The cost of breeding for male common toads

The potential impact of pairing on male survivorship and future breeding success in common toads was investigated between 1993 and 2014. A total of 8132 males arriving at a breeding pond in southern England were measured, weighed, individually marked and their breeding history recorded. The body condition (BC) of all males was estimated using (a) residuals from an ordinary least squares regression analysis of log10 body mass against log10 body snout-vent length (SVL; ordinary least squares) and (b) a scaled mass index (SMI), standardized for SVL. Each year each male was allocated to one of four categorical groups: (1) Paired, (2) Unpaired, and whether or not it returned to breed the following year: (3) Return, (4) No Return. The BC of both paired and unpaired males that subsequently returned was significantly higher than that of those that failed to return. Male pairing success was highest in the youngest males and lowest in the oldest. The overall cost for male common toads that successfully paired was a significantly decreased BC and survival rate. First time breeding males had a 21.2% chance of surviving and returning to breed the following year, increasing to 28.3–37.0% for those returning for up to five consecutive years.