, Volume 101, Issue 4, pp 407–415 | Cite as

Dietary energetics of the insectivorous Mexican free-tailed bat (Tadarida brasiliensis) during pregnancy and lactation

  • T. H. Kunz
  • J. O. WhitakerJr.
  • M. D. Wadanoli
Original Paper


Stomach content analysis of 20 pregnant (x body mass=13.4 g) and 18 lactating (x body mass=11.5 g) female Tadarida brasiliensis revealed that the diet, expressed as percent volume, consists largely of lepidopterans, coleopterans, hymenopterans, and dipterans, in decreasing order of importance. We found no significant difference in the diet of pregnant and lactating females when expressed as percent volume. However, when expressed as percent frequency, proportionately more pregnant females fed on lepidopterans, coleopterans, and dipterans than did lactating bats, and proportionately more lactating females fed on hymenopterans. We found no significant differences in the percentages of water, lean dry mass, fat, and energy density in the stomach contents of pregnant and lactating females. Water in stomach contents averaged 62.7% and fat and lean dry mass averaged 22.2% and 15.2%, respectively (expressed as percentage of wet mass); energy density averaged 31.2 kJ g−1 dry mass. This relatively high energy density of stomach contents, as compared to whole insects, can be attributed to the consumption of insects high in fat (especially flying ants) and the abdomens only of moths and beetles (other body parts being discarded). Estimates of nightly food intake increased markedly from mid- to late pregnancy, stabilized or decreased during late pregnancy, and increased again during early to mid-lactation. Average nightly feeding rate doubled from pregnancy to lactation and increased threefold during the first half of lactation. By adjusting our gravimetric estimates of nightly feeding rate upwards by 40% (based on estimates of field metabolic rate), we estimate that the average nightly energy intake of female T. brasiliensis ranges from 57 kJ day−1 in early lactation to 104 kJ day−1 in mid-lactation. These estimates represent nightly feeding rates averaging 39% and 73% of a female's body mass in the period from early to mid-lactation, respectively.

