Sorry to trouble you with posts on back to back days, but we just got good news from the Journal of Avian Biology. A paper by Gabby Jukkala and me that describes chick defense of loon parents towards decoys has just been granted final acceptance. We are delighted, because we have forged our way through numerous revisions of this paper over the past year or so. It is nice to see that our labors were not in vain.
In fact, the struggle to get this manuscript published is a good illustration of how peer review can lead to new perspectives and discoveries. The paper quantifies the defensive responses of parents to a decoy of an adult intruder; intruders attack and sometimes even kill small chicks. Gabby and I had been able to document that parents of small chicks (0 to 2 weeks) remain near them when a decoy is placed nearby (apparently to ward off surprise underwater attacks), whereas parents of older chicks (4 weeks+) confront the artificial intruder. But in response to reviewer comments, we sharpened our analyses and discovered two more behavioral patterns. While we had long known that males are especially apt to yodel when they have small chicks, we learned through this improved analysis that males with TWO chicks are four times as likely to yodel as males defending a SINGLE chick. This find suggests that males increase parental care in response to the value of the chicks. In addition, we noted that males are more than twice as likely to penguin dance in defense of their chicks as females.
In short, our new paper clarifies our picture of chick defense in loons. Males shoulder a disproportionate share of the burden for chick defense, as we document. Males spend far more time with chicks than do females, yodel at intruders (which females cannot do), and penguin dance much more often than females do. Moreover, male behavior is not mindless, all-out aggression. Indeed, it is nuanced, as males’ toughness towards intruders is combined with a cold calculation of how they can best maximize their Darwinian fitness.