Chapter 2 A Critical Review of the Effects of Marking on the Biology of Vertebrates Vertebrates often are marked to facilitate identification of free-ranging individual animals or groups for studies of behavior, population biology, and physiology. Marked animals provided data for many of the topics discussed in this volume. | Chapter 2 A Critical Review of the Effects of Marking on the Biology of Vertebrates Dennis L. Murray and Mark R. Fuller Vertebrates often are marked to facilitate identification of free-ranging individual animals or groups for studies of behavior population biology and physiology- Marked animals provided data for many of the topics discussed in this volume including home range use resource selection social behavior and population estimation. Markers can be classified into three general categories mutilations tags and bands and radiotransmitters. The appropriate marking technique for a study depends on several considerations including study objectives target species marker cost marker efficacy and marker effects on the animals Day et al. 1980 Nietfeld et al. 1994 . Studies using marked animals are characterized by the assumption that marking does not affect animals or that negative effects are not important Ricker 1956 Day et al. 1980 Nietfeld et al. 1994 . The assumption of no significant marking effects is critical because it is the basis for generalizing data collected from marked individuals to unmarked animals and populations. However the assumption has not been tested rigorously for most marker types or animal species despite the often necessary use of seemingly invasive marking techniques. The general paucity of marker evaluation studies apparently is related to the difficulties associated with conducting such tests in the field as well as the belief that marker evaluation is tangential to most study objectives and therefore of minor importance to the researcher. In addition studies that evaluate marker effects often suffer from small samples thus leading to qualitative conclusions or weak statistical inference White and Garrott 1990 . As a result researchers tend to choose markers that intuitively seem least likely to induce abnormal behavior or survival even though data supporting that assertion usually are weak or lacking. However if the assumption of no .
