Authored by Emily Bovee, CZAAWE lab assistant

A little teamwork can go a long way — especially when it comes to caring for the animals who call the Detroit Zoo home. Center for Zoo and Aquarium Animal Welfare and Ethics (CZAAWE) staff recently teamed up with fellow Zoo employees to ensure two of the Zoo’s feline residents have the best possible opportunity to bring a litter of cubs into the world. 

Amur tigers (Panthera tigris altaica) were the first species to be part of an Association of Zoos and Aquariums (AZA) Species Survival Plan, a program aimed at supporting the conservation of endangered species by maintaining the genetic diversity of AZA populations. Breeding animals in zoos can be surprisingly challenging, even for the most amorous of Amur tigers! As a solitary species, wild adult Amur tigers generally live alone. Females and males will only meet briefly to mate before parting ways. Tigers living in AZA-accredited zoos are often housed separately, thus the timing of breeding introductions is extremely important. The successful birth of healthy cubs requires some coordination and planning from experts in the field. The last time efforts were made to breed tigers at the Detroit Zoo was in 2003 when healthy cubs were born. 

Collaborations between different departments at the Detroit Zoo provide staff opportunities to examine the welfare of the animals from new and diverse perspectives. Recently, CZAAWE staff started working with mammal supervisor Melissa Thueme and animal care specialist Sarah Semegen to assist with tiger breeding efforts. The two resident Amur tigers, male Nikolai and female Ameliya, rotate through the public enclosure and a second outdoor tiger yard behind the scenes. 

CZAAWE uses an on-campus endocrinology lab to non-invasively measure indicators of physiological welfare such as hormones — a fancy way of saying we analyze a lot of poop! With the amount of poop collected from animals big and small throughout the Zoo, CZAAWE depends on the intrepid lab volunteers who spend hours crushing samples to prepare them for lab testing. This can include hormones that may indicate changes in reproductive states such as testosterone, estradiol and progesterone. 

Using fecal samples collected by animal care staff from Ameliya, CZAAWE first monitored estradiol, an estrogen hormone involved in the regulation of the estrous cycle. This allowed us to assess if Ameliya had an active cycle and determine the timing of her cycles. The hormone data supplements and confirms animal care staff behavioral observations, which can also be used to track reproductive cycles. Indicators of her estrous cycle included behaviors such as chuffing (an affectionate throaty vocalization!), rubbing on walls and mesh, rolling on the ground, and being friendly toward Nikolai and animal care staff. In only a few days, she can switch from snarling and swatting at Nikolai to chuffing and cheek rubbing! Using a combination of hormonal monitoring and behavioral cues, animal care staff can determine the ideal time for facilitating interactions between Ameliya and Nikolai that are more likely to result in a successful breeding attempt. 

After a potentially successful breeding introduction, the CZAAWE lab staff can shift to monitoring Ameliya’s progesterone levels. Progesterone is a hormone that maintains pregnancy and gets the body ready for and supports a developing fetus. Examining her progesterone levels will allow us to non-invasively detect a possible pregnancy and make sure our care protocols provide excellent support for the mother-to-be. While we are not yet listening for the pitter-patter of tiny tiger paws, we are hopeful that the continued collaboration between animal care staff and CZAAWE will mean healthy tiger cubs in the future.