Can settlement in natal-like habitat explain maladaptive habitat selection?

Abstract

The study of habitat selection has long been influenced by the ideal free model, which maintains that young adults settle in habitat according to its inherent quality and the density of conspecifics within it. The model has gained support in recent years from the finding that conspecifics produce cues inadvertently that help prebreeders locate good habitat. Yet abundant evidence shows that animals often fail to occupy habitats that ecologists have identified as those of highest quality, leading to the conclusion that young animals settle on breeding spaces by means not widely understood. Here, we report that a phenomenon virtually unknown in nature, natal habitat preference induction (NHPI), is a strong predictor of territory settlement in both male and female common loons (Gavia immer). NHPI causes young animals to settle on natal-like breeding spaces, but not necessarily those that maximize reproductive success. If widespread, NHPI might explain apparently maladaptive habitat settlement.

Keywords: NHPI; habitat selection; inadvertent social information; natal habitat preference induction.

Figure 1.

Natal dispersals of all males (yellow) and females (red) that both hatched and settled to breed in the main study area. Arrows point from natal to breeding lake. Not shown are 27 long-range dispersers that either hatched outside the main study area but settled within it (n = 6), hatched within the study area and settled outside it (n = 11), or both hatched and settled outside it (n = 10).

Figure 2.

Settlements on breeding lakes of 102 young loons by size (a) and pH (b) of natal lakes. Lakes are broken down into three classes of equal size with respect to both size and pH. Numbers beside arrows indicate loons from natal lakes of each size or pH class that settled as adults in a lake of the same or different size or pH class. Widths of arrows are proportional to the number of settlements.

Figure 3.

Observed and expected distributions of Euclidean distance between natal lake size/pH and first settlement lake size/pH. The greater proportion of individuals observed with very small Euclidean distances indicates NHPI.