Better than a Bird Brain?
Originally shared by ScienceSunday
Honey, where’d we leave the keys kids?
Female cowbird brains better than male at spatial memory
The story usually goes that males perform better than females on a range of spatial navigation and memory tasks – that’s true in humans and a wide variety of other species. But not so for brown-headed cowbirds. In this species, females seem to have the edge.
It’s thought that the superiority of males in spatial memory is linked to evolutionary demands. For example, polygynous male voles have to keep track of their mates over a wide range of locations, and they have a larger hippocampus (the region of the brain most closely linked to spatial memory) and perform better on spatial memory tasks than females of the same species; in contrast, in monogamous voles, no such sex differences exist.
This makes the brown-headed cowbird, Molothrus ater, an interesting case study. The females lay their eggs in the nests of other birds, and only the females scout out those locations and check up on the development of their brood later. So females, but not males, have an evolutionary selective pressure for heightened spatial memory.
A study published in the latest edition Biology Letters tested this idea by training birds to remember where food-filled cups were after varying amounts of time. Female cowbirds made fewer errors in returning to the correct location of food compared to males, and females also were more likely to fly to the food via shorter, more direct paths, even when the location through which they entered the room was varied.
In a report by Ivan Semeniuk in the The Globe and Mail , Claudia Mettke-Hofmann, an animal behaviour specialist from Liverpool John Moores University, who was not involved with the study, said that the results show that “better spatial performance is not an inherent characteristic of males, but evolves in relation to ecological demands.”
Previous work by the same group showed that female cowbirds have a larger hippocampus than the males. Although no one-to-one correlation was explored in this study, the results certainly are consistent with the idea that the larger hippocampus is linked to improved spatial memory in females.
So next time someone calls you a bird brain, that may not be such a bad thing after all…
Sources and more reading:
Bird study finds females have a better sense of direction by Ivan Semeniuk http://goo.gl/cEX2ts
Female cowbirds have more accurate spatial memory than males
Guigueno MF, Snow DA, MacDougall-Shackleton SA, and Sherry DF (2014) Biology Letters, 10(2) doi: 10.1098/rsbl.2014.0026
Females have a larger hippocampus than males in the brood-parasitic brown-headed cowbird. Sherry DF, Forbes MR, Khurgel M, Ivy GO (1993) Proc. Natl Acad. Sci. USA 90, 7839–7. -parasitic brown-headed cowbird. Proc. Natl Acad. Sci. USA 90, 7839–7843. (doi:10.1073/pnas.90.16.7839)