Do African egg-eating snakes (Dasypeltis) exhibit preference for eggs they eat?

African egg-eating snakes (genus Dasypeltis) are medium-sized obligate egg-eating species capable of swallowing large eggs compared to facultative egg-eating snakes of the same size. Dasypeltis have numerous adaptations for swallowing then crushing eggs to extract the content. Being dependent on an egg diet, it could be predicted that Dasypeltis have the ability to assess the quality of an egg then decide whether to reject or swallow it. For example, a small egg provides less food and takes less time to swallow than a large egg but swallowing a large egg could leave the snake more vulnerable to predation. Despite the possibility of Dasypeltis exhibiting egg preference, little research has addressed this. This study examined egg preference by five species of Dasypeltis in two laboratory experiments. In the first, five species of snakes were given a choice of the widest size range of eggs available from one order of birds. These included nine species of gallinaceous birds ranging from small, soft-shelled king quail eggs to large, hard-shelled turkey eggs. In the second experiment, snakes were given a choice of four eggs representing three genera of birds that occur in Africa represented by two galliform and two columbiform species. These eggs varied in volume, color, and hardness of shell. The results show Dasypeltis preferred certain eggs. Large snakes eat eggs of all sizes with preference for the largest, hardest eggs, while the smallest snakes ate only the smallest eggs. Snakes preferred columbiform eggs (dove and pigeon) over galliform eggs (king quail and Japanese quail). This study demonstrated that Dasypeltis in captivity do exhibit preferences for types and sizes of eggs.