Are Kirindy sifaka capital or income breeders? It depends

The capital and income breeding framework has only recently been used to explain variation in female reproductive strategies in primates. The application of this framework to primates and other mammals with long reproductive cycles has not been consistent. We evaluated data on Verreaux's sifaka (Propithecus verreauxi verreauxi) in the Kirindy Forest of western Madagascar to determine whether they are capital or income breeders. We found that Verreaux's sifaka can be classified as either capital or income breeders, depending on how these concepts are operationalized. These conflicting findings highlight why the capital/income framework is currently problematic and must be standardized if it is to be a useful framework for primatologists.