BOISE, IDAHO--Single men have any number of strategies to attract women, including hanging out with children in hopes of looking like a good dad. Some species of fish may have mastered this ploy long ago, according to research presented here on 20 July at the Animal Behavior Society meeting.
Time spent looking after offspring is costly for parents because it means less courting and mating, thereby reducing future reproductive success. But some males may have figured a way around this problem, according to behavioral ecologist Colette St. Mary of the University of Florida in Gainesville. St. Mary studied a species of fish called the sand goby that leaves child care entirely to the fathers. Males build a nest and care for the eggs of multiple females. They clean and guard the eggs and fan them to keep them oxygenated. But instead of losing time that could be spent wooing other lady fish, the male gobies have combined courtship with parental care by trying to impress females with their abilities as fathers. When females were looking, the males fanned the eggs longer and harder and spent more time building up and guarding the nest than they did if females weren't present, St. Mary said at the meeting.
Fortunately for the female gobies, fellows that made a big show of caregiving really were better fathers--the eggs they fertilized hatched at higher rates. Although this may be due in part to the extra fussing by the males, says St. Mary, it is more likely because the males were much less prone to eat their eggs while females were watching. Males ignored by females not only paid less attention to their eggs, they were far more likely to eat all the eggs in their nest and start over.
"The interesting thing here is that the levels of parental care are even higher than what you would expect if the males were just interested in survival of the young," says behavioral ecologist Oscar Ríos-Cárdenas of the State University of New York, Buffalo, who has observed similar courting tactics in male pumpkinseed sunfish. "I suspect they may be using it as advertisement to say, 'Look, I'm a good father!'"