Carmi Korine

The effect of bat (Rousettus aegyptiacus) dispersal on seed germination in eastern Mediterranean habitats

The fruit-bat Rousettus aegyptiacus (Pteropodidae) in Israel consumes a variety of cultivated and wild fruits. The aim of this study was to explore some of its qualities as a dispersal agent for six fruit-bearing plant species. The feeding roosts of the fruit-bat are located an average of 30 m from its feeding trees and thus the bats disperse the seeds away from the shade of the parent canopy. The bat spits out large seeds but may pass some (2%) of the small seeds (<4 mg) through its digestive tract. However, neither the deposited seeds nor the ejected seeds (except in one case) had a significantly higher percentage germinating than intact seeds. Although the fruit-bat did not increase the percentage germinating, seeds of three plant species subject to different feeding behaviors (deposited in feces or spat out as ejecta) had a different temporal pattern of germination from the intact seeds. The combined seed germination distribution generated by these different treatments is more even over time than for each treatment alone. It is sugested that this increases asynchronous germination and therefore enhances plant fitness by spreading the risks encountered during germination, especially in eastern Mediterranean habitats where the pattern of rainfall is unpredictable.

Guild structure, foraging space use, and distribution in a community of insectivorous bats in the Negev Desert

Large-scale anthropogenic habitat degradation is taking place in the Negev Desert and such degradation is considered to be the primary cause of population decline in many bat species. A study of bat community structure in the central Negev Desert Highlands was undertaken to examine habitat associations, activity patterns and the distribution of bats in relation to landscape structure. During 1999 and 2000, mist-nets and bat detectors were used to capture bats and to monitor their presence in natural and artificial sites. In total, 12 species of insectivorous bats were found. Communities of insectivorous bats were divided into three guilds based on foraging space: open space foragers, background-cluttered space foragers, and highly cluttered space foragers. Bats of the background-cluttered space guild foraged over a variety of habitats while bats from the other guilds were more restricted with regard to their foraging spaces. In both years, season had a significant effect on bat activity. Despite there being significantly more bat activity in artificial sites than in natural sites, bat species richness was least in the artificial sites. For most species of desert-dwelling bats, areas that are typified by dense vegetation cover and have a perennial water source are of primary importance.

Is the Egyptian fruit-bat Rousettus aegyptiacus a pest in Israel? An analysis of the bat's diet and implications for its conservation

The Egyptian fruit-bat Rousettus aegyptiacus is regarded as a pest for agriculture. However, no quantitative data on its diet have been collected in Israel or in other Mediterranean areas, and control measures in the past reduced populations of insectivorous bats in Israel. We therefore studied the relative importance of native versus commercially cultivated fruit plants by analysis of bat faeces. Droppings were collected during 1993‐1995 in two roost-sites in the Carmel National Park. Results show that the bat feeds mainly on fruits but leaves and pollen are also eaten. Leaf eating was observed mainly during winter, when bats may face times of severe decrease in fruit availability and quality. Only four fruit species (15%) of the bat’s diet are commercially grown and only two of these in the research area. Therefore the definition of the fruit-bat as a major agricultural pest should be re-examined. Two eAective methods for controlling damage caused by bats are discussed. # 1999 Published by Elsevier Science Ltd. All rights reserved.

Nitrogen and Energy Balance of the Fruit Bat Rousettus aegyptlacus on Natural Fruit Diets

The nitrogen and energy balances of the Egyptian fruit bat, Rousettus aegyptiacus (Pteropodidae), were determined in a series of studies of animals on five single-fruit diets differing in their nutritional content (carob, Ceratonoia siliqua; Persian lilac, Melia azedarach; loquat, Eriobotrya japponica; mulberry, Murus nigra; and sycamore, Ficus sycomorus). It was found that except for Persian lilac, these fruits, which are eaten in nature by the bats, can adequately supply their nitrogen requirements, while Persian lilac and loquat were insufficient for their energy demands. On the basis of average nutrient composition across the tested fruits, the Egyptian fruit bat (mean body mass 144 g) requires a mean intake of 6g dry matter per day for maintaining nitrogen balance, while a mean intake of 11 g dry matter per day is needed in order to fulfill its daily energy requirements. These results suggest that energy, rather than nitrogen, is the limiting nutritional component in the diet of the fruit bat. The maintenance nitrogen requirement determined from the balance studies, 0.247 g N kg-0.75 d⁻¹, is 55% lower than expected from allometric relations. When the lilac diet is excluded, it is even lower: 0.110 g N kg-0.75 d⁻¹ (76% lower than expected). The maintenance nitrogen requirement is also much lower than reported for other species of fruit bats. This may reflect an adaptation to periods of low fruit availability and thus nitrogen shortage within the distribution limits of R. aegyptiacus.

DIETARY IMPLICATIONS OF INTRAPOPULATION VARIATION IN NITROGEN ISOTOPE COMPOSITION OF AN OLD WORLD FRUIT BAT

Abstract We used nitrogen isotope analysis from pectoral muscle of the Egyptian fruit bat Rousettus aegyptiacus (Chiroptera: Pteropodidae) to determine intrapopulation variation in sources of dietary protein throughout the year in northern Israel. In Mediterranean climates, winter and summer are stable seasons, whereas spring and fall are transitional seasons. Number of species of fruit-bearing plants is higher during the transitional periods, and we therefore predicted that intrapopulation variation would be higher during spring than in winter and summer; we made no prediction for fall because sample size was small. We also reconstructed sources of dietary protein for each individual using nitrogen isotope ratios (δ15N) to determine whether individuals foraged on the same sources of food within each season. Intrapopulation variation in δ15N was significantly higher in spring (δ15N range: 9.7–17.5‰) compared to winter (8.8–11.1‰) and summer (9.5–11.2‰), suggesting that individuals during this period varied more in their use of protein sources. Dietary reconstruction revealed intrapopulation partitioning among the bats in the use of plant food items, and interspecific partitioning among plants in their dependence on dispersal by bats.

