Low food abundance prior to breeding results in female-biased sex allocation in Tengmalm’s Owl (Aegolius funerus)

Parents can enhance their fitness by favouring that sex whose reproductive value is expected to be highest. In species in which females are the larger sex with potentially greater fitness returns, one can assume that parents should bias their investment toward daughters to increase their daughters’ reproductive value (i.e. age-specific expectation of all present and future offspring) and, thereby, indirectly increase their own inclusive fitness....