Brood Parasitism

Copyright Steve Byland

Brown-headed cowbirds are brood parasites. Females, but not males, search for potential host nests in which to lay their eggs.  They revisit nests to monitor host egg laying and may even return to nests they have parasitized to determine the fate of their own eggs.  We found that females do better than males on spatial navigation tasks but not on touchscreen tests of spatial memory.  Females have a larger hippocampus than males but this sex difference also occurs in non-parasitic members of the Icterid family of birds, like red-winged blackbirds. Female brown-headed cowbirds have more hippocampal neurogenesis than males and non-parasitic blackbirds, with a peak in neurogenesis at the end of the breeding season when search for host nests has stopped.  Brood parasitism in cowbirds offers a window into the evolutionary modifications of cognition and the brain that accompany specialization in behaviour.

Selected Papers

Sherry, D. F., & Guigueno, M. F. (2019). Cognition and the brain of brood parasitic cowbirds. Integrative Zoology, 14, 145-157.

Sherry, D. F., Grella, S. L., Guigueno, M. F., White, D. J., & Marrone, D. F. (2017). Are there place cells in the avian hippocampus? Brain Behavior and Evolution, 90, 73-80.

Grella, S. L., Guigueno, M. F., White, D. J., Sherry, D. F., & Marrone, D. F. (2016). Context-dependent Egr1 expression in the avian hippocampus. PLOS One, 11, e0164333.

Guigueno, M. F., MacDougall-Shackleton, S. A., & Sherry, D. F. (2016). Sex and seasonal differences in hippocampal volume and neurogenesis in brood-parasitic brown-headed cowbirds (Molothrus ater). Developmental Neurobiology, 76, 1275-1290.

Guigueno, M. F., MacDougall-Shackleton, S. A., & Sherry, D. F. (2015). Sex differences in spatial memory in brown-headed cowbirds: males outperform females on a touchscreen task. PLOS One, 10, e0128302. doi:10.1371/journal.pone.0128302

Guigueno, M. F., Snow, D. A., MacDougall-Shackleton, S. A., & Sherry, D. F. (2014). Female cowbirds have more accurate spatial memory than males. Biology Letters, 10, 20140026 doi:10.1098/rsbl.2014.0026