Key words

Bats Energetics Diet composition Feeding rates Tadarida brasiliensis 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Angelo M, Slansky F Jr (1984) Body building by insects: tradeoffs in resource allocation with particular references to migratory species. Fla Entomol 67:22–41Google Scholar
  2. Anthony ELP, Kunz TH (1977) Feeding strategies of the little brown bat, Myotis lucifugus, in southern New Hampshire. Ecology 58:775–786Google Scholar
  3. Baldridge RS, Rettenmeyer CW, Watkins JF II (1980) Seasonal, nocturnal and diurnal flight periodicities of Nearctic army ant males (Hymenoptera:Formicidae). J Kans Entomol Soc 53:189–204Google Scholar
  4. Barclay RMR (1989) The effect of reproductive condition on the foraging behavior of female hoary bats, Lasiurus cinereus. Behav Ecol Sociobiol 24:31–37Google Scholar
  5. Bassett JE (1982) Habitat aridity and intraspecific differences in the urine concentrating ability of insectivorous bats. Comp Biochem Physiol 72:703–708Google Scholar
  6. Blaxter BK (1989) Energy metabolism in animals and man. Cambridge University Press, Cambridge, UKGoogle Scholar
  7. Buchler ER (1975) Food transit time in Myotis lucifugus (Chiroptera: Vespertilionidae). J Mammal 56:252–255Google Scholar
  8. Buchler ER (1976) Prey selection by Myotis lucifugus (Chiroptera: Vespertilionidae). Am Nat 110:619–628Google Scholar
  9. Carpenter RE (1969) Structure and function of the kidney and the water balance of desert bats. Physiol Zool 42:288–302Google Scholar
  10. Cummins KW, Wuycheck JC (1971) Caloric equivalents for investigations in ecological energetics. Mitt Int Ver Theor Angew Limmol 18:1–158Google Scholar
  11. Davis RB, Herreid CF II, Short HL (1962) Mexican free-tailed bats in Texas. Ecol Monogr 32:311–346Google Scholar
  12. Easterla DA, Whitaker JO Jr (1972) Food habits of some bats from Big Bend National Park, Texas. J Mammal 53:887–890Google Scholar
  13. Funakoshi K, Uchida TA (1975) Studies on the physiological and ecological adaptation of temperature insectivorous bats. I. Feeding activities in the Japanese long-fingered bat, Miniopterus schreibersi fuliginosus. Jpn J Ecol 25:217–234Google Scholar
  14. Geluso KN (1978) Urine concentrating ability and renal structure of insectivorous bats. J Mammal 59:312–323Google Scholar
  15. Griffin DR, Thompson D (1982) High altitude echolocation of insects by bats. Behav Ecol Sociobiol 10:303–306Google Scholar
  16. Hill JE, Smith JD (1984) Bats: a natural history. University of Texas Press, AustinGoogle Scholar
  17. Jones G, Rayner JMV (1988) Flight performance, foraging tactics and echolocation in free-living Daubenton's bats Myotis daubentoni (Chiroptera: Vespertilionidae). J Zool Lond 215:113–132Google Scholar
  18. Kaspari M (1991) Prey preparation as a way that grasshopper sparrows (Ammodramus savannarum) increase the nutrient concentration of their prey. Behav Ecol 2:234–241Google Scholar
  19. Kunz TH (1974) Feeding ecology of a temperate insectivorous bat (Myotis velifer). Ecology 55:693–711Google Scholar
  20. Kunz, TH (1980) Energy budgets of free-living bats. In: Wilson, DE, Gardner, AL (eds) Proceedings of the 5th International Bat Research Conference, Texas Tech University, Lubbock, Texas, pp 369–392Google Scholar
  21. Kunz TH (1987) Post-natal growth and energetics of suckling bats. In: Fenton MB, Racey PA, Rayner JMV (eds) Recent advances in the study of bats. Cambridge University Press, Cambridge, UK, pp 395–420Google Scholar
  22. Kunz TH (1988) Methods of assessing the availability of prey to insectivorous bats. In: Kunz TH (ed) Ecological and behavioral methods for the study of bats. Smithsonian Institution Press, Washington, DC, pp 191–210Google Scholar
  23. Kunz Th, Nagy Ka (1988) Methods of energy budget analysis. In: Kunz TH (ed) Ecological and behavioral methods for the study of bats. Smithsonian Institution Press, Washington, DC, pp 277–302Google Scholar
  24. Kurta A, Kunz TH (1987) Size of bats at birth and maternal investment during pregnancy. Symp Zool Soc Lond 57:79–106Google Scholar
  25. Kurta A, Bell GP, Nagy KA, Kunz TH (1989a) Energetics of pregnancy and lactation in free-ranging little brown bats (Myotis lucifugus). Physiol Zool 62:804–818Google Scholar
  26. Kurta A, Bell GP, Nagy KA Kunz TH (1989b) Water balance of free-ranging little brown bats (Myotis lucifugus) during pregnancy and lactation. Can J Zool 67:2468–2472Google Scholar
  27. Kurta A, Kunz TH, Nagy KA (1990) Energy and water flux in free-ranging big brown bats (Eptesicus fuscus). J Mammal 71:59–65Google Scholar
  28. McCracken GF, Gustin MK (1991) Nursing behavior in Mexican free-tailed bat maternity colonies. Ethology 89:305–321Google Scholar
  29. Pierson ED, Stack MH (1988) Methods of body composition analysis. In: Kunz TH (ed) Ecological and behavioral methods for the study of bats. Smithsonian Institution Press, Washington, DC pp 387–403Google Scholar
  30. Poulton EB (1929) British insectivorous bats and their prey. Proc Zool Soc Lond 1:277–303Google Scholar
  31. Ransome RD (1973) Factors affecting the timing of birth of the greater horse-shoe bat (Rhinolophus ferrumequinum). Per Biol 75:169–175Google Scholar
  32. Redford KH, Dorea JG (1984) The nutritional value of invertebrates with emphasis on ants and termites as food for mammals. J Zool Lond 203:385–395Google Scholar
  33. Reith CC (1982) Insectivorous bats fly in shadows to avoid moonlight. J Mammal 63:685–688Google Scholar
  34. Robbins CT (1983) Wildlife feeding and nutrition. Academic Press, New YorkGoogle Scholar
  35. Ross A (1967) Ecological aspects of the food habits of insectivorous bats. Proc West Found Vert Zool 1:205–263Google Scholar
  36. Rydell J (1991) Ecology of the northern bat (Eptesicus nilssoni) during pregnancy and lactation. Unpublished Ph.D. thesis, University of Lund, SwedenGoogle Scholar
  37. Short HL (1961) Growth and development of Mexican free-tailed bats. Southwest Nat 6:156–163Google Scholar
  38. Townsend CR, Calow P (eds) (1981) Physiological ecology: an evolutionary approach to resource use. Sinauer, Sunderland, MassGoogle Scholar
  39. Tuttle MD (1988) America's neighborhood bats. University of Texas Press, AustinGoogle Scholar
  40. Whitaker JO Jr (1972) Food habits of bats from Indiana. Can J Zool 50:877–883Google Scholar
  41. Whitaker JO Jr (1988) Food habits analysis of insectivorous bats. In: Kunz TH (ed) Ecological and behavioral methods for the study of bats. Smithsonian Institution Press, Washington, DC, pp 171–189Google Scholar
  42. Williams TC, Ireland LC, Williams JM (1973) High altitude flights of the free-tailed bat, Tadarida brasiliensis, observed with radar. J Mammal 54:807–821Google Scholar

Copyright information

© Springer-Verlag 1995

Authors and Affiliations

  • T. H. Kunz
    • 1
  • J. O. WhitakerJr.
    • 2
  • M. D. Wadanoli
    • 1
  1. 1.Department of BiologyBoston UniversityBostonUSA
  2. 2.Department of Life SciencesIndiana State UniversityTerre HauteUSA

Personalised recommendations