Roost Temperature Research Articles

Urban roost temperatures of large-spotted-genets: The effect of anthropogenic structures

Generally, large-spotted genets (Genetta tigrina) use tree hollows and canopies as daytime roosts during their inactive phase. However, there has been an increasing tendency for individuals to make use of anthropogenic structures, such as roofs, within urban landscapes in KwaZulu-Natal, South Africa. This study investigated the roosting thermal dynamics of large-spotted genets within the urban suburbs of Kloof. Roost temperatures were recorded with i-Button® temperature loggers at known large-spotted genet roosts in anthropogenic structures as well as in natural roost sites. Over the seasons, temperatures varied significantly between months and among different roosts. However, anthropogenic roost temperatures were higher than ambient temperatures throughout the study period. Furthermore, anthropogenic roosts had higher temperatures (with lower variability) than natural roost sites. This study highlighted the importance of anthropogenic structures as daytime roosts for large-spotted genets within an urban mosaic. However, high temperatures experienced during the summer can be detrimental to juvenile large-spotted genets resulting in plasticity of breeding behaviour and a switch to producing young in cooler months.

Energetic benefits of enhanced summer roosting habitat for little brown bats (Myotis lucifugus) recovering from white-nose syndrome.

Habitat modification can improve outcomes for imperilled wildlife. Insectivorous bats in North America face a range of conservation threats, including habitat loss and white-nose syndrome (WNS). Even healthy bats face energetic constraints during spring, but enhancement of roosting habitat could reduce energetic costs, increase survival and enhance recovery from WNS. We tested the potential of artificial heating of bat roosts as a management tool for threatened bat populations. We predicted that: (i) after hibernation, captive bats would be more likely to select a roost maintained at a temperature near their thermoneutral zone; (ii) bats recovering from WNS at the end of hibernation would show a stronger preference for heated roosts compared with healthy bats; and (iii) heated roosts would result in biologically significant energy savings. We housed two groups of bats (WNS-positive and control) in separate flight cages following hibernation. Over 7.5 weeks, we quantified the presence of individuals in heated vs. unheated bat houses within each cage. We then used a series of bioenergetic models to quantify thermoregulatory costs in each type of roost under a number of scenarios. Bats preferentially selected heated bat houses, but WNS-affected bats were much more likely to use the heated bat house compared with control animals. Our model predicted energy savings of up to 81.2% for bats in artificially heated roosts if roost temperature was allowed to cool at night to facilitate short bouts of torpor. Our results are consistent with research highlighting the importance of roost microclimate and suggest that protection and enhancement of high-quality, natural roosting environments should be a priority response to a range of threats, including WNS. Our findings also suggest the potential of artificially heated bat houses to help populations recover from WNS, but more work is needed before these might be implemented on a large scale.

Nightly clustering in communal roosts and the regular presence of adult females at night provide thermal benefits for juvenile Bechstein's bats

Thermal benefits from clustering during the reproductive period are assumed to explain the almost ubiquitous group living behaviour in female temperate zone bats. While there is evidence for such benefits in adult female bats in the field, to our knowledge no studies have quantified the thermal benefits of clustering in juvenile, non-volant bats. Using thermography, we assessed in the field (1) whether juvenile Bechstein's bats thermally benefitted from clustering during the absence of adult females at night; and (2) whether the regular nightly visits of adult females led to an increase in juveniles’ skin temperatures. We show that the juveniles did indeed thermally benefit from clustering when their mothers were absent. With increasing age, clustering juveniles experienced lower heat loss during the absence of adult females. Also the influence of roost temperatures on the juveniles’ skin temperature decreased when they became older, indicating improved thermoregulation abilities. We also observed a small, although significant increase in the juveniles’ surface skin temperature after visits by adult females. In conclusion, our study provides evidence that clustering at night is advantageous for non-volant juvenile bats, because it improves their thermoregulation at times when mothers are not present in the communal roost.

