CHOICES AND CONSEQUENCES OF HABITAT SELECTION FOR BIRDS

Abstract

The collection of papers in this special section explores the premise that avian habitat ecology can be approached as an interaction between choices made by individuals and consequences of those choices (Jones 2001). This seemingly simple distinction between choices and consequences is emerging as a powerful unifying concept in avian habitat ecology. It allows a richer understanding of the behavioral process by which habitat choices are made, and links behavior to populations. It allows apparently pathological, maladaptive behaviors (such as use of ecological traps; reviewed by Battin 2004) to be understood simply as one point along a continuum of the same process that produces adaptive habitat choice, such as the ideal-free distribution (Fretwell and Lucas 1970), by allowing choices and consequences to be based on different habitat characteristics (Kristan 2003). For example, habitat choice can be based on distribution of food resources, whereas the reproductive consequences of this choice may be determined by predation (Shochat et al. 2005). It also allows synthesis of multiple scales of habitat variation, which can both inform birds’ choices and bear consequences for their fitness at different stages in an annual cycle. A choice of habitat at first glance seems to be similar to a foraging decision, but the two differ notably in the speed with which individuals are able to judge the accuracy of their decisions. Optimal foraging theory, for example, relates choice of foraging patch to some measure of fitness, usually expressed in terms of energy gain, and this approach has been very successfully applied to understanding distributions and population dynamics of foraging birds (Stillman et al. 2000). A principal lesson of optimal foraging studies is that birds make sensible choices among available foraging patches, limited by individual variation in competitive ability and information availability. Feedback about the accuracy of a foraging decision is received promptly because changes in foraging rates and satiation happen rapidly, and birds can adjust their foraging behavior quickly in response to poor choices (e.g., leave a patch with low resource levels). In contrast, there is intrinsically less information for the selection of habitat for other purposes, such as breeding, and there will often be time lags between the time when a choice is made and the time when the consequences of the choice are realized (Orians and Wittenberger 1991). The information available to individuals when they choose breeding habitat may consist of past experiences and current cues about habitat quality (e.g., conspecifics, predators, or vegetation), but future conditions that determine the success or Manuscript received 27 February 2007; accepted 18 April 2007. 4 E-mail: wkristan@csusm.edu