphinx is a night-time activity.     

Nectarivory by Endemic Malagasy Fruit Bats During the Dry Season1

Madagascar has a distinctive fruit bat community consisting of Pteropus rufus, Eidolon dupreanum, and Rousettus madagascariensis. In this study, we observed fruit bat visits to flowering baobabs (Adansonia suarezensis and Adansonia grandidieri) and kapok trees (Ceiba pentandra) during the austral winter. Eidolon dupreanum was recorded feeding on the nectar of baobabs and kapok, P. rufus was observed feeding on kapok only and no R. madagascariensis were seen. Three mammals species, two small lemurs (Phaner furcifer and Mirza coquereli) and E. dupreanum, made nondestructive visits to flowering A. grandidieri and are therefore all potential pollinators of this endangered baobab. This is the first evidence to show that A. grandidieri is bat‐pollinated and further demonstrates the close link between fruit bats and some of Madagascar's endemic plants. Eidolon dupreanum was the only mammal species recorded visiting A. suarezensis and visits peaked at the reported times of maximum nectar concentration. Pteropus rufus visited kapok mostly before midnight when most nectar was available, but E. dupreanum visited later in the night. These differences in timing of foraging on kapok can be explained either by differing distances from the roost sites of each species or by resource partitioning. We advocate increased levels of protection, education awareness, and applied research on both mammal‐pollinated baobab species and fruit bats, and suggest that both baobabs and bats are candidate “flagship species” for the threatened dry forests of Madagascar.     

犬蝠夜栖息地及夜栖息巢特征的初步研究

<正>大多数种类的蝙蝠不会整个晚上都进行觅食,通常在觅食期间有一段长短不一的时间停留在临时地休息,此为夜栖息行为(Hatfield,1937;Krutzsch,1954;Barbour and Davis,1969;Kunz,1973,1974;Hirshfeld et al.,1977)。蝙蝠在夜栖息地进食(Vaughan,1976;Funakoshi and Maeda,2003)、休息并消化食物(Brigham,1991;Funakoshi and Maeda,2003),甚至社会交流(Kunz,1982;Kunz and Lumsden,2003)。不同种类的蝙蝠     

伏翼的季节性活动与温度及光等环境因子的关系

伏翼(Pipistrellus abramus Temminck)为夜行性食虫小蝙蝠类,广布于我国南北和邻近国家,常成小群栖息于城市近郊或小城镇房屋的瓦盖下及屋檐下空隙中。这种蝙蝠在许多地区都有冬眠现象。过去对其季节活动与环境因子关系缺少完整的研究。为此作者于1965-67,1977-79及1981年在上海郊区作了初步观察。结果表明伏翼在不同季节中,其飞出搜食活动具有明显的规律性变化。这种变化同环境因子,特别是温度和光等因子有密切关系。     

Activity Pattern of the Trawling Phyllostomid Bat,Macrophyllum macrophyllum,in Panamá1

We studied activity patterns of long‐legged bats, Macrophyllum macrophyllum (Phyllostomidae), in the Barro Colorado Nature Monument, Panamá, using radio‐telemetry. Activity of four males and five females equipped with radio‐transmitters were monitored for 4–7 entire nights each between April and July 2002. Bats exhibited maximum activity around dusk and high activity during the night. Males and females foraged for equal amounts of time in continuous flight (mean: 7 min, maximum 1 h) with interspersed resting phases (mean: 15 min, maximum 3 h). Activity of M. macrophyllum was sensitive to several factors. Time of emergence and return to day roost were correlated with time of sunset and sunrise, respectively. Maximum bat activity coincided with high abundance of aerial insects. Finally, heavy rain caused bats to reduce or cease flight activity. Direct observations and field video recordings support the assumption that M. macrophyllum employs two distinct foraging modes: trawling of insects from and capture of aerial insects at low heights above water. Combination of foraging modes gives M. macrophyllum high flexibility and efficiency in prey search. Activity, foraging mode, and morphology, which are similar to trawling bats from other families, distinguish M. macrophyllum from all other phyllostomid species and grant it access to open habitat above water, a habitat no other phyllostomid bat has conquered.     

