Frozen Dumbo - Establishment of the first large scale semen cryobank for wild African elephants and other endangered species

This project advances techniques for artificial insemination and sperm cryopreservation of both African and Asian elephants. With these methods at hand, population managers can enrich captive or isolated wild elephant populations without removing valuable individuals from their natural habitat.

Project details
Duration: since 2007
Third-party funded: yes
Involved Department(s): Dept Reproduction Management
Leibniz-IZW Project Leader(s): Thomas Hildebrandt (Dept Reproduction Management) 
Leibniz-IZW Project Team:

Robert Hermes, Frank Göritz, Susanne Holtze (all: Dept Reproduction Management)

Consortium Partner(s):

Schönbrunn Zoo (Austria), West Midland Safari Park (United Kingdom), Ouwehands Zoo Rhenen (The Netherlands), Zoo Zlin (Czech Republic)

Current Funding Organisation:

Beauval Conservation et Recherche (ABCR), Pittsburgh Zoo/PPG Aquarium, private donors

Research Foci:
Understanding traits and evolutionary adaptations
Understanding the environmental context
Developing theories, methods, and tools


The artificial reproduction project was created as a joint effort of the Leibniz-IZW, the ZooParc Beauval, the Schönbrunn Zoo and the Pittsburgh Zoo (USA). After obtaining semen from 14 wild bulls (Loxodonta africana) from the Phinda Private Game Reserve in South Africa in 2009/2010 by electro-ejaculation, a sperm bank was created in cooperation with the IZW Berlin. The frozen elephant semen (approx. 2 liters) is stored in cryotanks at -196°C in the ZooParc Beauval and is available to the European zoo community after the recommendation of the studbook keeper.

Until then, artificial insemination was very challenging logistically because fresh semen had to be transported from one zoo to another at the exactly time the elephant cow was ovulating. With the "Frozen Dumbo" project, frozen semen can be stored and used for insemination at the optimal time. The freezing of mammalian cells is delicate: Not every cell can withstand a cold shock of minus 196 degrees Celsius. They could be destroyed by the resulting ice crystals. In our method, the sperm is not cooled abruptly, but gradually.

Another successful sperm collection from wild African elephants took place in spring 2023 with the support of ZooParc Beauval and BioParc Valencia in the Selati Game Reserve in South Africa. Approximately 3 liters of high-quality ejaculate were cryopreserved and are currently awaiting export to the Biobank of ZooParc Beauval in France.

The work of the team around Prof. Hildebrandt has enabled the successful insemination of more than 40 elephant cows, 7 of them with frozen semen. For the first time in 2011, the female elephant Tonga was inseminated at Schönbrunn Zoo with the frozen semen of a free-living bull from South Africa.

The “Frozen Dumbo” project is intended to enrich the gene pool of the zoo elephants, as there are only a few procreative bulls left there. For his pioneering work on artificial insemination of African and Asian elephants Prof. Thomas Hildebrandt has been awarded the Conservation Legacy Award of the Pittsburgh Zoo & PPG Aquarium (Pennsylvania) in 2015. The prize money was 25,000 dollars and was invested to hold the first international Northern White Rhino Conference in Vienna in December 2015.

Selected media contributions

The Boston | Globe 01.12.2023 How to collect a sperm sample from an elephant

Beauval Nature - YouTube | 05.07.2023 Frozen Dumbo 3: toute une aventure

Selected Publications

  • Saragusty J, Prieto M, Courtiol A, Potier R, Goeritz F, Hildebrandt TB, Hermes R (2016): Sperm rescue in wild African elephants. Reproduction, Fertility and Development, 28(9), 1433-1442.
  • Saragusty J (2015): Directional freezing for large volume cryopreservation. In Cryopreservation and Freeze-Drying Protocols (pp. 381-397). Springer, New York, NY.
  • Hermes R, Saragusty J, Goeritz F, Bartels P, Potier R, Baker B, Streich JW, Hildebrandt TB (2013): Freezing African elephant semen as a new population management tool. PLoS ONE 8(3): e57616. doi:10.1371/journal.pone.0057616PloS ONE.
  • Hildebrandt TB, Hermes R, Saragusty J, Potier R, Schwammer H, Balfanz F, Vielgrader H, Baker B, Bartels P, Goeritz F (2012): Enriching the captive elephant population genetic pool through artificial insemination with frozen-thawed semen collected in the wild. Theriogenology 78: 1398-1404.
  • Behr B, Rath D, Hildebrandt TB, Goeritz F, Blottner S, Portas TJ, Bryant BR, Sieg B, Knieriem A, De Graaf SP, Maxwell WMC, Hermes R (2009): Index of sperm sex sortability in elephants and rhinoceros. Reprod Domest Anim, 44: 273-277.
  • Hermes R, Behr B, Hildebrandt TB, Blottner S, Sieg B, Frenzel A, Knieriem A, Saragusty J, Rath D (2009): Sperm sex-sorting in the Asian elephant (Elephas maximus). Anim Reprod Sci 112: 390-396.
  • Saragusty J, Hildebrandt TB, Behr B, Knieriem A, Kruse J, Hermes R (2009): Successful cryopreservation of Asian elephant (Elephas maximus) spermatozoa. Anim Reprod Sci 115: 255-266.