Head-body Temperature Difference in Free-ranging Rubber Boas

Although most studies of reptilian thermal biology have measured body temperature from a single location in an animal, the presence of regional temperature differences within the bodies of reptiles should be considered when conducting detailed studies of their thermal biology. As part of an extensive study of rubber boa (Charina bottae) thermal biology, we measured the oral and cloacal temperatures of 45
free-ranging rubber boas from June 1990 to August 1995. We used oral temperature as an indicator of head temperature and cloacal temperature as an indicator of body temperature. Oral temperatures ranged from 13.8 C to 32.2 C and cloacal temperatures ranged from 11.5 C to 34.5 C. During the daytime, rubber boas generally
exhibited warmer heads at average body temperatures below their thermal preference (thermal preference = 27.4 C) and cooler heads at average body temperatures above their thermal preference. At night, active rubber boas exhibited significantly higher head temperatures than body temperatures (mean difference = 2.0 C). This study represents the first report of regional body temperature differences exhibited by a reptile during nocturnal activity and supports the generalization that head temperature in reptiles
is maintained within more narrow limits than body temperature during the day. Further studies are required to fully understand both the causes and consequences of regional temperature differences in freeranging reptiles.
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Abstract/Description: Although most studies of reptilian thermal biology have measured body temperature from a single location in an animal, the presence of regional temperature differences within the bodies of reptiles should be considered when conducting detailed studies of their thermal biology. As part of an extensive study of rubber boa (Charina bottae) thermal biology, we measured the oral and cloacal temperatures of 45 free-ranging rubber boas from June 1990 to August 1995. We used oral temperature as an indicator of head temperature and cloacal temperature as an indicator of body temperature. Oral temperatures ranged from 13.8 C to 32.2 C and cloacal temperatures ranged from 11.5 C to 34.5 C. During the daytime, rubber boas generally exhibited warmer heads at average body temperatures below their thermal preference (thermal preference = 27.4 C) and cooler heads at average body temperatures above their thermal preference. At night, active rubber boas exhibited significantly higher head temperatures than body temperatures (mean difference = 2.0 C). This study represents the first report of regional body temperature differences exhibited by a reptile during nocturnal activity and supports the generalization that head temperature in reptiles is maintained within more narrow limits than body temperature during the day. Further studies are required to fully understand both the causes and consequences of regional temperature differences in freeranging reptiles.
Subject(s): herpetology