March 29, 2016

By Martha Fischer, Curator of Mammals/Ungulates and Elephants Director of the Center for Conservation in the Horn of Africa, Cheryl Asa, Ph.D., Director, Research and AZA Reproductive Management Center, and Karen Bauman, Laboratory Manager, Research Department

Every season is calving season at the Zoo—where seven species of antelope live. Two male addax calves, born in February, are going through introductions behind-the scenes in the privacy of the Zoo's Antelope Area.

One addax calf, named Moose, born February 22, is participating in an antelope mother-calf behavior research project that began in 1992 when Zoo staff in the Research Department and Animal Division sought to find out about the antelope mother/infant bonding process.

Recently born addax calf Recently born addax calf

Nearly 25 years later, we are still collecting and analyzing data because proper maternal care is critical for an infant to thrive and to learn species-appropriate behavior. During those years, a long-line of research and management leaders have contributed to this study. The Zoo kept at it because knowing about the maternal strategies of antelope helps us make better decisions about whether a mother antelope is behaving appropriately. We need to know when to intervene and hand-raise infants if mothers fail to provide the care needed to ensure these calves survive.

Their survival is critically important because so many of the species in our care at the Saint Louis Zoo are endangered in the wild. For instance, due to overhunting, there are fewer than 200 addaxes left in the wild. The Zoo's WildCare Institute works to save this and other antelope species through a range of strategies.

Kudu calf and mom Kudu calf and mom

At the Zoo, we do our best to offer superior care, and we have learned that different ungulate species (hoofed animals such as antelope, deer, cattle, and zebras) protect infants from predators by becoming either “hiders” or “followers."  Such hider species as white-tailed deer leave infants camouflaged in bushes and come to them only a few times a day for nursing to avoid drawing attention to the vulnerable baby.

In contrast, followers, like zebras and camels, keep their babies with the herd, protected by a group of adults. Those calves have almost constant access to their moms and may nurse as much as a few times per hour.

To learn more about the maternal strategies of antelope, the Research Department team began recording and analyzing interactions of mothers and infants of all antelope species.  The project started with seven species: addax, Arabian oryx, bongo, lesser kudu and Curvier’s, Mhorr and Speke’s gazelles, and subsequently expanded to include five other species: lowland nyala, Soemmering’s gazelle, Addra gazelle, steenbok and gerenuk.  The offspring of these species appear to be  “hiders.”      

Because new mothers can be nervous about being watched, and antelope are active on and off around the clock, researchers needed to collect data non-invasively, day and night, so they began to capture the antelopes’ behaviors using time-lapse, infrared video. Behavior interns then review the video footage back in the lab. The reviewing process involves close observation of all the images and/or the scoring of specific observed behaviors.  Among scored behaviors are nursing, proximity and grooming. 

This study has provided data for each species of “normal” behavior patterns so that curators and keepers can decide whether new mothers are showing proper maternal care and whether calves are thriving.  The Zoo can quickly act to make changes if babies are not doing well.  


Researcher reviews data Researcher reviews data