The destruction and conservation of the Egyptian Fruit bat Rousettus aegyptiacus in Cyprus: a historic review

In Cyprus, there are 16 species of bats most of which are threatened with extinction. With the exception of the megachiropteran Egyptian Fruit bat Rousettus aegyptiacus that feeds on fruit, the rest of them are insectivorous microchiropterans. The Fruit bat was declared as a pest by the Department of Agriculture of the Ministry of Agriculture, Natural Resources and Environment of Cyprus since the early 1900s. To reduce the number of this “pest”, the above-mentioned Department, since 1927, used fumigation, shooting, and the purchase of dead bats. Fumigating and closing caves not only destroyed Fruit bats by direct poisoning, but the entire cave ecosystems, including highly beneficial and protected insectivorous species. The first attempt to protect bats on the island was in 1988 with law No. 24 of 1988, ratifying the Convention on the Conservation of European Wildlife and Natural Habitats, 82/72/EEC. This convention protects all microchiroptera species except Pipistrellus pipistrellus that is strictly protected. R. aegyptiacus is rare, with small populations that are not at present endangered or vulnerable but at risk. Cyprus recently became a member state of the European Union. This provided the opportunity to include R. aegyptiacus in the Annexes II and IV of the council directive 92/42/EEC of May 21, 1993 on the conservation of natural habitats and of wild fauna and flora, which will guarantee the long-range protection and survival of this species.     

两种果蝠对光叶桑(Morus macroura)果实的取食及种子传播

从2005年3月到2006年5月,在中国科学院西双版纳热带植物园沟谷雨林保护区内研究了两种果蝠——棕果蝠(Rousettus leschenaulti)和犬蝠(Cynopterus sphinx)取食光叶桑(Morus macroura) 果实的行为、夜栖息地分布、散布种子方式及范围等。借助月光对果蝠的行为进行直接观察,发现它们的取食活动一般在天黑20~40 min开始,取食高峰发生在22: 00~22: 30 和23:00~23:30之间,这两个取食高峰期平均取食次数(平均值±标准误)为(13.5±2.5)和(15.0±2.3)次,最低的取食频率发生在19: 00~19: 30和20: 30~21: 00之间,分别取食(0.2±0.2)和(0.7±0.5)次。果蝠很少在母树上取食成熟的果实,相反它们用嘴叼下果实并携带到夜栖息地去进食,通常这些夜栖息地是具有密闭树冠、密集枝条的树种。夜栖息地在母树周围的分布根据环境中适合它们栖息的树种和分布而决定,不同母树周围其夜栖息地分布具有非常大的变异与空间异质性。钝叶榕(Ficus curtipes)、铁力木(Mesua ferrea) 和糖胶树(Alstonia scholaris) 是果蝠最喜爱的夜栖息地。在同样的情况下,尽管需要飞行更远的距离,两种果蝠都比较喜欢寻找具有许多枝条和小枝并且有复杂树冠的树木作为夜栖息地。两种果蝠取食光叶桑果实时,一部分种子通过消化道消化后被排泄出来,另外的一部分伴随着咀嚼后的果渣被吐出来,通过这两种方式,散布了大量的种子,再加上在飞行中也有排泄的习性,它们传播的种子在空间上更广泛。     

Day roost selection in female Bechstein's bats (Myotis bechsteinii): a field experiment to determine the influence of roost temperature

The decision where to live has far-reaching fitness consequences for animals. In contrast to most other mammals or birds that use sheltered nest sites, female Bechstein's bats frequently switch day roosts during one breeding season, and therefore must often decide where to spend the day. Selecting the right roost is important, because roost quality, e.g. microclimatic condition, influences survival and reproduction in bats. Although thermal factors are very important for the quality of roosts occupied by bats, whether bats base their day roost selection directly on roost temperature has not been tested in the field. Over one summer, we examined and tested the roost choice of 21 individually marked female Myotis bechsteinii living in one maternity colony. In a field experiment, we allowed the bats to choose between relatively warm versus cold bat boxes, while controlling for site preferences. We expected females to exhibit a preference for warm roosts during pregnancy and lactation to accelerate gestation and shorten the period of growth of their young. Roost occupancy over 160 census days reflected significant temperature differences among 89 surveyed roosts (14 tree holes and 75 bat boxes), and preferences changed with the season. Females significantly preferred cold roosts before parturition, whereas post-partum, they significantly favoured warm roosts. Temperature preferences were independent of the roost site, and thus roost selection was based directly on temperature. Boxes with significantly different daytime temperatures did not differ significantly at night. Consequently, bats would have to spend at least 1 day in a new roost to test it. Information transfer among colony members might facilitate knowledge of roost availability. Access to many roosts providing different microclimates is likely to be important for successful reproduction in the endangered Bechstein's bat.     

