Located deep in the heart of the Arizona Sonoran desert is an oasis, home to 29 cownose stingrays at the Phoenix Zoo’s Stingray Bay. Early in the fall of 2015, 15 of the 18 females gave birth. All of the births occurred at night with the exception of one light gray ray that gave birth midday on November 1, 2015. Lucky for us, we were there with a camera in hand to record the event.
Cownose stingrays are social animals and swim in large groups known as fevers. The pregnant or gravid rays will continue to swim with their fever during the entire birthing process. Cownose rays typically have only one baby or “pup” at a time. Twins can occur, but are extremely rare. Pups are completely independent from the moment of birth and have no connection to their mother once born.
At the onset of labor, a frenzy of male activity surrounds the gravid female. This activity is in preparation to mate with her as soon as the pup is born. Males will pursue the female until she is exhausted and her swimming slows. The chase prior to mating can last for days with the actual reproduction event lasting less than one minute. Gestation periods for cownose rays are estimated at 9-12 months.
With little to no slowing in her movement the gravid female gave birth to the pup, emerging backside first like a bullet shot from a gun.
In 2015, our gravid females began to deliver in early September. Each morning, we anticipated a new pup swimming with the fever since births often occurred overnight. To our surprise, however, one afternoon we noticed a small gray ray displaying signs of labor. As she was very light in color, it was easy to see the dark colored pup protruding slightly from her cloaca. Contractions rippled along her backside as labor progressed. Surrounding male rays also became noticeably more excited and raced to be by her side. With little to no slowing in her movement the gravid female gave birth to the pup, emerging backside first like a bullet shot from a gun. The pup drifted to the bottom of the tank while mother swam off being followed closely by a growing procession of male suitors.
At first glance, the pup resembled a burrito with its tail folded in half, pressed against its back, and wrapped tightly by its fins. He quickly unwrapped the fins, straightened the tail and began swimming erratically. Within moments the pup seemed to gain a sense of direction and attempted to join the fever. The fin motion of the pup’s stroke appeared less graceful than that of the adults at first. As the newborn swam, the tips of its fins almost touched overhead. There was also a noticeable kink in the tail. Both of these newborn traits disappeared within a few days.
The Zoo has produced cownose ray pups consistently for the last three years. Pups weigh on average between one and three pounds at birth and are identical in appearance to the adults. A stingray’s only form of defense is their barb, which is located over the tail at the base of the body on cownose rays. Pups are born with a fully functional barb and are able to defend themselves if necessary. Regular food consumption by pups typically begins within the first few days of life. To assure our pups receive the proper amount of food, they are separated from the fever. There they are closely monitored and acclimated to hand feeding in preparation for life in a touch-tank exhibit. The entire newborn collection was relocated to the Arizona Sonora Desert Museum in January of 2016 and is doing well in their new home.
Mari Belko is a Stingray Keeper at the Phoenix Zoo and holds a degree from Michigan State University. As a long-time diver, she has spent most of her life exploring the Pacific Ocean while living in Southern California. Even though diving has taken her all over the world, fueling her passion for the marine life, it wasn’t until a recent relocation to Arizona that this passion became a profession. It is deep in the desert at the Phoenix Zoo where Mari works with and studies stingrays on a daily basis. Drawn to them for their affection and intelligence, she hopes to show the world just how amazing these animals are.