title: Bat breath reveals metabolic substrate use in free-ranging vampires.
abstract: We analysed the stable carbon isotope ratio in exhaled CO(2) (delta(13)C(breath)) of free-ranging vampires to assess the type of metabolized substrate (endogenous or exogenous substrate) and its origin, i.e. whether the carbon atoms came from a C(4) food web (grass and cattle) or the C(3) food web in which they were captured (a rainforest remnant and its mammals). For an improved understanding of factors influencing the delta(13)C(breath) of vampires, we conducted feeding experiments with captive animals. The mean delta(13)C(breath) of starved bats was depleted in (13)C in relation to the diet by 4.6 per thousand (n = 10). Once fed with blood, delta(13)C(breath )levelled off within a short time approximately 2.2 per thousand above the stable carbon isotope signature of the diet. The median time required to exchange 50% of the carbon atoms in exhaled CO(2) with carbon atoms from the ingested blood was 18.6 min (mean 29.5 +/- 19.0 min, n = 5). The average delta(13)C of wing membrane and fur in free-ranging vampire bats suggested that bats almost exclusively foraged for cattle blood during the past weeks. The delta(13)C(breath) of the same bats averaged -19.1 per thousand. Given that all free-ranging vampires were starving and that the delta(13)C of cattle was more in enriched in (13)C by 5-6 per thousand than the delta(13)C(breath) of vampires, we conclude that the vampire bats of our study metabolised fat that was predominantly built from carbon atoms originating from cattle blood. Since delta(13)C of wing membrane and fur integrates over weeks and months respectively and delta(13)C(breath) over hours and days, we also conclude that vampire bats of the studied population consistently ignored rainforest mammals and chose cattle as their prey during and prior to our study.
authors: Leibniz Institute for Zoo and Wildlife Research, Research Group Evolutionary Ecology, Alfred-Kowalke-Str. 17, 10315, Berlin, Germany. voigt@izw-berlin.de
authors: Christian C
authors: CC
authors: Voigt
authors: Patricia
authors: P
authors: Grasse
authors: Katja
authors: K
authors: Rex
authors: Stefan K
authors: SK
authors: Hetz
authors: John R
authors: JR
authors: Speakman
mesh_terms: D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001944:Breath Tests; D002245:Carbon Dioxide / Q000378:metabolism*; D002247:Carbon Isotopes; D002417:Cattle / Q000097:blood*; D002685:Chiroptera / Q000378:metabolism*; D004734:Energy Metabolism; D045853:Exhalation; D005247:Feeding Behavior; D020387:Food Chain; D005518:Food Preferences; D008055:Lipids / Q000097:blood; D011235:Predatory Behavior; D013997:Time Factors
chemical_list: D002247:Carbon Isotopes; D008055:Lipids; D002245:Carbon Dioxide
references: Oecologia. 1986 Jun;69(3):395-406
references: 28311342
references: Oecologia. 1979 Jan;37(3):351-359
references: 28309221
references: Oecologia. 1983 Mar;57(1-2):32-37
references: 28310153
references: Oecologia. 2005 Feb;142(4):501-10
references: 15586297
references: Oecologia. 2004 Mar;139(1):11-22
references: 14730442
references: Rev Soc Bras Med Trop. 2002 Sep-Oct;35(5):461-4
references: 12621664
references: Science. 1978 Sep 8;201(4359):906-8
references: 17729570
references: Integr Comp Biol. 2002 Feb;42(1):21-33
references: 21708691
references: Oecologia. 2005 Jun;144(2):226-32
references: 15891840
references: J Vet Med B Infect Dis Vet Public Health. 2003 Dec;50(10):469-72
references: 14720182
references: Rapid Commun Mass Spectrom. 2006;20(9):1395-9
references: 16572383
references: J Exp Biol. 2003 Apr;206(Pt 8):1419-27
references: 12624176
references: Oecologia. 2004 Sep;141(1):1-6
references: 15309607
references: Science. 1977 Jul 15;197(4300):261-3
references: 327543
references: J Comp Physiol B. 2002 Apr;172(3):263-8
references: 11919707