Negative Effects of Invasive Sampling Methods
Animals are marked in order to perform mark-recapture studies, used to estimate population abundance and density of specific populations. Marking consists of exactly what the name implies; adding some kind of distinguishing mark, often a bright color, to an animal. Sometimes these markings and tracking devices may be quite conspicuous and they often come with consequences. Studies have shown, for example, that birds possessing colored bands are actually more attractive to mates.
Animals can also be affected internally by human study techniques. When animals are handled, levels of stress hormones increase and this can lead to a variety of consequences, such as the depression of immune functions. This could make an organism more susceptible to disease or other latent ailments, leading to sickness and potentially death. An outcome like this is especially disturbing in threatened or endangered species.
Furthermore, human study techniques could alter an animal’s behavior. An animal who has had a particularly traumatic experience during handling may avoid the location where it was trapped, leading to that animal becoming “trap shy". If the area being avoided is an important dispersal corridor or an area rich in food or mates, that animal could suffer from avoiding it. An animal that was lured into a trap by food and perceives that the food reward was worth being poked and prodded may become “trap happy" and frequent areas where it has been trapped, perhaps disturbing the resident fauna and flora. In addition, animals that are trap happy or trap shy tend to distort researchers’ views of population numbers and estimates.
Other, even more serious problems include outright harming animals (albeit without malice) through the use of data-gathering methods. Some tracking devices have been implanted in animals and in a number of cases these malfunctioned and risked causing the animals severe illness and even death. Many early studies based on molecular biology techniques required a great deal of genetic information that necessarily meant the destruction of the animal being sampled.