Winter and Summer Torpor in a Free-Ranging Subtropical Desert Bat: The Fishing Myotis (Myotis vivesi)

Use of torpor likely favors the survival of subtropical bats in harsh environments. The fishing myotis (Myotis vivesi) is a species endemic to desert islands in the Gulf of California, where summers are extremely hot and winters are cold and windy. We explored thermoregulating abilities of M. vivesi measuring skin temperature (Tskin) on free-ranging individuals in winter 2010 and 2011, and in summer 2010. We also measured ambient (Ta) and roost (Troost) temperatures during the study, and we obtained data for wind speed at night time during winter periods. We found that all bats entered torpor in both winters and that at least three individuals hibernated for several days, which had not been reported previously for bats in subtropical deserts. In summer, three individuals entered short bouts of shallow torpor in early mornings. Roosts were slightly warmer than Ta in winter at nightime, and in summer they never reached temperatures > 38.7°C, even at Ta ≈ 45°C. Roost occupancy in winter was higher during win...

Roost Temperature and Fidelity of Wahlberg's Epauletted Fruit Bat,Epomophorus wahlbergi, in an Urban Environment

Generally, Wahlberg's epauletted fruit bat (Epomophorus wahlbergi) roost in trees or under the eaves of buildings. This study investigated the roosting dynamics of E. wahlbergi in the urban environment of Pietermaritzburg, South Africa. To determine roost fidelity bats were radio-tracked to daytime roosts. Bats were found to change their daytime roosts regularly, and would change more frequently during winter than spring. Roost temperatures were measured by placing i-Button® temperature loggers at known roosts, either in man-made structures or vegetation. Temperatures varied across different roosts, but roost temperatures were generally higher than ambient temperatures. Roosts in man-made structures had higher temperatures than those in natural vegetation. This study showed the importance of temperature in E. wahlbergi daytime roosts, although other factors such as reproduction and social interactions, predator avoidance and proximity to food resources are likely to also affect selection of daytime roosts.

Roost temperature and fidelity of Wahlberg’s epauletted fruit bat, Epomophorus wahlbergi, in an urban environment

Generally,Wahlberg’s epauletted fruit bat (Epomophorus wahlbergi) roost in trees or under the eaves of buildings. This study investigated the roosting dynamics of E. wahlbergi in the urban environment of Pietermaritzburg, South Africa. To determine roost fidelity bats were radiotracked to daytime roosts. Bats were found to change their daytime roosts regularly, and would change more frequently during winter than spring. Roost temperatures were measured by placing i-Button® temperature loggers at known roosts, either in man-made structures or vegetation. Temperatures varied across different roosts, but roost temperatures were generally higher than ambient temperatures. Roosts in man-made structures had higher temperatures than those in natural vegetation. This study showed the importance of temperature in E. wahlbergi daytime roosts, although other factors such as reproduction and social interactions, predator avoidance and proximity to food resources are likely to also affect selection of daytime roosts.

Crecimiento postnatal y desarrollo del vuelo en el murciélago Leptonycteris yerbabuenae en Chiapas, México

