Behind the Scenes in CREW’s Endocrine Lab

While most people think animal pee and poop is disgusting, we ask for it to be brought to us!  In fact, it’s shipped from other zoos to us.  Why, you ask?  Because we can learn SO much from it!  We can use blood, saliva, urine and feces to tell us information about individual animals.

Endocrinology is the study of hormones, and by analyzing hormones in these samples we can gather basic information on an animal:

  • Is the animal mature?
  • Is the species a seasonal breeder, and what season do they breed in?

We can check where an animal is in their reproductive cycle:

  • How long until a female ovulates?
  • Is she pregnant?

Wildlife endocrinology helps with timing of pairing animals for breeding, as well as assisted reproductive techniques like artificial insemination and in-vitro fertilization.

How it works:

Samples are collected, labeled, and stored in a freezer, then shipped to us at CREW.

Fecal samples are freeze-dried, pounded to powder consistency, weighed and the hormones extracted out of the sample overnight in an alcohol solution.  Then the liquid extracts containing the hormones are diluted and analyzed.  Urine, saliva, and blood are usually able to be analyzed directly without extraction.

The enzyme-immuno assays we use tell us how concentrated the hormones  are in each sample – whether they are high or low in estrogen, progesterone, testosterone, or cortisol, for example – and we then can graph the results and monitor concentrations from samples collected over time (weeks, months, years).  These graphs tell us about:

Cycling or pregnant females


Much of what we learn through this technique provides us with new information and a better understanding of the characteristics of that species, which is very important when trying to manage a species in captivity, either by natural breeding or when using assisted reproduction.