Active density‐dependent habitat selection in a controlled population of small mammals

Abstract

Abstract. Density-dependent habitat selection has numerous and far-reaching implications to population dynamics and evolutionary processes. Although several studies suggest that organisms choose and occupy high-quality habitats over poorer ones, definitive experiments demonstrating active selection, by the same individuals at the appropriate population scale, are lacking. We conducted a reciprocal food supplementation experiment to assess whether voles would first occupy a habitat receiving extra food, then change their preference to track food supplements moved to another habitat. Meadow voles, as predicted, were more abundant in food-supplemented habitat than in others. Density declined when food supplements ceased because the voles moved to the new habitat receiving extra food. Although males and females appeared to follow different strategies, meadow-vole densities reflected habitat quality because voles actively selected the best habitat available. It is thus clear that behavioral decisions on habitat use can motivate patterns of abundance, frequency, and gene flow that have widespread effects on subsequent evolution.

Experimental evidence for an ideal free distribution in a breeding population of a territorial songbird

“…The absence of posttreatment crowding in this study suggests that subordinate males could not force territorial individuals to share resources, or that they found alternative territories elsewhere in the study area. Territory size was negatively correlated with food abundance (see also Stenger 1958, Smith andShugart 1987) and postharvest adjustments in territory size by males banded in the preharvest year indicate a high degree of behavioral plasticity and adaptive habitat selection (see also Haugen et al 2006, Morris and MacEachern 2010, Chalfoun and Schmidt 2012. The observed pattern is also consistent with food-value theory (Stenger 1958, Marshall andCooper 2004), which predicts that males from treated plots would increase the size of their territory to compensate for the postharvest decline in food abundance.…”

“…Indeed, the IDD tends to receive more support than the IFD (reviewed by Rodenhouse et al 1997, Piper 2011). Yet, there is a growing body of evidence suggesting that the IFD can indeed apply to birds (Weidinger 2000, Sebastian-Gonzalez et al 2010, Quaintenne et al 2011 and many other taxa (Beckmann and Berger 2003, Rieger et al 2004, Haugen et al 2006, Morris and MacEachern 2010.…”

“…In the same study area, Pe´rot and Villard (2009) found patterns in density and the proportion of territories producing at least one young that were consistent with an ideal free distribution, whereas The´riault et al (2012) found no evidence that Ovenbird males preferred plots treated through selection harvesting and, hence, no evidence that the treatment created ecological traps. Here, we examined the magnitude and duration of effects of selection harvesting on Ovenbird density, territory size, productivity (per unit area and per capita), and daily nest survival rate to determine whether adaptive habitat selection (sensu Morris and MacEachern 2010) occurred in response to experimental disturbance. On the basis of the IFD, we predicted a negative effect of treatment on density (through an increase in territory size) and productivity per unit area, but no treatment effect on productivity per capita.…”

Small mammal responses to coarse woody debris distribution at different spatial scales in managed and unmanaged boreal forests

“…Since meadow voles responded positively to CWD at the stand-scale, the lack of associations at the fine-scale that we observed may have been caused by several factors. An overriding regulatory factor (Krohne and Burgin, 1990), the lack of predation as well as other density-dependent factors such as intraspecific competition (Turner and Iverson, 1973;Oatway and Morris, 2007;Morris and MacEachern, 2010) may have had a significant impact on the local distribution of meadow voles.…”

“…Two related studies (Oatway and Morris, 2007;Morris and MacEachern, 2010) observed a strong spatial structure in enclosures at the scale of 50 m with meadow voles. Whereas Bowman et al (2001) found a similar pattern (from spatial autocorrelation analyses) for southern red-backed voles at the scale of 125 m in open forests, the pattern became weak at distances of more than 533 m. These distances match daily movements of voles and mice inside their home range (Tallmon and Mills, 1994;Ribble et al, 2002;Thompson et al, 2009).…”