Introduction: Neonate bats represent 12-43% of postpartum-maternal body mass, but unlike other small mammals with large offsprings, bats are altricial and totally dependent on maternal care for survival. Neonates of several bat species are born naked, with low thermoregulatory ability; therefore their growth and development are affected by factors such as humidity and temperature, likewise by sex and food availability, among others. Phyllostomidae is the most diverse family of bats in the Neotropics, nevertheless, there are few studies on the postnatal growth and development of their offspring and especially of glosophagine bats. For that reason, we described the postnatal growth and development of a population of Leptonycteris yerbabuenae inhabiting “The Laguitos” Cave, in the state of Chiapas, México. This species is distributed from the southern United States, through most of Mexico to Guatemala and El Salvador .In Mexico this species is listed as “threatened” by the Mexican government (SEMARNAT, 2010). Methods: Based on capture-recapture data, we examined the growth trajectories of three morphological variables and flight development of young Leptonycteris yerbabuenae during 1998 and 2001. Sexual variation, and inter-year variation among specimens of the same age category was assessed by a t Student test. The growth of each variable was measured with a lineal regression analysis, meanwhile the growth parameters were derived from a logistic growth equation and from a polynomial model. To describe the flight development in young bats, we classified these as non-volant, semivolant and volant as was done by Stern et al . (1997) in Phyllostomus hastatus . Results: The highest records for ambient and roost temperature were in 2001, and so were the lowest records for relative humidity compared with 1998 conditions (Fig. 1). Male and female young bats (Fig. 2) were morphologically similar in the three variables assessed in both years (Table 1). The body mass and length of the forearm increased linearly the first three weeks in both years, while the length of the epiphysis grew until the second week in 1998 and day 10 in 2001, then the growth rate decreased in all variables (Figure 3, Table 2). The sustained flight was achieved at ages 15 and 20 days in 2001 and 1998, respectively (Table 3). Discussion and conclusions: This study shows that neonates of Leptonycteris yerbabuenae from Chiapas born naked and with the ear meatus closed compared with those of Carbo, Sonora (Gould 1975), what reveals intraspecific variability of these traits. The morphological similarity between male and females young bats was expected; because there is not secondary sexual dimorphism in adults. Neonates of 1998 had lesser body mass and greater length of the fourth metacarpal-phalangeal epiphyseal gap than specimens of 2001. Differences between years were persistent during growth phase, and maybe these results were consequences of different weather conditions that prevailed in each year. The growth parameters derived from the logistic model for forearm length (0.07-0.10) and body mass (0.06-0.10) of L. yerbabuenae were similar to other neotropical phyllostomid bats, but lower than vespertilionid bats. These results may be influenced by phylogenetic distance or by environmental conditions. The sustained flight started five days earlier in 2001 compared with 1998, probably influenced by different environmental conditions that prevailed each year. Therefore the sustained flight was achieved at an age similar to those of other phyllostomid bats. Key words: Cave, Chiroptera, Phyllostomidae, relative humidity, temperature, growth trajectories.

Roost selection by female Hemprich's long-eared bats

Selection of suitable roosts by bats can have fitness benefits by providing shelter and a place to rear young. Assuming that lactating bats behave differently from, and have greater food requirements than pregnant bats, we predicted that near the end of pregnancy, desert-dwelling bats would move to roosts appropriate to their changing needs. We followed radio-tagged pregnant and lactating female Hemprich's long-eared bats, Otonycteris hemprichii, to their roosts and characterized the shape of 38 roosts by measuring their linear dimensions, compass direction of the outer rock face, roost temperature (Tr) and the distance from the roost to the bats’ main foraging site. We also compared roosts used by bats to randomly chosen “potential” roosts. During reproduction, female O. hemprichii roosted mainly in cracks. Throughout the bats’ reproductive period, most of the roosts faced the morning sun. Temperatures in roosts used by pregnant bats or distances to their main foraging site were not different from those used by lactating individuals. However, pregnant females used horizontal cracks while lactating females used vertical cracks. Comparing roosts used by bats to “potential” roosts, we found that the former had smaller daily amplitudes of Tr than the “potential” ones. Female O. hemprichii used only a small number of the available roosts in the area, and re-used some of them year after year. We suggest that, in contrast to bats that live in temperate habitats, O. hemprichii do not need to seek roosts with temperature conditions specific to the periods of pregnancy or lactation because natural changes in Tr suffice, and other factors are involved in the decision to choose a roost or to abandon it.

