Northern Prairie Wildlife Research Center
Mark R. Fuller, Kirk K. Bates, U.S. Geological Survey, Biological Resources Division, Raptor Research Center, Snake River Field Station, Boise State University, 970 Lusk Avenue, Boise, ID 83706 USA, William S. Seegar, Edgewood Research Development and Engineering Center, Aberdeen Proving Ground, MD 21010-5423 USA, and Robert E. Kenward, Institute of Terrestrial Ecology, Furzebrook Research Station, Wareham, Dorset BH20 5AS United Kingdom
W. W. Cochran stated that it is axiomatic that radio marking affects wildlife. The effects can be subtle, or overt. They might or might not have consequences for the well-being of the animal, or the objectives of the project. Our examples are drawn mostly from recent literature (largely 1990's) about effects of radio-marking, and we present new data. We focus on the effects on birds (except water birds) in association with various transmitter attachment methods (other than implants). There are trade-offs among different marking methods and among transmitter attachment methods. For example smaller lighter transmitters can be mounted on tail feathers and few effects have been associated with this attachment. But only relatively small transmitters can be placed on tails, which limits the longevity or signal strength of the transmitter. Larger, longer lasting transmitters can be attached on the back by a harness but there are several undesirable effects that have been associated with this method.
We highlight some methods, such as modeling flight performance, to predict potential effects, and we describe pilot studies and experiments that have been useful in understanding the effects of radio marking on birds. We present the results of comparisons among unmarked or alternatively marked (e.g., leg band) birds and those with various transmitter attachments. We include results from tests for: effects on behavior, such as preening; on reproductive success; on foraging; and social interactions; and effects on flight speed, flight distance, and carrying capacity. Also, we provide examples of how radio marking effects can vary among ages, sexes, and seasons. Our review will provide attendees a background about the types of effects one should consider if radio marking is a potential study method, and it will provide an introduction to recent literature about radio marking.