The use of ultrasonography to assess reproductive investment and output in pythons

Zachary Stahlschmidt, Jake Brashears, Dale Denardo

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


Reproductive investment and output are integral fitness components, often incorporated into life-history trade-off models and important to population dynamics. The trade-offs associated with reproduction can be dramatic in species such as snakes that make especially large investments into reproduction. Unfortunately, traditional methods used to determine reproductive investment and output are effective in many (but not all) situations. Thus, we used portable ultrasonography to serially estimate reproductive investment and reproductive output in three python species that exhibit significant variation in phylogeny, geographic range, body size, egg size, and clutch size: ball pythons (Python regius), Children's pythons (Antaresia childreni), and water pythons (Liasis fuscus). At each time point of measurement (range: 1-49 days pre-oviposition), ultrasound estimates of viable clutch size were highly accurate in all three species. However, ultrasound estimates of mean viable egg mass, and thus viable clutch mass, significantly differed from the actual values (range: 23-73% error). Interestingly, this error was considerably smaller as females approached oviposition, suggesting that female pythons transfer a significant amount of water into their eggs during the week before oviposition. Thus, water balance during late-stage egg development may be an integral part of reproductive success. The results obtained in the present study form the foundation for future assessments of reproductive investment, and also provide insight into the use of ultrasound technology to assist such efforts.

Original languageEnglish (US)
Pages (from-to)772-778
Number of pages7
JournalBiological Journal of the Linnean Society
Issue number4
StatePublished - Aug 2011


  • Effort
  • Egg
  • Ova
  • Population biology
  • Reproduction
  • Snake

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics


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