Factors underlying migratory bat aggregations in chestnut groves

ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 21:105-114 (2013) - DOI: https://doi.org/10.3354/esr00496 Factors underlying migratory bat aggregations in chestnut groves Susanne Szentkuti1,*, Fabio Bontadina1,2*,**, Martina Spada3, Marco Moretti4, Nicola Zambelli5, Adriano Martinoli3, Raphaël Arlettaz1 1Institute of Ecology and Evolution, Division of Conservation Biology, University of Bern, Baltzerstrasse 6, 3012 Bern, Switzerland 2SWILD, Urban Ecology & Wildlife Research, Wuhrstrasse 12, 8003 Zurich, Switzerland 3Department of Theoretical and Applied Sciences, Università degli Studi dell’Insubria, Via J. H. Dunant 3, 21100 Varese, Italy 4WSL Swiss Federal Research Institute, Community Ecology Unit, Via Belsoggiorno 22, 6500 Bellinzona, Switzerland 5Centro protezione chirotteri Ticino (CPT), 6714 Semione, Switzerland *These authors contributed equally to this study**Corresponding author. Email: fabio.bontadina@swild.ch ABSTRACT: Deciduous woodlands have undergone major structural changes in Europe in the course of the last century. Dense woodlands have, for instance, replaced traditionally managed, open sweet chestnut groves, and have led to biodiversity losses. Surveys carried out in the southern Alps have shown that the frequency of occurrence of the rare migratory Leisler’s bat Nyctalus leisleri in bat boxes is much higher in managed than in unmanaged chestnut groves, pointing to the importance of traditional groves as stopover sites. To identify the reasons for this habitat preference we investigated whether managed chestnut groves constitute a more appropriate foraging ground than closed stands, and whether bat boxes in managed chestnut groves offer more suitable temperature conditions for roosting. Foraging habitat selection and roost usage were investigated by means of radiotracking and temperature loggers, respectively. Foraging Leisler’s bats predominantly selected deciduous woodlands over other habitat types, but showed no distinct preference for either type of chestnut grove over other forest types. In managed chestnut groves, bats used cooler boxes than others available in the same habitat, but there was no difference in temperature between the boxes used in managed versus unmanaged groves. Our results provide no evidence that foraging opportunities or roost temperature dictate the forest-specific pattern of bat box occupancy. As an alternative explanation, we suggest that managed chestnut groves may represent optimal lekking arenas due to their open structure and high roost density. Whatever the reason for this habitat preference, partially maintaining traditional management, resulting in a semi-open, mosaic landscape, is likely key to maintaining chestnut groves attractive for this migratory bat. KEY WORDS: Habitat selection · Radiotracking · Open forest stand · Management · Chiroptera · Castanea sativa · Leislers bat · Nyctalus leisleri Full text in pdf format PreviousNextCite this article as: Szentkuti S, Bontadina F, Spada M, Moretti M, Zambelli N, Martinoli A, Arlettaz R (2013) Factors underlying migratory bat aggregations in chestnut groves. Endang Species Res 21:105-114. https://doi.org/10.3354/esr00496 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 21, No. 2. Online publication date: August 13, 2013 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2013 Inter-Research.

Thermoregulation in free-ranging Nycteris thebaica (Nycteridae) during winter: No evidence of torpor

Bats are among the most heterothermic mammals, with nearly all species investigated under free-ranging conditions to date exhibiting some degree of daily torpor and/or hibernation. We investigated thermoregulation during late winter by seven Nycteris thebaica in a warm, semi-arid habitat in northern South Africa, using temperature-sensitive transmitters to measure skin temperature (Tskin). Unexpectedly, we found no evidence for any expression of daily torpor or hibernation based on a total of 86 days of data from 7 bats (one male and six females), despite air temperatures as low as ∼10°C. Instead, daytime Tskin was distributed unimodally with most values in the 33–35°C range, and a minimum Tskin of 28.4°C at a roost temperature of 24.6°C. There are several possible reasons why N. thebaica may avoid torpor, including predation in roosts, and the long nightly foraging periods of this species compared to many others.

Cool gleaners: Thermoregulation in sympatric bat species

Thermoregulatory behavior in temperate bats is influenced by gender, food availability, ambient temperature and reproduction. Ecologically and morphologically similar bat species (Myotis bechsteinii, M. nattereri, and Plecotus auritus; Vespertilionidae) facing similar diurnal conditions should therefore not differ in their thermoregulatory behavior. Identified day roosts (n=23) of radio-tagged bats (n=30) were spread over an area of 33.1ha, but ambient temperature did not differ between roosting sites. Furthermore, there was no significant difference in cardinal direction, roost height, canopy coverage, and breast height diameter between day roosts used by the three species. Minimum roost temperatures and isolation values, however, differed significantly between our species with lowest values in P. auritus. The range of skin temperatures (min–max) recorded by temperature-sensitive transmitters was not species-specific with the lowest ranges in late pregnancy (mean±SD: 7.1±1.1°C) and highest in post-lactation (mean±SD: 13.1±1.1°C). The minimum skin temperature, however, was species-specific with the lowest values in P. auritus (mean±SD: 20.2±1.1°C), intermediate in M. nattereri (mean±SD: 23.4±1.0°C), and the highest in M. bechsteinii (mean±SD: 26.8±1.0°C). Species-specific usage of energy-saving mechanisms might represent an important niche differentiation of species. Different mechanisms might allow, e.g. one species to occupy colder roosts with higher temperature variations or to shorten foraging times due to distinct thermoregulatory behavior.

