Story posted January 24, 2003
According to research on the Savannah sparrow by a Bowdoin professor and two former Bowdoin honors thesis students, males of the species work just as hard and do just as good a job at raising their young as do the females.
Chalk one up for dads.
The findings by Nathaniel T. Wheelwright, professor of biology and director of the Bowdoin Scientific Station on Kent Island, and co-authors Kimberly A. Tice '99 and Corey R. Freeman-Gallant '91 (now a professor at Skidmore College), will appear in the upcoming issue of Animal Behaviour, the international journal of the Association for the Study of Animal Behaviour.
The team investigated how Savannah sparrows care for their young after they leave their nest on Kent Island, the site of the Bowdoin research facility in the Bay of Fundy, New Brunswick, Canada. Their goal was to determine the consequences of being raised by male versus female birds.
Their discovery of the commendable parenting skills of the male Savannah sparrow was unexpected. "Males of almost all species studied tend to withhold parental care - they're reluctant to spend time and effort delivering food, and they avoid putting themselves in situations where they themselves may be preyed upon," said Wheelwright.
"Most evolutionary biologists believe that a key reason for the differences between the parenting skills of the sexes is the fact that males always harbor a tiny doubt about their paternity," according to Wheelwright. Savannah sparrows do so with good reason. The team's recent research using DNA-fingerprinting has revealed that more than 50% of nestlings are not sired by the male feeding them, but rather by a neighboring male.
Nonetheless, males put as much effort into fledgling care as do females. More importantly, the survival of fledglings cared for by males was comparable to those cared for by females. Few previous studies of birds have been able to compare the quality of parenting by males and females because of the difficulty of following the young once they leave the nest.
The team also discovered that female and male Savannah sparrows do not divide their broods by sex; male and female parents are equally likely to care for sons or daughters, rather than choosing favorites based on sex.
Male parents were also more likely to be the caregivers for smaller fledglings and offspring from early broods. Presumably this frees up the females to concentrate on second clutches.
Click this link to read the January 2002 SUN article on Wheelwright and Freeman-Gallant's research on how female Savannah sparrows choose their mates.