Best time to experience and record
Many soil animals can be found all year round in suitable biotopes, but during frost, great heat and drought many soil animals retreat into deeper soil layers. The best time to experience and collect soil animals is therefore spring and autumn with mild temperatures between 5 and 20 °C and humid underground. But even in midsummer some species can still be found in humid places, e.g. in the garden, near water bodies or in compost heaps. Also in the winter, some species are still active on the snow, as for example some springtail-species, or under the snow in the leaf litter.
There are different methods to collect or record soil animals. The simplest method is the hand collection, i.e. the manual search. The most important tool here is a spring steel forceps and for small animals like mites or springtails a brush or an exhauster. With the hand collection one searches the typical places of residence of ground animals. For example, one turns over stones, a piece of wood, board, a rotten branch or tree trunk. Some animals then sit there on the ground, wood or stone. Under the bark of rotten wood as well as on living trees (e.g. pine, plane tree, maple), one can find dead wood inhabitants by removing the bark with a knife in places. However, most species are found in the leaf litter and the first few centimeters in the ground. The litter and the soil should be moist, but not dry and not completely wet. You can search the leaf litter or the soil directly or you can put the material on a white plane sheet or a big bag so that the sometimes very fast-moving animals cannot bury themselves or flee otherwise. One can also take substrate in a bucket or bag home and look through or sort it out in a shallow tub under a lamp. It is best to return the substrate to its place of origin afterwards and never dispose of it in the garden or any other place, as the native fauna could be distorted by other species.
Many species can only be reliably determined in dead condition and must therefore be killed. For this purpose the animal is killed directly in 70-95% alcohol (isopropanol, ethanol).
One of the most commonly used methods for catching ground animals that are active on the ground surface and in the litter is the use of pitfall traps or barber traps (named after their inventor). In this method, cup-like vessels (e.g. yoghurt cups) are filled with a killing or preserving liquid (e.g. propanediol, saturated saline solution), buried at ground level, provided with a small roof to protect them from rain (= dilution/overflow) and changed every 2 to 4 weeks. Due to this simple and inexpensive method of catching ground animals without a great deal of time, ground zoology experienced an enormous boom. A big disadvantage of pitfalls, however, is that without distinction hundreds of different animals are killed, which fall into the traps, among them partly also vertebrates like mice and amphibians. This “by-catch” is unfortunately very often not further processed and therefore thrown away. It is therefore always necessary to consider beforehand which goals one is aiming for with the trap catch and whether its use is really justified.
You can take the living animals home with you to identify or photograph them. A container filled with a few small ventilation holes in the lid and some wet litter is quite sufficient here. In order not to have to kill animals unnecessarily, one can take only 1-2 specimens of one species with some experience and if necessary with the use of a magnifying glass already in the field and/or release surplus specimens and not determinable young or females.
For each collection or sampling one should make small protocols in a notebook. They help to record all the important information about the circumstances of the find and later also to attach a label to the conserved animals.
The following information should always be included:
– Collector (Who?)
– Date (When?)
– Place (Where?), i.e. e.g. country, state/district, nearest town, name of area (forest, mountain), coordinates (WGS84, decimal degree), biotope (e.g. deciduous forest, garden) and, if applicable, information on vegetation (beech, maple, nettle field) or subsoil (decayed humus, stony, basalt, lime. Maps (paper form, smartphone) or a GPS device are helpful for determining the location.
– Collection method (How?), such as hand trap (HF), ground trap (BF) or other methods.
Preservation & Collection
The preservation of soil animals is usually done in 70 to 96 % ethanol or isopropanol, which you can buy for about 5 to 10 € per liter in the pharmacy or on the Internet. The animals are put together with a label small glass tubes (e.g., lamellar stopper glasses) and almost completely sealed. The label must contain at least the following information: Species, country, area or nearby larger town, place of discovery, date, collector, collection number, if applicable number of a permanent specimen). For each species, larger glasses with the name of the species are used in which these preparation tubes are placed. In order to avoid drying out of the tubes, the vessels are filled to the brim with alcohol. They should be checked regularly and alcohol should be added in case of evaporation (if the evaporation loss is very high, some 90% alcohol should be added).
Even though soil animals are not yet included in the annexes of the Federal Ordinance on the Protection of Species of Wild Fauna and Flora or the appendices of the FFH Directive or the EC Species Protection Ordinance, anyone who kills animals or wants to start a natural history collection should be aware of the purpose. The material should either be left to a natural history collection or a separate collection should be created. Only by means of collections can the distribution of species, the ecological preferences of a species or the decline of species be recognized and documented. However, questionable finds or new species views of older specific material can also be verified and documented.
A separate collection should therefore always contain all important information on the species (name, number, sex) and circumstances of discovery (see Logging finds). The individual tubes should also contain labels that are self-explanatory for third parties. Every collector should determine the later whereabouts of the collection (e.g. specialized museum) to ensure the preservation of the collection and the professional use of his work. Important collections of terrestrial animals can be found in the following museums and cities: Senckenberg Museum für Naturkunde Görlitz, Museum für Naturkunde Berlin, Zoologische Staatssammlung München, Senckenberg Museum Frankfurt, Zoologisches Museum der Universität Hamburg, Staatliches Museum für Naturkunde Karlsruhe.