Forest Environmental Conditions Shape Carcass Mass but Not Antler Investment of Red Deer Stags (Cervus elaphus L.)—Study from Western European Populations

Population stability depends on environmental conditions and their changes, as well as the availability of energy resources. Animals allocate their energy to maintenance, growth, reproduction, and energy storage; therefore, trade-offs are expected between life history traits. Access to abundant resources is expected to manifest itself in the investment of male individuals in sexually selected traits, such as carcass mass and antler size. The study aimed to analyze environmental climate conditions on the carcass and antler mass, as well as on antler form in red deer (Cervus elaphus L.) populations. We analyzed the carcasses and the antler masses and forms of 550 red deer stags from three populations in Central–Western Europe that differ in climate conditions that were hunter-harvested between the 2017 and 2021 hunting seasons. Our data indicated that carcass mass was shaped by the location of the population, stag age, precipitation, and temperature, as well as the number of frost days from January to the harvest date. Antler mass and antler investment depended on stag age but not climatic factors. Regular antler forms were more often observed in the harsh environmental conditions. Our observation confirms that resource trade-off is related to carcass mass of red deer.