Interactive Effects of Food Supplementation and Snake Fungal Disease on Pregnant Pygmy Rattlesnakes and Their Offspring

In viviparous organisms, the ability to feed while pregnant may mitigate energetic trade-offs experienced during the reproductive process and enhance fecundity. However, anorexia during pregnancy has been reported in many crotaline snakes. The potential costs and benefits of feeding while pregnant are not completely described in the literature, and experimental studies have been conducted in a limited number of taxa, rendering our understanding of the forces that may underlie the evolution of anorexia in pregnant snakes incomplete. Here, we examine the impact of food supplementation during mid to late pregnancy on mothers and offspring in a viviparous crotaline snake species, the Pygmy Rattlesnake (Sistrurus miliarius). Specifically, we offered multiple large meals to mothers held in outdoor enclosures and measured a suite of maternal and offspring traits including maternal body condition, offspring length and mass, maternal disease state, and offspring foraging behaviors. We focused on interactions between feeding, clinical signs of snake fungal disease (SFD), and the presence of its causative agent, Ophidiomyces ophiodiicola, in mothers. Pregnant females fed readily when offered food, but feeding did not impact offspring traits. Food supplementation significantly increased maternal postparturient body condition, but also increased clinical signs of disease in mothers and led to a significantly higher reproductive failure rate in the treatment group, particularly in mothers afflicted with SFD. Our results suggest that food supplementation during pregnancy may disrupt the reproductive process in pregnant rattlesnakes, and that such disruption is particularly pronounced in mothers suffering from SFD.