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

We investigated the patterns of torpor use and body temperature (Tb) in reproductive Hemprich’s long‐eared bats (Otonycteris hemprichii; body mass ∼20 g) in the central Negev Desert highlands. We hypothesized that Tb 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 (Tr) using temperature data loggers. Before field data collection, we simultaneously measured skin temperature and Tb in three female bats in the laboratory and derived field body temperatures (Tbf) from these data. Female bats often used both deep and shallow daily torpor during the first two trimesters of pregnancy, with Tbf frequently dropping as low as 15°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 Tbf always >29°C, possibly to facilitate milk production. Tbf of pregnant and nursing bats varied with daily oscillations in Tr. Passive rewarming was not evident before the animals exited their roosts to forage.

Effect of water restriction on temperature regulation of the fruit-bat Rousettus aegyptiacus

1. 1. The thermoregulatory responses of the fruit-bat, Rousettus aegyptiacus, the only fruit-bat out of 32 bat species in Israel, were studied over a wide range of ambient temperature during normal hydration and during water restriction. 2. 2. The thermoneutral zone of the normally-hydrated fruit-bat ranged between 31–36°C. Oxygen consumption in this range averaged 0.95 ± 0.15 ml g−1 h−. 3. 3. Evaporative water loss and respiration frequency during normal hydration incrased as power functions of ambient temperature and were significantly correlated (P < 0.02). The normally-hydrated, heat exposed fruit-bat effectively regulated its body temperature and dissipated the total metabolic heat production by evaporative cooling. 4. 4. In bats fed on oven-dried apples (water restriction), body mass decreased by 20.72 ± 2.78%. Oxygen consumption between 32–36°C increased significantly and body temperature was relatively high. Evaporative water loss decreased sinificantly, except at 36°C where evaporative water loss was not significantly different from that during normal hydration, suggesting the preference for body temprature regulation at the cost of increased water loss. At this ambient temperature, dry thermal conductance increased significantly compared to normal hydration, facilitating non-evaporative heat loss. 5. 5. We conclude that the Israeli population of Rousettus aegyptiacus is adapted to the relatively warm climate and can cope with a decreased water content in its exclusive fruit diet and effectively regulate its body temperature and metabolic rate.

Comparison of fruit syndromes between the Egyptian fruit-bat (Rousettus aegyptiacus) and birds in East Mediterranean habitats

Abstract This study analyses the fruit syndrome of the Egyptian fruit-bat, Rousettus aegyptiacus, the only fruit-bat found in East Mediterranean habitats. Two different sets of bat-fruit syndromes were revealed. One follows the general bat-fruit syndrome and one represents a special case of bat-dispersed fruit syndrome only found in East Mediterranean habitats. The latter syndrome is characterized by dry fruits with a relatively high protein content. Fruit species that belong to this syndrome are available mostly in winter (when the fruit-bat faces a severe shortage in fruit availability and inadequate fruit quality). The fruit syndromes and dietary overlap between frugivorous birds (based on the literature) and the fruit-bat were also studied. Features associated with each set of fruit species generally follow the known bat and bird syndromes. Bird-dispersed fruits tend to be small, with a high seed mass to pulp mass, variable in fat content and characterized by a high ash content. However, when the shared fruit species were included in the analysis, no significant differences were found in fruit features between the bird-dispersed and bat-dispersed fruit syndromes. A limited and asymmetrical dietary overlap was observed between these two taxa, mainly between introduced and cultivated fruits.

The Relationship between Cutaneous Water Loss and Thermoregulatory State in Kuhl’s Pipistrelle Pipistrellus kuhlii, a Vespertillionid Bat

Total evaporative water loss is the sum of respiratory water loss (RWL) and cutaneous water loss (CWL) and constitutes the main avenue of water loss in bats. Because bats fly and have large surface-to-volume ratios, they potentially have high rates of RWL and CWL. Most species of small insectivorous bats have the ability to reduce their body temperature (Tb) at rest, which substantially reduces energy expenditure and water loss. We hypothesized that bats reduce evaporative water loss during bouts of deep hypothermia (torpor) by decreasing RWL and CWL. We measured Tb, RWL, CWL, and resting metabolic rate (RMR) in Kuhl’s pipistrelle Pipistrellus kuhlii, a small insectivorous bat. In support of our hypothesis, we found that RWL decreased with decreasing RMR. We found that CWL was lower in torpid individuals than in normothermic bats; however, bats in deep torpor had similar or higher CWL than bats in shallow torpor, suggesting that they exert a less effective physiological control over CWL when in deep torpor. Because insectivorous bats spend most of their lives in torpor or hibernation, the regulation of CWL in different heterothermic states has relevant ecological and evolutionary consequences.

Changes in Milk Composition of the Egyptian Fruit Bat, Rousettus aegyptiacus (Pteropodidae), during Lactation

Composition of milk of the free-ranging Egyptian fruit-bat ( Rousettus aegyptiacus ) was studied from early to peak lactation. Carbohydrates were the main component during early lactation and fats were the main component in milk from mid- to peak lactation. Dry-matter and energy content of the milk increased during mid-lactation and stabilized at peak lactation. Increases were a consequence of increased fat content, but carbohydrate and protein contents remained relatively stable. We conclude that the milk composition of R. aegyptiacus is related to diet and frequent suckling by young. We suggest that the inability of R. aegyptiacus to produce concentrated milk of high fat and energy contents and a low protein content is compensated for by prolonged lactation.