There are good reasons why so many species have remained undiscovered for so long – they are really good at hiding. Thus, researchers looking for species new to science often must employ a wide variety of sophisticated techniques.
Each scientist searches extensively in the micro-habitats where it is most likely they will find interesting species of their group. For example, bird experts walk trails through the forest, especially along edges where a mixture of forest and open field birds can be found and where the birds can be better seen than in the dense forest. Mammal experts seek out areas where mammals find water, salt or prey. Ant experts search through leaf litter and soil for tiny species that have been overlooked by others. Of course, species are sometimes found in unexpected places.
For organisms that use songs and other sounds to communicate, sound detection and recording is a good way to recognize something different. Virtually all birds, frogs, many insects, and, surprisingly, many fish produce distinct calls, each unique to a particular species.
By recording all sounds in a specific environment, such as the forest canopy or a coral reef, and using sound analysis software to assess the data, scientists can quickly pinpoint those elements of the sound spectrum that are different from all known animal songs. Often such songs are not audible to the human ear because they use frequencies that are too low (infrasounds) or too high (ultrasounds) for us to perceive. In such instances special recording equipment must be used. In South Africa RAP researchers have already discovered a number of species new to science of katydids by tracking never-before-heard ultrasonic sounds.
Many unnamed species are very shy or live in places that are virtually inaccessible to researchers. In such cases we often use traps or remote recording devices. Pitfall traps left on the forest floor or hung in the canopy attract and capture many small organisms that are active only at night or are particularly cryptic. Sometimes traps are baited with a broad spectrum of artificial pheromones, chemical attractants that mimic the scent of a mating partner. Flying insects can be lured to traps equipped with ultraviolet light.
For particularly shy animals, such as most mammals, remote camera traps sometimes help document never-before-seen species of rodents or occasionally deer. Such traps consist of a well camouflaged camera, which will take a photo if the animal trips an invisible infrared or a laser beam. Some traps will also detect the body heat of an approaching animal or react to the sound of it, taking a photograph that otherwise would be impossible to get.
The canopy fogging technique is often used for large scale surveys that sample many groups of organisms at once. In canopy fogging, the crown of a tree is fumigated with a chemical compound that knocks out all arthropods (insects, arachnids, millipedes etc.), but leaves all vertebrates unharmed (thus, even if the tree has a colony of birds living there, they will not suffer from the fumigation). Within minutes after the fogging, a rain of insects falls on a sheet placed below the tree, often yielding many species scientists have never seen.
Surveys of the marine life of coral reefs generally involve scuba diving and snorkeling along transect routes among the coral, recording all species of invertebrates, corals and fishes observed.
Old fashioned hard work and determination is still often the best way to find interesting species. Scientists spend long hours, often all night in the rain, or all day in the hot sun, to find species they suspect should be there, or to find undescribed species that had eluded other scientists. True dedication is required.