Modifying the physiological responses to handling stress in beluga sturgeon Huso huso (Linnaeus, 1758); Interactive effects of feeding time and dietary fat

The present study investigated the interaction of feeding times with two dietary fat levels on physiological responses to handling stress in juvenile Beluga sturgeon. Fish were fed with two different diets (high energy; HE: 24% fat and low energy; LE: 12% fat) for 8 weeks at two feeding times; 09:00 and 16:00 (during the day) or 21:00 and 04:00 (during the night). At the end of the trial, blood samples were taken and the resting fish were held in a net out of water for 90 s as the handling stressor. Three hours after application of stress, post‐stress blood was taken. Cortisol, glucose, and lactate concentrations were considered as stress indicators. The mean values of cortisol and lactate levels did not reveal a significant difference between pre‐ and 3‐hr post‐stress samples, but the average concentration of glucose showed a significant difference. Cortisol, lactate and glucose concentrations were not influenced by the difference in the diets. Moreover, the cortisol and lactate concentrations were not affected by the different feeding times, while glucose levels were significantly affected by the feeding times with the lowest level in fish fed during the day. With respect to stress indicators, the results revealed that feeding times affected pre‐ and post‐stress secondary response to handling stress, but the rate and magnitude of metabolites (cortisol, glucose and lactate) were not affected by dietary fat levels. Therefore, it is necessary to examine the best feeding times with the interaction of feed ingredients in sturgeon farming.     

An analysis of Bat Hawk Macheiramphus alcinus diet in the Melaky Region of lowland western Madagascar

We present information on the prey taken by the Bat Hawk Macheiramphus alcinus in two different areas of lowland western central Madagascar. These are the first dietary data from Madagascar for this widespread Old World species. The recovered remains were almost exclusively of bats and birds, with a few examples of reptiles and insects. In total, 178 pellets were analysed. On the basis of minimum number of individuals and biomass, bats accounted for 58.3% and 30.3%, respectively, and birds 36.1% and 69.7%, respectively. Amongst the nine species of bats recovered from the pellets, four were represented by multiple individuals, particularly taxa belonging to the families Molossidae and Vespertilionidae that fly in open areas, and for the 11 species of identified birds, all were represented by a single individual. These patterns are interpreted as a specialisation of feeding on bats during a narrow window of time at dusk, as they leave day roost sites, and then using birds in a more general manner to fill in nutritional needs.     

Virological and Serological Findings in Rousettus aegyptiacus Experimentally Inoculated with Vero Cells-Adapted Hogan Strain of Marburg Virus

The Egyptian fruit bat, Rousettus aegyptiacus, is currently regarded as a potential reservoir host for Marburg virus (MARV). However, the modes of transmission, the level of viral replication, tissue tropism and viral shedding pattern remains to be described. Captive-bred R. aegyptiacus, including adult males, females and pups were exposed to MARV by different inoculation routes. Blood, tissues, feces and urine from 9 bats inoculated by combination of nasal and oral routes were all negative for the virus and ELISA IgG antibody could not be demonstrated for up to 21 days post inoculation (p.i.). In 21 bats inoculated by a combination of intraperitoneal/subcutaneous route, viremia and the presence of MARV in different tissues was detected on days 2–9 p.i., and IgG antibody on days 9–21 p.i. In 3 bats inoculated subcutaneously, viremia was detected on days 5 and 8 (termination of experiment), with virus isolation from different organs. MARV could not be detected in urine, feces or oral swabs in any of the 3 experimental groups. However, it was detected in tissues which might contribute to horizontal or vertical transmission, e.g. lung, intestines, kidney, bladder, salivary glands, and female reproductive tract. Viremia lasting at least 5 days could also facilitate MARV mechanical transmission by blood sucking arthropods and infections of susceptible vertebrate hosts by direct contact with infected blood. All bats were clinically normal and no gross pathology was identified on post mortem examination. This work confirms the susceptibility of R. aegyptiacus to infection with MARV irrespective of sex and age and contributes to establishing a bat-filovirus experimental model. Further studies are required to uncover the mode of MARV transmission, and to investigate the putative role of R. aegyptiacus as a reservoir host.     