Interspecific variation in thermoregulation among three sympatric bats inhabiting a hot, semi-arid environment

Bats in hot roosts experience some of the most thermally challenging environments of any endotherms, but little is known about how heat tolerance and evaporative cooling capacity vary among species. We investigated thermoregulation in three sympatric species (Nycteris thebaica, Taphozous mauritianus and Sauromys petrophilus) in a hot, semi-arid environment by measuring body temperature (T(b)), metabolic rate and evaporative water loss (EWL) at air temperatures (T(a)) of 10-42 °C. S. petrophilus was highly heterothermic with no clear thermoneutral zone, and exhibited rapid increases in EWL at high T(a) to a maximum of 23.7 ± 7.4 mg g⁻¹ h⁻¹ at T(a) ≈ 42 °C, with a concomitant maximum T(b) of 43.7 ± 1.0 °C. T. mauritianus remained largely normothermic at T(a)s below thermoneutrality and increased EWL to 14.7 ± 1.3 mg g⁻¹ h⁻¹ at T(a) ≈ 42 °C, with a maximum T(b) of 42.9 ± 1.6 °C. In N. thebaica, EWL began increasing at lower T (a) than in either of the other species and reached a maximum of 18.6 ± 2.1 mg g⁻¹ h⁻¹ at T(a) = 39.4 °C, with comparatively high maximum T(b) values of 45.0 ± 0.9 °C. Under the conditions of our study, N. thebaica was considerably less heat tolerant than the other two species. Among seven species of bats for which data on T(b) as well as roost temperatures in comparison to outside T(a) are available, we found limited evidence for a correlation between overall heat tolerance and the extent to which roosts are buffered from high T(a).

Body temperature patterns of big brown bats during winter in a building hibernaculum

Abstract Hibernating bats display a wide range of thermoregulatory patterns during hibernation, but to date, the majority of research on the topic has been done on cavernicolous bats. Thus, we measured skin temperature of free-living big brown bats (Eptesicus fuscus) during winter in a building hibernaculum in western Indiana. Torpor bouts were considerably shorter than bouts used by cavernicolous bats, lasting a mean of 3.3 days, whereas arousals lasted on average 5.0 h. There was a significant correlation between roost temperature and length of the euthermic period and a larger proportion of bats aroused on warm days, suggesting big brown bats might be taking advantage of warm nights to forage, although evidence for winter feeding is ambiguous in this population. As has been recorded for other noncavernicolous bats during hibernation, most individuals took advantage of partial passive rewarming during some arousals. We estimate these passive arousals could save bats, on average, 96 mg of fat over the co...

Metabolism during winter in a subtropical hibernating bat, the Formosan leaf-nosed bat (Hipposideros terasensis)

The 60-g subtropical Formosan leaf-nosed bat, Hipposideros terasensis, hibernates in the wild at warm roost (and hence body) temperatures up to 23°C. For small hibernators, torpid metabolic rate is temperature dependent and thus hibernation in warm hibernacula is predicted to be energetically costly. This species, however, rarely feeds during the hibernation season to offset the expected high energetic costs. In this study we used a respirometry system to quantify physiological characteristics of euthermic and torpid H. terasensis in winter. We tested the hypothesis that H. terasensis exhibits metabolic inhibition during torpor. Our results showed that H. terasensis saved 94.6% energy by using torpor at air temperatures of 15°C, compared with its euthermic metabolic rate at that air temperature. Torpor metabolic rate declined with declining air temperature to around 14°C, but then increased at lower air temperatures of 10–14°C. Above 14°C, the slope of − 13.0°K ± 1.4°K between metabolic rates and body temperatures in an Arrhenius plot (or Q10 = 4.4) suggests that, in addition to direct temperature effects, H. terasensis exhibited metabolic inhibition during torpor. A model used to evaluate energy expenditure of H. terasensis showed that at 20°C and 23°C a 55-g bat needs 194 kJ (4.9 g fat) and 273.2 kJ (6.9 g fat), respectively, to survive a 70-day hibernation period.

