PARENTAL NEST DEFENSE ON VIDEOTAPE: MORE REALITY THAN “MYTH“

Abstract

PREDATION IS RECOGNIZED as the primary source of mortality in most passerine species (e.g. Ricklefs 1969, Martin 1992a); thus, it is no surprise that parental has received considerable scientific attention (see below). By defense, we refer to any parental behavior that decreases the probability that a predator (or brood parasite) will harm the contents and that simultaneously entails some cost to the bird engaged in the behavior-either by increasing the bird's risk of injury or death (Montgomerie and Weatherhead 1988) or by at least increasing its expenditure of time and energy (Buitron 1983). Bradley and Marzluff (2003) used an innovative combination of approaches to investigate potential predation by three species of rodents; in the discussion section of that paper, they made the general assertion that nest by parent birds seems to be more myth than reality. That statement is at odds with a vast scientific literature on the topic that spans several decades (e.g. Skutch 1955, reviews by Montgomerie and Weatherhead 1988, Martin 1992b, Sealy et al. 1998). A simplistic search for the phrase nest defense in one online database (Wildlife and Ecology Studies Worldwide) produced a list of >90 papers published on by birds for 1994-2004 alone. Fifty of those papers deal with by