Tracking Black Rhino Reproduction Using Hormone Monitoring

Hello everyone!  In the Endocrinology Lab, I have the privilege of working with a wide variety of species some of which are critically endangered species including the black rhino. Currently Brookfield Zoo is home to two black rhinos, a male, Nakili, and a female, Layla. They are deemed breeding partners and are slowly being introduced to each other in the hopes of a successful pregnancy in the near future.   

Black rhinos Layla (left) and Nakili (right) have been deemed breeding partners.

Black rhinos were the most abundant rhino species throughout the 1900’s, until 1960, hitting their lowest point in 1995 due to poaching and habitat destruction. Numbers dropped from an astounding 850,000 to under 1,000. As of 2010, numbers have increased to near 5,000. Zoos continue to play an integral role in assisting black rhino breeding success and providing a safety net to the wild population.  

Historically, Brookfield Zoo had the first successful black rhino birth in a North American Zoo. Since then, there have been 10 successful births which is no small feat.  Black rhinos have 15-16 month gestation periods and produce one calf. Their reproductive rate is at most 1 calf every 2.5-5 years, so it can take some time to build up populations. 

One way the Endocrinology Lab can assist is to monitor the reproductive activity in the female breeding rhino. This will tell us if the female is cycling normally, having consistent ovulations, and potentially diagnose a pregnancy. The lab has been monitoring black rhinos for approximately 12 years. Prior to Layla’s arrival, black rhino Shima was a successful breeder and her progesterone data was used in comparison to Layla to determine her reproductive maturity and patterns. Similar to humans, progesterone levels increase in black rhinos when there is an ovulation or if the individual becomes pregnant.  

Measuring fecal progesterone metabolites in a former proven breeding female black rhino Shima to track her estrous cycles and calculate cycle length.  Each cycle represents an ovulation.

Through this comparison, it was determined that Layla was ovulating regularly and introductions to the male would be beneficial. As of right now, Layla and Nakili have been introduced and shown interest in each other. If Layla does become pregnant, the cycling pattern will stop and progesterone levels will remain elevated and sustained throughout the duration of her pregnancy.    

Black rhino Shima’s pregnancy profile. Fecal progesterone metabolite levels remained elevated through the pregnancy (note the scale of the graph) and decreased rapidly following birth. This profile will be used to compare to any potential pregnancies in black rhino Layla.

Our goal is to assist the zookeepers in achieving a successful breeding event in any way we can. By keeping historical data from other female rhinos, it makes it much easier to compare females’ ovulatory activity to each other and diagnose pregnancy. We are very optimistic Layla and Nakili will have a successful pregnancy in the near future!

Jocelyn Bryant
Endocrinology Lab Manager

Posted: 1/11/2017 11:22:21 AM by Bryan Todd Oakley

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