Hibernation in warm hibernacula by free-ranging Formosan leaf-nosed bats, Hipposideros terasensis, in subtropical Taiwan

The subtropical Formosan leaf-nosed bats, Hipposideros terasensis (Hipposideridae), show little activity during winter. It has never been determined whether in winter they exhibit hibernation and multi-day periods of low body temperature. The objectives of this study were to understand the winter activity pattern of H. terasensis and to examine whether it enters hibernation during winter. We monitored the skin temperature (T (sk)) of nine free-ranging H. terasensis by attaching temperature-sensitive transmitters during the winters of 2007-2008 and 2008-2009. The results showed that H. terasensis entered hibernation from late December to early March. H. terasensis, however, differs from temperate hibernating bats in several ways: (1) it is capable of hibernation at roost temperature (T (r)) and T (sk)>20°C; (2) hibernation at high T (r) and T (sk) does not lead to a relatively high arousal frequency; and (3) adults do not increase body mass in autumn prior to hibernation. To test the hypothesis that H. terasensis feeds frequently during the hibernation period to compensate for the high energetic demands of hibernating in warm hibernacula, we recorded the number and timing of bats that emerged from and entered into a hibernaculum, which contained more than 1,000 bats. From 30 December 2007 to 29 February 2008, an average of only 8.4 bats (<1%) per night (29 nights) emerged from the hibernaculum. Adult bats lost an average of 13-14% of body mass during an approximately 70-day hibernation period. We suggest that H. terasensis might have remarkably low torpid metabolic rates during hibernation.

Divergent Microclimates in Artificial and Natural Roosts of the Large-Footed Myotis (Myotis macropus)

The thermal environment of day roosts is considered one of the most influential factors affecting the survival, growth and reproduction of microbats. The use of torpor is a common energy saving strategy employed by microbats in temperate regions. The efficiency of entry into, and arousal from, torpor is governed by roost microclimate, primarily roost temperature. The large-footed myotis Myotis macropus roosts in both tree cavities and a man-made tunnel at Yan Yean reservoir in Victoria, Australia. We investigated the thermal properties of both roost types in comparison to available tree cavities and ambient temperature over four time periods from October 2003 to May 2005. Tree cavities and tunnel roosts remained significantly warmer at night, cooler during the day, and were more stable than ambient temperatures. In addition, roost tree cavities were significantly cooler between 10:00–13:00 h compared to available tree cavities, and there was a trend for roost tree cavities to be slightly warmer at night a...

The Effect of Roost Environment on Roost Selection by Non-Reproductive and Dispersing Asian Parti-Coloured BatsVespertilio sinensis

Abstract. Roosting of Asian parti-coloured bats (Vespertilio sinensis) in man-made structures is frequently results in conflict with humans. Therefore, to determine optimal alternative roosts, we studied roost preference of this species by testing the effects of roost temperature, surrounding environment and the distance from the nearest nursery colony on roost selection by V. sinensis in manipulative field experiments. We installed white (cooler) and black (warmer) bat boxes at shaded and sun-exposed sites. Although no nursery colonies were formed in the bat boxes, a few individuals (1–5) roosted during the lactation period, while many individuals (≥20) roosted during the post-lactation period. During lactation, bats used both white and black boxes, but preferred using the boxes placed at the shaded sites over those placed at the sun-exposed sites. On the other hand, during the post-lactation period, almost all individuals used the white boxes rather than the black boxes. However, adult females preferred...

