Reproductive Responses to Rainfall in the Namaqualand Speckled Tortoise

Abstract

Abstract Although many tortoise species inhabit drought-prone regions with potentially limiting resources, these species have long, iteroparous lives. To assess reproductive responses to variation in rainfall, and to understand interactions among egg size, body size, body condition, and rainfall, we studied egg production in the Namaqualand Speckled Padloper, Homopus signatus signatus, in Springbok, South Africa, in five consecutive spring seasons. Annual rainfall was low and varied substantially (131–226 mm). The percentage of females that were gravid (36–75%) differed among years and correlated with the amount of rain in the months prior to nesting. Gravid females had a higher body condition than that of non-gravid females, presumably because individual variation in resource acquisition caused some females to forfeit reproduction. The body condition of gravid and non-gravid females differed among years and was lowest in the year of lowest rainfall. In most years, egg size correlated to female size, but ...