Accepted categories of threat

EX (Extinct) or EX?– extinct or probably extinct species, whose occurrence in Poland has not been confirmed for at least the last fifty years (e.g., Margaritifera margaritifera, Xylocopa violacea, Dendroleon pantherinus, Cochlodina costata, Adapsilia coarctata), or noted after 1954 but there is no doubt that that the species disappeared at least ten years ago from the last localities and the last breeding individuals died out (Chalicodoma parietina, Limoniscus violaceus, Branchinecta paludosa). This category combines two IUCN categories for extinct species: EX and EW (see IUCN Red List Categories, 1994) but does not include attempts at breeding of species, if not made within the framework of official restitution programs.

CR (Critically Endangered) – Critically endangered species, whose numbers have decreased to a critical level (from a few to some hundreds of individuals), which persists at single localities, or whose rate of decline (in the sense of numbers and/or area) is within the range of values established by the IUCN. The survival of species belonging to this category is rather unlikely without active protection focused, among others, on elimination of causes of extinction.
Typical examples: Parnassius apollo, Bupestris splendens, Coenagrion armatum, Chilostoma cingulellum, Vertigo arctica.

EN (Endangered) – species facing a very high risk of extinction because of small populations, fragmented, insular range and/or quick rate of population decline (in the sense of numbers and/or area), meeting criteria A-E of this category of threat, as defined by the IUCN. Taxa classified among this category are believed likely to move into the Critically Endangered category, if the causal factors continue operating.
Typical examples: Rosalia alpina, Carabus fabricii, Maculinea arion, Somatochlora alpestris, Unio crassus.

VU (Vulnerable) – species facing a high risk of extinction due to continuing population decline (even on a local scale), habitat loss or over-exploitation; however, the observed or prognosticated rate of their decline is slower than in the case of taxa assigned to the higher categories of threat (criteria A-E). As Vulnerable one can list species whose populations are still relatively numerous and/or stable but with poor prospects for the future. Their regress may occur and intensify if factors responsible for their decline, identified in Poland and neighbouring countries, continue operating.
Typical examples: Astacus astacus, Cerambyx cerdo, Dytiscus latissimus, Cicadetta podolica, Psophus stridulus, Hirudo medicinalis.

LR (Lower Risk) – species of lower risk, which neither show clear symptoms of population decline (do not qualify the categories of endangered taxa), nor are rare; they may even locally and/or temporarily show an increase in numbers or occupied area but which require monitoring/control, because the causal factors threatening their existence have not been eliminated. In the IUCN recommendations there are no precise criteria for the category of LR (= NT + LC) (see Species 31-32, 1999), that is why in this publication the auxiliary/additional criteria were adopted; included to this category were taxa which met at least one of the following criteria: (a) unclear or unfavourable conservation status of species in the neighbouring countries (among others, inclusion into the RDB of European Vertebrates, 1997), (b) species represented by unstable marginal populations, (c) endemic species, scarce relic species or unique taxon, occurring only locally, (d) species is covered by international conventions and/or conservation programs.
Typical examples: Messor structor, Lycaena dispar, Pericallia matronula, Aphrophora major, Helix lutescens.