The Use of Torpor in Reproductive Female Hemprich’s Long‐Eared Bats (Otonycteris hemprichii)

We investigated the patterns of torpor use and body temperature (T(b)) in reproductive Hemprich's long-eared bats (Otonycteris hemprichii; body mass approximately 20 g) in the central Negev Desert highlands. We hypothesized that T(b) regulation in female O. hemprichii during reproduction is shaped by a trade-off between the energy and temperature requirements of embryo and pup growth and the mother's own need to use torpor and passive rewarming to save energy and water. We predicted that patterns of torpor use change during pregnancy but change little if at all during nursing. We used radio telemetry to track, find the roosts of, and measure the skin temperatures of eight pregnant and 15 nursing bats during the years 2002-2004; we measured roost temperature (T(r)) using temperature data loggers. Before field data collection, we simultaneously measured skin temperature and T(b) in three female bats in the laboratory and derived field body temperatures (T(bf)) from these data. Female bats often used both deep and shallow daily torpor during the first two trimesters of pregnancy, with T(bf) frequently dropping as low as 15 degrees C. Pregnant females used only shallow torpor during the last trimester of pregnancy, perhaps to permit faster growth of the embryo. During nursing, the bats used only shallow torpor, with T(bf) always >29 degrees C, possibly to facilitate milk production. T(bf) of pregnant and nursing bats varied with daily oscillations in T(r). Passive rewarming was not evident before the animals exited their roosts to forage.

Birth size and postnatal growth in cave‐ and bridge‐roosting Brazilian free‐tailed bats

As the human population continues to expand, increased encroachment on natural landscapes and wildlife habitats is expected. Organisms able to acclimate to human-altered environments should have a selective advantage over those unable to do so. Over the past two decades, bats have increasingly begun to roost and raise offspring in spaces beneath pre-cast concrete bridges. Few studies have examined the health or fitness of individuals living in these anthropogenic sites. In the present study, we examined birth size and postnatal growth, as surrogates of reproductive success, in Brazilian free-tailed bat pups born at a natural and a human-made roost. Based on putative stress-related conditions (noise from vehicular traffic, chemical pollutants and a modified social environment) present at bridges, we predicted that bats at these sites would have reduced reproductive success. Contrary to our prediction, pups born at a bridge site were on average heavier and larger at birth and grew faster than those born at a cave site. Also, both birth size and growth rates of pups differ between years. We attribute observed differences to a combination of roost-related conditions (i.e. roost temperature and proximity to foraging areas), climate and maternal effects with larger mothers raising larger pups. Thus, some bridge roosts, at least in the short term, are suitable, and in some cases may provide better conditions, for raising young bat pups than cave roosts.

Which factors regulate the reproduction of ectoparasites of temperate-zone cave-dwelling bats?

We studied the factors which regulate the reproduction of ectoparasites of temperate-zone cave-dwelling bats, using the Schreiber's bat (Miniopterus schreibersii) and its ectoparasites as a model. For this, we searched 969 bats during 2003 and 2004 at important stages of the bat yearly cycle and found four ectoparasite species regularly occurring on them: two nycteribiids (Nycteribia schmidlii and Penicillidia conspicua), one wing mite (Spinturnix psi), and one hard tick (Ixodes simplex simplex). These parasites were present throughout the yearly cycle, but their reproductive activity greatly fluctuated seasonally. Also, we found that sex, age, and reproductive status of the host strongly influenced the reproductive activity of parasites. Overall, the four parasite species had a similar reproductive pattern, reproducing more intensively during the pregnancy and nursing seasons of M. schreibersii, mainly on pregnant and juvenile bats. Moreover, parasites greatly reduced reproductive activity during winter, while bats were in deep torpor or hibernating. We conclude that reproduction in ectoparasites of M. schreibersii and of many other temperate cave-dwelling bats is mostly regulated by the reproductive cycle of their bat hosts, but also limited by roost temperatures during winter. The fact that the reproductive cycle of parasite species of such distinct taxonomic groups are similarly adjusted to that of their bat host suggests that this adjustment is a highly adaptive trait.