Use of brook char (Salvelinus fontinalis) physiological responses to stress as a teaching exercise

Fish hematological changes during osmotic and cold stress are used to introduce the physiological reactions of the animal to an acute stress. Brook char (Salvelinus fontinalis) were subjected to 1 h of stress before being anesthetized and having blood taken from their caudal vein. Glucose, hemoglobin, hematocrit, and osmolarity were determined in the blood samples. Analyses showed that glucose concentration tends to increase and hematocrit tends to decrease in stressed fish. Changes in hemoglobin concentration occurred only in cold-stressed fish. A rise in blood glucose concentration is the result of cortisol secreted by the hypothalamic-pituitary-adrenal axis. The glucose produced is used as an osmolyte or energy source to resist or combat the stress. In stressed fish, changes in hematocrit could be the result of the osmoconcentration of the blood plasma, as shown by the increase in osmolarity for the same group. In cold-stressed fish, a decrease in hemoglobin concentration could be the result of hemodilution by body cell water.     

Roosting Requirements of Two Frugivorous Bats (Sturnira lilium and Arbiteus intermedius) in Fragmented Neotropical Forest1

As tropical forest fragmentation accelerates, scientists are concerned with the loss of species, particularly those that play important ecological roles. Because bats play a vital role as the primary seed dispersers in cleared areas, maintaining healthy bat populations is critical to natural forest regeneration. Observations of foraging bats suggest that many Neotropical fruit‐eating species have fairly general habitat requirements and can forage in many different kinds of disturbed vegetation; however, their roosting requirements may be quite different. To test whether or not general foraging requirements are matched by equally broad roosting requirements, we used radiotelemetry to locate roost sites of two common frugivorous bat species (Sturnira lilium and Artibeus intermedius) in a fragmented forest in southeastern Mexico. Sturnira lilium roosted inside tree cavities and selected large‐diameter roost trees in remnant patches of mature forest. Fewer than 2 percent of trees surveyed had a mean diameter equal to or greater than roost trees used by . S. lilium, Artibeus intermedius roosted externally on branches and vines and under palm leaves and selected roost trees of much smaller diameter. Compared to random trees, roost trees chosen by A. intermedius were closer to neighboring taller trees and also closer in height to these trees. Such trees likely provide cryptic roosts beneath multiple overlapping crowns, with sufficient shelter from predators and the elements. While males of A. intermedius generally roosted alone in small trees within secondary forest, females roosted in small groups in larger trees within mature forest and commuted more than three times farther than males to reach their roost sites. Loss of mature forest could impair the ability of frugivorous bats to locate suitable roost sites. This could have a negative impact on bat populations, which in turn could decrease forest regeneration in impacted areas.     

Activity patterns of Pipistrelle bats (Pipistrellus pipistrellus) in north-east Scotland

Pipistrellus pipistrellus emerge from their nursery roosts in north-east Scotland about 35 minutes after sunset, at light intensities of between 15 and 35 lux. Cloud cover, windspeed, ambient temperature, rain, light mist and moonlight have no apparent effect on the time or pattern of emergence. Throughout pregnancy and lactation, emergence lasts for about an hour. After weaning, when the adult females have left the roost, their young take about 40 minutes to emerge. The average rate of initial emergence is proportional to colony size, and the maximum rate of emergence occurs half way through the exodus.
During pregnancy in May and June most bats leave the roost once each night soon after dusk and return between midnight and dawn. After parturition in late June the activity pattern becomes bimodal and the numbers of bats outside the roost show peaks after dusk and immediately before dawn. There is intermittent activity in the vicinity of the roost all night and bats make two or three flights each night. After weaning in August the activity pattern gradually ceases to be bimodal, and the number of flights per bat falls to between one and two. The average time spent outside the roost varies between 2–5 and 5 hours during the summer. The recorded activity patterns of night-flying insects are all bimodal, with peaks after dusk and before dawn, corresponding with the maximum number of bats outside the roost during lactation.