I grab my raincoat and notebook and head over for more cheetah watching. Our breeding facility is not accessible to guests. After arriving, I try to control my excitement and optimism about the possible outcome of today’s breeding attempt. I’m pretty sure today is the day that Lindiwe and Noka will breed successfully.
My hopefulness increases as I view a short video recorded by our animal care staff just hours earlier, showing positive signs of interest between Lindiwe and Noka. These include both cheetahs laying down next to each other in their adjacent enclosures and touching noses through the fence. Noka then proceeds to make a vocalization called a stutter-bark in Lindiwe’s direction. The stutter-bark is a rarely heard vocalization primarily used by male cheetahs in breeding situations. We believe the stutter-bark plays a significant role in a male cheetah’s attempt to breed a female.
Listen to a cheetah stutter-bark:
To better understand the possible role of the stutter-bark vocalization, a little background on cheetah reproduction is needed. In most mammals (including humans), the release of eggs happens spontaneously and predictably (with cycles of varying length). However, there are a number of species that possess a different type of reproductive strategy where eggs are released from the ovaries after some sort of stimuli but not on a predictable cycle. The stimuli could include the physical act of mating, among many other possibilities.
In cheetahs, the stimuli that lead to egg release are not clearly understood. In the wild, female cheetahs are predominantly solitary, so we think that when a male encounters a female, the stutter-bark vocalization may be part of the reproductive strategy to help bring a female cheetah into estrus.
Our team moves Lindiwe to a neighboring enclosure while Noka is brought into Lindiwe’s enclosure, which he thoroughly investigates by patrolling the area, sniffing, and spraying. While he is investigating, we record details about both cheetahs’ behavior. We are hoping for a “strong” behavioral response from them, including both cats being very focused on each other, the female rolling on the ground and flicking her tail. Most of all, we are hoping that she won’t be aggressive toward him and that Noka will stutter-bark while pacing her fence line.
The breeding attempt continues for approximately 30 minutes, during which time we see the positive signs we are hoping for from both cheetahs. We decide to attempt an introduction between Noka and Lindiwe. At this point we’re also considering the possible downsides of an introduction with a female cheetah that may not be in estrus and, as a result, can be unpredictable and aggressive. This is definitely something we do not want in a breeding situation! Having weighed the costs and benefits, we move forward with our introduction: a keeper opens a fence separating Lindiwe and Noka while I continue observing and taking notes.
The breeding attempt begins positively, with no aggression from the male or female. Lindiwe is active and moving while the male stutters quietly toward her. He begins to follow her but occasionally gets a little too close, resulting in Lindiwe turning and moving toward him slightly. Then she turns and continues to walk around the enclosure. Noka is somewhat focused on her but is also not responding very strongly and appears to be somewhat distracted. After some time, we decide that the male’s response is not adequate and reluctantly separate the cats in the hope for a better response tomorrow.
If Lindiwe is truly coming into estrus, we expect to see a much stronger response from Noka. We do not currently have a scientific test that will tell us if Lindiwe is in estrus on the day of the introduction. If we attempt a blood draw, the possible stress associated with the procedure could affect the female’s reproductive hormones. Our current approach is to noninvasively examine Lindiwe’s reproductive hormones by collecting her fecal samples and determining her hormone levels back at the Behavioral Biology endocrinology lab. Stay tuned for my next blog post detailing the laboratory approaches I use to determine reproductive hormone levels in cheetahs and my determination (via hormone levels) of whether Lindiwe was truly in estrus during this breeding attempt.
Corinne Pisacane is a senior research technician in the Behavioral Biology Division of the San Diego Zoo Institute for Conservation Research.