476 Natural Resources Systems Copyright Goodheart-Willcox Co., Inc. Live trapping is also a physical observa- tion method that requires researchers to be on the ground in the species’ environment. The traps used in live trapping catch and hold the animal without causing them physical harm. Unfortunately, some species suffer more in live traps than others and some have higher acciden- tal mortality rates with live traps. Animals may freeze, overheat, starve, or become overstressed. The captured animals are marked and released after data is collected. This is referred to as the mark-recapture technique. The mark-recapture technique requires capturing, marking, releas- ing, and recapturing animals during repeated samplings, Figure 19-12. Advances in technology, such as remote sensing, have made it possible to track animals without physically entering their environment once the specimens have been collared or tagged. Tracking devices used with animals include satellite or GPS tracking collars, leg bands, tags, data loggers, and attached or implanted tracking devices. A tracking device, such as a traditional metal leg band, may be detrimental if it is obtrusive and interferes with their natural activities. Metal bands or collars, for example, can snag on vegetation or wear on fur or feathers. Newer technolo- gies, such as implanted microchips, may make it easier for researchers to track an animal without recapturing it to collect data. See Figure 19-13. Researchers are attaching small external cameras to animals to view the animal’s actions from the animal’s point of view. Search online for television series featuring cheetahs, meerkats, and other animals. Did You Know? Has the revitalization of the Florida Everglades increased the wading bird populations in Florida? Explain your answer. Thinking Critically Emily Barker/Shutterstock.com Figure 19-12. Some wildlife organizations have sport fisherman tag certain species of fish to help extend their studies at little or no cost. Anglers are provided with tagging equipment and contact information to report captures, tagging, and recaptures. Figure 19-13. Migratory butterflies and insects are marked with paper tags to help researchers gather information on their flight pathways and areas where they rest. The tag on this butterfly weighs about 2% of the monarch’s body weight. Would you be able to carry something constantly that was 2% of your own body weight? Bob Hilscher/Shutterstock.com