NOTE / NOTE Food supplementation and abundance estimation in the white-footed mouse Pei-Jen L. Shaner Abstract: Food availability often drives consumer population dynamics. However, food availability may also influence capture probability, which if not accounted for may create bias in estimating consumer abundance and confound the effects of food availability on consumer population dynamics. This study compared two commonly used abundance indices (min- imum number alive (MNA) and number of animals captured per night per grid) with an abundance estimator based on ro- bust design model as applied to the white-footed mouse (Peromyscus leucopus (Rafinesque, 1818)) in food supplementation experiments. MNA consistently generated abundance estimates similar to the robust design model, regardless of food supplementation. The number of animals captured per night per grid, however, consistently generated lower abundance estimates compared with MNA and the robust design model. Nevertheless, the correlations between abundance esti- mates from MNA, number of animals captured, and robust design model were not influenced by food supplementa- tion. This study demonstrated that food supplementation is not likely to create bias among these different measures of abundance. Therefore, there is a great potential for conducting meta-analysis of food supplementation effect on consumer population dynamics (particularly in small mammals) across studies using different abundance indices and estimators. Re ´sume ´: La disponibilite ´ de la nourriture explique souvent la dynamique de population des consommateurs. Cependant, la disponibilite ´ de la nourriture peut aussi affecter la probabilite ´ de capture, ce qui, si on n’en tient pas compte, cause une erreur dans l’estimation de l’abondance des consommateurs et obscurcit les effets de la disponibilite ´ de la nourriture sur la dynamique de population des consommateurs. Notre e ´tude compare deux indices d’abondance couramment utilise ´s (nombre minimal d’individus vivants (MNA) et nombre d’animaux capture ´s par nuit par grille) avec un estimateur d’abondance base ´ sur un mode `le de design robuste chez des souris a ` pieds blancs (Peromyscus leucopus (Rafinesque, 1818)) dans des expe ´riences d’addition de nourriture. La me ´thode de MNA produit toujours des estimations comparables a ` celles du mode `le de design robuste, quel que soit le supple ´ment de nourriture fourni. La me ´thode du nombre d’animaux capture ´s par grille par nuit sous-estime syste ´matiquement l’abondance par comparaison aux me ´thodes de MNA et du mod- e `le de design robuste. Ne ´anmoins, il n’y a pas d’influence de l’addition de nourriture sur les corre ´lations entre les estima- tions d’abondance par les me ´thodes de MNA, du nombre d’animaux capture ´s et du mode `le de design robuste. Notre e ´tude de ´montre que l’addition de nourriture ne risque pas de ge ´ne ´rer des erreurs dans ces diverses mesures de l’abondance. Il y a donc une excellente possibilite ´ de mener a ` bien des me ´ta-analyses des effets de l’addition de nourriture sur la dynamique de population des consommateurs (particulie `rement chez les petits mammife `res) a ` partir d’e ´tudes qui utilisent diffe ´rents in- dices et estimateurs d’abondance. [Traduit par la Re ´daction] Introduction Food availability often drives consumer population dy- namics. For example, in eastern North America, population abundance of Peromyscus leucopus (Rafinesque, 1818) (white-footed mouse) and Peromyscus maniculatus (Wagner, 1845) fluctuates with acorn mast events (Wolff 1996; Elkin- ton et al. 1996; McCracken et al. 1999; McShea 2000; Elias et al. 2004). However, Peromyscus populations responded to food supplementation in some experiments but not in others (Bendell 1959; Hansen and Batzli 1978; Gilbert and Krebs 1981; Taitt 1981; Briggs 1986; Wolff 1986; Duquette and Millar 1995; Galindo-Leal and Krebs 1998; Terman 1999). A possible explanation for such discrepancies is that different abundance measures were used in different studies without considering the potential influences of food supplementa- tion on measures of mouse abundance. Although abundance estimators based on statistical mod- Received 23 February 2006. Accepted 19 June 2006. Published on the NRC Research Press Web site at http://cjz.nrc.ca on 28 September 2006. P.-J.L. Shaner. 1 Department of Environmental Sciences, University of Virginia, 291 McCormick Road, Charlottesville, VA 22904, USA. 1 Present address: Virginia Department of Conservation and Recreation, Division of Natural Heritage, 217 Governor Street, Richmond, VA 23219, USA (e-mail: pei-jen.shaner@dcr.virginia.gov). 1210 Can. J. Zool. 84: 1210–1215 (2006) doi:10.1139/Z06-101 # 2006 NRC Canada